Effect of QRS duration and morphology on cardiac resynchronization therapy outcomes in mild heart failure: results from the Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) study.
BACKGROUND
Cardiac resynchronization therapy (CRT) decreases mortality, improves functional status, and induces reverse left ventricular remodeling in selected populations with heart failure. We aimed to assess the impact of baseline QRS duration and morphology and the change in QRS duration with pacing on CRT outcomes in mild heart failure.


RESULTS
Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) was a multicenter randomized trial of CRT among 610 patients with mild heart failure. Baseline and CRT-paced QRS durations and baseline QRS morphology were evaluated by blinded core laboratories. The mean baseline QRS duration was 151±23 milliseconds, and 60.5% of subjects had left bundle-branch block (LBBB). Patients with LBBB experienced a 25.3-mL/m(2) mean reduction in left ventricular end-systolic volume index (P<0.0001), whereas non-LBBB patients had smaller decreases (6.7 mL/m(2); P=0.18). Baseline QRS duration was also a strong predictor of change in left ventricular end-systolic volume index with monotonic increases as QRS duration prolonged. Similarly, the clinical composite score improved with CRT for LBBB subjects (odds ratio, 0.530; P=0.0034) but not for non-LBBB subjects (odds ratio, 0.724; P=0.21). The association between clinical composite score and QRS duration was highly significant (odds ratio, 0.831 for each 10-millisecond increase in QRS duration; P<0.0001), with improved response at longer QRS durations. The change in QRS duration with CRT pacing was not an independent predictor of any outcomes after correction for baseline variables.


CONCLUSIONS
REVERSE demonstrated that LBBB and QRS prolongation are markers of reverse remodeling and clinical benefit with CRT in mild heart failure.


BACKGROUND
URL: http://www.clinicaltrials.gov. Unique identifier: NCT00271154.
Division of Cardiology, Medical University of South Carolina, 25 Courtenay Dr, ART 7031, Charleston, SC 29425-5920, USA. goldmr@musc.edu
Michael R
MR
Gold
Christophe
C
Thébault
Cecilia
C
Linde
William T
WT
Abraham
Bart
B
Gerritse
Stefano
S
Ghio
Martin
M
St John Sutton
Jean-Claude
JC
Daubert
D000368:Aged; D002037:Bundle-Branch Block / Q000150:complications; D058406:Cardiac Resynchronization Therapy; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology; D006333:Heart Failure / Q000209:etiology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications; D012720:Severity of Illness Index; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy; D020257:Ventricular Remodeling / Q000502:physiology