Increasing Frequency of Left Ventricular Assist Device Exchanges in the United States

Abstract

Background: Recent reports indicate an increased prevalence and earlier onset of pump thrombosis and associated pump exchanges after left ventricular assist device (LVAD) implantation. Questions remain regarding the current rate and clinical effect of pump exchanges.

Methods: All United States Medicare fee-for-service patients undergoing LVAD implantations (n = 3,166) between January 2009 and December 2012 were identified by procedural codes present on carrier claims collected by the Centers for Medicare & Medicaid Services. Pump exchange, pump removal, heart transplantation, and death were collected from subsequent carrier claim and denominator files. Comorbidities present before implantation were generated using the Elixhauser comorbidity index.

Results: Compared with patients who received LVADs before March 1, 2011, LVAD recipients after March 1, 2011, were older on average (63.9 vs 62.2 years, p < 0.01), more likely to be male (82.3% vs. 79.4%, p = 0.04), and had a higher incidence of common comorbidities. The later cohort had higher occurrence of pump exchange by Kaplan-Meier time-to-event estimates and Fisher exact tests at 3 months (1.8 vs 0.8, p = 0.02), 6 months (3.3 vs 1.0, p < 0.01), and 12 months (4.9 vs 2.2, p < 0.01). Cox regression analysis found time-dependent pump exchange was associated with worse survival (hazard ratio, 2.5; 95% confidence interval, 1.8 to 3.62; p < 0.01) after adjusting for age, gender, and comorbidities.

Conclusions: Although LVAD exchanges remain relatively uncommon, a significant increase in the incidence of the procedure has occurred since March 1, 2011. Pump exchanges are highly associated with death, and further research is required to understand the cause of this disturbing trend and surveillance to determine its trajectory.