Long term outcome after septal reduction therapies in patients with hypertrophic cardiomyopathy: insights from the SHaRe registry

Abstract Background Long term outcome after septal reduction therapies SRT in HCM patients is largely unresolved, since most available studies report post-operative results up to 1 year. Purpose To evaluate the long term outcome and its predictors in patients with HCM from the SHaRe Registry (Sarcomeric Human Cardiomyopathy Registry) Registry. Methods Data from 11 high-volume HCM specialty centers from the international SHaRe Registry were used to describe the natural history of patients with SRT. Patients were followed from SRT until last follow-up or meeting the composite outcome of heart failure (cardiac transplantation, implantation of an LV assist device (LVAD), left ventricular ejection fraction (LVEF) <35%, development of NYHA class III-IV symptoms), ventricular arrhythmias (sudden cardiac death (SCD), resuscitated cardiac arrest, or appropriate implantable cardioverter-defibrillator (ICD) therapy) or HCM related death. Cox proportional hazards models were used to identify predictors of prognosis and incident development. Results Of the 10385 patients part of the ShaRe Registry, 1835 (18%, 968 (53%) males) underwent a SRT during a median follow-up of 6.8 (IQR 3.4-9.8). A total of 455 (25%) had Alcohol Septal Ablation (ASA) and 1377 (75%) had myectomy. Patients who underwent myectomy were younger (49±18 vs 56±15 years, p<0.01), more frequent with a sarcomeric mutation (396 (29%) vs 111 (24%), p<0.01), where less frequently severely symptomatic (373 (82%) vs 971 (71%) in NYHA Class III, p<0.01) and presented a more dilated left atrium (396 (29%) vs 111 (24%), p<0.01). Peri-procedural mortality was extremely low (2 (0.4%) and 4 (0.3%) in ASA and myectomy respectively). Over 6.8 years after the procedure, 77 (4%) died because of HCM (0.6%/year), 236 (13%) presented a composite HF outcome (1.9%/year) and 87 (5%) a composite VA outcome (0.7%/year). Development of the composite HF events was associated with older age at procedure (56±15 vs 49±18 years, p<0.01), the presence of a sarcomere mutation (82 (36%) vs 425 (27%), p<0.01) and a more severely dilated LA (45±10 vs 42±11 years, p<0.01). Patients who presented a composite VA event were younger at procedure (38±20 vs 54±18 years, p<0.01), developed more often a LV EF< 50% (29 (33%) vs 351 (20%), p<0.01) and a more severely dilated LA (47±7 vs 43±11 years, p<0.01) and greater LV maximal wall thickness (24±6 vs 21±6 years, p<0.01). Significant predictors of the composite HF outcome were the presence of a sarcomeric variants (hazard ratio [HR], 2.3 [95% CI, 1.3–5.6.5]) and LA diameter ≥ 45 mm (HR, 2.6 [95% CI, 1.7–3.5]). No significant difference was present between the two procedures in overall mortality, HF and VA composite outcome. Conclusions SRT were performed in 18% of patient with HCM and associated with a low peri-procedural mortality. Long term outcome was favourable but not uneventful, mainly driven by heart faluire related events.