Is CABG Still Better than PCI in Diabetes?

Past studies have suggested that patients with diabetes do better, in terms of long-term survival, if they receive coronary artery bypass grafting (CABG) compared to percutaneous coronary intervention (PCI). The past 30 years, though, have witnessed major advances in PCI, moving from balloon angioplasty to bare metal stents to drug-eluting stents. Fewer changes have occurred with CABG, though the death rate has decreased over the years.

Some have suggested that the major gains with PCI have mainly to do with preventing restenosis and re-intervention, rather than improving mortality. Others have suggested that the new everolimus-eluting stents have begun to decrease the mortality gap in diabetics who receive PCI vs CABG, raising the question: is CABG still better than PCI in patients with diabetes?

Most likely CABG is better, according to a new meta-analysis of randomized controlled trials (RCTs).¹

“This study shows that the (relative) difference between outcomes, especially all-cause mortality, between PCI and CABG has not changed over the past 30 years in diabetics with multivessel or left main vessel disease... This is despite improvements in PCI and changes in usual care,” wrote first author Peter Herbison, DSC, emeritus professor at the Dunedin School of Medicine, University of Otago (Dunedin, New Zealand).

In the study, researchers searched Medline, EMBASE, and the Cochrane Controlled Trials Register for RCTs comparing PCI to CABG published from inception through March 2015. Trials were selected without language restrictions and had to include participants with diabetes and left main coronary artery or multivessel disease. The meta-analysis looked at four main outcomes: all-cause mortality, cardiovascular mortality, major adverse cardiac or cerebrovascular event (MACCE), and the combined outcome of mortality, stroke, and MI.

The analysis included 14 studies covering 4868 diabetics, with follow-up occurring up to three decades. All studies had low to moderate risk of bias.

Key Results:

• 30% increased long-term mortality for PCI vs CABG (RR of 1.30, 95% CI 1.07 to 1.58, in favor of CABG)

• No change in mortality advantage or other main outcomes for CABG vs PCI over the past 30 years

• Analyzing by different types of stents did not change these results

• Similar results for insulin-requiring vs non-insulin requiring diabetics

• Rate of death decreased by 6% per year with PCI and by 7% per year with CABG

• No difference in mortality between CABG vs PCI for nondiabetics

The 30% mortality advantage for CABG vs PCI confirms estimates from past reviews on this topic. The results also fall within the range determined by the landmark FREEDOM trial, which showed that the risk of a composite of death/stroke/MI was 21-46% higher in insulin-dependent and non-insulin-dependent diabetics who had PCI, compared to those who underwent CABG.²

“On current evidence, CABG must be the preferred option over PCI in patients with diabetes and multivessel coronary artery disease when otherwise judged to be in clinical equipoise,” the authors concluded, “CABG reduces mortality and reintervention compared to PCI, unlike the situation in nondiabetics. Whether the newer generation of DES [drug-eluting stents] may bridge the gap in the future remains a hypothesis to be proven.”

Take-home Points

• Meta-analysis found 30% increased long-term mortality for PCI vs CABG in diabetics.

• No change in mortality advantage of CABG over PCI for the last 30 years.

• Analyzing by different types of stents did not change these results.

• CABG is preferred over PCI in patients with diabetes.

References:

1. Herbison P, Wong CK. Has the difference in mortality between percutaneous coronary intervention and coronary artery bypass grafting in people with heart disease and diabetes changed over the years? A systematic review and meta-regression. BMJ Open. 2015 Dec 30;5(12):e010055.

2. Dangas GD, et al. Long-term outcome of PCI versus CABG in insulin and non-insulin-treated diabetic patients: results from the FREEDOM trial. J Am Coll Cardiol. 2014;64:1189-1197.