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Mechanical Circulatory Support in Cardiogenic Shock: Shock Team or Bust?
Journal Pre-proof Mechanical Circulatory Support in Cardiogenic Shock: Shock team or Bust? Daniel H. Kim, MD FRCPC PII:
S0828-282X(19)31393-5
DOI:
https://doi.org/10.1016/j.cjca.2019.11.001
Reference:
CJCA 3506
To appear in:
Canadian Journal of Cardiology
Received Date: 10 September 2019 Revised Date:
24 October 2019
Accepted Date: 2 November 2019
Please cite this article as: Kim DH, Mechanical Circulatory Support in Cardiogenic Shock: Shock team or Bust?, Canadian Journal of Cardiology (2019), doi: https://doi.org/10.1016/j.cjca.2019.11.001. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc. on behalf of the Canadian Cardiovascular Society.
Mechanical Circulatory Support in Cardiogenic Shock: Shock team or Bust? Daniel H Kim MD FRCPC Division of Cardiology, University of Alberta, Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada.
Corresponding Author Daniel H. Kim MD, FRCPC Interventional, Advanced Heart Failure, Transplant/MCS Program University of Alberta & Mazankowski Alberta Heart Institute Edmonton, Alberta, Canada Email: [email protected]
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Abstract Cardiogenic Shock (CS) accounts for 15% of all Cardiac Intensive Care Unit admissions, with Acute Myocardial Infarction Cardiogenic Shock (AMICS) accounting for 30% of these. In contrast to other areas in cardiac care where survival has continued to improve over the last two decades, CS still carries a mortality of around 40%. Temporary Mechanical Circulatory Support (tMCS) therapies have shown inconsistent results in improving outcomes in CS, with the overall evidence not supporting its use, at least not in unselected patients. Some of the main stumbling blocks leading to disappointing results of tMCS in CS are: 1) Challenging patient identification and selection; 2) Delayed timing; 3) Lack of a systematic approach; 4) Inappropriate utilization of adjunct therapies and tools; 5) Lack of escalation/de-escalation and long-term planning; 6) Disparities in regional/center access to MCS. Among the most promising solutions to this challenge, is the Cardiogenic Shock Team (CST), which takes a standardized multidisciplinary approach to the acute management of CS. This paradigm brings expertise from Advanced Heart Failure, Interventional Cardiology, Cardiac Surgery, Cardiac Intensive Care, Nursing and others to effectively address all of the issues aforementioned. Unsurprisingly, hurdles to implementation exist, such as establishing effective team dynamics, maintenance of competence and securing and maintaining adequate resources. However, although the shock team approach is still in the early stages of clinical evolution, preliminary studies have been encouraging and suggest the value of broader application and evaluation.
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Summary Cardiogenic Shock (CS) accounts for 15% of all Cardiac Intensive Care Units, with AMICS accounting for 30% of these. Unfortunately, CS still has a mortality of around 40%. Temporary Mechanical Circulatory Support (tMCS) therapies have shown inconsistent results in improving outcomes in CS due to various stumbling blocks. The Cardiogenic Shock Team (CST) presents an attractive and promising solution to this clinical challenge, with preliminary encouraging results, suggesting the value of broader application and evaluation.
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Background The Critical Care Cardiology Trials Network Registry, a multicenter network of CICUs in North America, demonstrated in multiple 2-month snapshots, that cardiogenic shock (CS) accounts for 15% of all admissions to CICU. Acute Myocardial Infarction Cardiogenic Shock (AMICS)
accounts for 30% of these admissions, with the remaining 70% attributable to Non-ischemic (28%), Ischemic-without AMI (18%), Other cardiac (17%) and Unknown/Missing causes (8%) 1. Furthermore, AMICS complicates 8% of all STEMI presentations, with a trend showing increasing incidence over time, from 6.5% in 2003 to 10.1% in 2010 2. Advances in the management of cardiac diseases may account for continued improvement in overall cardiovascular mortality over the last two decades 3,4 Although CS outcomes have marginally improved over the same time period, the overall outcomes remain poor with inhospital mortalities between 30 to 50% 2,5,6. Of note, differences in outcomes based on etiologies exist suggesting heterogeneity in population. In one study, AMICS mortality was found to be 56%, while acute decompensated heart failure (ADHF) related CS had a mortality of 40% 7. Ultimately, the overall lack of improvement in outcomes may be reflective of the fact that CS therapies and interventions, as currently utilized, have shown limited success in changing this unfavorable outlook. Recently, it has been proposed that a standardized approach with the implementation of a Cardiogenic Shock Team (CST) may improve outcomes and effectiveness of existing therapies, more specifically temporary Mechanical Circulatory Support (tMCS) 8,9. Prior to examining the rationality of this proposed paradigm, it may be worthwhile to explore some of the obstacles underlying the lack of progress in this area.
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Unmet Expectations It is now recognized that temporary Mechanical Circulatory Support (tMCS) devices, at least within the current practice framework, are not the panacea for the CS dilemma. When the first successful mechanical support of a patient in cardiogenic shock was performed in 1967 10, one could not be blamed for being optimistic. An intraaortic balloon pump (IABP) was used to successfully resuscitate a 45-year-old woman in profound CS. Following this groundbreaking event, there was the expectation that, in time, tMCS devices would lead to the successful management of patients in CS. Despite early studies signaling improved CS outcomes with IABP, larger randomized trials have failed to demonstrate either short or long-term benefit 11,12.
The development of devices that did not rely on native pulsatile flow like the IABP and had greater hemodynamic support capabilities, such as the Impella pump (Abiomed Inc, Danvers, Massachusetts) and the TandemHeart (Cardiac Assist, Inc., Pittsburgh, Pennsylvania) renewed the optimism for the effective treatment for CS. Despite initial observational studies showing benefit 13,14, small randomized studies 13,15,16 and a larger meta-analysis 17 failed to show positive results for these tMCS platforms in CS. Even recognizing that these studies have design and selection bias issues, they do illustrate the current landscape where the lack of positive evidence fails to provide guidance for clinical practice.
Veno-Arterial Extra-Corporeal Membrane Oxygenation (VA-ECMO) offered an alternative capable of full biventricular and oxygenation support. Despite the promise of broader and more
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balanced support, a recent meta-analysis showed that VA-ECMO supported CS patients still have very high mortality, with only 43% surviving to discharge 18. Acknowledging the selection bias and the probability that these patients maybe sicker, even when compared to less supportive devices such as Impella, VA-ECMO does not seem to yield better outcomes 19. It has been proposed that VA-ECMO, with optimized LV unloading may provide better support, while also lessening adverse effects such as increased afterload, LV distention and its sequelae. Supporting this hypothesis, Russo et al, found in a large meta-analysis of Cardiogenic Shock observational studies that VA-ECMO with IABP for LV unloading was associated with a lower overall mortality (54% vs 65%, risk ratio: 0.79; 95% CI: 0.72 to 0.87; p < 0.00001) 20. The same was seen when Impella was used as the primary LV unloading method in patients supported by VA-ECMO 21. Unfortunately, notwithstanding the apparent positive effect of this strategy, overall mortality remained high.
Alas, over fifty years after the first successful IABP supported CS patient salvage, tMCS strategies have struggled to live up to expectations. However, despite the discouraging and even counter-intuitive nature of the evidence, one must consider the probability that the largely unsupportive data, may be considerably influenced by device unrelated factors, and perhaps due to deficiencies in care processes.
