Anatomical left ventricular lead location and clinical outcome: not a one size fit all strategy

Abstract

This editorial refers to ‘Left ventricular lead position for cardiac resynchronization: a comprehensive cinegraphic, echocardiographic, clinical, and survival analysis’ by Y.-X. Dong et al., on page 1139 Cardiac resynchronization therapy (CRT) has successfully altered the natural course of symptomatic heart failure in patients with co-existing conduction disease. 1 – 3 Cardiac resynchronization therapy exerts its physiological impact through instituting synchronized ventricular contraction, leading to favourable remodelling and improvement in ejection fraction. Despite the success of this therapeutic modality, a significant minority of patients may not respond adequately to this pacing therapy. Besides selecting the right patient and thoughtful programming of these devices, the location of the left ventricular (LV) lead is now understood to be a major determinant of response to CRT. Much of the effort over the past several years has been directed to establish the most optimal anatomical location for pacing the left ventricle. Interestingly, the methodology between most studies has been variable, the included population different and evidently the results have been conflicting. 4,5 Now, a decade after implementation of what we all recognize as novel and successful intervention, we are still debating and evaluating the best ‘anatomical site’ for pacing. In this issue of the journal, Dong et al., 6 have retrospectively analysed a cohort of 457 patients who received either a CRT-P or defibrillator over the course of a 7-year period at Mayo Clinic. The authors classified their LV lead location in the short axis along the antero-septum, anterior, antero-lateral, postero-lateral, posterior, and postero-septum and in the longitudinal axis into basal, midventricular, and apical segments. The apical segment was further sub-stratified into the anterior, lateral, posterior, and septal walls. 6 Clinical follow-up involved assessing the New York Functional Class (NYHA) class (un-blinded), echocardiographic evaluation of ventricular ejection fraction and remodelling, while survival status was obtained using the national death and location database. There was an improvement in the NYHA class and a non-significant trend to improved remodelling across all lead locations, with the magnitude of improvement better in the nonanterior location. Survival at 4 years was poorest at 48% with in the subgroup of patients with a lead in the anterior location, as compared with the antero-lateral (72%) and postero-lateral (62%) locations. Interestingly, there were no differences in outcomes when lead location was stratified along the longitudinal axis, i.e. the clinical outcome with the lead in the apical location was no different in comparison to basal/mid-ventricular location. 6