A subset of hypertrophic cardiomyopathy patients is predisposed to angulated septum

Abstract

Background Hypertrophic cardiomyopathy (HCM) is a complex genetic disease with marked morphofunctional heterogeneity. Some HCM patients develop obstructive symptoms later in life, long after cessation of hypertrophic progression. The mechanism underlying this phenomenon is poorly understood. It is known that aorto-septal angulation progresses with age. However, the relationship between age, septal angulation, and HCM subtype has not been explored. In this present study, we examined the relationship between age, aorto-septal angulation and subtypes of HCM. Methods Control normal subjects (n=19) and consecutive HCM patients with apical, concentric, and septal subtypes (n=53) were identified from the MRI database at YaleNew Haven Hospital. Angulated septal angle, the angle between the right septal surface and anterior aortic wall during end systole and diastole, was measured blindly by two readers. Disagreements between two reads >10˚ were excluded. In addition, we further age stratified our cohort of septal subtype (above or below 40 years) to explore differences in the pattern of aorto-septal angle over age. Results Patients with septal, but not apical or concentric subtypes, exhibit more acute angulated septum versus controls in end-systole (p=0.008, 0.326, and 0.167, respectively). The acuity of this angle increased with age in controls (p=0.0009). Interestingly, HCM patients with septal hypertrophy deviated from this pattern, demonstrating early angulation without progression over age (p=0.918). The associations above remained significant in end-diastole.