[Meta-analysis: its role in clinical decision making in cardiology]

Clinical decision-making in cardiology requires accurate estimates of the efficacy of diagnostic and therapeutic procedures. Defined as the quantitative integration of results from different studies on the same scientific question, meta-analyses are well-suited to summarize the evidence on the efficacy of clinical interventions. Meta-analyses aim at obtaining combined estimates of effect using all relevant information in a systematic fashion, complementing narrative reviews and expert committee reports. In this paper, the advantages and limitations of meta-analyses and their usefulness in clinical decision making in cardiology are illustrated using three recent examples in the literature--i.e., use of beta-blockers in secondary prevention of ischemic heart disease, intravenous streptokinase in acute myocardial infarction and fish intake in primary prevention of cardiovascular mortality. The steps to follow when conducting a meta-analysis are also discussed. Finally, a list of the most important meta-analyses in cardiology published to date is included for easy reference.