Outcomes in patients with hypertrophic cardiomyopathy developing left ventricular systolic dysfunction after septal reduction therapy

Abstract

Abstract Background In hypertrophic cardiomyopathy (HCM), systolic dysfunction (SD), defined by a left ventricular ejection fraction (LVEF) <50% is associated with a poor prognosis. After septal reduction therapy (SRT), anticipated alterations in left ventricular geometry and septal desynchrony may lead to reduction in LVEF. The prognostic significance of a reduction in LVEF <50% following SRT has not been established. Purpose To investigate the relationship between new development of SD post SRT and outcomes in HCM patients. Methods Of the 4110 HCM patients at our referral centre, 179 patients (4.4%) developed SD during follow up. The composite cardiac outcome was defined as the occurrence of new resuscitated cardiac arrest, ventricular tachycardia or ventricular fibrillation, and cardiac death after the onset of SD. Results Of the 179 patients who developed systolic dysfunction (SD), 67 patients developed it after undergoing septal reduction therapy (SRT) (4 patients underwent alcohol septal ablation, and 63 patients underwent septal myectomy). Both groups had similar characteristics with respect to age at the time of SD identification (59.9 ± 13.5 years vs. 59.6 ± 14.2 years, P=0.88), gender (76% men vs. 66% men, P=0.18), and genotype (24% had pathogenic or likely pathogenic variants vs. 28%, P=0.07). Despite similar LVEF at the time of presentation with SD between the two groups (44.1 ± 4.2% vs. 44.4% ± 4.9%, P=0.75), patients who underwent SRT had a lower maximal wall thickness (17.4 ± 4.9mm vs. 19.2 ± 5.2mm, P=0.02), larger end-diastolic diameter (5.3 ± 0.8mm vs. 4.8 ± 0.8mm, P<0.001) and end-systolic diameters (3.8 ± 0.7mm vs. 3.2 ± 0.8mm, P<0.001) than patients without SRT. Furthermore, patients who underwent SRT had a longer QRS complex duration (162.3 ± 20.6ms vs. 125.1 ± 31ms, p<0.001) and lower brain natriuretic peptide (BNP) (359.3 ± 632.9pg/ml vs. 690.8 ± 841.8pg/ml, p=0.04) during follow up than patients without prior SRT. During a mean follow up of 4.7 ± 4.1 years, the incidence of the composite cardiac outcome was significantly lower in patients who underwent SRT than in patients without prior SRT (7.5% vs. 20.5%, P=0.02). Notably, there were no observed sudden cardiac deaths observed in those who developed SD post SRT. Conclusion The prognosis for patients with HCM who underwent SRT and subsequently developed SD was significantly more favourable than for those who did not have a history of SRT. Thus, changes in left ventricular geometry and LVEF after SRT may not necessarily translate into a worsened prognosis.