Changes in Cardiopulmonary Exercise Testing Parameters Following Continuous Flow Left Ventricular Assist Device Implantation and Heart Transplantation

Background: Reduced exercise tolerance from impaired cardiac output is an important criterion for left ventricular assist device (LVAD) implantation. However, little is known about how exercise capacity changes after LVAD and how changes compare with patients undergoing heart transplantation. Methods and Results: We compared changes in cardiopulmonary exercise testing performed pre- and postoperatively in patients who underwent HeartMate II LVAD implantation (n = 25) and heart transplantation (n = 74) at the Mayo Clinic in Rochester, Minnesota, between 2007 and 2012. Preoperatively, patients undergoing LVAD and transplant had markedly reduced exercise time (mean 5.1 minutes [45% predicted] and 5.0 minutes [44% predicted], respectively), low peak oxygen consumption (VO2; mean 11.5 mL.kg. min [43% predicted] and 11.9 mL.kg.min [38% predicted]), and abnormal ventilatory gas exchange (ratio of minute ventilation to carbon dioxide production [VE/VCO2] nadir 39.4 and 37.4). After LVAD and transplant, there were similar improvements in exercise time (mean Delta +1.2 vs. 1.7 minutes, respectively, P =.27) and VE/VCO2 nadir (mean Delta 3.7 vs. 4.2, P = .74). However, peak VO2 increased posttransplant but did not change post-LVAD (mean A +5.4 vs. + 0.9 mL.kg.min, respectively, P <.001). Most patients (72%) had a peak VO2 < 14 mL.kg.min post-LVAD. Conclusions: Although improvements in exercise capacity and gas exchange are seen after LVAD and heart transplant, peak VO2 doesn't improve post-LVAD and remains markedly abnormal in most patients.