Letters to the Editor
To the Editor:
We thank Patel et al.1 for their thoughtful comments on the utility of concomitant cardiac resynchronization therapy (CRT) and left ventricular assist device (LVAD) therapy. We want to take this opportunity to emphasize that the cardiac and noncardiac physiology in LVAD patients is different from typical heart failure with reduced ejection fraction (HFrEF) patients. As a result, the pathophysiology and response to therapies is different. In the last few years, our group and others have demonstrated that what we know about HFrEF patients should not be applied to LVAD patients and, as such, needs to be studied again. The focus of our study was to evaluate differences in LVAD unloading, measured during a hemodynamic ramp study, between patients with and without active CRT.2 The primary results showed that there was no difference in the slope of decrease in pulmonary capillary wedge pressure between patients with active CRT and those with other modes of pacing. The findings of this study confirm previous clinical reports that have suggested a lack of benefit in mortality and all-cause hospitalization for those active CRT,3 or even the possibility of harm from arrhythmias.4 Furthermore, our study, the first study to evaluate the hemodynamic benefits of CRT in the LVAD population, gives mechanistic insight into the lack of clinical benefit. In the current study, we have demonstrated the effect of chronic CRT therapy on the hemodynamics of LVAD patients, given the pacing mode patients were on at the time of entry into the study was maintained.
We agree that the best way to assess this question is through a controlled, randomized study. We are currently nearing completion of a randomized study in which patients serve as a control to themselves. Patients are randomly assigned to either biventricular pacing or right ventricular (RV) pacing for a 1–2 week period, with subsequent crossover to the alternative mode of pacing for another 1–2 week period. Interim results of the first 21 patients enrolled were recently presented at the International Society of Heart and Lung Transplant Meeting and indicated that there was an increase in step count, six-minute walk test difference, and quality of life measures during the RV pacing mode.5 This study will be completed shortly, and final results will be reported at that time.
Until then, we believe that our current study fills a gap in the literature regarding the hemodynamic effects of CRT in the LVAD population. Based on the evidence that has accumulated to date, we will continue to turn off the left ventricular lead in most of our patients, to preserve battery life, limit generator replacements and potentially avoid proarrhythmic effects.
David M. Tehrani
Division of Cardiology
Department of Medicine
University of Chicago Medical Center
1. Patel N, Gluck J, Jaiswal A. The role of cardiac resynchronization therapy in patients with left ventricular assist support. ASAIO J 2019.65: e42.
2. Tehrani DM, Adatya S, Grinstein J, et al. Impact of cardiac resynchronization therapy on left ventricular unloading in patients with implanted left ventricular assist devices. ASAIO J 2019.65: 117–122.
3. Gopinathannair R, Birks EJ, Trivedi JR, et al. Impact of cardiac resynchronization therapy on clinical outcomes in patients with continuous-flow left ventricular assist devices. J Card Fail 2015.21: 226–232.
4. Choi AD, Fischer A, Anyanwu A, et al. Biventricular pacing in patients with left ventricular assist devices—is left ventricular pacing proarrhythmic? J Am Coll Cardiol 2010.55: A22.E208.
5. Chung B, Grinstein J, Sayer G, et al. Improved exercise performance and quality of life with right ventricular pacing over biventricular pacing in LVAD patients, in International Society for Heart and Lung Transportation 38th Annual Meeting and Scientific Sessions. April 11–14, 2018.Nice, France.