Optimizing RV lead position in RV cardiomyopathy: Are we there yet?

Abstract

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is an inherited arrhythmic cardiomyopathy characterized by progressive fibro-fatty replacement of the right ventricular myocardium [1,2]. One of the major advances in the management of this lifethreatening disease is the use of ICD (Implantable Cardioverter Defibrillator) to prevent sudden death as well as treat sustained ventricular arrhythmias [3]. The defibrillating lead is invariably placed in the right ventricle and may be affected by the progressive disease process, as such, long term lead performance in ARVD/C is of significant interest. In this current issue of Indian Pacing and Electrophysiology journal, Lane et al. compared the lead parameters in ICD and CRT-D (Cardiac Resynchronization TherapyDefibrillator) and indices of ventricular function among patients with Arrhythmogenic and Dilated cardiomyopathies (DCM) [4]. The authors conducted a retrospective record review of 1676 patients undergoing ICD or CRT-D implant at St Bartholomew s and the Heart Hospitals, London between 2011 and 2016 and identified 18 patients with a confirmed diagnosis of ARVC who had a de-novo device placement. These patients were followed with a comparator group of 18 patients with confirmed diagnosis of idiopathic DCM for a mean of 30 months. Compared to DCM, ARVC patients started with a lower R wave amplitude at baseline (D 5.6 mV, p < 0.001), however, no significant changewas observed in the lead parameters irrespective of septal versus non-septal locations. Similarly, RV lead threshold was significantly higher in the ARVC patients when compared to DCM group (D þ0.2V, p 1⁄4 0.031) which remain unchanged over time. Therewas limited data for LV lead threshold for ARVC patients as compared to the DCM patients who depicted significant increase with time. The authors also show a progressive decline in LV function in ARVC over 5 years with no change in DCM group. Data on TAPSE was restricted to ARVC patients which showed no significant change with time. Contrary to prior reports [5], the authors found that the RV leads in the septal position had lower sensing during follow up compared to RV apical leads, which in fact had improved sensing. Right ventricular septum is characteristically spared in ARVC and often thought to be the best location for lead deployment due to its stable sensing parameters. The discrepancy in findings may be due to differences in the population and/or related to the small sample size and retrospective nature of this study. Progressive RV structural involvement would likely impact sensing in the RV apex which is usually affected in severe phenotypes. Another important finding of the study was the significant reduction of LVEF with progression in time in ARVC group as compared to the DCM group. Left ventricular involvement is well recognized in ARVC which may parallel or