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Editor's Correspondence
Feb 27, 2012

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

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.

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