Predictors of response to exercise training in severe chronic congestive heart failure

We prospectively assessed whether baseline central hemodynamics and exercise capacity can predict improvement of V̇O2 at ventilatory threshold (VT) after exercise training in patients with severe chronic congestive heart failure. Eighteen patients (mean ± SEM; age 52 ± 2 years), half of them listed for transplant, underwent 3 weeks of exercise training (interval cycle and treadmill walking; 5 × /week) and 3 weeks of activity restriction in a random-order crossover trial. Baseline data were not significantly different for groups with exercise training first and activity restriction first: cardiac index at rest (2.1 ± 0.1 L/m2/min), maximum cardiac index (3.1 ± 0.2 L/m2/min) (Fick), and echocardiographic ejection fraction (21 ± 1%). The same was true for cardiopulmonary exercise data (cycle ergometry; ↑ 12.5 W/min): V̇O2 at VT (9.3 ± 0.4 ml/kg/min), maximum V̇O2 (12.2 ± 0.7 ml/kg/min), VT in percentage of predicted maximum V̇O2 (31 ± 2%), heart rate at VT (95 ± 4 beats/ min), and decrease of dead space-to-tidal volume ratio from rest to VT (33 ± 1 → 29 ± 1). Improvement of V̇O2 at VT after training (2.2 ± 0.4 ml/kg/min; p < 0.001) was not related to baseline central hemodynamics (r = < 0.10 for each), but was greater in patients with a lower baseline V̇O2 at VT (r = −0.65; p < 0.01), peak V̇O2 (r = −0.66; p < 0.01), VT in percentage of predicted maximum V̇O2 (r = −0.74; p < 0.001), heart rate at VT (r = −0.63; p < 0.01), and smaller decrease of dead space-to-tidal volume ratio from rest to VT (r = 0.65; p < 0.01). Ejection fraction after exercise training (24 ± 2%) and activity restriction (23 ± 2%) did not differ significantly compared with baseline, and patient status (heart failure and cardiac rhythm) remained stable. Three parameters accounted for 84% of the variance of improvement in V̇O2 at VT: V̇O2 at VT in percent predicted maximum V̇O2, decrease of dead space-to-tidal volume ratio, and heart rate at VT. The findings suggest that there was a greater increase in V̇O2 at VT after exercise training in patients with greater peripheral deconditioning at baseline. The improvement was unrelated to central hemodynamics. Clinically stable patients with severe chronic congestive heart failure, potential heart transplant candidates, and those awaiting transplantation may benefit from involvement in a short-term exercise training program.