To perform a meta-analysis of all reported randomised trials that directly compare coronary artery bypass graft (CABG) with percutaneous transluminal coronary angioplasty (PTCA) in patients with multivessel disease.

MEDLINE and BIOSIS previews were searched from 1985 to 1995 for studies published in the English language. Randomised trials were identified using the search strategy designed for the Cochrane Collaboration. References of retrieved articles were checked, and professional contacts were pursued to identify all relevant trials.

Study designs of evaluations included in the review

Randomised trials were included.

Specific interventions included in the review

Coronary revascularisation: coronary artery bypass graft (CABG) and percutaneous transluminal coronary angioplasty (PTCA).

Participants included in the review

Patients with multi-vessel disease. Overall, 15% had 1-vessel, 57% had 2-vessel and 28% had 3-vessel disease. Patients with left main disease, recent myocardial infarction (MI), and prior CABG or PTCA were excluded.

Outcomes assessed in the review

Death, and combined death and nonfatal MI (separately analysed for periprocedural events and for those occurring during follow-up); freedom from angina (defined as Canadian Cardiovascular Society class 1); repeat revascularisation with CABG; repeat revascularisation with PTCA.

How were decisions on the relevance of primary studies made?

The authors do not state how the papers were selected for the review, or how many of the authors performed the selection.

The authors do not report the method used to assess validity, or how the validity assessment was performed.

The data were extracted by two independent reviewers and any disagreements were resolved by a third party. All trial investigators were contacted for descriptions of their study populations.

How were the studies combined?

Meta-Analyst software was used to combine all outcomes with both the Mantel-Haenszel fixed-effect method and the DerSimonian and Laird random-effects method (see Other Publications of Related Interest). The odds ratio (OR) was used as the point estimate, with 95% confidence intervals (CIs).

How were differences between studies investigated?

No statistical test of heterogeneity is reported. However, both random-effects and fixed-effect methods were used to calculate the ORs. One study included both 1-vessel and multi-vessel disease patients; meta-analysis was undertaken both including and excluding this trial.

Five randomised controlled trials (RCTs) were included (n=2,943).

The fixed-effect and random-effects methods gave similar levels of statistical significance, except where noted. Hence, only results for the fixed-effect method are reported.

Since the results obtained when including and excluding 1-vessel disease patients were essentially identical, only the former results are reported.

Results at 1 to 3 years of follow-up: overall risk of death was similar in CABG (3.7%) and in PTCA (3.9%) patients, OR 0.93 (95% CI: 0.63, 1.34, p=0.67).

Combined risk of death or nonfatal MI was also similar in CABG (10.1%) and PTCA patients (9.8%), OR 1.03 (95% CI: 0.81, 1.32, p=0.81).

CABG patients were significantly more likely to be angina free (80.7 versus 73.1%), OR 1.57 (95% CI: 1.32, 1.87, p<0.00001).

CABG patients were also significantly less likely to undergo either a subsequent CABG (1 versus 19.7%), OR 0.04 (95% CI: 0.02, 0.07, p<0.00001) or subsequent PTCA (6 versus 22.9%), OR 0.21 (95% CI: 0.16, 0.27, p<0.00001).

In-hospital results: the in-hospital death rate was similar in both the CABG and PTCA patients (1.4 versus 1.2%), OR 1.15 (95% CI: 0.60, 2.18, p=0.68), as was the combined risk of death or nonfatal MI (5.7 versus 4.4%), OR 1.33(95% CI: 0.96, 1.86, p=0.091).

CABG and PTCA patients have similar overall risks of death and nonfatal MI at 1 to 3 years of follow-up, but relative risk differences in mortality of up to 25% cannot be excluded. CABG patients have significantly less angina and less repeat revascularisation than PTCA patients. Generalisation of these results to other patient groups is limited by the stringent entry criteria.

The meta-analysis is clear and well-discussed. Greater detail of search terms used for retrieving articles, and description of validity assessment would enhance this review.

This study suggests that CABG may be superior to PTCA in terms of morbidity outcome and similar in terms of mortality.

Agency for Health Care Policy and Research, grant number HS 08362; Robert Wood Johnson Foundation

DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-88.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.