The Role of Beta Blockers in the Prevention of Gastrointestinal Bleeding After Left Ventricular Assist Device Implantation

Abstracts S443 Turkey Yuksek Ihtisas Hospital, Ankara, Turkey; 2Cardiology, Turkey Yuksek Ihtisas Hospital, Ankara, Turkey. Purpose: The Thoratec®HeartMate 3 (HM3) ventricular assist device (VAD) is a new compact, intrapericardial, centrifugal flow pump with a full magnetically levitated rotor and a wide range of operation (2-10 L/min) to accommodate a broad range of clinical needs. We analyzed our experience Heartware®VAD (HVAD) and HM3 VAD implantation through minimally invasive left thoracotomy (MILT) and J sternotomy implantation techniques Methods: Between March 2015 and October 2016, 31 patients underwent through MILT VAD implantation and were included in this study. Twenty three patients had HVAD (group A), whereas 8 patients underwent HM3 (group B). To compare outcomes of these pumps, measures were the length of entubation, haemolysis, blood loss and transfusion, intensive care unit (ICU) and hospital stay, right ventricular (RV) failure and requirement support with devices, stroke, pump thrombosis, bleending and driveline infection in hospital. Results: There was no difference in ICU length of stay (p 0,22), post-operative blood product administration (p 0,11) and total time on mechanical ventilation (p 0,46), RVF (p 0,76), duration of cardiopulmonary bypass (p 0,32). After adjusting for age, INTERMACS profile and Pennsylvania and Michigan Risk Scores, RVSWI and CVP/PCWP ratio did not differ between the two groups. In-hospital cerebrovascular events were 13% in group A and 0% in group B respectively. Conclusion: The Full MagLev technology enables rapid speed changes and allows the development of artifcial pulsatile flow and the HM3 assist system can be successfully implanted with MILT techniques. This technique has proved to be safe and reproducible, with good clinical outcome. Further large collaborative studies are needed to identify advantages of the this approach. 1( 356) Comparison of Activated Partial Thromboplastin Time (aPTT) and Anti-Factor Xa for Low Intensity Unfractionated Heparin Monitoring in Patients with Mechanical Circulatory Support Devices (MCSD) O. Volod ,1 L.D. Lam,2 M. Barglowski,1 J. Mirocha,3 C. Runyan,2 J. Moriguchi,4 L.S. Czer,4 F. Arabia.5  1Pathology, Cedars Sinai Medical Center, Los Angeles, CA; 2Comprehensive Transplant Center, Cedars Sinai Medical Center, Los Angeles, CA; 3Cedars Sinai Research Institute, Cedars Sinai Medical Center, Los Angeles, CA; 4Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA; 5Center for Surgical Device Management, Cedars Sinai Medical Center, Los Angeles, CA. Purpose: Low intensity intravenous unfractionated heparin (LIIV-UFH) remains the mainstay therapy for bridging patients on MCS devices (MCSDs). The optimal level of anticoagulation for low intensity protocols has not been standardized. Recently, many institutions are switching from aPTT to anti-factor Xa assay (heparin assay) for UFH monitoring. There is still uncertainty if the heparin assay is superior to aPTT in MCSD patient population. We evaluated the relationship between heparin assay and aPTT for monitoring LIIV-UFH in patients with various types of MCSDs. Methods: 25 MCSD patients on LIIV-UFH intended to bridge with warfarin who underwent simultaneous aPTT and heparin assay measurements at our institution were included for retrospective analysis. Study cohort included a total of 222 paired values: 10 TAH patients (78 values), 11 HeartWare (HW) patients (100 values) and 4 HeartMate II (HMII) patients (44 values) . Only data with low intensity heparin assays between 0.10 IU/ml and 0.40 IU/ml were included. Patients INTERMACS profiles was also gathered for analysis. Results: A dose-response curve calculated from the data using regression analysis showed a high degree of variability in aPTT for a heparin assay level 0.10IU/ml- 0.40 IU/ml irrespective of the type of device: TAH r2 =  0.14, with p =  0.0009, HW r2 =  0.04 , with p =  0.060 and HMII r2 =  0.25, with p =  0.0005. The patterns of discordance were observed in both directions: supratherapeutic aPTT value (as high as 130 seconds) despite low intensity heparin level or normal aPTT ( as low as 30 seconds) despite measurable heparin level. Conclusion: Levels of aPTT were disproportionally prolonged or normal relative to the corresponding heparin assay levels in MCSD patients irrespective of the type of device or INTERMACS profiles. Concurrent use of aPTT and heparin assay to guide heparin therapy may be misleading. The heparin assay appears to be more reliable than aPTT in patients with MCSDs.

