ORLANDO – New evidence further strengthens the case for coronary artery bypass grafting over percutaneous coronary intervention as the preferred revascularization strategy in diabetic patients with multivessel coronary artery disease.
An analysis of 4,819 such patients in a British Columbia province-wide registry who underwent revascularization during 2007-2014 led to the conclusion that the 30-day adjusted risk of the primary composite endpoint of death, MI, or stroke was 39% lower in those who underwent coronary artery bypass grafting (CABG), Dr. Krishnan Ramanathan reported at the American Heart Association scientific sessions.
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Dr. Krishnan Ramanathan
From day 31 through 5 years of follow-up, the relative risk reduction was 36% in favor of CABG, again after adjustment for age, sex, presentation with stable ischemic heart disease or stabilized acute coronary syndrome (ACS), urgency, renal insufficiency, liver disease, peripheral arterial disease, and left ventricular ejection fraction, added Dr. Ramanathan of the University of British Columbia in Vancouver.
These results in a broad patient population in real-world clinical practice, albeit in an observational, nonrandomized setting, mirror those in the earlier randomized FREEDOM trial sponsored by the National Heart, Lung, and Blood Institute. The 5-year rate of the composite of death, MI, or stroke in FREEDOM was 18.7% in the CABG group and 26.6% with percutaneous coronary intervention (PCI). The number needed to treat with CABG instead of PCI in FREEDOM in order to avoid one case of the composite endpoint was 12.6 (N Engl J Med. 2012 Dec 20;367[25]:2375-84).
An important difference between the British Columbia and the FREEDOM trial is that the registry contained a much higher proportion of diabetic patients with multivessel disease who presented with acute coronary syndrome. Indeed, the ratio of stabilized ACS to stable ischemic heart disease patients in the registry was 62% to 38% as compared with 36% to 64% in FREEDOM. The registry patients underwent a median of 7.8 days of stabilization from the time of initial catheterization to CABG.
The registry data really shore up the advantages of CABG over PCI in diabetics with multivessel disease and ACS, Dr. Ramanathan noted. In the registry, the 30-day composite endpoint occurred in 4.4% of CABG-treated ACS patients, compared with 8.3% with PCI. For 31 days through 5 years, the rates were 21.4% versus 34.7%. The differences favoring CABG were highly significant at both time points.
FREEDOM led to two important revisions in the 2014 guidelines on coronary revascularization, issued by the American College of Cardiology, American Heart Association, American Academy of Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiac Angiography and Interventions, and Society of Thoracic Surgeons. In a focused update issued earlier this year, a new class I recommendation was issued calling for a heart team approach to revascularization in patients with diabetes mellitus and complex multivessel coronary artery disease (CAD). And a recommendation for CABG over PCI for improving survival in diabetic patients with multivessel CAD was upgraded from class IIa to class I.
Even though FREEDOM was a major randomized trial that might be expected to be practice changing, that hasn’t happened. A report from the ACC’s National Cardiovascular Data ACTION Registry presented earlier this year at the ACC annual scientific session documented that the most common revascularization strategy for diabetic patients with multivessel CAD following a non–ST elevation ACS remains PCI, as has been the case since the registry was created. In fact, following the 2012 publication of FREEDOM, the proportion of such patients treated by PCI took a sharp uptick in 2013-2014, according to Dr. Ramanathan.
In the British Columbia registry, 64% of diabetic patients with multivessel disease and an ACS were treated by PCI, 36% by CABG.
“Overall, CABG in stabilized ACS patients is underutilized,” he said.
Discussant Dr. Marc Ruel declared, “The salient finding about the British Columbia study is not so much about the stable ischemic heart disease patients, but about the high proportion of ACS patients in the study. CABG was better than PCI for all major adverse cardiovascular events and each component of the endpoint.”
Bruce Jancin/Frontline Medical News
Dr. Marc Ruel
Dr. Ruel, professor and chair of cardiac surgery at the University of Ottawa Heart Institute, coauthored a meta-analysis of randomized controlled trials comparing CABG to PCI in diabetic patients. Half of the trials used later-generation drug-eluting stents. At 5 years of follow-up, the relative risk of all-cause mortality in diabetic patients allocated to CABG was 0.67 (Lancet Diabetes Endocrinol. 2013 Dec;1[4]:317-28).
“Remember that 0.67 because it’s a recurring number in our literature,” he advised.