Biventricular / Left Ventricular Pacing in Hypertrophic Obstructive Cardiomyopathy: An Overview

Abstract

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant inherited genetic disease characterized by compensatory pathological left ventricle (LV) hypertrophy due to sarcomere dysfunction. In an important proportion of patients with HCM, the site and extent of cardiac hypertrophy results in severe obstruction to LV outflow tract (LVOT), contributing to disabling symptoms and increasing the risk of sudden cardiac death (SCD). In patients with progressive and/or refractory symptoms despite optimal pharmacological treatment, invasive therapies that diminish or abolish LVOT obstruction relieve heart failure-related symptoms, improve quality of life and could be associated with long-term survival similar to that observed in the general population. The gold standard in this respect is surgical septal myectomy, which might be supplementary associated with a reduction in SCD. Percutaneous techniques, particularly alcohol septal ablation (ASA) and more recently radiofrequency (RF) septal ablation, can achieve LVOT gradient reduction and symptomatic benefit in a large proportion of HOCM patients at the cost of a supposedly limited septal myocardial necrosis and a 10-20% risk of chronic atrioventricular block. After an initial period of enthusiasm, standard DDD pacing failed to show in randomized trials significant LVOT gradient reductions and objective improvement in exercise capacity. However, case reports and recent small pilot studies suggested that atrial synchronous LV or biventricular (biV) pacing significantly reduce LVOT obstruction and improve symptoms (acutely as well as long-term) in a large proportion of severely symptomatic HOCM patients not suitable to other gradient reduction therapies. Moreover, biV/LV pacing in HOCM seems to be associated with significant LV reverse remodelling.

Dyssynchronization reduces dynamic obstruction without affecting systolic function in patients with hypertrophic obstructive cardiomyopathy: a pilot study

“…As an alternative, biventricular pacing (BiV) to reduce dynamic obstruction in hypertrophic obstructive cardiomyopathy (HOCM) has yielded encouraging results for reducing intraventricular obstruction and for clinical improvement [13][14][15][16][17][18][19][20][21]. However, while its effectiveness was demonstrated, the long-term effect of BiV-pacing on LV function among patients with HOCM and preserved LV ejection fraction is unknown.…”

Quantification of local changes in myocardial motion by diffeomorphic registration via currents: Application to paced hypertrophic obstructive cardiomyopathy in 2D echocardiographic sequences

“…Biventricular pacing has been suggested as a potential alternative to surgery to reduce the obstruction (Berruezo et al, 2011;Vatasescu et al, 2012). This is the treatment received by the patients of our study.…”

“…Naturally, the threshold retained for such a clustering conditions the interpretations. We set this threshold to a reduction P 50%, based on our previous observations (Berruezo et al, 2011) and the available literature (Gersh et al, 2011;Vatasescu et al, 2012). However, the gradient value that is reached at follow-up may be another indicator of interest for response.…”

Cardiac pacing in patients with hypertrophic obstructive cardiomyopathy

“…LV/BiV pacing might be able to induce a supplementary reduction in LVOT gradient by an alteration in the contraction of a larger area of the LV. The reversed LV depolarization sequence [caused by pre-excitation of the LV posterolateral/lateral wall during LV/BiV pacing] may activate the longitudinally oriented epicardial fibers earlier, advancing the lateral wall longitudinal displacement with regard to interventricular septal longitudinal displacement 19 .…”