Disproportionate exercise-induced pulmonary hypertension in relation to cardiac output in heart failure with preserved ejection fraction: a non-invasive echocardiographic study.

Abstract

Pulmonary hypertension (PH) and pulmonary vascular remodelling are common in patients with heart failure with preserved ejection fraction (HFpEF). Many patients with HFpEF demonstrate an abnormal pulmonary haemodynamic response to exercise that is not identifiable at rest. This can be estimated non-invasively by the mean pulmonary artery pressure-cardiac output relationship (mPAP/CO slope). We sought to characterize the pathophysiology of disproportionate exercise-induced PH in relation to CO (DEi-PH) and its prognostic impact in patients with HFpEF. A total of 345 patients (166 HFpEF and 179 controls) underwent ergometry exercise stress echocardiography with simultaneous expired gas analysis. DEi-PH was defined as the mPAP/CO slope >5.2 mmHg/L/min (median value). At rest, there were no differences in right ventricular (RV) function and severity of PH between HFpEF patients with and without DEi-PH. Compared with controls (n=179) and HFpEF without DEi-PH (n=83), HFpEF with DEi-PH (n=83) demonstrated worse exercise capacity (lower peak oxygen consumption), depressed RV systolic function, impaired RV-pulmonary artery coupling, limitation in CO augmentation, more right-sided congestion, and worse ventilatory efficiency (higher minute ventilation vs. carbon dioxide volume) during peak exercise. Kaplan-Meier analyses showed that HFpEF patients with DEi-PH had higher rates of composite outcomes of all-cause mortality or heart failure events than those without (log-rank p=0.0002). Patients with HFpEF and DEi-PH demonstrated distinct pathophysiologic features that become apparent only during exercise. These data suggest that DEi-PH is a pathophysiologic phenotype of HFpEF and reinforce the importance of exercise stress echocardiography for detailed characterization of HFpEF.