Left ventricular mechanics before and after myectomy in patients with hypertrophic obstructive cardiomyopathy

Abstract

Objectives The objective of this paper is to detect changes in left ventricular (LV) mechanics after surgical myectomy in patient with hypertrophic obstructive cardiomyopathy (HOCM). Background Septal myectomy is the gold standard method to relieve LV outflow tract pressure gradient in patients with HOCM. Myocardial mechanics are abnormal in those patients, demonstrating low longitudinal strain, high circumferential strain, and high apical rotation, compared with healthy patients. The aim of this study was to determine whether functional improvement after myectomy is associated with improved myocardial mechanics. Patients and methods A total of 15 patients (60% males and 40% female) with HOCM refractory to medical treatment were subjected to septal myectomy. Clinical data and paired echocardiographic studies before and within 6 months after myectomy were analyzed and compared. Myocardial mechanics including longitudinal and circumferential strain and rotation and LV synchronization were assessed using two-dimensional strain software (velocity vector imaging). Results Results showed significant symptomatic relief. LV outflow gradient decreased dramatically from 63.13 ± 10.25 to 9.96 ± 2.72 mmHg (P < 0.0001) and left atrial volume index decreased from 37.8 ± 5.61 to 26.38 ± 3.37 cm3/m2 (P < 0.05). E/e′ decreased from 15.23 ± 2.39 to 9.18 ± 1.42 (P < 0.05). Low longitudinal strain decreased at the myectomy site (basal septum), increased in the basal inferior segment, and remained unchanged globally − 6.43 ± 6.54 to − 8.70 ± 2.30 (P = 0.232). High circumferential strain decreased from − 28.47 ± 3.35 to − 18.26 ± 2.86 (P < 0.05). High LV twist normalized from 16.52 ± 2.25 to 14.02 ± 2.27 (P < 0.05). Conclusion Patients with HOCM show mechanical adaptations to chronic elevated afterload similar to patients with severe aortic stenosis in whom there is increased circumferential strain, increased basal and apical rotation, and LV twist. However, within 6 months after myectomy, global longitudinal strain remained unchanged, circumferential strain and rotation decreased, LV twist normalized, and LV dyssynchrony showed no significant changes. Thus, improvement of symptoms after myectomy is mainly because of improvement of the predictors of diastolic function.