Registry Puts CABG Over PCI for Multivessel Disease in Diabetes

Patrice Wendling

December 19, 2017

VANCOUVER, BC — In patients with diabetes undergoing revascularization for multivessel disease, including acute coronary syndromes (ACS), the risk of major adverse events is lower with CABG than PCI, according to results from a Canadian registry[1].

"The real jewel or pearl of this analysis is that it's not only validating the FREEDOM results," but "we also found that there was heterogeneity between those who had ACS at presentation and those who were the classic FREEDOM, more stable patients. In fact, there was even a more pronounced benefit in those with ACS," senior author Dr Michael Farkouh (University of Toronto, ON) told | Medscape Cardiology.

The FREEDOM trial showed that bypass surgery had lower long-term rates of overall major adverse cardiovascular events than PCI with drug-eluting stents in diabetic patients with stable ischemic heart disease (SIHD) but excluded those presenting with ACS within 72 hours.

Still, the results were quickly adopted in British Columbia and translated to the ACS population, such that about 50% of ACS patients went on to have bypass surgery for multivessel disease compared with only about 10% in the US, Farkouh observed.

This allowed the researchers to examine the impact of acuity on major adverse cardiac or cerebrovascular events (MACCE), defined as the composite of all-cause death, nonfatal MI, and nonfatal stroke, in 4661 diabetic patients who underwent revascularization for multivessel disease between 2007 and 2014. Of these, 2947 (63%) presented with ACS.

At 30 days, patients treated with CABG rather than PCI had lower rates of MACCE (3.3% vs 6.1%) and MI (1.1% vs 4.5%), but higher rates of stroke (1.4% vs 0.6%; P<0.01 for all). All-cause death, which just barely achieved significance in favor of CABG in the FREEDOM trial, was numerically lower (1.0% vs 1.6%; P=0.10) in the registry analysis, published in the December 19, 2017 issue of the Journal of the American College of Cardiology.

The odds of MACCE and its individual components, except for stroke, remained lower in the CABG group after multivariable adjustment and in a propensity-matching model.

Among ACS patients, the adjusted odds for MACCE strongly favored CABG over PCI (adjusted odds ratio [AOR] 0.49; 95% CI 0.34–0.71), while among SIHD patients, MACCE risk was not affected by the revascularization strategy (AOR 1.46; 95% CI 0.71–3.01; P interaction<0.01).

"We've seen benefit of CABG late but never early," Farkouh said. "But there is some rationale for this because if you have complete revascularization with surgery you may prevent more acute or early myocardial infarctions, and that's what we saw in the study."

When the researchers looked long term (31 days to 5 years), unadjusted MACCE rates favored CABG over PCI in patients with ACS (20.8% vs 33.4%) and in those with SIHD (12% vs 22.8%; both P<0.01).

Following multivariable adjustment, however, the benefit of CABG over PCI no longer varied by acuity, with a hazard ratio for MACCE of 0.67 in patients with ACS and 0.55 in those with SIHD (P interaction=0.28).

Sensitivity analyses suggest the increased use of DES over the study period and introduction of second-generation DES had little impact on CABG's advantage in early and late follow-up, according to the investigators, led by Dr Krishnan Ramanathan (University of British Columbia, Vancouver).

"This is not definitive by any stretch, but it is generating the hypothesis that maybe when patients present with non-ST segment MI [NSTEMI] that we should take a step back at the point of the angiogram and consider them up front for bypass surgery in the acute setting; and that's a change in practice for America," Farkouh said.

In a related editorial[2], Drs Sripal Bangalore (New York University School of Medicine, New York City) and Deepak L Bhatt (Brigham and Women's Hospital, Boston, MA) write that the study provides "valuable insights" into the outcomes of diabetic patients with multivessel disease but point out that patients presenting with STEMI within 72 hours were excluded.

They suggest the lower short-term risk with CABG in the registry could be due to residual confounding. But they also observe that the inability to identify the true culprit lesion in diabetic NSTEMI patients undergoing PCI could result in "less protection against recurrent ischemic events than does complete revascularization with CABG. Regardless, the long-term outcomes should be tested in a randomized trial."

Farkouh said the published report includes more comprehensive statistical analyses than when the controversial results were first presented in 2015 but agreed that residual confounding may still be an issue in an observational study and that a randomized trial is needed.

"This is hypothesis generating, it's not definitive, and I want to be on the record with that and that we agree with all the detractors and those who are waiting for more definitive results, and we are putting our shekels on the table and doing that trial," he said.

The trial will randomize stable ACS, non-STEMI patients with diabetes to PCI or bypass surgery as the front-line approach and follow them for both 30-day and long-term outcomes.

"We do believe that if these effect sizes that we see are real, we'll have a real impact on the way we practice and will change the way we practice in ACS patients with diabetes and multivessel disease."

The authors report no relationships relevant to the study. Bangalore reports serving on the advisory boards forAbbott Vascular, Daiichi-Sankyo, the Medicines Company, Pfizer, and Amgen; receiving research grant support from Abbott Vascular, the National Heart, Lung, and Blood Institute; and honoraria from Abbott Vascular, Daiichi-Sankyo, Merck, Abbott, Pfizer, Boehringer Ingelheim, and AstraZeneca. Bhatt reports numerous relationships with institutions and industry including serving on a CME steering committee for WebMD.

Follow Patrice Wendling on Twitter: @pwendl. For more from | Medscape Cardiology, follow us on Twitter and Facebook.


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