Abstract 20229: Pulmonary Vascular Response Patterns to Exercise Predict Exercise Capacity and Outcomes in Heart Failure
Background: Elevated pulmonary arterial pressure (PAP) at rest in patients with left ventricular systolic dysfunction (LVSD) purports a poor prognosis. However, PAP response patterns to exercise in LVSD and their relationship to functional capacity and outcomes have not been characterized.
Methods: We studied 60 consecutive patients with LVSD (age 60±12 years, left ventricular ejection fraction 0.31±0.07, peak VO2 12.2±3.7 ml/kg/min, mean±SD) and 19 age- and sex- matched controls who underwent bicycle ergometry cardiopulmonary exercise testing with simultaneous hemodynamic monitoring.
Results: During low-level exercise (30 Watts), LVSD subjects compared to controls, had greater augmentation in PAPs (15±1 vs. 5±1 mmHg), transpulmonary gradients (5±1 vs. 1±1 mmHg), and effective pulmonary arterial elastance (0.05 ±0.02 vs. -0.03±0.01 mmHg/ml, p<0.0001 for all). A linear increment in PAP relative to work was observed throughout exercise in 65% of LVSD patients (PAP slope=0.28±0.12 mmHg/watt), which exceeded that observed in controls (0.07±0.02mmHg, P<0.0001). Exercise capacity and survival was less in patients with higher PAP slope (above median) than in patients with lower PAP slope. In the remaining 35% of LVSD patients, exercise induced a steep initial increment in PAP (0.41±0.16 mmHg/W) followed by a plateau pattern. The PAP plateau pattern, compared to a linear pattern, was associated with reduced exercise capacity (peak VO2=10.6±2.6 vs. 13.1±4.0 ml/kg, respectively, P=0.005), lower right ventricular (RV) stroke work index augmentation with exercise (5.7±3.8 vs. 9.7±5.0 g/m2, respectively P=0.002), and reduced survival.
Conclusions: A steep initial increment in PAP in response to exercise and failure to augment PAP throughout exercise are associated with decreased exercise capacity and reduced survival in patients with LVSD. Exercise-induced pulmonary hypertension and RV dysfunction may therefore represent therapeutic targets in LVSD.
- © 2010 by American Heart Association, Inc.