FUNCTIONAL-CAPACITY IN HEART-FAILURE - COMPARISON OF METHODS FOR ASSESSMENT AND THEIR RELATION TO OTHER INDEXES OF HEART-FAILURE

Background. Left ventricular (LV) dysfunction plays a primary role in the pathogenesis of congestive heart failure and correlates with progn osis, but a strong quantitative relation between exercise performance and indexes of LV function has not been demonstrated. We examined the relation between LV ejection fraction at rest, oxygen consumption at p eak exercise (VO2), patient and physician assessments of clinical seve rity, and other clinical attributes in 804 patients with moderate hear t failure. Methods and Results. Ejection fraction correlated weakly wi th VO2, and mean ejection fraction was related to severity of symptoms . There was a statistical association between the patient's self-asses sed quality of life questionnaire score and the physician-assigned New York Heart Association (NYHA) functional class; NYHA class was statis tically associated with exercise performance. To identify other factor s that might influence exercise capacity, comparisons of clinical attr ibutes were made between patients grouped by VO2 within each stratum o f LV function. Exercise performance was inversely related to plasma no repinephrine levels within the ejection fraction <25% stratum. The per centage of patients reaching their anaerobic threshold was not differe nt between groups, yet the peak heart rate increased with VO2 within a ll strata. Elevated venous pressure and cardiomegaly were inversely re lated to exercise performance. Conclusions. Clinical scales based on p hysician and patient assessment of symptoms were statistically associa ted with exercise capacity but do not accurately predict individual ex ercise performance. The strong association of heart rate response to e xercise performance suggests that the variability of the chronotropic response to exercise contributes to differences in exercise capacity a mong patients with a similar degree of LV dysfunction.