Conference Coverage

DAPT produces better CABG outcomes than aspirin alone

Publish date: November 13, 2017
By
Mitchel L. Zoler, PhD
MDedge News

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DAPT must also show clinical benefits

Results from the DACAB trial showed that using aspirin and ticagrelor improved vein-graft patency, compared with using aspirin alone. It was a compelling result, but for the intermediate, imaging-based outcome of graft patency at 1 year after surgery. This finding is conclusive evidence that dual-antiplatelet therapy has some benefit.

But the findings from this trial, modestly sized with 500 patients, failed to prove that the clinical benefit from dual-antiplatelet therapy was worth the adverse effect of an increase in the rate of major and bypass-related bleeding. The study was underpowered to prove that dual-antiplatelet therapy had a clear beneficial impact on clinical outcomes such as cardiovascular death, MI, and stroke, although this combined rate went in the right direction with dual therapy, compared with aspirin alone. We need to see proof of a benefit for these clinical outcomes to justify using a treatment that causes an increase in major bleeds.

The DACAB results alone are not enough to justify a change in practice. It would be an important finding if the results could be replicated in a larger study. And if dual-antiplatelet therapy was proven to have a net clinical benefit for patients, we would still want to target it to patients with a higher ischemic risk and, in general, avoid using it in patients with a high bleeding risk.

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John H. Alexander, MD , is a cardiologist and professor of medicine at Duke University in Durham, N.C. He has been a consultant to and has received research funding from several companies, including AstraZeneca, the company that markets ticagrelor (Brilinta). He made these comments as designated discussant for the DACAB study and in a video interview .


 

AT THE AHA SCIENTIFIC SESSIONS

ANAHEIM, CALIF. – Treatment with dual-antiplatelet therapy following coronary artery bypass grafting with a saphenous vein maintained vein-graft patency better than aspirin alone in a randomized, multicenter trial with 500 patients.

After 1 year of dual-antiplatelet therapy (DAPT) with ticagrelor (Brilinta) and aspirin, 89% of saphenous-vein grafts remained patent, compared with a 77% patency rate in saphenous-vein grafts in patients treated with aspirin alone, a statistically significant difference for the study’s primary endpoint, Qiang Zhao, MD, said at the American Hart Association scientific sessions. The data, collected at six Chinese centers, also showed a nominal decrease in the combined rate of cardiovascular death, MI, and stroke: 2% with DAPT and 5% with aspirin alone. It further showed an increase in major or bypass-related bleeds: 2% with DAPT and none with aspirin alone, reported Dr. Zhao, professor and director of cardiac surgery at Ruijin Hospital in Shanghai, China.

Dr. Qiang Zhao Mitchel L. Zoler/Frontline Medical News

Dr. Qiang Zhao

But with a study of 500 patients that was only powered to address vein-graft patency the trial was underpowered to prove that the reductions in cardiovascular death, MI, and stroke outweighed the increase in major bleeds.

“If this result were repeated in a larger study it would be important,” John H. Alexander, MD, professor of medicine at Duke University in Durham, N.C., commented in a video interview.

The Compare the Efficacy of Different Antiplatelet Therapy Strategy After Coronary Artery Bypass Graft Surgery (DACAB) trial randomized patients who underwent coronary artery bypass grafting (CABG). They averaged about 64 years of age, and received an average of nearly four grafts each including an average of nearly three saphenous vein grafts. The study assigned patients to one of three treatment arms starting within 24 hours after surgery: 168 received ticagrelor 90 mg twice daily plus aspirin 100 mg once daily, 166 got ticagrelor alone, and 166 received aspirin alone. Treatment continued for 1 year.

Dr. Timothy J. Gardner Mitchel L. Zoler/Frontline Medical News

Dr. Timothy J. Gardner

Although arterial grafts are much preferred for CABG, “saphenous vein grafts are still plenty used,” commented Timothy J. Gardner, MD, a cardiac surgeon and medical director of the Center for Heart & Vascular Health of Christiana Care in Newark, Del. That’s especially true when patients require multivessel bypass, in which case placement of saphenous veins grafts are a virtual given in current U.S. practice, Dr. Gardner said in an interview.

“Some surgeons and physicians currently prescribe DAPT to CABG patients, but there is not much evidence of its benefit. The DACAB trial is useful, but you need to show that it does not just improve patency but that patients also have better outcomes. The excess of major bleeds is a big deal. It gives one pause about adopting DAPT as standard treatment,” Dr. Gardner said.

DACAB received no commercial funding. Dr. Zhao has been a speaker on behalf of and has received research funding from AstraZeneca, the company that markets ticagrelor (Brilinta). He has also been a speaker for Johnson & Johnson and Medtronic and has received research funding from Bayer, Novartis, and Sanofi. Dr. Gardner had no disclosures.

On Twitter @mitchelzoler

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