Surgical myectomy improves pulmonary hypertension in obstructive hypertrophic cardiomyopathy

Aims: Characterization of pulmonary hypertension (PH) and the effects of myectomy in hypertrophic cardiomyopathy (HCM) remain poorly defined. The aim of the study was to investigate the effect of myectomy on PH in HCM. Methods and results: This is a retrospective analysis of 306 consecutive symptomatic HCM patients (70% NYHA class III-IV) with evaluation of echocardiographic right ventricular systolic pressure (RVSP) both preceding (median 3 days) and following (median 4 days) myectomy. Compared with patients without PH (RVSP <35 mmHg, n = 145, 47%), patients with moderate or severe PH (RVSP ≥50 mmHg, n = 51, 17%) were older, predominantly female, had a greater prevalence of atrial fibrillation, higher natriuretic peptide levels, higher left ventricular outflow tract gradient, higher E velocity, and larger left atria. Reduction of RVSP post-myectomy was evident in patients with moderate or severe PH [59 (IQR 54-71) to 50 (IQR 39-62) mmHg, P < 0.0001] and in all patients with PH [RVSP ≥ 35 mmHg, n = 161, 43 (IQR 39-54) to 41 (IQR 35-52) mmHg, P < 0.0001]. In a subgroup of patients with longterm data, PH continued to decline during follow-up. Clinical variables associated with improvement in PH in these patients were higher left atrial volume index (R = 0.43, P = 0.0069) and moderate or severe mitral regurgitation (R = 0.33, P = 0.038). Conclusion: Surgical myectomy is associated with improvement in PH, most pronounced in moderate or severe PH. These data provide insight into pulmonary haemodynamics following obstruction relief and can help to guide therapeutic expectations.