Overview of systematic reviews on invasive treatment of stable coronary artery disease

Objectives: The aim of the study was to evaluate the validity of the systematic reviews as a source of best evidence and to present and interpret the evidence of the systematic reviews on effectiveness of surgery and percutaneous interventions for stable coronary artery disease. Methods: Electronic databases were searched without language restriction from January 1966 to March 2004. The databases used included the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, DARE, the Health Technology Assessment Database, MEDLINE(R), MEDLINE(R) In-Process & Other Non-Indexed Citations. We included systematic reviews of randomized clinical trials on patients with stable coronary heart disease undergoing percutaneous coronary intervention or coronary artery bypass surgery in comparison with medical treatment or a comparison between invasive techniques. At least one of the following outcomes had to be reported: death, myocardial infarction, angina pectoris, revascularization. The methodological quality was assessed using a modified version of the scale devised by Oxman and Guyatt (1991). A standardized data-extraction form was used. The method used to evaluate clinical relevance was carried out with updated method guidelines from the Cochrane Back Research Group. Quantitative synthesis of the effectiveness data is presented. Results: We found nineteen systematic reviews. The median score of validity was 13 points (range, 6-17 points), with a maximum of 18 points. Coronary artery bypass surgery gives better relief of angina, and the need for repeated procedures is reduced after bypass surgery compared with percutaneous interventions. There is inconsistent evidence as to whether bypass surgery improves survival compared with percutaneous intervention. A smaller need for repeated procedures exists after bare metal stent and even more so after drug-eluting stent placement than after percutaneous intervention without stent placement. However, according to the current evidence, these treatment alternatives do not differ in terms of mortality or myocardial infarction. Conclusions: We found some high-quality systematic reviews. There was evidence on the potential of invasive treatments to provide symptomatic relief. Surgery seems to provide a longer-lasting effect than percutaneous interventions with bare metal stents or without stents. Evidence in favor of drug-eluting stents so far is based on short-term follow-up and mostly on patients with single-vessel disease.