Hemodynamic Exercise Testing: A Valuable Tool in the Selection of Cardiac Transplantation Candidates

Hemodynamic Exercise Testing: A Valuable Tool in the Selection of Cardiac Transplantation CandidatesChomsky DB, Lang CC, GH., Shyr Y, Yeoh TK, Pierson RN, Davis SF, Wilson JR Circulation 1996;94:3176-3183 Background. Peak oxygen consumption (VO2), a noninvasive index of peak exercise cardiac output (CO), is widely used to select candidates for heart transplantation. However, peak exercise VO2 can be influenced by noncardiac factors such as deconditioning, motivation, or body composition and may yield misleading prognostic information. Direct measurement of the CO response to exercise may avoid this problem and more accurately predict prognosis. Methods and Results. Hemodynamic and ventilatory responses to maximal treadmill exercise were measured in 185 ambulatory patients with congestive heart failure (CHF) who had been referred for cardiac transplantation (mean left ventricular ejection fraction, 22 + 7%; mean peak VO2 12.9 + 3.0 mL/kg/min). Cardiac output response to exercise was normal in 83 patients and reduced in 102. By univariate analysis, patients with normal CO responses had a better 1-year survival rate (95%) than did those with reduced CO responses (72%) (P 14 mL/kg/min (88%) was not different from that of patients with peak VO2 of ≤ 14 mL/kg/min (79%). However, survival was worse in patients with peak VO2 ≤ 10 mL/kg/min (52%) versus those with peak VO2 ≥ 10 mL/kg/min (89%) (P < 0.0001). By Cox regression analysis, exercise CO response was the strongest independent predictor of survival (risk ratio, 4.3), with peak VO2 dichotomized at 10 mL/kg/min (risk ratio, 3.3) as the only other independent predictor. Patients with reduced CO responses and peak VO2 ≤ 10 mL/kg/min had an extremely poor 1-year survival rate (38%). Conclusions. Both CO response to exercise and peak exercise VO2 provide valuable independent prognostic information in ambulatory patients with heart failure. These variables should be used in combination to select potential heart transplantation candidates. Comment. The use of exercise responses in risk-stratifying patients with CHF continues to gain momentum. Accurate risk stratification is particularly important in the context of choosing patients for transplantation, yet it remains highly imprecise. This study shows the importance of the CO response to exercise, particularly in conjunction with cardiopulmonary exercise tesing to help establish prognosis.