The outcomes of coronary artery bypass grafting (CABG), when compared with percutaneous coronary intervention (PCI) might vary according to the patient characteristics, such as the presence of diabetes or the number of diseased vessels. However, no randomized trial to date has been large enough to provide adequate statistical power for sub-group analysis, and meta-analyses have been hampered by inconsistent reporting in published trials.

Hlatky et al. pooled individual patient data from ten randomized trials providing data on 7812 patients. PCI was performed with balloon angioplasty in six trials and bare-metal stents in four trials. 575 of 3889 patients (15%) assigned to CABG died compared with 628 of 3923 (16%) patients assigned to PCI over a median follow-up of 5.9 years. In patients with diabetes, mortality was substantially lower in the CABG group than in the PCI group (hazard ratio 0.70), but mortality was similar in groups without diabetes (hazard ratio, 0.98). 20% of patients aged over 65 died following CABG, compared to a death rate of 24% in the same population following PCI. This interaction remained after adjustment for sex, diabetes, smoking, hypertension, history of myocardial infarction, heart failure and three-vessel disease (p=0.002). No other baseline characteristics were found to significantly alter outcomes.

The results must be interpreted with caution; patients included in the analysis had only single- or double-vessel disease (the recently published SYNTAX trial was not included), a group in which CABG is already known to have no prognostic benefit. Furthermore, internal mammary grafts were underused in the surgical group, and drug-eluting stents were not used in the PCI studies included. Nonetheless, the finding that CABG is the preferred treatment method in diabetics agrees with the findings of the BARI trial. Furthermore, the study suggests that CABG is also preferred for those aged greater than 65 – but it should be noted that only 5% of the patients in this study were aged greater that 75.

• Hlatky MA, Boothroyd DB, Bravata DM, et al. Coronary artery bypass surgery compared with percutaneous coronary interventions for multivessel disease: A collaborative analysis of individual patient data from ten randomised trials. Lancet 2009; DOI:10.1016/S0140-6736(09)60552.
• Taggart DP. PCI or CABG in coronary artery disease? Lancet 2009; DOI:10.1016/S0140-6736(09)60574-2.