Outcomes in Guideline-Based Class I Indication Versus Earlier Referral for Surgical Myectomy in Hypertrophic Obstructive Cardiomyopathy.

Background In patients with obstructive hypertrophic cardiomyopathy, surgical myectomy (SM) is indicated for severe symptoms. We sought to compare long-term outcomes of patients with obstructive hypertrophic cardiomyopathy where SM was based on guideline-recommended Class I indication (Functional Class or FC ≥3 or angina/exertional syncope despite maximal medical therapy) versus earlier (FC 2 and/or impaired exercise capacity on exercise echocardiography with severe obstruction). Methods and Results We studied 2268 consecutive patients (excluding <18 years, ≥ moderate aortic stenosis and subaortic membrane, 56±14 years, 55% men), who underwent SM at our center between June 2002 and March 2018. Clinical data, including left ventricular outflow tract gradient, were recorded. Death and/or appropriate internal defibrillator discharge were primary composite end points. One thousand three hundred eighteen (58%) patients met Class I indication and 950 (42%) underwent earlier surgery; 222 (10%) had a history of obstructive coronary artery disease. Basal septal thickness, and resting and maximal left ventricular outflow tract gradient were 2.0±0.3 cm, 61±44 mm Hg, and 100±31 mm Hg, respectively. At 6.2±4 years after SM, 248 (11%) had composite events (13 [0.6%] in-hospital deaths). Age (hazard ratio [HR], 1.61; 95% CI, 1.26-1.91), obstructive coronary artery disease (HR, 1.46; 95% CI, 1.06-1.91), and Class I versus earlier SM (HR, 1.61; 95% CI, 1.14-2.12) were associated with higher primary composite events (all P<0.001). Earlier surgery had better longer-term survival (similar to age-sex-matched normal population) versus surgery for Class I indication (76 [8%] versus 193 [15%], P<0.001). Conclusions In patients with obstructive hypertrophic cardiomyopathy, earlier versus surgery for Class I indication had a better long-term survival, similar to the age-sex-matched US population.