Sipahi et al1 report a meta-analysis to evaluate the impact of QRS duration in patients with heart failure receiving cardiac resynchronization therapy (CRT) as measured by composite clinical events. This analysis including 5 randomized controlled trials attempts to address a discordance between Heart Failure Society of America (HFSA) and European Society of Cardiology (ESC) guidelines recommending CRT in patients with New York Heart Association (NYHA) III/IV heart failure and a QRS interval greater than 120 milliseconds, and published data suggesting greater benefit at higher QRS cutoffs. The conducted meta-analysis represents a post hoc subgroup analysis, according to QRS cutoff values used in each study. There are 2 major concerns that threaten the validity of the authors' conclusions in this study, namely multiplicity of analysis and loss of randomization.
Magee CD, Byars LA, DeZee KJ. Limitations of Subgroup Analyses in Meta-analysis of Cardiac Resynchronization Therapy by QRS Duration. Arch Intern Med. 2012;172(4):375–376. doi:10.1001/archinternmed.2011.1499
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