Abstract 15813: Impact of QRS Duration on Clinical Event Reduction with Cardiac Resynchronization Therapy: A Meta-Analysis of Randomized Controlled Trials
Context: Cardiac resynchronization therapy (CRT) is effective in reducing clinical events in patients with heart failure and prolonged QRS duration. Current guidelines recommend CRT in class III and IV systolic heart failure patients with QRS≥120 ms. However, one-third to one-half of these patients do not respond to CRT.
Objectives: To determine whether the effect of CRT on clinical events (all-cause death, hospitalizations) is different in patients with severely (i.e. ≥150 ms) vs. moderately (i.e. <150 ms) prolonged QRS by performing a meta-analysis of randomized controlled trials.
Methods: Searches of MEDLINE and SCOPUS databases were conducted for randomized controlled CRT trials. Fixed effect models were used to obtain meta-analytic risk ratios and 95% confidence intervals (CI); random effects models were used if there was evidence of heterogeneity. A meta-regression analysis was performed to examine the relationship between the QRS duration and risk ratio.
Results: A total of 5 randomized trials enrolling 4,340 patients were included. In patients with severely prolonged QRS (usually ≥150 ms, n= 2,588) there was a significant reduction in composite clinical events with CRT (I2=45.6%, RR=0.60 [95% CI: 0.49–0.73], p<0.000001). On the contrary, there was no such benefit for patients with moderately prolonged QRS (usually <150 ms, n=1,734) (I2=0%, RR 0.93 [95%CI: 0.79–1.10], p=0.38), resulting in a significantly different effect between the two QRS groups (p<0.001). On meta-regression, there was a highly statistically significant relationship between the baseline QRS duration and log risk ratio (p=0.00017) with benefit of CRT appearing at a QRS duration of approximately 150 ms and above (Figure).
Conclusions: CRT was very effective in reducing adverse clinical events in heart failure patients with QRS duration ≥150 ms, but did not reduce such events in patients with QRS <150 ms. These findings have implications for the selection of patients for CRT.
- © 2010 by American Heart Association, Inc.