Exercise pulmonary hypertension by the mPAP/CO slope in primary mitral regurgitation

Abstract

Aims Exercise-induced pulmonary hypertension (PH), defined by a mean pulmonary arterial pressure over cardiac output (mPAP/CO) slope >3 mmHg/L/min has important diagnostic and prognostic implications. The aim of this study is to investigate the value of the mPAP/CO slope in patients with more than moderate primary MR with preserved ejection fraction and no or discordant symptoms. Methods and Results A total of 128 consecutive patients were evaluated with exercise echocardiography and cardiopulmonary testing. Clinical outcome was defined as the composite of mitral valve intervention, new-onset atrial fibrillation, cardiovascular hospitalization, and all-cause mortality. Mean age was 63 years, 61% male, and mean LVEF 66 ± 6%. The mPAP/CO slope correlated with peak VO2 (r = -0.52, p < 0.001), while peak sPAP did not (r = -0.06, p = 0.584). Forty-six percent (n = 59) had peak exercise sPAP ≥60 mmHg, and 37% (n = 47) had mPAP/CO slope >3 mmHg/L/min. Event-free survival was 55% at 1-year and 46% at 2-years, with reduced survival in patients with mPAP/CO slope >3 mmHg/L/min (HR 4.9, 95%CI 2.9–8.2, p < 0.001). In 53 cases (41%), mPAP/CO slope and peak sPAP were discordant: Patients with slope >3 mmHg/L/mmHg and sPAP <60 mmHg (n = 21) had worse outcome versus peak sPAP ≥60 mmHg and normal slope (n = 32, log-rank p = 0.003). The mPAP/CO slope improved predictive models for outcome, incremental to resting and exercise sPAP, and peak VO2. Conclusions Exercise PH defined by the mPAP/CO slope >3 mmHg/L/min is associated with decreased exercise capacity and higher risk of adverse events in significant primary MR and no or discordant symptoms. The slope provides a greater prognostic value than single sPAP measures and peak VO2.