An assessment of regression of left ventricular hypertrophy following alcohol ablation of the interventricular septum in patients with hypertrophic cardiomyopathy with left ventricular outflow tract obstruction

Abstract

Background: Hypertrophic obstructive cardiomyopathy (HOCM) is characterised by asymmetric myocardial hypertrophy, which is most pronounced in the interventricular septum (IVS) and is responsible for the dynamic obstruction of the left ventricular outflow tract (LVOT). Successful alcohol septal ablation (ASA) of the IVS allows to reduce the thickness of the parabasal part of the IVS myocardium and, in most cases, to permanently reduce the gradient in the LVOT.

Aim: To assess, using cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE), the impact of gradient reduction in the LVOT on the type and severity of left ventricular (LV) remodelling.

Methods: The study included 30 patients (aged 56.9 ± 11.9 years) with HOCM and the mean peak gradient (PG) in the LVOT of 123 ± 33 mm Hg who underwent ASA. MRI measurements were performed before and at 6 months after ASA and TTE measurements were performed before, at 3 months and at 6 months after ASA.

Results: PG in the LVOT decreased to an average of 52 ± 37 mm Hg (p < 0.0001) at 3 months after ASA and to 37 ± 28 mm Hg (p < 0.0001) at 6 months after ASA. TTE revealed a decrease in IVS thickness outside the scar following ASA from 23.6 ± 3.5 mm to 19.3 ± 4.0 mm (p < 0.0001) and 19.4 ± 0.4 mm (p < 0.0001) at 3 and 6 months, respectively. There was also a decrease in lateral wall (PW) thickness from 15.9 ± 3.2 mm to 14.9 ± 2.9 mm (p = 0.046) and 14.16 ± 2.00 (p = 0.0065) at 3 and 6 months, respectively. MRI revealed a decrease in IVS thickness from 23.7 ± 2.8 mm to 18.04 ± 4.00 mm (p = 0.0001) at 6 months following ASA. We observed a regression of the PW hypertrophy from 13.2 ± 3.35 mm to 12.18 ± 2.4 mm (p = 0.0225). There was a decrease in IVS mass from 108.9 ± 20 g to 91.5 ± 29 g (p = 0.0006). There was a trend towards a decreased LV mass and LV mass excluding IVS mass at 6 months.

Conclusions: A significant decrease in PG in the LVOT is associated with a decrease in LV mass and with regression of LV hypertrophy outside the scar after ASA.