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ANAHEIM -- Dual antiplatelet therapy with ticagrelor (Brilinta) and aspirin significantly improved saphenous vein graft (SVG) patency 1 year after coronary artery bypass graft (CABG) versus monotherapy, without an excess risk for major bleeding, researchers reported here.

In the intention-to-treat results, 88.7% of grafts among people treated with the dual antiplatelet therapy (DAPT) remained patent compared with 82.8% among patients on ticagrelor monotherapy and 76.2% among patients on aspirin monotherapy (P=0.006 compared with DAPT), according to Qiang Zhao, MD, of Ruijing Hospital, Shanghai Jiaotong University School of Medicine in Shanghai, and colleagues.

Zhao said that DAPT was well tolerated. There were three major acute cardiac events -- one death and two heart attacks – in the DAPT group compared with two heart attacks and two strokes in the ticagrelor monotherapy group, and two deaths, three heart attacks, and four strokes in the aspirin monotherapy group, he reported at a press conference at the American Heart Association (AHA) meeting.

But AHA discussant John Alexander, MD, of the Duke Clinical Research Institute in Durham, North Carolina, pointed out that "this study confirms that more potent anti-platelet therapy improves vein graft patency, but doesn't answer the question of whether it improves clinically important outcomes for patients. We really need the results of larger clinical outcome trials that have major cardiac events as primary outcomes, and enough patients, to really assess the true trade-off in bleeding events."

As a result, the finding may not be sufficient to change clinical practice, he said.

"There is no evidence-based standard treatment after coronary artery bypass surgery," Alexander stated. "Aspirin has been well studied, and has level 1 evidence in the guidelines to improve vein graft patency and other clinical outcomes post-coronary artery bypass graft surgery. There have been a number of studies -- all of which have limitations -- looking at either observational or post-randomization subgroups -- looking at dual anti-platelet therapy with clopidogrel [Plavix] or ticagrelor or prasugrel [Effient], but none have really been definitive."

Zhao's group noted that saphenous vein graft procedures are the most commonly used graft in CABG, but the use of the vein is associated with a failure rate of 10% to 25% at 1 year, and 50% at 1 years after the surgery. Previous studies have indicated that DAPT reduces major acute cardiac events (MACE) -- cardiovascular death, MI, stroke -- in patients with acute coronary syndrome who undergo CABG, but the author noted that data regarding how the dual therapy would impact graft patency remains limited.

For the DACAB trial, Zhao's group assessed the efficacy and safety of DAPT with ticagrelor and aspiring versus ticagrelor alone and aspirin alone, 1 year after elective CABG surgery. The open-label trial enrolled 500 patients (mean age 64) with an indication for CABG from six Chinese hospitals, and randomized the to one of three arms:

• 90 mg ticagrelor twice daily plus 100 mg aspirin daily (n=168)
• 90 mg ticagrelor twice daily (n=166)
• 100 mg aspirin daily (n=166)

Exclusion criteria included hemodynamic instability, a previous need for DAPT or a vitamin K antagonist, and a high risk for serious bleeding.

The majority (80%) of study participants were men, and more than 40% were diagnosed with diabetes, while more than 70% had a hyperlipidemia diagnosis, and more than 70% had hypertension. About half the patients had a history of smoking.

The trial's primary outcome was SVG patency, assessed via CT scan and coronary angiography, at 1 year. The scans were evaluated by an independent committee blinded to treatment assignment, the authors noted. Secondary outcomes included MACE or recurrence of angina within a year.

The authors reported that the overall MACE events were low, although they were highest in the aspirin monotherapy (5.4%) and lowest with combination therapy (1.8%).

As for bleeding rates, non-CABG-related bleeding and minimal bleeding events were higher with the dual therapy versus ticagrelor and aspiring monotherapies (30.4% versus 12.1% versus 9.0% for non-CABG-related bleeding; 28.6% versus 11.4% versus 7.8% for minimal bleeding), the authors stated. But major bleeding (CABG-related plus non-CABG-related) rates came in at 1.8% for DAPT, 1.2% for ticgrelor monotherapy and zero for aspirin alone, they reported.

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