The ideal level of anticoagulation should be individually tailored. Target values of heparin assay level between 0.15 IU/ml to 0.3 IU/ml appears to be safe for bridging using low intensity heparin dose. Multicenter large studies using different instruments and reagents are necessary to establish uniform evidence - based guidelines. 1( 357) The Role of Beta Blockers in the Prevention of Gastrointestinal Bleeding After Left Ventricular Assist Device Implantation R. Kaur , R. Singh, S. Phillips, K. Abdullah, S.S. Desai, P. Shah.  Heart Failure and Heart Transplant, Inova Heart and Vascular Hospital, Fairfax, VA. Purpose: Gastrointestinal bleeding (GIB) affects between 15 to 30% of LVAD recipients. Small bowel arteriovenous malformations (AVM) have been implicated in about one-third of GIB events. It is believed that LVADs reduce pulse pressure that triggers an increase in sympathetic tone, causing smooth-muscle relaxation, arteriovenous dilation and AVM. This mechanism of AVM is also seen in patients with advanced liver disease and portal hypertension. Beta-blockers cause splanchnic vasoconstriction reducing portal and collateral blood flow. Hence, we sought to determine the role of beta-blockers in reducing the incidence of GIB in LVAD recipients. Methods: We conducted a retrospective study of patients implanted with a continuous-flow LVAD from January 2011 to June 2016 at our institution. We determined ambulatory prescription of a beta-blocker at three consecutive times points early after LVAD implant to categorize patients into two groups beta-blocker (BB) vs no beta-blocker (noBB). Incidence rates of GIB were compared between groups. Kaplan Meier methods were used to calculate GIB-free survival. The incidence and events/year were compared between both groups. Results: During the study period we implanted 172 LVADs and 148 ambulatory LVAD patients were evaluated. During a median follow-up of 2.5 years (every 3 months), 75 patients (50.7%) were on BB and 73 patients (49.3%) were not. Clinical characteristics between the BB and noBB group were similar (table with age, sex, INTERMACS profile, LVAD type, DM, HTN, AF, BTT/DT, Cr, Albumin, Bilirubin, EF, LVIDD). The survival free of GIB in the BB group was 77% and 69% in the noBB group (p =  0.344). The mean number of GIB events/year in the BB group was 0.91 compared to 1.87 in the noBB. Conclusion: Our study found a non-significant trend towards lower GIB in LVAD patients who received BB while on chronic support. Larger studies with sufficient power will need to be conducted to determine the potential mitigating effect of BB on LVAD-induced GIB.

1( 358) Initiation of a Standardized International Normalized Ratio Management Protocol Reduces Out of Range Days in an Ambulatory LVAD Population M.A. Thompson ,1 R.C. Jackson,2 M. Frakes,2 L.T. Hamann,1 R. John,3 R.J. Cogswell.4  1CV Specialty Nursing, University of MN Health, Minneapolis, MN; 2Fairview Pharmacy Services, University of MN Health, Minneapolis, MN; 3Cardiovascular Surgery, University of MN Health, Minneapolis, MN; 4Cardiology, University of MN Health, Minneapolis, MN. Purpose: Pump thrombosis remains one of the leading causes of morbidity and mortality in left ventricular assist device (LVAD) patients.