Stumbling Blocks Although multiple factors likely contribute to the varying effectiveness of tMCS in CS, the following six factors are worthy of discussion (Table 1): 1) Challenging patient identification and
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selection; 2) Delayed timing; 3) Lack of a systematic approach; 4) Inappropriate utilization of adjunct therapies and tools; 5) Lack of escalation/de-escalation and long-term planning; 6) Disparities in regional/center access to MCS. 1) Challenging patient identification and selection negatively affect the odds of any successful intervention. Although criteria defining CS are relatively consistent, heterogeneity exists 6. Ultimately a considerable degree of clinical judgement is required, leading to inconsistent and often delayed triage. An example of this variability was seen in the IMPRESS Trial where all patients had to be mechanically ventilated as per protocol and almost all had suffered a cardiac arrest. This represents a CS population further into the spectrum of decompensation than what most would consider ideal for successful mechanical support 16. 2) Delayed timing is a concern for many interventions in cardiology. The most obvious example would be in the management of STEMI, a point highlighted by the Canadian STEMI guidelines 22. Similarly, delays in tMCS implementation are also detrimental. Tehrani et al, found that every 1hour delay in escalation to tMCS was associated with a 9.9% increased risk of death 7. Further supporting this notion, other studies have found that early utilization of tMCS, before the coronary intervention in AMI CS for example, is associated with better outcomes 14,23. Unfortunately, considering the complexity of these patients and some of the challenges explored here, delays in treatment are common. 3) The Lack of a systematic approach is a concern both at the individual patient care level and at the population aggregate level, where it may impair one’s ability of evaluate effectiveness of therapies delivered. Mirroring the general clinical landscape, the majority of studies on tMCS and CS lack a standardized protocol, being observational or retrospective. This fact, in turn,
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provides very little guidance as to how to systematize management of these patients. Significant benefit could be gained by the implementation of clear standardized processes addressing all aspects of CS management, including, but not limited to diagnosis and therapeutic interventions. 4) Inappropriate utilization of adjunct therapies and tools also contribute to the modest outcomes. A recent Cochrane Review looking at studies of vasoactive agents in CS found no evidence for the benefit of vasoactive agents in the setting of CS 24. Moreover, vasoactive agents can have negative consequences in CS, with higher dosing and greater number of agents being factors associated with worse outcomes 25,26. As such, studies have supported the concept that tMCS should be employed early, avoiding significant escalation of vasoactive agents 23, a practice that many may be reluctant to adopt. This issue is also exemplified in the, not uncommonly practiced, multi-vessel coronary intervention in CS, despite studies showing lack of benefit 27. Perhaps the most pertinent instance of non-evidence-based practice is the very low utilization of invasive hemodynamic monitoring in right heart catheterization (RHC) in CS, despite studies showing significant improved outcomes with its use, including lower mortality 7,28,29. 5) Lack of escalation/de-escalation and long-term strategies is an important concern as evolution of the clinical state is often rapid and unpredictable, requiring timely and constant reevaluations as well as therapeutic and approach adaptations. Adverse events in CS are frequent and time-sensitive, so delays in diagnosis and response can have dire effects. Moreover, lack of medium and long-term planning regularly leads to suboptimal
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communication with other health providers and patients’ families, an important hindrance to the therapeutic relationship. 6) Disparities in regional/center access to MCS presents another significant challenge to the care of patients with CS. This is especially important when timeliness of appropriate support is directly associated with outcomes as previously mentioned. Moreover, even if tMCS is available, lack of expertise or adequate procedural volume is associated with poorer outcomes 30
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The Cardiogenic Shock Team (CST) It may be stated that many of the issues above are pervasive in other areas of cardiology. Consequently, despite limited evidence on any specific hard-endpoint benefits, there is a growing trend of establishing “heart teams” in areas of significant patient complexity such as Adult Congenital Heart Disease (ACHD), Heart Transplant (HTx) or high resource burden interventions such as MCS or Transcatheter Aortic Valve Replacement (TAVR) 31.
Likewise, CS management is a multifaceted clinical problem, with complex patients and care delivery challenges. Additionally, there is need for expediency in both decision-making and intervention, combined with the requirement for early and ongoing expert management. In essence, CS creates a “breadth and depth” challenge in care that could be greatly improved by a Standardized Multidisciplinary Shock Team approach. As it is often the case in Medicine, this is not a novel idea. In 1967, in his paper “A Shock Team in a General Hospital”, Edward Frank described a team comprised of “two physician and a nurse technician”, who, activated by an
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alarm, mobilized their portable equipment to the bedside of the shock patient 32. Even in the very early days of CS care, he seemed to grasp the importance of a dynamic team model, concluding that “the successful management of shock … involves the early detection and prompt correction of the many and often unpredictable defects that cause and result from the persisting, diffuse deficiency of blood flow”.
Evidence for the CST Although the CST is not a new notion, the relatively recent adoption of this model in its entirety, means there is a paucity of data available on its usefulness. In one of the first studies published on the modern operationalization of a CST, Taleb et al shared their experience with a CST approach in refractory CS. They reported on 123 patients managed by a CST and tMCS and compared to a historic cohort from their center, also treated with tMCS but without CST evaluation 33. Acute coronary syndromes accounted for 61.0% (Shock team arm) and 70.2% (control arm) of CS in the study. There was improved 30-day all-cause mortality in patients with refractory cardiogenic shock treated by their Utah Cardiac Recovery Shock Team (Hazard ratio 0.61; 95% CI, 0.41-0.93). Of note, the CST benefit was seen irrespective of CS cause. In a contemporaneous study, Tehrani et al studied 204 consecutive patients with CS. They found that compared to 30-day survival of 47% in 2016, after implementation of a Standardized Team Based Care for Cardiogenic Shock, survival in 2017 and 2018 improved to 57.9% and 76.6% respectively (p<0.01). Interestingly, this change seemed to be less pronounced in patients with advanced heart failure as the cause of CS. This could be due to better pre-CST survival in this population (ADHF 60% vs AMICS 44%) and the less acute time course, making
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the overall impact of appropriate and timely intervention less pronounced. Of particular interest, RHC which was protocol mandated, was associated with 39% absolute increase in survival (71% vs 32%, p<0.01) 7. From a broader implementation perspective, the National Cardiogenic Shock initiative, enrolled 171 consecutive patients from 35 participating centers 23. However, unlike the previously discussed studies, the NCSI enrolled only AMICS patients and used only Impella devices. Moreover, invasive monitoring and early initiation of tMCS was emphasized in the protocol. The survival to discharge was 72% and lactate >4 mg/dL (AUC=0.71) and Cardiac Power Output (CPO) <0.6 W (AUC=0.72) predicted mortality post tMCS. Perhaps just as importantly, this study illustrates the concept that high uptake of beneficial interventions such as right heart catheterization (92%), or establishing new, even counterintuitive clinical best practices such as implanting tMCS prior to coronary intervention (74%), can be achieved by the implementation of standardized protocols, such as can be actuated by CSTs.
The CST Approach The multidisciplinary nature of the CST brings together the expertise and skillset necessary to tackle the complex and quickly shifting clinical state of a patient in CS. Table 2 shows an example of CST composition. Ultimately, the CST creates the framework to address the issues raised previously. 1) Challenging patient identification and selection are made more efficiently and consistently, performed initially by a dedicated Shock Physician, the “Shock Doc”, then by the group following activation 8. Table 3 outlines the CS criteria that trigger consideration for tMCS.
