Pulmonary vascular response to exercise in symptomatic heart failure with reduced ejection fraction and pulmonary hypertension.

AIMS

To study pulmonary vascular response patterns to exercise in heart failure with reduced ejection fraction (HFrEF) and pulmonary hypertension (PH).

METHODS AND RESULTS

In this prospective single-centre cohort study, consecutive symptomatic HFrEF patients (n = 40) with mean pulmonary arterial pressure (MPAP) ≥25 mmHg, pulmonary artery wedge pressure (PAWP) >15 mmHg, and cardiac index <2.5 L/min.m(2) , received protocol-driven titrated sodium nitroprusside (SNP) and diuretics to reach mean arterial blood pressure 65-75 mmHg and PAWP ≤15 mmHg. Patients performed symptom-limited supine bicycle testing under continued SNP administration. Afterwards, SNP was gradually withdrawn, renin-angiotensin system blockers uptitrated, and hydralazine added to maintain haemodynamic targets. Subsequently, bicycle testing was repeated. Patients presented with pulmonary vascular resistance (PVR) = 3.8 ± 1.4 Wood Units at rest, decreasing to 2.9 ± 0.9 Wood Units after decongestion, with PH was completely reversed (MPAP <25 mmHg) in 22%. From rest to maximal exercise, the cardiac index did not change significantly (P = 0.334 under SNP; P-value = 0.552 under oral therapy). A dynamic exercise-induced PVR increase >3.5 Wood Units was noted in 19 patients (48%) under oral therapy vs. five (13%) under SNP. Such exercise-induced PVR increase was associated with a 33% relative decrease in right ventricular stroke work index (P = 0.037).

CONCLUSIONS

Even after thorough decongestion and under continuous afterload reduction, PH secondary to HFrEF is completely reversible in only a minority of patients. Others demonstrate an exercise-induced PVR increase, associated with impaired right ventricular stroke work, which might be ameliorated by nitric oxide donor support.