Novel scoring system using postoperative cardiopulmonary exercise testing predicts future explantation of left ventricular assist device

Background: Although cardiopulmonary exercise (CPX) testing is an established tool for predicting survival in patients with heart failure (HF), its prognostic impact on explantation of left ventricular assist device (LVAD) was unknown. Methods and Results: We enrolled 33 patients who had undergone implantation of extracorporeal pulsatile flow LVAD and symptom-limited CPX testing at 3 months after operation, and who were followed between 2005 and 2014. Patients who received conversion to continuous flow LVAD were excluded. On Cox regression analysis, E1 (maximum load ≥51W; HR, 27.55), E2 (minute ventilation/carbon dioxide output [VE/VCO₂] slope ≤34; HR, 16.86), and E3 (peak oxygen consumption [PV˙O₂] ≥12.8 ml . kg^–1 . min^–1; HR, 18.35) significantly predicted explantation expectancy during 2 years after LVAD implantation (P<0.05 for all). Explantation score, the sum of positive E1–3, significantly stratified 2-year cumulative explantation rate into low (0 points), intermediate (1–2 points), and high (3 points) expectancy groups (0%, 29%, and 86%, respectively, P<0.001). When the scoring system was used for 45 patients with continuous flow LVAD, the 2 patients who had explantation were assigned to the high expectancy group. Conclusions: Explantation score, calculated simply from 3 postoperative symptom-limited CPX testing parameters, is a novel tool to predict explantation expectancy of LVAD and to select good candidates for the weaning test.