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Bringing more clarity to this issue, utilizing classification schemes such as the recent SCAI CS Stages, allow CST members to more easily communicate with all team members and referring caregivers 34. The CST concomitantly performs patient risk stratification as an essential component of the early evaluation process. In this, patient risk scores such as the Cardshock Score 35 and the IHVI Risk Score (Inova Heart and Vascular Institute) 7 may help refine the clinical selection of the patients that may benefit most from advanced CS interventions. It is important to note that there is lack of broad corroborating evidence for these scores. This precludes their outright adoption for routine clinical use, but nevertheless they provide a more coherent framework for the CST in their assessment. 2) Delayed timing and 3) Lack of a systematic approach are addressed by agreed upon CST activation protocols 7,36 and standardized algorithms shown to improve delivery of care leading to improved outcomes 7,23,33. Figure 1 illustrates an example of a standardized algorithm for CS, where the first contact is the ADHF cardiologist who does the initial triage and then coordinates subsequent steps. Emphasis at the initial stage is on rapid, early stabilization, an insight stated as early as 1975 by Peter Rosen in his Shock Team paper: “A team approach for the stabilization of life- threatening pathophysiology is recommended. Once stabilization has been achieved, more conventional diagnosis and therapy can be introduced” 37. 4) Inappropriate utilization of adjunct therapies and tools can be minimized by this team approach. For instance, considering the data previously addressed on vasoactive agents 38,39 the CST can establish agreed-upon protocols, encouraging judicious and limited titration of vasoactive agents, leading to earlier escalation to tMCS. This may also help lessen the deleterious effects of high dose vasopressors which can attenuate the cardiac recovery
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potential 26. Perhaps, most importantly, CSTs foster the increased utilization of beneficial interventions such as RHC based hemodynamic monitoring in CS, through both direct involvement and standardized and shared protocols. 5) Lack of escalation/de-escalation and long-term strategies should and can be addressed by the CST. This includes frequent clinical evaluations, hemodynamics such as CPO and Pulmonary Arterial Pulsatility Index (PAPi), biomarkers such as lactate, and imaging as appropriate (Table 3 and Figure 2). The CST follows a close reassessment schedule and facilitates the use and appropriate interpretation of the previously cited factors, essential in evaluating the changing severity of the shock state impacting the escalation or de-escalation of therapies. Daily discussions and frequent communication with other healthcare providers is vital, as are discussions with families, establishing crucial therapeutic rapport for more difficult discussions that may become necessary later. It is also important to regularly review all activations through a formal quality assurance process. Finally, early involvement of the palliative care team is essential, both for support and to allow appropriate and timely discussions to occur as the clinical course evolves. 6) Disparities in regional/center access to MCS could be improved over the long-term by establishing local CSTs with appropriate resources. However, this is not feasible in many cases, for both personnel and resource related shortcomings. As seen in many other areas of cardiac care, a “hub and spoke” model, with a standardized CST care pathway can help overcome this hurdle, as put forward by the American Heart Association Scientific Statement on management of CS 6. One such process proposed by Rab et al, categorizes centers into three levels: Level I: Dedicated Shock Care Centers, capable of providing the full gamut of CS care, including
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advanced MCS; Level II: PCI Capable Centers where initial stabilization can be undertaken, with transfer to a Level I Center for refractory CS patients; Level III: Non-PCI capable hospitals where rapid transfer to a Level I center would occur after initial triage (Figure 3) 40. In the last update from the NCSI, 27.1% of patients were transferred from another institution to a “Shock Care” Center, with the majority of them surviving (87%) 23. The transfer process undoubtedly introduces a significant selection bias, accounting for the high survival. Nevertheless, this data helps demonstrate the feasibility of a CST centered “hub and spoke” model in CS.
Implementation hurdles A number of challenges exist when considering implementation of CST programs. In order to balance expertise with expediency, it is important to ensure that the composition of the team is manageable and functional, which sometimes can be difficult to establish. This can be achieved by designating one individual, the “Shock Doc” responsible for the initial triage, subsequent activation and ongoing coordination of care 8. It is also wise to consider initially implementing CSTs on a limited scale. This could mean only daytime activations, limiting scope to specific areas such as the catheterization laboratory and/or Cardiac Intensive Care Unit. With gained experience, confidence and stakeholder engagement, stepwise expansion can be undertaken, eventually including collaboration with other non-MCS hospitals using harmonized transfer protocols, in the “hub and spoke” CST model. It is essential to maintain competence, especially as activation and procedural volumes can be sporadic. Continuing education and in-services for team members ensure appropriate and ongoing level of proficiency. Furthermore, as this is a resource intensive undertaking, having
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the support of institutional administration from the outset is vital, both for successful implementation and longer-term sustainability.
Conclusion It is apparent that the initial excitement of tMCS as the answer to the problem of CS was overstated. However, it is likely that the issue is one of “how” to effectively utilize a very promising clinical technology, rather than an inherent lack of effectiveness of the tools themselves. The CST model seems to provide the most suitable partner to the tMCS evolution. Even though the evidence for the broad implementation of CST is still lacking, creating a systematic approach to the management of CS with the employment of CSTs would ensure a more cogent approach to the utilization of resource intensive resources, such as tMCS, in this complex and high mortality population. It would also create the opportunity to consistently gather better quality data, leading to more rigorous evaluation of the effectiveness of new interventions and processes through quality assurance and research activities. Ultimately, the CST provides an expert, collaborative group that more cohesively considers complex issues that reflect the stage of CS evolution 34, including complexities, such as heterogeneous etiologies, RV failure, pulmonary or multi-organ involvement, dysrhythmias, all considered to rationally decide whether or not to initiate therapies such as tMCS, in this very high stakes patient population. As it was with tMCS, CSTs may not provide the complete solution. Nevertheless, as CS Lewis wrote: ““Two heads (In this case many) are better than one, not because either is infallible, but because they are unlikely to go wrong in the same direction” 41
.
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Disclosures: None
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Table 1 Stumbling Blocks to Effective Cardiogenic Shock Management
1) Challenging patient identification and selection 2) Delayed timing 3) The Lack of a systematic approach 4) Inappropriate utilization of adjunct therapies and tools 5) Lack of escalation/de-escalation and long-term strategies 6) Disparities in regional/center access to MCS
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Table 2 Cardiogenic Shock Team Members
•
Advanced Heart Failure/Transplant Cardiologist (First call)
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Advanced Heart Failure/Transplant Cardiac Surgeon
•
MCS Specialist
•
Interventional Cardiologist
•
Cardiac Intensivist
•
Cardiac Cath Lab, Perfusion or OR Team as appropriate
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Table 3 Hemodynamic Criteria for Cardiogenic Shock that trigger temporary MCS consideration •
Required Criteria
•
SBP <90 mm Hg or drop >30 mm Hg despite initial support (Refractory hypotension and/or hypoperfusion despite adequate volume resuscitation and at least one vasoactive agent at moderate)
•
Supporting Criteria
• • •
Cardiac Index < 1.8 (2.2 if vasoactive support) or CPO <0.6 W or PAPi < 0.9 (Severe RV failure) Capillary Wedge Pressure or LVEDP > 15 Evidence of hypoperfusion: Lactate > 2, SVR > 2100 dynes.sec/cm
•
Relative Contraindications
• •
Age >70 (age >65 if significant co-morbidities) Advanced pre-existing organ/system dysfunction (Renal, hepatic, pulmonary, neurologic, vascular) Conditions significantly impacting 1-year survival (e.g. advanced malignancies) Active co-morbidities that affect ability to tolerate or implement tMCS (e.g. Active bleeding or contraindication to anticoagulation)
• •
CPO (Cardiac Power Output); PAPi (Pulmonary Arterial Pulsatility Index); LVEDP (Left Ventricular End Diastolic Pressure); SVR (Systemic Vascular Resistance)
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Table 4 SCAI Cardiogenic Shock Classification 34 •
STAGE A: At risk of Cardiogenic Shock Patient who is not in cardiogenic Shock but is a risk of developing it.
