PCI for Blocked Arteries of Lasting Benefit in Diabetes

According to Roxana Mehran, MD, of the Cardiovascular Research Foundation in New York City, and colleagues, through a median of three years of follow-up, the mortality rate following a successful procedure was significantly lower than an unsuccessful one (10.4% versus 13%, P<0.05).

There was also a substantial reduction in the need for CABG during follow-up after a successful PCI (2.4% versus 15.7%, P<0.01), the researchers reported online in the American Journal of Cardiology.

Patients who did not have diabetes also had a significant reduction in the need for CABG after a successful procedure (3.2% versus 12.2%, P<0.01), although there was not a significant mortality difference based on procedural success.

"The finding that patients with diabetes seem to benefit more from recanalization [in terms of mortality] could be explained by the higher event rates in this high-risk subgroup, which increases the statistical power to detect a significant difference in mortality," the authors explained.

So to explore the issue, they evaluated data on 1,742 patients who underwent PCI for 1,802 chronic total occlusions at three centers in the U.S., South Korea, and Italy from 1998 to 2007. About a quarter (23%) had diabetes, and of those, 42% were insulin dependent.

The procedural success rate did not differ based on diabetes status -- it was 69.6% for patients with diabetes and 67.9% for those without diabetes (P=0.53).

In general, mortality during follow-up was higher in those with diabetes, although the difference reached statistical significance in patients who had a successful procedure (13% versus 6.6%, P=0.01) but not in those who had a failed procedure (10.4% versus 5%, P=0.058).

In a multivariate model, insulin dependence was the strongest predictor of mortality in patients with diabetes, associated with a doubling of the risk of death (HR 2.25, 95% CI 1.04 to 4.87).

The vast majority of patients -- 96.4% of the diabetics and 94% of the non-diabetics -- received a stent during PCI. Most of the stents were drug-eluting.

The rate of major adverse cardiac events -- all-cause mortality, MI, and target vessel revascularization -- was significantly lower when drug-eluting stents were used in place of bare-metal stents in all patients regardless of diabetes status.

The difference was solely driven by a lower rate of target vessel revascularization in patients with diabetes (14.8% versus 54.1%) and without diabetes (17.6% versus 26.5%), which held up in multivariate analyses (P<0.01 for both).

Regardless of diabetes status, the rate of stent thrombosis was not increased when drug-eluting stents were used, "suggesting that drug-eluting stents are safe for chronic total occlusion PCI in patients with and without diabetes," according to the researchers.

"However, an adequately powered randomized trial or a well-designed very large registry is needed to confidently answer the question whether drug-eluting stents are as safe as bare-metal stents in chronic total occlusion PCI."

• Explain that three-year follow-up of diabetic patients undergoing successful PCI for chronic total occlusions found significantly lower mortality and requirement for later bypass grafting compared with those with a failed procedure.
• Note that PCI success rates were equivalent for those with and without diabetes.

Claessen B, et al "Long-term clinical outcomes of percutaneous coronary intervention for chronic total occlusions in patients with versus without diabetes mellitus" Am J Cardiol 2011; DOI: 10.1016/j.amjcard.2011.05.021.