Impact of surgical myectomy on electrocardiographic changes in patients of hypertrophic obstructive cardiomyopathy

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Hypertrophic cardiomyopathy (HCM) is the commonest genetically inherited cardiac condition affecting 1 in 500 of the population. [1] The amelioration of patient symptomatology and decreased morbidity after surgical myectomy is previously documented. [2]. However, no data is available regarding the associated electrocardiographic changes that may occur after surgical myectomy, especially in patients showed improvement of functional status. Aim of study: The study was conducted to investigate the electrocardiographic changes following surgical myectomy in hypertrophic obstructive cardiomyopathy (HOCM) patients, and its relation to cardiac mechanics Methods The study included 25 patients (mean age: 35.44 ± 12.3 years, 52% male) with HOCM who were subjected to successful surgical myectomy. 12-lead surface ECG and echocardiographic examination including 2D strain imaging were performed pre and post myectomy. Results Postoperatively, 84% of patients developed new complete left bundle branch block (LBBB), 4% developed right BBB (RBBB) and 4% developed complete AV block necessitating permanent pacing. These Changes were associated with increased QRS width and QT interval prolongation in almost all patients (p < 0.001). Following surgery, there was significant reduction in left atrium size, left ventricle mass, LV outflow tract gradient, mitral and annular systolic & diastolic velocities (S’, E’, A’) and EF%(p < 0.001 for all) compared with its preoperative values. At segmental level only LV septal εsys% showed significant inverse correlation to QRS duration (r = 0.47, P < 0.02). No significant correlation was detected between QRS & QTc duration and any other LV wall εsys%. In contrast: QTc intervals showed inverse correlation to the magnitude of reduction in RV εsys %, r=-0.59,P < 0.001 and the magnitude of reduction in RV TTP-SD (r=-.42, P < 0.03). Conclusion Left bundle branch block is a common conduction abnormality after septal myectomy but it did not influence the clinical improvement or structural remodeling. Post myectomy, prolongation of QRS duration was a powerful aspect of mechanical dysfunction especially of septal mechanics than QT interval prolongation. Electrical and mechanical dysfunction is commonly associated while mechanical heterogeneity is not always coexisting.