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STAGE B: Beginning Cardiogenic Shock Patient with evidence of relative hypoperfusion or tachycardia without hypoperfusion
•
STAGE C: Classic Cardiogenic Shock Patient that has hypoperfusion that requires interventions beyond volume resuscitation
•
STAGE D: Deterioration/Doom Patient with Stage C CS but deteriorating and not responding to initial interventions
•
STAGE E: Extremis Patient in cardiac arrest with ongoing CPR and/or ECMO and supported by multiple intervention
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Table 5 tMCS in Cardiogenic Shock Trials Study Year Reference IABP-SHOCK II 2012 11 PROTECT II 2012 15
IMPRESS 2017 16
Burkhoff et all 2016 13
Thiele et al 2017 17
Karami et al 2019 19
Design N Intervention RTC N=598 IABP vs OMT RTC N=452 IABP vs Impella 2.5 RTC N=48 IABP vs Impella CP RTC N=42 IABP vs TandemHeart Meta-analysis n-148 IABP vs TH/Impella Retrospective N=128 ECMO vs Impella CP/5.0
Main Results
Other
No difference in 30-day mortality between IABP (39.7%) vs Control (41.3%) p=0.69
6 year follow up (2018) 12 IABP showed no all-cause mortality benefit
No difference in 30-day MAE IABP (40.1% vs 35.1% for Impella 2.5 (35.1%) p=0.227
Impella provided better hemodynamic support (greater cardiac power output)
No difference in 30-day mortality between IABP (50%) vs Impella CP (46%) p=0.92).
All patients were mechanically ventilated
TH trended to improved hemodynamics compared to IABP p=NS
No difference in 30-day mortality between IABP (36%) vs TH (47%) p=NS
No difference in 30-day mortality (RR 1.01, 95% CI 0.70 to 1.44, P = 0.98)
tMCS increased MAP and decreased lactate better than IABP
No difference in 30-day mortality between Impella (53%) and ECMO (49%) p=0.30)
Device related complications were higher in ECMO (39.5%) vs Impella (16.7%) p=0.01, mostly bleeding or infection
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Figure 1. Shock Team tMCS Algorithm
Identification of refractory cardiogenic shock patient (SCAI Stage C, D or E) Consult AHFTX/MCS Team
Refractory CS: SBP <90 mm despite fluids and at least one vasoactive agent at moderate dose
Is the patient likely to recover or candidate for durable MCS/HTx?
If NO Continue optimization of conventional therapies +/-IABP
If YES Proceed with tMCS
Is there significant Biventricular Failure, Respiratory Failure or Recurrent Ventricular Arrhythmias?
If YES Proceed with VA ECMO
If continued deterioration consider palliation
If NO Is there Isolated RV failure
If YES Proceed with VA ECMO or Protek Duo/Impella RP
If NO Proceed with Impella(CP/5.0)
22
Figure 2. Shock Team Post tMCS Decision Algorithm
Post tMCS Decision Making -Initial reassessment at 1, 2 and 4 hours - Then at least every 12 hours
Multidisciplianry Team Involvement (AHFTx/MCS, ICU, IC Cardiology, etc)
If Improvement within 24-48 hours
Continue Bridge to Recovery Strategy (Reasess q24hours)
Poor Prognostic Indicators: ≥ 2 Inotropic Agents Lactate >4 CPO <0.6 PAPi <0.9
Muli-parametric monitoring (clinical, hemodynamic, biomarker & imaging)
If No change within 48-72 hours
If Deterioration within 24-48 hours
Is patient a candidate for MCS or HTx?
Continue Bridge to Decision Strategy but consider escalating to durable MCS if no contraindications If YES Proceed with Bridge to Candidacy Strategy CentriMag then durable MCS once more stable and end organ recovery is seen
If NO Proceed with Palliation
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Figure 3. Cardiogenic Shock Team Hub and Spoke Model
Activation Pathway: Consult “Shock Doc” at Level I Center
EMS Action: Triage and if CS Criteria Met Transport to Level III Center
Level I Shock Care Center Action: Advise, Activate CST and Receive Transfer
Level III Non-PCI Capable Center Action: Triage and if CS Criteria Met Transfer
Level II PCI Capable Center Action: Initial stabilization +/-PCI then transfer if refractory CS
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References 1. Berg DD, Bohula EA, van Diepen S, et al. Epidemiology of Shock in Contemporary Cardiac Intensive Care Units. Circ Cardiovasc Qual Outcomes 2019;12:e005618. 2. Kolte D, Khera S, Aronow WS, et al. Trends in incidence, management, and outcomes of cardiogenic shock complicating ST-elevation myocardial infarction in the United States. J Am Heart Assoc 2014;3:e000590. 3. Sidney S, Quesenberry CP, Jr., Jaffe MG, et al. Recent Trends in Cardiovascular Mortality in the United States and Public Health Goals. JAMA Cardiol 2016;1:594-9. 4. Lopez AD, Adair T. Is the long-term decline in cardiovascular-disease mortality in highincome countries over? Evidence from national vital statistics. Int J Epidemiol 2019. 5. Thiele H, Ohman EM, Desch S, Eitel I, de Waha S. Management of cardiogenic shock. Eur Heart J 2015;36:1223-30. 6. van Diepen S, Katz JN, Albert NM, et al. Contemporary Management of Cardiogenic Shock: A Scientific Statement From the American Heart Association. Circulation 2017;136:e232e68. 7. Tehrani BN, Truesdell AG, Sherwood MW, et al. Standardized Team-Based Care for Cardiogenic Shock. J Am Coll Cardiol 2019;73:1659-69. 8. Rab T. "Shock Teams" and "Shock Docs". J Am Coll Cardiol 2019;73:1670-2. 9. Doll JA, Ohman EM, Patel MR, et al. A team-based approach to patients in cardiogenic shock. Catheter Cardiovasc Interv 2016;88:424-33. 10. Kantrowitz A, Tjonneland S, Freed PS, Phillips SJ, Butner AN, Sherman JL, Jr. Initial clinical experience with intraaortic balloon pumping in cardiogenic shock. JAMA 1968;203:113-8. 11. Thiele H, Zeymer U, Neumann FJ, et al. Intraaortic balloon support for myocardial infarction with cardiogenic shock. N Engl J Med 2012;367:1287-96. 12. Thiele H, Zeymer U, Thelemann N, et al. Intraaortic Balloon Pump in Cardiogenic Shock Complicating Acute Myocardial Infarction: Long-Term 6-Year Outcome of the Randomized IABPSHOCK II Trial. Circulation 2018. 13. Burkhoff D, Cohen H, Brunckhorst C, O'Neill WW, TandemHeart Investigators G. A randomized multicenter clinical study to evaluate the safety and efficacy of the TandemHeart percutaneous ventricular assist device versus conventional therapy with intraaortic balloon pumping for treatment of cardiogenic shock. Am Heart J 2006;152:469 e1-8. 14. Basir MB, Schreiber TL, Grines CL, et al. Effect of Early Initiation of Mechanical Circulatory Support on Survival in Cardiogenic Shock. Am J Cardiol 2017;119:845-51. 15. O'Neill WW, Kleiman NS, Moses J, et al. A prospective, randomized clinical trial of hemodynamic support with Impella 2.5 versus intra-aortic balloon pump in patients undergoing high-risk percutaneous coronary intervention: the PROTECT II study. Circulation 2012;126:171727. 16. Ouweneel DM, Eriksen E, Sjauw KD, et al. Percutaneous Mechanical Circulatory Support Versus Intra-Aortic Balloon Pump in Cardiogenic Shock After Acute Myocardial Infarction. J Am Coll Cardiol 2017;69:278-87. 17. Thiele H, Jobs A, Ouweneel DM, et al. Percutaneous short-term active mechanical support devices in cardiogenic shock: a systematic review and collaborative meta-analysis of randomized trials. Eur Heart J 2017;38:3523-31. 25
