Abstract 12258: The Role of Electrical Delay (QLV) to Predict Left Ventricular Reverse Remodeling with Cardiac Resynchronization Therapy
Introduction: Despite the well documented benefits of CRT, the non-responder rate remains problematic. QRS duration and morphology are the most consistent predictors of response. To evaluate whether markers of electrical dyssynchrony provide incremental prognostic information, we evaluated the role of the QLV interval to predict outcomes as part of a prospective substudy of the SMART-AV trial.
Methods: A total of 426 patients enrolled in SMART-AV were analyzed. The QLV was defined as the time interval from the first deflection on a surface ECG to the peak of the LV electrogram and was measured in a blinded core lab. The primary endpoint (CRT response) of this trial was a > 15 ml reduction in LVESV from implant to 6 months, as assessed by the core lab. Multivariate logistic regression models were utilized to analyze the association between QLV and CRT response adjusting for baseline covariates. Data are presented as Mean (±SD) unless noted otherwise.
Results: The baseline characteristics for the study patients were 66% male, mean age 66 ± 11 years, left ventricular ejection fraction 28% ± 9%, QRS width 149 ± 25 msec and LVESV 129 ± 62 ml. The overall reduction in LVESV was -20 ± 42 ml and the CRT response rate was 53%. Patients were grouped by QLV tertiles with cutoffs of 80 ms and 110 ms. The changes in LVESV with CRT for the 3 groups are shown in Figure. The response rates for the QLV tertiles were 41%, 48% and 71%, respectively (P<0.001). QLV added significant predictive value for CRT response after accounting for baseline covariates in the regression models including QRS duration and morphology (Figure). Patients in the highest tertile of QLV had a greater than 3.5 fold increase in their odds of response vs. the shortest tertile.
Conclusions: Baseline electrical dyssynchrony as assessed by QLV, predicted the magnitude of structural response to CRT. The QLV interval can be measured at implant and may provide a simple means of selecting LV stimulation site and possibly maximizing CRT response.
- © 2011 by American Heart Association, Inc.