Exercise-induced pulmonary hypertension in hypertrophic cardiomyopathy: a combined cardiopulmonary exercise test-echocardiographic study

Pulmonary arterial hypertension (PAH), documented in a significant portion of hypertrophic cardiomyopathy (HCM) patients, has been shown to adversely impact prognosis. In most HCM patients congestive symptoms are consistently elicited by exercise, thus suggesting the need for a provocative test to assess cardiac hemodynamics during effort. Combining cardiopulmonary exercise test (CPET) with echocardiography, we aimed to evaluate the presence of exercise induced pulmonary arterial hypertension (EiPAH), its role in functional limitation and its prognostic significance in a cohort of patients with obstructive and non-obstructive HCM. Study population included 182 HCM patients evaluated combining CPET and stress echocardiography. Left-ventricular outflow tract (LVOT) velocities, trans-tricuspid gradient, and cardiopulmonary variables were continuously measured. Thirty-seven patients (20%) developed EiPAH, defined as systolic pulmonary arterial pressure (sPAP) > 40 mmHg during exercise. EiPAH was associated with lower exercise performance, larger left atrial volumes, higher LVOT gradient and higher VE/VCO2 slope. At multivariable analysis baseline sPAP (p < 0.0001) and baseline LVOT obstruction (p = 0.028) were significantly associated with EiPAH. Kaplan-Meier curve analysis showed EiPAH was a significant predictor of HCM-related morbidity (Hazard Ratio 6.21, 95% CI 1.47-26.19; p = 0.05; 4.21, 95% CI 1.94-9.12; p < 0.001 for the primary and the secondary endpoint respectively). EiPAH was present in about one fifth of HCM patients without evidence of elevated pulmonary pressures at rest and was associated with adverse clinical outcome. Diagnosing EiPAH by exercise echocardiography/CPET may help physicians to detect early stage of PAH thus allowing a closer clinical monitoring and individualized therapies.