Changes in left atrial function, left ventricle remodeling, and fibrosis after septal myectomy for obstructive hypertrophic cardiomyopathy

Abstract

Background: This study aimed to investigate the impact of septal myectomy on left atrial function, left ventricle remodeling, and fibrosis in patients with obstructive hypertrophic cardiomyopathy.

Method: From May 2012 to September 2016, preoperative cardiac magnetic resonance imaging of 507 adult patients who underwent septal myectomy at Fuwai Hospital was retrospectively collected. Until October 2019, 57 patients were followed up with postoperative cardiac magnetic resonance imaging at 11.9 months (interquartile range, 6.4-25.3). Preoperative and postoperative left atrium and left ventricle changes, as well as late gadolinium enhancement as a surrogate of myocardial fibrosis, were analyzed.

Results: Patients with hypertrophic cardiomyopathy requiring myectomy showed increased left atrium volume, stroke volume, left ventricular ejection fraction, and left ventricle mass, as well as decreased left ventricle end-systolic volume. Echocardiography demonstrated that myectomy decreased the left ventricle outflow tract gradient, left atrium diameter, left ventricular ejection fraction, and posterior wall thickness. Postoperative cardiac magnetic resonance imaging showed that the minimal left atrium volume (P < .001), stroke volume (P = .009), left ventricle ejection fraction (P < .001), and left ventricle mass (166.9 [interquartile range, 135.8] vs 149.3 [interquartile range, 100.5] g, P < .001) decreased, whereas the left ventricle end-systolic volume (P = .001) and left atrium ejection fraction (37.9% ± 14.6% vs 47.8% ± 14%, P < .001) increased. However, left ventricle myocardial fibrosis, as detected by late gadolinium enhancement, still progressed after myectomy in patients with obstructive hypertrophic cardiomyopathy (15.2% ± 9.6% vs 18.6% [interquartile range, 21.6], P = .009).

Conclusions: Septal myectomy alleviated left ventricle hypertrophy and reversed left atrium and left ventricle remodeling in patients with obstructive hypertrophic cardiomyopathy. Late gadolinium enhancement in the left ventricle increased despite myectomy in patients with obstructive hypertrophic cardiomyopathy.

Keywords: hypertrophic cardiomyopathy; late gadolinium enhancement; left atrium volume; left ventricle mass; septal myectomy.