INVASIVE EXERCISE HEMODYNAMICS OF PATIENTS SUPPORTED BY A LONG-TERM CONTINUOUS-FLOW LEFT VENTRICULAR ASSIST DEVICE

Abstracts

particularly in high-level SCI. However, cardiovascular autonomic control and its evolution in the acute period after SCI are poorly characterised. We aimed to evaluate cardiovascular autonomic function over the first year after SCI and its relationship with markers of susceptibility to cardiac arrhythmia. We tested 40 people < 2 weeks, 1-, 3- and >6months after acute SCI. Supine beat-to-beat blood pressure and heart rate variability, and electrocardiographic (ECG) markers of arrhythmia risk (QT variability index [QTVI] and P wave duration [PWD]) were determined at each visit. Low frequency variability of systolic arterial pressure (LFSAP) was used to determine sympathetic autonomic function. LFSAP was reduced in all participants at < 2 weeks. By 1-month post-injury two distinct groups emerged: autonomically-complete SCI with sustained low LFSAP (2.1
0.6mmHg2) and autonomically-incomplete SCI (11.19
3.6mmHg2), p¼0.018) with higher LFSAP. These groups remained distinct at subsequent time-points. Those with autonomically complete lesions showed increased risk for ventricular (QTVI >6-months: autonomically-complete SCI -0.75
0.3; autonomically incomplete SCI -2.0
0.4; p¼0.01) and atrial (PWD >6-months: autonomicallycomplete SCI 141
9ms; autonomically incomplete SCI 120
11ms; p>0.05) arrhythmia that developed over time. In order to develop treatments for cardiovascular dysfunction we must first understand the typical progression of changes in autonomic control after SCI. Assessment of autonomic function is most informative 1-month after injury and LFSAP may provide a simple measure to assess autonomic function non-invasively. Impaired autonomic function conveys an increased risk for cardiac arrhythmia after SCI. Heart and Stroke Foundation of Canada

Canadian Cardiovascular Society (CCS) Moderated Presentations LVAD COMPLICATIONS: BREATHLESSNESS, BLEEDING AND BUGS Monday, October 23, 2017 CCTN/CHFS Research Competition Award Finalist 255 INVASIVE EXERCISE HEMODYNAMICS OF PATIENTS SUPPORTED BY A LONG-TERM CONTINUOUS-FLOW LEFT VENTRICULAR ASSIST DEVICE S Wright, K Anderson, S Esfandiari, J Goodman, F Billia, S Mak Ajax, Ontario

S157 BACKGROUND: Patients with advanced heart failure receiving implantable left ventricular assist devices (LVADs) as a bridge to candidacy/transplant or as destination therapy are now living with circulatory support for increasingly longer intervals. LVADs improve survival and quality of life, however the physiology of non-pulsatile circulatory support during exercise is incompletely understood. To better understand the potential limitations to activity, we are conducting a study of the hemodynamic responses to submaximal exercise, and here we report our early experience. METHODS: We studied advanced heart failure patients (N ¼ 11; mean age ¼ 57
13) at least 3 months after continuous flow LVAD implantation, using right-heart catheterization to measure pulmonary artery pressures and cardiac output. Mixed venous blood was sampled for oximetry (SvO2) and blood lactate. After making supine clinical measurements, patients were transferred to a cycle ergometer in a semiupright position (w25 ). Subjects were studied at rest in the semi-upright position and at light (15W) and moderate (25W) submaximal exercise. Hemodynamic data are reported at one minute prior to exercise and after 6-8 minutes of each exercise condition. Systolic and mean pulmonary artery pressures (sPAP/mPAP) and mean pulmonary artery wedge pressure (PAWP) were measured, and cardiac index (CI) and right ventricular stroke work index were calculated (RVSWi). RESULTS: All subjects demonstrated pulmonary hemodynamics acceptable for transplant based on ISHLT guidelines at baseline. Six subjects completed the protocol, while five terminated exercise prematurely, reporting fatigue or breathlessness. Patients who terminated prematurely trended toward greater body mass index (32
4 vs. 28
3 kg/m2, p¼0.09) and lower resting heart rate (64
12 vs. 77
10 b/min, p¼0.07). Hemodynamic data are presented in Table 1. All subjects completed light exercise, which was associated with substantial increases in sPAP, mPAP, and PAWP. CI increased modestly and SvO2 decreased substantially. Six subjects completed moderate exercise, while 3 attempted but did not complete the condition. In these subjects, pulmonary pressures remained elevated, and CI did not increase appreciably further. Blood lactate concentrations remained low (ie., < 2.5 mmol/L) throughout exercise in subjects who completed both stages of exercise. However, blood lactate concentrations increased >3.5 mmol/ L prior to failure in those who terminated prematurely (Figure 1). CONCLUSION: Patients supported by continuous-flow LVADs demonstrate substantial increases in pulmonary artery pressures during even light exercise. A proportion of patients demonstrate poor exercise tolerance associated with a sharp increase in serum lactate concentration. Further research is

