Background: QRS duration is an important risk factor for both sudden cardiac death and all-cause mortality in patients with moderate to severe left ventricular systolic dysfunction. However, it is unknown whether baseline QRS duration can help predict the mortality benefit from implantable cardioverter-defibrillators (ICDs) when used for primary prevention purposes.
Objective: Our objective was to examine the relationship between baseline QRS duration and mortality reduction with ICDs implanted for primary prevention by performing a meta-analysis of all available randomized clinical trials.
Methods: A systematic literature search of SCOPUS (covering MEDLINE and EMBASE) was conducted for randomized controlled clinical trials involving ICDs. Primary prevention trials of systolic dysfunction that reported all-cause mortality according to subgroups on the basis of baseline QRS duration were included.
Results: A total of four randomized controlled clinical trials enrolling 3561 patients were included. Patients with QRS durations less than 120 ms [n = 2002, hazard ratio 0.78, 95% confidence interval (CI) 0.63-0.96, P = 0.018] and at least 120 ms (n = 1559, hazard ratio 0.59, 95% CI 0.48-0.73, P = 0.0000009) had significant decreases in all-cause mortality. On heterogeneity analysis, a strong trend for greater magnitude of benefit in patients with QRS at least 120 ms was observed (22% risk reduction vs. 41% risk reduction, P = 0.066).
Conclusion: For primary prevention purposes, ICDs are effective in reducing all-cause mortality in moderate to severe systolic dysfunction regardless of QRS duration. However, patients with a baseline QRS duration of at least 120 ms seem to derive a greater mortality benefit from ICDs.