COMPARISON OF LEFT-VENTRICULAR RESPONSES TO THE 6-MINUTE WALK TEST, STAIR CLIMBING, AND MAXIMAL UPRIGHT BICYCLE EXERCISE IN PATIENTS WITH CONGESTIVE-HEART-FAILURE DUE TO IDIOPATHIC DILATED CARDIOMYOPATHY

Submaximal exercise tests have been advocated to assess exercise capac ity in chronic heart failure, but hemodynamic responses have not been characterized. To determine left ventricular (LV) responses during sub maximal exercise, the LV ejection fraction (EF) and volumes were evalu ated by using an ambulatory radionuclide detector in 13 patients with idiopathic dilated cardiomyopathy during upright maximal graded bicycl e exercise, stair climbing and a 6-minute walk test. The 3 tests elici ted different responses in volumes and, to a lesser degree, in LVEF. T he maximal bicycle exercise led to a decrease in LVEF from 22 +/- 9% t o 17 +/- 8% (p <0.05), with marked increases in both end-diastolic vol ume (EDV) (+15 +/- 10%, p <0.001) and end-systolic volume (ESV) (+23 /- 18%, p <0.001). Stair climbing tended to reduce LVEF (from 24 +/- 1 1% to 21 +/- 10%, p = 0.05), with a lesser increase in volumes, which was more marked for ESV (+8 +/- 9%, p <0.01) than for EDV (+4 +/- 4%, p <0.01). The 6-minute walk test did not significantly change LVEF (23 +/- 10% vs 22 +/- 10%), but increased both EDV (+10 +/- 6%, p <0.001) and ESV (+8 +/- 8%, p <0.01) moderately and proportionally. Exercise capacity indexes (peak oxygen consumption, maximal bicycle work rate, stair climbing time, and the distance covered during the 6-minute walk test) correlated significantly with one another. There was no correla tion between submaximal exercise tolerance-indexes and resting or exer cise LVEF. This study shows that (1) LVEF changes are inadequate to re port on LV volume changes during exercise; (2) the 3 tests induce diff erent LV volume changes; (3) the 6-minute walk test induces significan t changes in LV volumes but no change in LVEF. (C) 1997 by Excerpta Me dico, Inc.