Stick with long-term DAPT for ACS patients undergoing PCI

Short-term treatment with dual antiplatelet therapy (DAPT) may cause an increased risk of myocardial infarction (MI) in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) with current-generation drug-eluting stents (DES), according to results from the SMART-DATE trial. The study was conducted by Korean researchers and presented at the American College of Cardiology's (ACC) 67th Annual Scientific Session, March 10-12, in Orlando, FL.

They found that although the combined incidence of all-cause mortality, MI, or stroke within 18 months did not differ significantly in ACS patients treated for either 6 months or 12 months with DAPT, patients treated for only 6 months had more than twice the risk for MI compared with those treated for 12 months. Long-term DAPT, they concluded, should remain the standard of care in these patients.

Their results were published simultaneously in The Lancet.

"Based on our findings, we can't say that short-term DAPT is safe in patients with ACS who have received drug-eluting stents," said lead author and principal investigator Hyeon Cheol Gwon, MD, professor, Division of Cardiology, Sungkyunkwan University, and director, Cardiac Center, Samsung Medical Center, Seoul, South Korea, and principal investigator of the study. "We conclude that current guidelines that recommend prolonged DAPT in patients with ACS who are not at excessive risk for bleeding should continue to be followed."

In patients with ACS, current international guidelines—including those from the ACC and the American Heart Association (AHA)—recommend DAPT for at least 12 months for those not at excessive risk of bleeding.

Data on the minimal necessary duration of treatment in these patients who undergo PCI, however, are limited. Recently, results from two studies suggested that a 6-month course of DAPT may be as beneficial in reducing patient risk for death, MI or stroke, bleeding, and other adverse events. But enrollment in these studies was small, and no definitive conclusions could be made.

For this prospective, multicenter, randomized, open-label trial, Dr. Gwon and colleagues included 2,712 ACS patients (median age: 63 years; 75% male) from 31 centers in South Korea who were implanted with current generation DES. They randomized patients to a 6-month DAPT group (n=1,357), who received aspirin plus a P2Y12 inhibitor for 6 months and aspirin alone thereafter; or to a ≥ 12-month DAPT group (n=1,355), who were treated with aspirin plus a P2Y12 inhibitor for at least 12 months.

A composite of all-cause death, MI, or stroke was the primary endpoint of the study. At 18 months, this occurred in 4.6% of patients in the 6-month DAPT group, compared with 4.2% of patients in the second group (absolute risk difference: 0.4%; upper limit of one-sided 95% CI: 1.8%; P=0.007 for noninferiority). This result demonstrated the noninferiority of a 6-month course of DAPT compared with 12 months.

Importantly, researchers found an increased incidence of MI in the 6-month DAPT group (1.9% vs 0.8%, respectively; HR: 2.42; 95% CI: 1.16-5.07; P=0.02), which translated to a 2.4-fold higher risk in the 6-month DAPT group.

Despite this, the rate of all-cause death did not differ significantly between the two groups (2.4% vs 3.0%, respectively; HR: 0.80; 95% CI: 0.50-1.28; P=0.35), nor did the rate of stroke (0.8% vs 0.9%; HR: 0.92; 95% CI: 0.41-2.08; P=0.84).

At 6 to 18 months after stenting, patients in the 6-month DAPT group treated with aspirin alone had a 5.1-fold greater risk of MI compared with the 12-month DAPT group. During this time, researchers also observed a 69% higher risk of dying from any cause or having an MI or stroke in patients in the 6-month DAPT group.

More patients in the 6-month DAPT group had stent thrombosis compared with the 12-month group (1.1%, vs 0.7%; HR: 1.50; 95% CI: 0.68-3.35; P=0.32), but this difference did not reach significance.

Researchers also assessed the rate of bleeding, as defined by the Bleeding Academic Research Consortium (types 2, 3, and 5). This did not differ significantly between the two groups, at 2.6% in the 6-month DAPT group and 3.7% in the ≥ 12-month DAPT group (HR: 0.73; 95% CI: 0.47-1.13; P=0.16).

They defined net adverse clinical events as the composite of all-cause death, MI, stroke, or bleeding, and this result also did not differ significantly between the groups (7.1 vs 7.3%, respectively; HR: 0.97; 95% CI: 0.72-1.29; P=0.81).

According to Dr. Gwon, his research team will follow these patients for an extra 18 months, for a total of 3 years’ follow-up.

The study was funded by Abbott Vascular Korea, Medtronic Vascular Korea, Biosensors Korea, and Dong-A ST.