Authors
Hsing JM, Selzman KA, Leclercq C, et al.
Title
Paced left ventricular QRS width and ECG parameters predict outcomes after cardiac resynchronization therapy: PROSPECT-ECG substudy.
References
Circ Arrhythm Electrophysiol 2011:851-7.
Background
For patients with symptomatic New York Heart Association class III or IV, ejection fraction ≤ 35%, and QRS ≥ 130 ms, cardiac resynchronization therapy (CRT) has become an established treatment option. However, use of these implant criteria fails to result in clinical or echocardiographic improvement in 30% to 45% of CRT patients.
Purpose
In a prospective, multicenter setting, the Predictors of Response to CRT (PROSPECT) study tested the performance of these parameters to predict CRT response. PROSPECT-ECG is a substudy of the prospective observational PROSPECT trial. ECGs collected before, during, and after CRT implantation were analyzed to identify important predictors for clinical and echocardiographic improvement after CRT implantation.
Design
Prospective, multicenter, nonrandomized study. Patients with heart failure symptoms referred for CRT according to the current guidelines for the treatment of chronic heart failure were evaluated for enrollment 53 centers in Europe, Hong Kong, and the United States enrolled 498 patients with standard CRT indications (New York Heart Association class III or IV heart failure, left ventricular ejection fraction ≤ 35%, QRS ≥ 130 ms, on stable medical regimen). Primary outcomes were improvement in clinical composite score (CCS) and reduction of left ventricular end systolic volume (LVESV) of >15% after 6 months Age, sex, cause of cardiomyopathy, myocardial infarction location, right ventricular function, mitral regurgitation, preimplantation QRS width, preimplantation PR interval, preimplantation right ventricular-paced QRS width, preimplantation axis categories, LV-paced QRS width, postimplantation axis categories, difference between biventricular (Bi-V) pacing and preimplantation QRS width, and QRS bundle branch morphological features were analyzed univariably in logistic regression models to predict outcomes. All significant predictors (α=0.1), age, and sex were used for multivariable analyses. Cardiomyopathy cause interaction and subanalyses were also performed.
Exclusion Criteria
QRS < 130 ms
Follow-Up
6 months
Treatment Regimen
Cardiac resynchronization therapy (CRT)
Results
Primary Endpoints In multivariable analyses, only QRS left bundle branch (LBBB) morphological features predicted both CCS (odds ratio [OR]=2.46, P=0.02) and LVESV (OR=2.89, P=0.048) response. The difference between Bi-V and preimplantation QRS width predicted CCS improvement (OR=0.89, P=0.04). Secondary outcomes LV-paced QRS width predicted LVESV reduction (OR=0.86, P=0.01). Specifically, an LV-paced QRS width of ≤ 200 ms was predictive of nonischemic LVESV reduction (OR=5.12, P=0.01).
Summary
The ECG is a simple and inexpensive tool that can help identify candidates for CRT and guide the selection of the optimal vein for resynchronization. In PROSPECT-ECG, only QRS left bundle branch morphological features predicted both CCS and LVESV response; LV-paced QRS width predicted LVESV response, and the difference between Bi-V and pre-implantation QRS widths predicted CCS response. In addition, the study presented a potentially novel ECG parameter, LV-paced QRS width, as a predictor of LVESV response. Some ECG parameters were more predictive of CRT response in patients with a non-ischemic cardiomyopathy.