Diabetes patients undergoing coronary artery bypass graft (CABG) have a lower risk of mortality than those who receive percutaneous coronary intervention (PCI), the results of recent trials suggest.

A total of 198 patients with diabetes and severe coronary artery disease were recruited to the VA CARDS study, a prospective, multicentre study conducted between 2006 and 2010. Ninety seven patients were randomly assigned to CABG and 101 to PCI with drug eluting stents (DES).

Patients were eligible for inclusion if they had diabetes and multivessel disease including the left anterior descending coronary artery. Objective evidence of ischaemia was required for stenoses between 50% and 70%.

The choice of stent was at the cardiologist’s discretion, but a single stent type per patient was recommended. The stents used were Taxus (n = 35), Cypher (n = 20), Xience/Promus (n = 18), Endeavor (n = 2), mixed DES (n = 16), and mixed bare metal stents (n = 1). Patients were followed for at least two years; the primary outcome measure was a composite of nonfatal MI or death.

There was a reduction in all-cause mortality in the CABG group 5% vs PCI 21%; hazard ratio (HR) 0.30 (95% CI:0.11-0.80) but an increased risk for nonfatal MI in the CABG group 15% vs PCI 6.2%, HR 3.32 (95% CI:1.07-10.30). The composite primary end point favoured surgery with a combined risk for death or nonfatal MI of 18.4% for CABG vs 25.3% for PCI; HR 0.89 (95% CI:0.47-1.71).

However, the study was stopped because of slow recruitment and only enrolled 25% of the intended sample size. This left it underpowered for the primary end point with wide confidence intervals.

Patients with diabetes often present with extensive coronary disease.

With symptoms and ischaemia on functional imaging there is a clear mandate for intervention in such patients. Interventional cardiology techniques and stent technology are constantly evolving and these patients may be treated with complex stent procedures.

Previous studies comparing stents with CABG have been in favour of the surgical approach but were criticised for failing to include the latest stent technology such as DES.

The authors were still optimistic that they have contributed useful information to the debate as this was the first trial to compare contemporary surgical techniques with the newest generation DES.

An accompanying editorial1 agreed that surgery is the best option in diabetes patients with multivessel disease and complex anatomy, based on the current body of evidence.

The results from four trials were cited (SYNTAX, CARDIA, FREEDOM and VA CARDS) with 159 deaths in the CABG groups and 244 deaths in the PCI groups.

Dr Peter Savill

• Kamalesh M, Sharp TG, Tang C et al. Percutaneous coronary intervention versus coronary bypass surgery in United States veterans with diabetes. J Am Coll Cardiol 2013; 61:808-816