An Individual Patient Meta-Analysis of Five Randomized Trials Assessing the Effects of Cardiac Resynchronization Therapy on Morbidity and Mortality in Patients With Symptomatic Heart Failure
What variables prior to device implantation predict the response to cardiac resynchronization therapy (CRT)?
A meta-analysis of five randomized trials (MIRACLE, MIRACLE ICD, CARE-HF, REVERSE, RAFT) was conducted comparing CRT with no CRT with more than 6 months of follow-up. The two outcomes were all-cause mortality and first hospitalization for heart failure or death. A total of 4,317 patients were studied comparing CRT with no active control or CRT-D with implantable cardioverter-defibrillator (ICD). Patients with New York Heart Association (NYHA) functional class I and not in sinus rhythm or with a pre-existing pacemaker were excluded from the trial.
A total of 3,782 patients were analyzed. The median age was 66 (58-73) years, QRS duration was 160 (146-176) ms, left ventricular (LV) ejection fraction was 24% (20-28%), and 78% had a left bundle branch block (LBBB); 22% of patients were women. A significant interaction between CRT and QRS duration was observed for both the composite outcome (p < 0.0001) and all-cause mortality alone (p = 0.0013), suggesting that a longer QRS may receive greater benefit from CRT. After adjusting for QRS duration, LBBB on electrocardiogram was not a significant predictor of CRT responder.
In those patients in sinus rhythm, QRS is a predictor of the effects of CRT on morbidity and mortality with symptomatic heart failure and LV dysfunction.
This meta-analysis confirms that patients with a QRS >140 ms with >NYHA class II heart failure symptoms and moderate to severe LV dysfunction in sinus rhythm will benefit from CRT therapy.
Keywords: Heart Diseases, Defibrillators, Follow-Up Studies, Cardiac Pacing, Artificial, Heart Failure, Bundle-Branch Block, Ventricular Function, Pacemaker, Artificial, Electrocardiography, New York, Cardiac Resynchronization Therapy
< Back to Listings