18. Wilson-Smith AR, Bogdanova Y, Roydhouse S, et al. Outcomes of venoarterial extracorporeal membrane oxygenation for refractory cardiogenic shock: systematic review and meta-analysis. Ann Cardiothorac Surg 2019;8:1-8. 19. Karami M, den Uil CA, Ouweneel DM, et al. Mechanical circulatory support in cardiogenic shock from acute myocardial infarction: Impella CP/5.0 versus ECMO. Eur Heart J Acute Cardiovasc Care 2019:2048872619865891. 20. Russo JJ, Aleksova N, Pitcher I, et al. Left Ventricular Unloading During Extracorporeal Membrane Oxygenation in Patients With Cardiogenic Shock. J Am Coll Cardiol 2019;73:654-62. 21. Pappalardo F, Schulte C, Pieri M, et al. Concomitant implantation of Impella on top of veno-arterial extracorporeal membrane oxygenation may improve survival of patients with cardiogenic shock. Eur J Heart Fail 2017;19:404-12. 22. Wong GC, Welsford M, Ainsworth C, et al. 2019 Canadian Cardiovascular Society/Canadian Association of Interventional Cardiology Guidelines on the Acute Management of ST-Elevation Myocardial Infarction: Focused Update on Regionalization and Reperfusion. Can J Cardiol 2019;35:107-32. 23. Basir MB, Kapur NK, Patel K, et al. Improved Outcomes Associated with the use of Shock Protocols: Updates from the National Cardiogenic Shock Initiative. Catheter Cardiovasc Interv 2019;93:1173-83. 24. Schumann J, Henrich EC, Strobl H, et al. Inotropic agents and vasodilator strategies for the treatment of cardiogenic shock or low cardiac output syndrome. Cochrane Database Syst Rev 2018;1:CD009669. 25. Bellumkonda L, Gul B, Masri SC. Evolving Concepts in Diagnosis and Management of Cardiogenic Shock. Am J Cardiol 2018;122:1104-10. 26. Squara P, Hollenberg S, Payen D. Reconsidering Vasopressors for Cardiogenic Shock: Everything Should Be Made as Simple as Possible, but Not Simpler. CHEST 2019;156:392-401. 27. de Waha S, Jobs A, Eitel I, et al. Multivessel versus culprit lesion only percutaneous coronary intervention in cardiogenic shock complicating acute myocardial infarction: A systematic review and meta-analysis. Eur Heart J Acute Cardiovasc Care 2018;7:28-37. 28. Nalluri N, Patel NJ, Atti V, Kumar V, Basir MB, O'Neill WW. Temporal Trends in Utilization of Right-Sided Heart Catheterization Among Percutaneous Ventricular Assist Device Recipients in Acute Myocardial Infarction Complicated by Cardiogenic Shock. Am J Cardiol 2018;122:20147. 29. Strom JB, Zhao Y, Shen C, et al. National trends, predictors of use, and in-hospital outcomes in mechanical circulatory support for cardiogenic shock. EuroIntervention 2018;13:e2152-e9. 30. Shaefi S, O'Gara B, Kociol RD, et al. Effect of cardiogenic shock hospital volume on mortality in patients with cardiogenic shock. J Am Heart Assoc 2015;4:e001462. 31. Mesana T, Rodger N, Sherrard H. Heart Teams: A New Paradigm in Health Care. Can J Cardiol 2018;34:815-8. 32. Frank ED. A shock team in a general hospital. Anesth Analg 1967;46:740-5. 33. Taleb I, Koliopoulou AG, Tandar A, et al. Shock Team Approach in Refractory Cardiogenic Shock Requiring Short-Term Mechanical Circulatory Support. Circulation 2019;140:98-100. 34. Baran DA, Grines CL, Bailey S, et al. SCAI clinical expert consensus statement on the classification of cardiogenic shock: This document was endorsed by the American College of 26
Cardiology (ACC), the American Heart Association (AHA), the Society of Critical Care Medicine (SCCM), and the Society of Thoracic Surgeons (STS) in April 2019. Catheter Cardiovasc Interv 2019;94:29-37. 35. Harjola VP, Lassus J, Sionis A, et al. Clinical picture and risk prediction of short-term mortality in cardiogenic shock. Eur J Heart Fail 2015;17:501-9. 36. Truesdell AG, Tehrani B, Singh R, et al. 'Combat' Approach to Cardiogenic Shock. Interv Cardiol 2018;13:81-6. 37. Rosen P. Shock team approach to resuscitation. J Med Assoc Ga 1975;64:96-8. 38. Samuels LE, Kaufman MS, Thomas MP, Holmes EC, Brockman SK, Wechsler AS. Pharmacological criteria for ventricular assist device insertion following postcardiotomy shock: experience with the Abiomed BVS system. J Card Surg 1999;14:288-93. 39. Rohm CL, Gadidov B, Leitson M, Ray HE, Prasad R. Predictors of Mortality and Outcomes of Acute Severe Cardiogenic Shock Treated with the Impella Device. Am J Cardiol 2019;124:499504. 40. Rab T, Ratanapo S, Kern KB, et al. Cardiac Shock Care Centers: JACC Review Topic of the Week. J Am Coll Cardiol 2018;72:1972-80. 41. Lewis CS. C.S. Lewis : essay collection and other short pieces. In: Walmsley L, ed. London :: HarperCollins; 2000.
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S0828-282X(19)31393-5
DOI:
https://doi.org/10.1016/j.cjca.2019.11.001
Reference:
CJCA 3506
To appear in:
Canadian Journal of Cardiology
Received Date: 10 September 2019 Revised Date:
24 October 2019
Accepted Date: 2 November 2019
Please cite this article as: Kim DH, Mechanical Circulatory Support in Cardiogenic Shock: Shock team or Bust?, Canadian Journal of Cardiology (2019), doi: https://doi.org/10.1016/j.cjca.2019.11.001. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc. on behalf of the Canadian Cardiovascular Society.
Mechanical Circulatory Support in Cardiogenic Shock: Shock team or Bust? Daniel H Kim MD FRCPC Division of Cardiology, University of Alberta, Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada.
Corresponding Author Daniel H. Kim MD, FRCPC Interventional, Advanced Heart Failure, Transplant/MCS Program University of Alberta & Mazankowski Alberta Heart Institute Edmonton, Alberta, Canada Email: [email protected]
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Abstract Cardiogenic Shock (CS) accounts for 15% of all Cardiac Intensive Care Unit admissions, with Acute Myocardial Infarction Cardiogenic Shock (AMICS) accounting for 30% of these. In contrast to other areas in cardiac care where survival has continued to improve over the last two decades, CS still carries a mortality of around 40%. Temporary Mechanical Circulatory Support (tMCS) therapies have shown inconsistent results in improving outcomes in CS, with the overall evidence not supporting its use, at least not in unselected patients. Some of the main stumbling blocks leading to disappointing results of tMCS in CS are: 1) Challenging patient identification and selection; 2) Delayed timing; 3) Lack of a systematic approach; 4) Inappropriate utilization of adjunct therapies and tools; 5) Lack of escalation/de-escalation and long-term planning; 6) Disparities in regional/center access to MCS. Among the most promising solutions to this challenge, is the Cardiogenic Shock Team (CST), which takes a standardized multidisciplinary approach to the acute management of CS. This paradigm brings expertise from Advanced Heart Failure, Interventional Cardiology, Cardiac Surgery, Cardiac Intensive Care, Nursing and others to effectively address all of the issues aforementioned. Unsurprisingly, hurdles to implementation exist, such as establishing effective team dynamics, maintenance of competence and securing and maintaining adequate resources. However, although the shock team approach is still in the early stages of clinical evolution, preliminary studies have been encouraging and suggest the value of broader application and evaluation.
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Summary Cardiogenic Shock (CS) accounts for 15% of all Cardiac Intensive Care Units, with AMICS accounting for 30% of these. Unfortunately, CS still has a mortality of around 40%. Temporary Mechanical Circulatory Support (tMCS) therapies have shown inconsistent results in improving outcomes in CS due to various stumbling blocks. The Cardiogenic Shock Team (CST) presents an attractive and promising solution to this clinical challenge, with preliminary encouraging results, suggesting the value of broader application and evaluation.
