Pulmonary hypertension and exercise intolerance in patients with heart failure

OBJECTIVES This study was undertaken to investigate the relationship betwee n pulmonary hypertension and exercise performance in patients with heart fa ilure. BACKGROUND The exercise capacity of patients with heart failure is frequent ly reduced. Pulmonary hypertension may contribute to this exercise intolera nce by impairing blood flow through the pulmonary circulation. METHOD Three hundred twenty patients with heart failure underwent upright t readmill exercise testing with hemodynamic monitoring. The incidence of pul monary hypertension and the relationship between pulmonary vascular resista nce (PVR) and exercise cardiac output and minute oxygen consumption (VO2) w ere examined. RESULTS Pulmonary vascular resistance was normal (<1.5 Wood Units; Group 1) in 28% of the patients, mildly elevated (1.5 to 2.49 Wood Units; Group 2) in 36%, moderately elevated (2.5 to 3.49 Wood Units; Group 3) in 17% and se verely elevated (>3.5 Wood Units; Group 4) in 19%. Increasing PVR was assoc iated with significantly lower peak exercise VO2 (Group 1: 13.9 +/- 3.7; 2: 13.7 +/- 3.4; 3: 11.8 +/- 2.4; 4: 11.5 +/- 2.6 L/min, p < 0.01 Groups 3 and 4 vs. 1) and lower peak exercise cardiac output (Group 1: 10.0 +/- 2.8, 2: 9.0 +/- 3.0; 3: 7.4 +/- 2.1; 4: 6.3 +/- 2.0 L/min, p < 0.05, Groups 2, 3 an d 4 vs. 1). The pulmonary wedge pressure decreased during exercise, consist ent with impaired left ventricular filling, in 36% of patients with severe pulmonary hypertension (Group 4) versus only 13% of patients with normal PV R if < 0.01). CONCLUSIONS Pulmonary vascular resistance is frequently increased in heart failure and is associated with a reduced cardiac output response to exercis e, suggesting that pulmonary hypertension impairs exercise performance in h eart failure. (C) 1999 by the American College of Cardiology.