Heart failure (HF) symptoms, related to pulmonary capillary hypertension, are frequent in hypertrophic cardiomyopathy (HCM). Pulmonary hypertension (PH) is the consequence of left ventricular (LV) diastolic pressure elevation and/or functional mitral regurgitation. We aimed to evaluate determinants and prognostic significance of rest and exercise in HCM.

We included 235 patients referred for clinical work-up of HCM. Rest pulmonary artery systolic pressure (PASP) was measurable in 214 (91%) patients (48±16 years, 161 males). A symptom-limited semi-supine bicycle exercise was carried out in 188 patients. PASP was measurable during exercise in 108 patients (57%). Resting PH (≥36mmHg) was present in 56 patients (26.2%) and exercise PH (≥60mmHg) in 38 patients (35.2%). Mutivariate correlates of rest PASP were sinus rhythm (β=–0.15, P=0.021), LV obstruction tract (LVOT) peak gradient (β=0.22, P=0.001) and left atrial volume (β=0.39, P<0.0001). Multivariate resting correlates of exercise PASP were PASP (β=0.28, p=0.001) and mitral regurgitation (MR) grade (β=0.48, P<0.0001). LVOT peak gradient emerged as an independent correlate of exercise PASP when MR was excluded. Patients with rest PH had a worse event-free survival at 4 years (24.8±8.8 vs 66.2±5.2%, P<0.0001), survival without HF (55.6±10.5 vs 81.8±4.3%, P=0.005), and overall survival (84.2±7.1 vs 97.1±1.7%, P=0.001). Patients with exercise PH had also a worse event-free survival (47.7±9.5 vs 65.7±7.5%, P=0.007) and a worse survival without HF (64.1±9.4 vs 83.4±5.5%, P=0.016). By contrast, there was no difference regarding overall survival (p=0.49).

In patients with HCM, the main determinants of rest PH are sinus rhythm, LVOT peak gradient and left atrium volume. Determinants of exercise PH are rest PASP, grade of MR and rest LVOT gradient. Rest and exercise PH predict a poor outcome in HCM.