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Background The Critical Care Cardiology Trials Network Registry, a multicenter network of CICUs in North America, demonstrated in multiple 2-month snapshots, that cardiogenic shock (CS) accounts for 15% of all admissions to CICU. Acute Myocardial Infarction Cardiogenic Shock (AMICS)
accounts for 30% of these admissions, with the remaining 70% attributable to Non-ischemic (28%), Ischemic-without AMI (18%), Other cardiac (17%) and Unknown/Missing causes (8%) 1. Furthermore, AMICS complicates 8% of all STEMI presentations, with a trend showing increasing incidence over time, from 6.5% in 2003 to 10.1% in 2010 2. Advances in the management of cardiac diseases may account for continued improvement in overall cardiovascular mortality over the last two decades 3,4 Although CS outcomes have marginally improved over the same time period, the overall outcomes remain poor with inhospital mortalities between 30 to 50% 2,5,6. Of note, differences in outcomes based on etiologies exist suggesting heterogeneity in population. In one study, AMICS mortality was found to be 56%, while acute decompensated heart failure (ADHF) related CS had a mortality of 40% 7. Ultimately, the overall lack of improvement in outcomes may be reflective of the fact that CS therapies and interventions, as currently utilized, have shown limited success in changing this unfavorable outlook. Recently, it has been proposed that a standardized approach with the implementation of a Cardiogenic Shock Team (CST) may improve outcomes and effectiveness of existing therapies, more specifically temporary Mechanical Circulatory Support (tMCS) 8,9. Prior to examining the rationality of this proposed paradigm, it may be worthwhile to explore some of the obstacles underlying the lack of progress in this area.
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Unmet Expectations It is now recognized that temporary Mechanical Circulatory Support (tMCS) devices, at least within the current practice framework, are not the panacea for the CS dilemma. When the first successful mechanical support of a patient in cardiogenic shock was performed in 1967 10, one could not be blamed for being optimistic. An intraaortic balloon pump (IABP) was used to successfully resuscitate a 45-year-old woman in profound CS. Following this groundbreaking event, there was the expectation that, in time, tMCS devices would lead to the successful management of patients in CS. Despite early studies signaling improved CS outcomes with IABP, larger randomized trials have failed to demonstrate either short or long-term benefit 11,12.
The development of devices that did not rely on native pulsatile flow like the IABP and had greater hemodynamic support capabilities, such as the Impella pump (Abiomed Inc, Danvers, Massachusetts) and the TandemHeart (Cardiac Assist, Inc., Pittsburgh, Pennsylvania) renewed the optimism for the effective treatment for CS. Despite initial observational studies showing benefit 13,14, small randomized studies 13,15,16 and a larger meta-analysis 17 failed to show positive results for these tMCS platforms in CS. Even recognizing that these studies have design and selection bias issues, they do illustrate the current landscape where the lack of positive evidence fails to provide guidance for clinical practice.
Veno-Arterial Extra-Corporeal Membrane Oxygenation (VA-ECMO) offered an alternative capable of full biventricular and oxygenation support. Despite the promise of broader and more
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balanced support, a recent meta-analysis showed that VA-ECMO supported CS patients still have very high mortality, with only 43% surviving to discharge 18. Acknowledging the selection bias and the probability that these patients maybe sicker, even when compared to less supportive devices such as Impella, VA-ECMO does not seem to yield better outcomes 19. It has been proposed that VA-ECMO, with optimized LV unloading may provide better support, while also lessening adverse effects such as increased afterload, LV distention and its sequelae. Supporting this hypothesis, Russo et al, found in a large meta-analysis of Cardiogenic Shock observational studies that VA-ECMO with IABP for LV unloading was associated with a lower overall mortality (54% vs 65%, risk ratio: 0.79; 95% CI: 0.72 to 0.87; p < 0.00001) 20. The same was seen when Impella was used as the primary LV unloading method in patients supported by VA-ECMO 21. Unfortunately, notwithstanding the apparent positive effect of this strategy, overall mortality remained high.
Alas, over fifty years after the first successful IABP supported CS patient salvage, tMCS strategies have struggled to live up to expectations. However, despite the discouraging and even counter-intuitive nature of the evidence, one must consider the probability that the largely unsupportive data, may be considerably influenced by device unrelated factors, and perhaps due to deficiencies in care processes.
Stumbling Blocks Although multiple factors likely contribute to the varying effectiveness of tMCS in CS, the following six factors are worthy of discussion (Table 1): 1) Challenging patient identification and
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selection; 2) Delayed timing; 3) Lack of a systematic approach; 4) Inappropriate utilization of adjunct therapies and tools; 5) Lack of escalation/de-escalation and long-term planning; 6) Disparities in regional/center access to MCS. 1) Challenging patient identification and selection negatively affect the odds of any successful intervention. Although criteria defining CS are relatively consistent, heterogeneity exists 6. Ultimately a considerable degree of clinical judgement is required, leading to inconsistent and often delayed triage. An example of this variability was seen in the IMPRESS Trial where all patients had to be mechanically ventilated as per protocol and almost all had suffered a cardiac arrest. This represents a CS population further into the spectrum of decompensation than what most would consider ideal for successful mechanical support 16. 2) Delayed timing is a concern for many interventions in cardiology. The most obvious example would be in the management of STEMI, a point highlighted by the Canadian STEMI guidelines 22. Similarly, delays in tMCS implementation are also detrimental. Tehrani et al, found that every 1hour delay in escalation to tMCS was associated with a 9.9% increased risk of death 7. Further supporting this notion, other studies have found that early utilization of tMCS, before the coronary intervention in AMI CS for example, is associated with better outcomes 14,23. Unfortunately, considering the complexity of these patients and some of the challenges explored here, delays in treatment are common. 3) The Lack of a systematic approach is a concern both at the individual patient care level and at the population aggregate level, where it may impair one’s ability of evaluate effectiveness of therapies delivered. Mirroring the general clinical landscape, the majority of studies on tMCS and CS lack a standardized protocol, being observational or retrospective. This fact, in turn,
7
provides very little guidance as to how to systematize management of these patients. Significant benefit could be gained by the implementation of clear standardized processes addressing all aspects of CS management, including, but not limited to diagnosis and therapeutic interventions. 4) Inappropriate utilization of adjunct therapies and tools also contribute to the modest outcomes. A recent Cochrane Review looking at studies of vasoactive agents in CS found no evidence for the benefit of vasoactive agents in the setting of CS 24. Moreover, vasoactive agents can have negative consequences in CS, with higher dosing and greater number of agents being factors associated with worse outcomes 25,26. As such, studies have supported the concept that tMCS should be employed early, avoiding significant escalation of vasoactive agents 23, a practice that many may be reluctant to adopt. This issue is also exemplified in the, not uncommonly practiced, multi-vessel coronary intervention in CS, despite studies showing lack of benefit 27. Perhaps the most pertinent instance of non-evidence-based practice is the very low utilization of invasive hemodynamic monitoring in right heart catheterization (RHC) in CS, despite studies showing significant improved outcomes with its use, including lower mortality 7,28,29. 5) Lack of escalation/de-escalation and long-term strategies is an important concern as evolution of the clinical state is often rapid and unpredictable, requiring timely and constant reevaluations as well as therapeutic and approach adaptations. Adverse events in CS are frequent and time-sensitive, so delays in diagnosis and response can have dire effects. Moreover, lack of medium and long-term planning regularly leads to suboptimal
8
communication with other health providers and patients’ families, an important hindrance to the therapeutic relationship. 6) Disparities in regional/center access to MCS presents another significant challenge to the care of patients with CS. This is especially important when timeliness of appropriate support is directly associated with outcomes as previously mentioned. Moreover, even if tMCS is available, lack of expertise or adequate procedural volume is associated with poorer outcomes 30
.
The Cardiogenic Shock Team (CST) It may be stated that many of the issues above are pervasive in other areas of cardiology. Consequently, despite limited evidence on any specific hard-endpoint benefits, there is a growing trend of establishing “heart teams” in areas of significant patient complexity such as Adult Congenital Heart Disease (ACHD), Heart Transplant (HTx) or high resource burden interventions such as MCS or Transcatheter Aortic Valve Replacement (TAVR) 31.
