Interventricular Electrical Delay Is Predictive of Response to Cardiac Resynchronization Therapy

Michael R Gold; Jagmeet P Singh; Kenneth A Ellenbogen; Yinghong Yu; Nicholas Wold; Timothy E Meyer; Ulrika Birgersdotter-Green

doi:10.1016/j.jacep.2016.02.018

Interventricular Electrical Delay Is Predictive of Response to Cardiac Resynchronization Therapy

JACC Clin Electrophysiol. 2016 Aug;2(4):438-447. doi: 10.1016/j.jacep.2016.02.018. Epub 2016 May 18.

Authors

Michael R Gold¹, Jagmeet P Singh², Kenneth A Ellenbogen³, Yinghong Yu⁴, Nicholas Wold⁴, Timothy E Meyer⁴, Ulrika Birgersdotter-Green⁵

Affiliations

¹ Medical University of South Carolina, Charleston, South Carolina, USA. Electronic address: goldmr@musc.edu.
² Massachusetts General Hospital, Boston, Massachusetts, USA.
³ Virginia Commonwealth University Medical Center, Richmond, Virginia, USA.
⁴ Boston Scientific, St. Paul, Minnesota, USA.
⁵ University of California San Diego, San Diego, California, USA.

PMID: 29759863
DOI: 10.1016/j.jacep.2016.02.018

Abstract

Objectives: This study was conceived to evaluate the relationship between interventricular electrical delay, as measured by the right ventricle-left ventricle (RV-LV) interval, and outcomes in a prospectively designed substudy of the SMART-AV (SMARTDELAY determined AV Optimization) trial.

Background: Despite the well-documented benefit of cardiac resynchronization therapy (CRT), the nonresponder rate remains an important clinical problem. Implanting LV leads by traditional anatomic criteria has limited impact on outcomes. However, pacing at sites with late electrical activation improves CRT response rates. Thus, we hypothesized that interventricular electrical delay is associated with improved CRT outcomes.

Methods: This was a multicenter study of patients with advanced heart failure undergoing CRT implantation. In 419 subjects, the unpaced RV-LV interval was measured in sinus rhythm. LV volumes and ejection fraction were measured by echocardiography at baseline and after 6 months of CRT by a blinded core laboratory. Quality of life (QOL) was assessed by a standardized questionnaire.

Results: When separated by quartiles based on interventricular delay, the magnitudes of LV volumes, ejection fraction and the QOL measure increased significantly with prolongation of RV-LV delay (p < 0.05). The LV end-systolic volume response rate increased progressively from 30% to 75% (p < 0.001), and the QOL response rate increased from 50% to 65% (p = 0.08). Patients in the highest quartile of RV-LV had a 5.98-fold increase (p < 0.001) in their odds of a reverse remodeling response, with female sex, ischemic etiology, and baseline LV end-systolic volume being the other independent predictors of response.

Conclusions: Baseline interventricular delay is a potent independent predictor of remodeling and QOL responses with CRT.

Keywords: cardiac resynchronization therapy; heart failure; interventricular delay; left ventricular reverse remodeling; outcomes.