HEMODYNAMIC EXERCISE TESTING - A VALUABLE TOOL IN THE SELECTION OF CARDIAC TRANSPLANTATION CANDIDATES

Background Peak exercise oxygen consumption (V over dot O-2), a noninv asive index of peak exercise cardiac output (CO), is widely used to se lect candidates for heart transplantation. However, peak exercise V ov er dot O-2 can be influenced by noncardiac factors such as decondition ing, motivation, or body composition and may yield misleading prognost ic 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 exe rcise were measured in 185 ambulatory patients with chronic heart fail ure who had been referred for cardiac transplantation (mean left ventr icular ejection fraction, 22+/-7%; mean peak V over dot O-2. 12.9+/-3. 0 mL . min(-1) . kg(-1). CO response to exercise was normal in 83 pati ents and reduced in V over dot O-2. By univariate analysis, patients w ith normal CO responses had a better 1-year survival rate (95%) than d id those with reduced CO responses (72%) (P<.0001). Survival in patien ts with peak V over dot O-2 of >14 mL . min(-1) . kg(-1) (88%) was not different from that of patients with V over dot O-2 of less than or e qual to 14 mL . min(-1) . kg(-1) (79%) (P=NS). However, survival was w orse in patients with peak V over dot O-2 of less than or equal to 10 mL . min(-1) . kg(-1) (52%) versus those with peak V over dot O2 >10 m L . min(-1) . kg(-1) (89%) P<.0001). By Cox regression analysis, exerc ise CO response was the strongest independent predictor of survival (r isk ratio, 4.3), with V over dot O-2 dichotomized at 10 mL . min(-1) . kg(-1) (risk ratio, 3.3) as the only other independent predictor. Pat ients with reduced CO responses and peak V over dot O-2 of less than o r equal to 10 mL . min(-1) . kg(-1) had an extremely poor 1-year survi val rate (38%). Conclusions Both CO response to exercise and peak exer cise V over dot O-2 provide valuable independent prognostic informatio n in ambulatory patients with heart failure. These variables should be used in combination to select potential heart transplantation candida tes.