S158

needed to understand the factors that limit physical capacity in these patients.

Ontario Graduate Scholarship

256 RISK OF PERI-OPERATIVE BLEEDING AND OUTCOMES DURING LEFT VENTRICULAR ASSIST DEVICE IMPLANTATION R Miller, A Gregory, W Kent, B Clarke Calgary, Alberta BACKGROUND:

There has been a progressive increase in patients undergoing left ventricular assist device (LVAD)

Canadian Journal of Cardiology Volume 33 2017

implantation. Bleeding complications remain an important cause of morbidity, mortality and blood product exposure contributes to allosensitization and RV dysfunction in the peri-implant period. Existing data has focused on long-term bleeding complications while rates of peri-operative bleeding are relatively unknown. We assessed factors associated with packed red blood cell (PRBC) transfusion within 30 days peri and post-operatively for patients undergoing initial LVAD implantation and the complications associated with PRBC transfusion. METHODS AND RESULTS: We conducted a retrospective cohort study of patients undergoing initial LVAD implantation between January 1, 2003 until December 31, 2015 at Foothills Medical Centre in Calgary Alberta. We collected demographic information, surgical implant details, hemodynamics, laboratory investigations, rates of PRBC transfusion, and outcomes including intensive care unit (ICU) length of stay (LOS), ventilation duration, and mortality. We performed ordinal multivariate regression analysis to determine factors associated with PRBC transfusion and to assess the association between transfusion and our outcomes. We identified 54 patients, mean age 53.1+/-10.8, undergoing initial surgical LVAD implantation, of which 17 (31.5%) died during follow-up. Patient characteristics are shown in Table 1. A mean of 1.6+/-4.1 units of PRBC was tranfused peri-operatively and 6.7+/-7.6 in the 30 days post-operatively. Nine patients (16.7%) received no PRBC transfusion and 29 patients (53.7%) received more than 4 units of PRBC. In multivariate analysis, higher hemoglobin (adjusted odds ratio (OR) 0.67 per 10 mg/dL, 95% CI 0.49-0.89, p¼0.006) and minimally invasive surgery (adjusted OR 0.26, 95% CI 0.08-0.83, p¼0.02) were associated with a lower PRBC transfusion requirements while higher creatinine (adjusted OR 1.10, 95% CI 1.02e1.19, p¼0.02) was associated with an increase. In a separate model, pre-operative hemoglobin < 110 g/L was associated with a 4-fold increase in PRBC transfusion (adjusted OR 4.7, 95% CI 1.63e13.4, p < 0.01). After correcting for age and sex, higher PRBC transfusion was associated with an increase in ICU LOS (adjusted OR 1.15, 95% CI 1.07-1.24, p < 0.01), and ventilation duration (adjusted OR 1.12, 95%CI 1.05-1.20, p < 0.01 and all-cause mortality (adjusted OR 1.08, 95% CI 1.00-1.16, p¼0.05). CONCLUSION: In patients undergoing LVAD implantation, blood product exposure is common in the peri-operative period. Higher hemoglobin, lower creatinine, and minimally invasive surgery are associated with lower rates of PRBC