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LV Assist Device Therapy as a Bridge to Recovery
Study Questions:
Can patients undergoing left ventricular assist device (LVAD) bridge-to-recovery protocol accomplish cardiac and physical functional capacities compared with those of healthy controls?
Methods:
The study cohort was comprised of 58 male patients, in whom 18 continuous-flow LVADs were implanted, 16 LVADs were explanted (recovered), and 24 patients became heart transplant candidates (HTx); 97 were healthy controls. All study participants underwent a cardiopulmonary exercise test with continuous measurements of respiratory gas exchange and noninvasive (rebreathing) hemodynamic data. Cardiac function was represented by peak exercise cardiac power output (mean arterial blood pressure x cardiac output) and functional capacity by peak exercise oxygen consumption (peak VO2).
Results:
The explanted patients in the present study were tested at an average of 3.3 ± 1.1 years (range, 0.3-5.8 years) following device explantation. The study investigators reported that all patients demonstrated a significant exertional effort at attaining anaerobic threshold with the mean peak exercise respiratory exchange ratio >1.10. Peak exercise cardiac power output was significantly higher in healthy controls and explanted LVAD patients compared with other patients (healthy, 5.35 ± 0.95; explanted, 3.45 ± 0.72; LVAD implanted, 2.37 ± 0.68; HTx, 1.31 ± 0.31 watts; p < 0.05), as was peak VO2 (healthy, 36.4 ± 10.3; explanted, 29.8 ± 5.9; implanted, 20.5 ± 4.3; HTx, 12.0 ± 2.2 ml/kg/min-1; p < 0.05). In the LVAD explanted group, 38% of the patients achieved peak cardiac power output and 69% achieved peak O2 consumption within the ranges of healthy controls.
Conclusions:
The study authors concluded that a substantial number of patients who recovered sufficiently to allow explantation of their LVAD could even achieve cardiac and physical functional capacities nearly equivalent to those of healthy controls.
Perspective:
Although this is a small study, the findings are important because these results suggest that cardiac and functional recovery, once achieved with an LVAD bridge-to-recovery program, is sustainable for several years following LVAD explantation. Therefore, all LVAD patients should be actively managed to promote recovery of LV function. It would be interesting to know the INTERMACS score of each of the patients in this study. Most of the explanted patients in this study had nonischemic cardiomyopathy and the natural history of such patients depends on the underlying etiology (with HIV cardiomyopathy having the worst prognosis and peripartum and alcoholic cardiomyopathy having the best prognosis). Larger prospective studies are now needed to validate the important findings of this study.
Keywords: Anaerobic Threshold, Arterial Pressure, Cardiac Output, Cardiac Surgical Procedures, Cardiomyopathies, Exercise Test, Heart-Assist Devices, Heart Failure, Heart Transplantation, Oxygen Consumption, Recovery of Function
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