SMART-DATE Trial Shows Increased Risk of Heart Attack With Short-Term DAPT in ACS Patients
March 12, 2018—The SMART-DATE trial was presented by Principal Investigator Hyeon Cheol Gwon, MD, in a Late Breaking Trial session at the American College of Cardiology's (ACC) 67th annual scientific session held March 10–12 in Orlando, Florida. The study findings were simultaneously published online in The Lancet.
The study found that patients with acute coronary syndrome (ACS) who were given dual antiplatelet therapy (DAPT) for only 6 months had more than double the risk of a heart attack compared with those treated for at least 12 months after receiving a drug-eluting stent (DES). By comparison, the combined rate of death from any cause, heart attack, or stroke within 18 months was not significantly different in patients with ACS who were randomly assigned to receive DAPT for either 6 months or at least 12 months after receiving a DES.
In the ACC announcement, Dr. Gwon commented, "Based on our findings, we can't say that short-term DAPT is safe in patients with ACS who have received DES. 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."
Dr. Gwon noted that this is the largest trial to address the optimal duration of DAPT in patients with ACS.
Current guidelines published by the ACC and the American Heart Association recommend that ACS patients who are not at excessive risk for bleeding should be treated with DAPT for at least 12 months after the implantation of a DES. However, there is limited evidence that 12 months or more is the optimal duration for DAPT, stated Dr. Gwon.
A broader context of these findings is that two recently reported studies suggested that 6 months of DAPT might offer similar benefits in terms of reducing patients' risk for death, heart attack, or stroke, bleeding, or other adverse events. These studies, however, had too few participants to provide definitive answers, Dr. Gwon advised.
As summarized in the ACC announcement, the SMART-DATE trial enrolled 2,712 Korean patients (median age, 63 years; 75% men) with ACS who were undergoing angioplasty. Patients were randomly assigned to receive either DAPT for at least 12 months (DAPT-12) or DAPT for 6 months followed by aspirin alone for at least another 6 months (DAPT-6). The primary endpoint was the combined rate of death from any cause, heart attack, or stroke within 18 months after stent implantation.
The investigators found that at 18 months, 63 patients (4.7%) in the DAPT-6 group and 56 patients (4.2%) in the DAPT-12 group had experienced at least one of the primary endpoint events. Thus, over the entire 18-month follow-up period, DAPT-6 was significantly noninferior to DAPT-12. Rates of death from any cause were not significantly different in the two groups (2.6% for DAPT-6 vs 2.9% for DAPT-12).
However, the risk of heart attack was 2.4-fold higher in the DAPT-6 group, with heart attacks occurring in 1.8% of DAPT-6 patients versus 0.8% of DAPT-12 patients. Moreover, during the period between 6 and 18 months after stent implantation when patients in the DAPT-6 group were being treated with aspirin only, there was a 5.1-fold higher risk of having a heart attack in DAPT-6 patients compared with DAPT-12 patients. During this period, patients in the DAPT-6 group also had a 69% higher risk of dying from any cause or having a heart attack or stroke.
Dr. Gwon advised that limitations of the study include the absence of blinding and the absence of a control group that was randomly assigned to receive a placebo. However, he noted that study statisticians and those whose role was to assess outcomes worked independently from those overseeing the trial. Patients in the trial will be followed for an additional 18 months, for a total of 3 years of follow-up.