Trend Towards Lower Rates of Gastrointestinal Bleeding in Patients Transplanted with HeartWare vs. HeartMate-2 for End Stage Heart Failure

Abstract

Purpose: Left ventricular assist device (LVAD) augment systemic circulation and improves quality of life in patients suffering from end stage heart failure. Until recently, LVAD implantations had been performed with first generation pulsatile devices. Newer generation pumps work by a central rotor containing permanent magnets. The HeartMate-2 (HM-2), a 2nd generation LVAD is FDA approved for bridge to transplant and destination therapy. Their continuous flow mechanism allows reduction in pump size since external venting is no longer required for long-term pulsatile LVADs. Their generation pumps such as HeartWare (HW) have no bearings, longer durability, smaller size, and are easier to implant. They work by a central rotor containing permanent magnets which use a centrifugal pump where the rotors are shaped to accelerate the blood circumferentially and cause it to move toward the outer rim of the pump. For HM-2, several centers have reported rate of GI bleeds ranging from 15% - 40%. The purpose of this retrospective case control study is to compare the odds of GI bleed in patients implanted with HM-2 vs. HW pumps. Methods: Medical records of 98 patients (84 with HM-2 and 14 with HW), ages 28 - 77 at Penn State Hershey Medical Center from July 2006 through November 2011, were selected. GIB was defined as one guiac-positive stool with a subsequent transfusion of at least two units of PRBC. Results: In HM-2 vs. HW patients, GIB occurred in 20 (24%) vs. 1 (7%), respectively. There was no difference in median [IQR] time to onset of bleed for HM-2 vs. HW which were 51.5 [25.5- 347] vs. 49 [49, 49], p=1.0, respectively. In the multivariable logistic regression, age, sex, and extracorporeal membrane oxygenation (ECMO) prior to LVAD placement were not associated with increased incidence of GI bleed. Odd ratio showed a tread towards decreased rate of GI bleed with HW vs HM-2 (OR=0.21. p=0.190). Heart-Mate-2 Parameters Anticoagulation: Warfarin with goal INR of 1.5 - 2.0 with Aspirin 81 mg daily Speed: 9,000-10,000 rotation per minute (RMP) Flow: 3.5 - 6 L/min as appropriate for body surface area Power: 4 - 8 Watts. HeartWare Parameters Anticoagulation: Warfarin with goal INR of 2.0 - 3.0 combined with aspirin 81 mg daily Speed: 2,600 - 3,200 rpm Flow: 3.5 - 6 L/min as appropriate BSA Power: 3 - 6 watts Conclusion: There is an early trend to a decrease rate of GIB with the 3rd generation HeartWare LVAD pumps. This could be explained by the decreased rotations per minute leading to decreased shear stress. HW devices are offered solely to transplant candidates, which could add bias. Further prospective study as numbers of HW implants accrue will be necessary.