Likewise, CS management is a multifaceted clinical problem, with complex patients and care delivery challenges. Additionally, there is need for expediency in both decision-making and intervention, combined with the requirement for early and ongoing expert management. In essence, CS creates a “breadth and depth” challenge in care that could be greatly improved by a Standardized Multidisciplinary Shock Team approach. As it is often the case in Medicine, this is not a novel idea. In 1967, in his paper “A Shock Team in a General Hospital”, Edward Frank described a team comprised of “two physician and a nurse technician”, who, activated by an
9
alarm, mobilized their portable equipment to the bedside of the shock patient 32. Even in the very early days of CS care, he seemed to grasp the importance of a dynamic team model, concluding that “the successful management of shock … involves the early detection and prompt correction of the many and often unpredictable defects that cause and result from the persisting, diffuse deficiency of blood flow”.
Evidence for the CST Although the CST is not a new notion, the relatively recent adoption of this model in its entirety, means there is a paucity of data available on its usefulness. In one of the first studies published on the modern operationalization of a CST, Taleb et al shared their experience with a CST approach in refractory CS. They reported on 123 patients managed by a CST and tMCS and compared to a historic cohort from their center, also treated with tMCS but without CST evaluation 33. Acute coronary syndromes accounted for 61.0% (Shock team arm) and 70.2% (control arm) of CS in the study. There was improved 30-day all-cause mortality in patients with refractory cardiogenic shock treated by their Utah Cardiac Recovery Shock Team (Hazard ratio 0.61; 95% CI, 0.41-0.93). Of note, the CST benefit was seen irrespective of CS cause. In a contemporaneous study, Tehrani et al studied 204 consecutive patients with CS. They found that compared to 30-day survival of 47% in 2016, after implementation of a Standardized Team Based Care for Cardiogenic Shock, survival in 2017 and 2018 improved to 57.9% and 76.6% respectively (p<0.01). Interestingly, this change seemed to be less pronounced in patients with advanced heart failure as the cause of CS. This could be due to better pre-CST survival in this population (ADHF 60% vs AMICS 44%) and the less acute time course, making
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the overall impact of appropriate and timely intervention less pronounced. Of particular interest, RHC which was protocol mandated, was associated with 39% absolute increase in survival (71% vs 32%, p<0.01) 7. From a broader implementation perspective, the National Cardiogenic Shock initiative, enrolled 171 consecutive patients from 35 participating centers 23. However, unlike the previously discussed studies, the NCSI enrolled only AMICS patients and used only Impella devices. Moreover, invasive monitoring and early initiation of tMCS was emphasized in the protocol. The survival to discharge was 72% and lactate >4 mg/dL (AUC=0.71) and Cardiac Power Output (CPO) <0.6 W (AUC=0.72) predicted mortality post tMCS. Perhaps just as importantly, this study illustrates the concept that high uptake of beneficial interventions such as right heart catheterization (92%), or establishing new, even counterintuitive clinical best practices such as implanting tMCS prior to coronary intervention (74%), can be achieved by the implementation of standardized protocols, such as can be actuated by CSTs.
The CST Approach The multidisciplinary nature of the CST brings together the expertise and skillset necessary to tackle the complex and quickly shifting clinical state of a patient in CS. Table 2 shows an example of CST composition. Ultimately, the CST creates the framework to address the issues raised previously. 1) Challenging patient identification and selection are made more efficiently and consistently, performed initially by a dedicated Shock Physician, the “Shock Doc”, then by the group following activation 8. Table 3 outlines the CS criteria that trigger consideration for tMCS.
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Bringing more clarity to this issue, utilizing classification schemes such as the recent SCAI CS Stages, allow CST members to more easily communicate with all team members and referring caregivers 34. The CST concomitantly performs patient risk stratification as an essential component of the early evaluation process. In this, patient risk scores such as the Cardshock Score 35 and the IHVI Risk Score (Inova Heart and Vascular Institute) 7 may help refine the clinical selection of the patients that may benefit most from advanced CS interventions. It is important to note that there is lack of broad corroborating evidence for these scores. This precludes their outright adoption for routine clinical use, but nevertheless they provide a more coherent framework for the CST in their assessment. 2) Delayed timing and 3) Lack of a systematic approach are addressed by agreed upon CST activation protocols 7,36 and standardized algorithms shown to improve delivery of care leading to improved outcomes 7,23,33. Figure 1 illustrates an example of a standardized algorithm for CS, where the first contact is the ADHF cardiologist who does the initial triage and then coordinates subsequent steps. Emphasis at the initial stage is on rapid, early stabilization, an insight stated as early as 1975 by Peter Rosen in his Shock Team paper: “A team approach for the stabilization of life- threatening pathophysiology is recommended. Once stabilization has been achieved, more conventional diagnosis and therapy can be introduced” 37. 4) Inappropriate utilization of adjunct therapies and tools can be minimized by this team approach. For instance, considering the data previously addressed on vasoactive agents 38,39 the CST can establish agreed-upon protocols, encouraging judicious and limited titration of vasoactive agents, leading to earlier escalation to tMCS. This may also help lessen the deleterious effects of high dose vasopressors which can attenuate the cardiac recovery
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potential 26. Perhaps, most importantly, CSTs foster the increased utilization of beneficial interventions such as RHC based hemodynamic monitoring in CS, through both direct involvement and standardized and shared protocols. 5) Lack of escalation/de-escalation and long-term strategies should and can be addressed by the CST. This includes frequent clinical evaluations, hemodynamics such as CPO and Pulmonary Arterial Pulsatility Index (PAPi), biomarkers such as lactate, and imaging as appropriate (Table 3 and Figure 2). The CST follows a close reassessment schedule and facilitates the use and appropriate interpretation of the previously cited factors, essential in evaluating the changing severity of the shock state impacting the escalation or de-escalation of therapies. Daily discussions and frequent communication with other healthcare providers is vital, as are discussions with families, establishing crucial therapeutic rapport for more difficult discussions that may become necessary later. It is also important to regularly review all activations through a formal quality assurance process. Finally, early involvement of the palliative care team is essential, both for support and to allow appropriate and timely discussions to occur as the clinical course evolves. 6) Disparities in regional/center access to MCS could be improved over the long-term by establishing local CSTs with appropriate resources. However, this is not feasible in many cases, for both personnel and resource related shortcomings. As seen in many other areas of cardiac care, a “hub and spoke” model, with a standardized CST care pathway can help overcome this hurdle, as put forward by the American Heart Association Scientific Statement on management of CS 6. One such process proposed by Rab et al, categorizes centers into three levels: Level I: Dedicated Shock Care Centers, capable of providing the full gamut of CS care, including
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advanced MCS; Level II: PCI Capable Centers where initial stabilization can be undertaken, with transfer to a Level I Center for refractory CS patients; Level III: Non-PCI capable hospitals where rapid transfer to a Level I center would occur after initial triage (Figure 3) 40. In the last update from the NCSI, 27.1% of patients were transferred from another institution to a “Shock Care” Center, with the majority of them surviving (87%) 23. The transfer process undoubtedly introduces a significant selection bias, accounting for the high survival. Nevertheless, this data helps demonstrate the feasibility of a CST centered “hub and spoke” model in CS.
Implementation hurdles A number of challenges exist when considering implementation of CST programs. In order to balance expertise with expediency, it is important to ensure that the composition of the team is manageable and functional, which sometimes can be difficult to establish. This can be achieved by designating one individual, the “Shock Doc” responsible for the initial triage, subsequent activation and ongoing coordination of care 8. It is also wise to consider initially implementing CSTs on a limited scale. This could mean only daytime activations, limiting scope to specific areas such as the catheterization laboratory and/or Cardiac Intensive Care Unit. With gained experience, confidence and stakeholder engagement, stepwise expansion can be undertaken, eventually including collaboration with other non-MCS hospitals using harmonized transfer protocols, in the “hub and spoke” CST model. It is essential to maintain competence, especially as activation and procedural volumes can be sporadic. Continuing education and in-services for team members ensure appropriate and ongoing level of proficiency. Furthermore, as this is a resource intensive undertaking, having
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the support of institutional administration from the outset is vital, both for successful implementation and longer-term sustainability.
