People who undergo bypass surgery for narrowed coronary vessels may be less likely to need re-intervention than those treated using angioplasty with stents

Narrowing of coronary arteries can be alleviated by complete replacement using bypass surgery or, alternatively, unblocking and supporting the vessels open using angioplasty and stents. Analysis of RCTs to 2004 indicates re-intervention (to alleviate subsequent narrowing) is needed less commonly after surgery than after stenting. Risk of death or heart attack following either treatment appeared the same, but this may be because too few trial participants were collected together in the review and variation between trials (heterogeneity) may be masking true differences. Further trials of new techniques in a greater variety of patients with subsequent systematic review are needed.

Authors' conclusions: 

CABG is associated with reduced rates of major adverse cardiac events, mostly driven by reduced repeat revascularisation. However, the RCT data are limited by follow-up, unrepresentative samples and rapid development of both surgical techniques and stenting. Research on real-world patient population or patient level data meta-analyses may identify risk factors and groupings who may benefit most from one strategy over the other.

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Background: 

Coronary artery bypass graft surgery (CABG) replaces obstructed vessels with ones from other parts of the body. Alternatively, obstructions are remodelled using catheter-based techniques such as percutaneous coronary angioplasty with the use of stents. Though less invasive, stenting techniques are limited by the re-narrowing of treated vessels (restenosis). We examined evidence on cardiac-related outcomes occurring after CABG or stenting, with implications for resource use, resource allocation and informing patient choice.

Objectives: 

To examine evidence from randomised controlled trials (RCTs) on benefit of stents or CABG in reducing cardiac events in people with stable angina or acute coronary syndrome (ACS).

Search strategy: 

CENTRAL (Issue 2 2004), EMBASE (1990 to 2004), MEDLINE (1990 to 2004) and handsearching to July 2004.

Selection criteria: 

Only RCTs comparing stents used with PTCA with CABG were included. Participants were adults with stable angina or ACS and unstable angina and had either single or multiple vessel disease. Published and unpublished sources were considered.

Data collection and analysis: 

Outcomes included composite event rate (major adverse cardiac event, event free survival), death, acute myocardial infarction (AMI), repeat revascularisation and binary restenosis as well as information on design and baseline characteristics. Quality assessment was completed independently. Meta-analyses are presented as odds ratios, 95% confidence intervals (CI) using a fixed-effect model. Heterogeneity between trials was assessed.

Main results: 

Nine studies (3519 patients) were included. Four RCTs included patients with multiple vessel disease, five focused on single vessel disease. Four studies reported beyond 1 year. No statistical differences were observed between CABG and stenting for meta-analysis of mortality or AMI, but there was heterogeneity. Composite cardiac event and revascularisation rates were lower for CABG than for stents. Odds ratios resulting from meta-analysis of event rate data at 1 year were, odds ratio 0.43 (95% CI 0.35 to 0.54) and at 3 years, odds ratio 0.37 (95% CI 0.29 to 0.48). Odds ratios for revascularisation at 1 year were, odds ratio 0.18 (95% CI 0.13 to 0.25) and at 3 years, odds ratio 0.09 (95% CI 0.02 to 0.34). Binary restenosis at 6 months (single vessel trials) favoured CABG, odds ratio 0.29 (95% CI 0.17 to 0.51).

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