A cardiac resynchronization therapy (CRT) efficacy review 1 included 14 studies with a total of 4420 subjects, effectiveness review included 106 studies with a total of 9209 subjects, and 89 studies with a total of 9677 subjects reported safety outcomes with implantation of a CRT device. All patients in the CRT studies had left ventricular (LV) systolic dysfunction (mean LV ejection fraction, LVEF range, 21%-30%), prolonged QRS duration (mean range, 155-209 milliseconds), and 91% had New York Heart Association (NYHA) class 3 or 4 heart failure symptoms despite optimal pharmacotherapy. According to the RCT data, CRT improved LVEF (WMD 3.0%, 95% CI 0.9% to 5.1%), quality of life (weighted mean reduction in Minnesota Living With Heart Failure Questionnaire, 8.0 points, 95% CI 5.6 to10.4 points), and functional status (improvements of >/=1 NYHA class were observed in 59% of CRT recipients in the randomized trials). CRT decreased hospitalizations by 37% (95% CI 7% to 57%), and all-cause mortality decreased by 22% (95% CI 9% to 33%).
The pooled effectiveness estimates from the observational studies for functional outcomes were consistent with those estimates from the efficacy RCTs. Safety data found that implant success rate was 93.0% (95% CI 92.2% to 93.7%) and 0.3% of patients died during implantation (95% CI 0.1% to 0.6%). During a median 11-month follow-up, 6.6% (95% CI 5.6% to 7.4%) of CRT devices exhibited lead problems and 5% (95% CI 4% to 7%) malfunctioned.
The incremental benefits of combined CRT plus implantable cardioverter-defibrillator devices vs CRT-alone devices in patients with left ventricular systolic dysfunction remain uncertain.
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