Abstract 15615: Exercise Intolerance in Heart Failure with preserved Ejection Fraction: Central vs Peripheral Determinants
Objectives: To characterize the impact of cardiac and peripheral abnormalities on exercise capacity in heart failure with preserved ejection fraction (HFpEF). Background: Exercise intolerance is a hallmark of HFpEF, yet its mechanisms remain unclear.
Methods: Patients with HFpEF (n=109) and controls (n=73) exercised to volitional fatigue with simultaneous invasive (n=96) or noninvasive (n=86) hemodynamic assessment and expired gas analysis to determine oxygen consumption (peak VO2).
Results: At rest, HFpEF had higher left ventricular (LV) filling pressures but similar heart rate, stroke volume, EF and cardiac output (CO, Table). With exercise, patients displayed reduced peak VO2 and blunted increases in heart rate, stroke volume, EF, and CO compared to controls. LV filling pressures increased dramatically in HFpEF with secondary elevation in pulmonary artery pressures. However, enhancement in LV end diastolic volume with exercise was similar in HFpEF and controls. Reduced peak VO2 in HFpEF was attributable to CO limitation, as the slope of the increase in CO relative to VO2 was attenuated in HFpEF (5.9 ± 2.5 vs 7.4 ± 2.6, p = 0.0005). Conversely, O2 extraction relative to VO2 was greater in HFpEF than controls (8.9 ± 3.4 vs 5.5 ± 2.0 min/dl, p < 0.0001). These differences were consistently observed with both upright and supine exercise. Enhancements in CO for any increase in LV filling pressure or preload volume were reduced in HFpEF compared with controls.
Conclusions: Exercise capacity in HFpEF is limited by inadequate cardiac output relative to metabolic needs. While diastolic dysfunction causes exertional congestion and pulmonary hypertension in HFpEF, impairments in net systolic ejection reserve drive cardiac output limitation.
- © 2012 by American Heart Association, Inc.