Conclusion It is apparent that the initial excitement of tMCS as the answer to the problem of CS was overstated. However, it is likely that the issue is one of “how” to effectively utilize a very promising clinical technology, rather than an inherent lack of effectiveness of the tools themselves. The CST model seems to provide the most suitable partner to the tMCS evolution. Even though the evidence for the broad implementation of CST is still lacking, creating a systematic approach to the management of CS with the employment of CSTs would ensure a more cogent approach to the utilization of resource intensive resources, such as tMCS, in this complex and high mortality population. It would also create the opportunity to consistently gather better quality data, leading to more rigorous evaluation of the effectiveness of new interventions and processes through quality assurance and research activities. Ultimately, the CST provides an expert, collaborative group that more cohesively considers complex issues that reflect the stage of CS evolution 34, including complexities, such as heterogeneous etiologies, RV failure, pulmonary or multi-organ involvement, dysrhythmias, all considered to rationally decide whether or not to initiate therapies such as tMCS, in this very high stakes patient population. As it was with tMCS, CSTs may not provide the complete solution. Nevertheless, as CS Lewis wrote: ““Two heads (In this case many) are better than one, not because either is infallible, but because they are unlikely to go wrong in the same direction” 41
.
15
Disclosures: None
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Table 1 Stumbling Blocks to Effective Cardiogenic Shock Management
1) Challenging patient identification and selection 2) Delayed timing 3) The Lack of a systematic approach 4) Inappropriate utilization of adjunct therapies and tools 5) Lack of escalation/de-escalation and long-term strategies 6) Disparities in regional/center access to MCS
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Table 2 Cardiogenic Shock Team Members
•
Advanced Heart Failure/Transplant Cardiologist (First call)
•
Advanced Heart Failure/Transplant Cardiac Surgeon
•
MCS Specialist
•
Interventional Cardiologist
•
Cardiac Intensivist
•
Cardiac Cath Lab, Perfusion or OR Team as appropriate
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Table 3 Hemodynamic Criteria for Cardiogenic Shock that trigger temporary MCS consideration •
Required Criteria
•
SBP <90 mm Hg or drop >30 mm Hg despite initial support (Refractory hypotension and/or hypoperfusion despite adequate volume resuscitation and at least one vasoactive agent at moderate)
•
Supporting Criteria
• • •
Cardiac Index < 1.8 (2.2 if vasoactive support) or CPO <0.6 W or PAPi < 0.9 (Severe RV failure) Capillary Wedge Pressure or LVEDP > 15 Evidence of hypoperfusion: Lactate > 2, SVR > 2100 dynes.sec/cm
•
Relative Contraindications
• •
Age >70 (age >65 if significant co-morbidities) Advanced pre-existing organ/system dysfunction (Renal, hepatic, pulmonary, neurologic, vascular) Conditions significantly impacting 1-year survival (e.g. advanced malignancies) Active co-morbidities that affect ability to tolerate or implement tMCS (e.g. Active bleeding or contraindication to anticoagulation)
• •
CPO (Cardiac Power Output); PAPi (Pulmonary Arterial Pulsatility Index); LVEDP (Left Ventricular End Diastolic Pressure); SVR (Systemic Vascular Resistance)
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Table 4 SCAI Cardiogenic Shock Classification 34 •
STAGE A: At risk of Cardiogenic Shock Patient who is not in cardiogenic Shock but is a risk of developing it.
•
STAGE B: Beginning Cardiogenic Shock Patient with evidence of relative hypoperfusion or tachycardia without hypoperfusion
•
STAGE C: Classic Cardiogenic Shock Patient that has hypoperfusion that requires interventions beyond volume resuscitation
•
STAGE D: Deterioration/Doom Patient with Stage C CS but deteriorating and not responding to initial interventions
•
STAGE E: Extremis Patient in cardiac arrest with ongoing CPR and/or ECMO and supported by multiple intervention
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Table 5 tMCS in Cardiogenic Shock Trials Study Year Reference IABP-SHOCK II 2012 11 PROTECT II 2012 15
IMPRESS 2017 16
Burkhoff et all 2016 13
Thiele et al 2017 17
Karami et al 2019 19
Design N Intervention RTC N=598 IABP vs OMT RTC N=452 IABP vs Impella 2.5 RTC N=48 IABP vs Impella CP RTC N=42 IABP vs TandemHeart Meta-analysis n-148 IABP vs TH/Impella Retrospective N=128 ECMO vs Impella CP/5.0
Main Results
Other
No difference in 30-day mortality between IABP (39.7%) vs Control (41.3%) p=0.69
6 year follow up (2018) 12 IABP showed no all-cause mortality benefit
No difference in 30-day MAE IABP (40.1% vs 35.1% for Impella 2.5 (35.1%) p=0.227
Impella provided better hemodynamic support (greater cardiac power output)
No difference in 30-day mortality between IABP (50%) vs Impella CP (46%) p=0.92).
All patients were mechanically ventilated
TH trended to improved hemodynamics compared to IABP p=NS
No difference in 30-day mortality between IABP (36%) vs TH (47%) p=NS
No difference in 30-day mortality (RR 1.01, 95% CI 0.70 to 1.44, P = 0.98)
tMCS increased MAP and decreased lactate better than IABP
No difference in 30-day mortality between Impella (53%) and ECMO (49%) p=0.30)
Device related complications were higher in ECMO (39.5%) vs Impella (16.7%) p=0.01, mostly bleeding or infection
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Figure 1. Shock Team tMCS Algorithm
Identification of refractory cardiogenic shock patient (SCAI Stage C, D or E) Consult AHFTX/MCS Team
Refractory CS: SBP <90 mm despite fluids and at least one vasoactive agent at moderate dose
Is the patient likely to recover or candidate for durable MCS/HTx?
If NO Continue optimization of conventional therapies +/-IABP
If YES Proceed with tMCS
Is there significant Biventricular Failure, Respiratory Failure or Recurrent Ventricular Arrhythmias?
If YES Proceed with VA ECMO
If continued deterioration consider palliation
If NO Is there Isolated RV failure
If YES Proceed with VA ECMO or Protek Duo/Impella RP
If NO Proceed with Impella(CP/5.0)
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Figure 2. Shock Team Post tMCS Decision Algorithm
Post tMCS Decision Making -Initial reassessment at 1, 2 and 4 hours - Then at least every 12 hours
Multidisciplianry Team Involvement (AHFTx/MCS, ICU, IC Cardiology, etc)
If Improvement within 24-48 hours
Continue Bridge to Recovery Strategy (Reasess q24hours)
Poor Prognostic Indicators: ≥ 2 Inotropic Agents Lactate >4 CPO <0.6 PAPi <0.9
Muli-parametric monitoring (clinical, hemodynamic, biomarker & imaging)
If No change within 48-72 hours
If Deterioration within 24-48 hours
Is patient a candidate for MCS or HTx?
Continue Bridge to Decision Strategy but consider escalating to durable MCS if no contraindications If YES Proceed with Bridge to Candidacy Strategy CentriMag then durable MCS once more stable and end organ recovery is seen
If NO Proceed with Palliation
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Figure 3. Cardiogenic Shock Team Hub and Spoke Model
Activation Pathway: Consult “Shock Doc” at Level I Center
EMS Action: Triage and if CS Criteria Met Transport to Level III Center
Level I Shock Care Center Action: Advise, Activate CST and Receive Transfer
Level III Non-PCI Capable Center Action: Triage and if CS Criteria Met Transfer
Level II PCI Capable Center Action: Initial stabilization +/-PCI then transfer if refractory CS
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