SECURITY: 6 Months of DAPT Noninferior to 12 Months in Low-Risk Patients After PCI
Among low-risk patients, 6 months of dual antiplatelet therapy (DAPT) is as good as 12 months at preventing adverse events after implantation of second-generation drug-eluting stents (DES), according to a study in the November 18/25, 2014, issue of the Journal of the American College of Cardiology.
Although it ended early due to slow enrollment and minimal event rate differences between the treatment groups, the SECURITY trial, originally presented at the 2014 Transcatheter Cardiovascular Therapeutics scientific symposium in Washington, DC, adds to the ongoing debate over the optimal length of therapy, the authors say.
The goal is not to determine a precise time frame that applies across the board, David E. Kandzari, MD, of Piedmont Heart Institute (Atlanta, GA), told TCTMD in a telephone interview. Rather, what needs to be established is the safety of stopping therapy early for patients who cannot comply with the therapy—whether they have an upcoming surgery or are at high risk for bleeding, he suggested.
For SECURITY (Second Generation Drug-Eluting Stent Implantation Followed by Six- Versus Twelve-Month Dual Antiplatelet Therapy), Antonio Colombo, MD, of the San Raffaele Scientific Institute (Milan, Italy), and colleagues enrolled 1,399 low-risk patients with stable (61.6%) or unstable angina or documented silent ischemia undergoing implantation with a second-generation DES from July 2009 to June 2014. Patients were randomized to receive DAPT (aspirin plus 75 mg of clopidogrel daily) for 6 (n = 682) or 12 months (n = 717).
Mean patient age was 65.2 years, 31% had diabetes, and 43.8% had multivessel disease. Stent types were:
Follow-up was available in 91% of the cohort at 12 months and 82.1% at 24 months. At 12 months, 96.1% of the patients in the 12-month group and 33.8% in the 6-month group were still on DAPT. At 24 months, most of the patients in both the 6-month group (96.5%) and the 12-month group (97.9%) were on aspirin alone.
Shorter Therapy Consistently Favored
With respect to the primary composite endpoint (cardiac death, MI, stroke, definite or probable stent thrombosis, or BARC type 3 or 5 bleeding at 12 months), there were no differences between the 6- and 12-month DAPT groups (4.5% vs 3.7%; P = .469), and the criteria for noninferiority were met (P < .05 for noninferiority).
There were also no differences between the study groups in the composite secondary endpoint (cardiac death; spontaneous MI; stroke; definite or probable stent thrombosis; or BARC type 2, 3, or 5 bleeding) at 12 months or between 12 and 24 months. The same pattern was seen for all individual endpoints, including no difference in definite or probable stent thrombosis at 12 months (P = .694) and between 12 and 24 months (P = .305).
Cox regression multivariable analysis showed that 6 vs 12 months of DAPT was not an independent predictor of the primary endpoint (HR 1.272; 95% CI 0.754-2.145; P = .367). However, age ≥ 75 years, stent type (Endeavor Resolute vs Biomatrix/Xience/Promus), higher mean number of stents, longer mean stent length, and larger mean stent size all were associated with a worse outcome.
Fitting in With Other Data
Citing similar findings from earlier DAPT trials, including EXCELLENT, PRODIGY, and OPTIMIZE, Dr. Colombo and colleagues say SECURITY “contributes to the evidence that reduced DAPT is safe and effective with currently used DES in patients with the characteristics of our study population.
“One of the most evident results of our study, compared with previous studies, is the low rate of adverse cardiovascular events at clinical follow-up,” they continue. “This is consistent with improvements related to the introduction of second-generation DES in clinical practice and the low-risk clinical and lesion profiles of the patients in our study.”
The authors caution that the finding of increased events with the Endeavor Resolute stent is likely due to chance, especially considering the low overall event rate. Additionally, “our study population’s low risk profile and the 12-month DAPT duration were both insufficient to increase the hazard of bleeding events,” they write.
Moreover, the investigators acknowledge, the fact that “[a]lmost 34% of patients in the 6-month group continued DAPT after 6 months… could have affected our results.”
Dr. Kandzari said this “somewhat confounds the results of the study.” But, he added, “it highlights that, despite protocols or the best intentions, whether it's physician or patient preference or patient need, still a large number of patients will continue on longer-term antiplatelet therapy.”
Shorter Duration Appears Safe—but DAPT Study Could Change the Game
In an editorial accompanying the study, David R. Holmes Jr., MD, of the Mayo Clinic College of Medicine (Rochester, MN), writes, “With patients similar to those in the SECURITY trial, and in the absence of rigorous data to the contrary, shorter DAPT duration seems very reasonable to consider and is increasingly used in the art of taking care of these patients.”
The DAPT Study—which randomized more than 20,000 patients to either 12 or 30 months of DAPT—will be presented next week at the 2014 American Heart Association Scientific Sessions in Chicago, IL. According to Dr. Kandzari, it will deliver ultimate guidance on this issue.
“If the DAPT trial shows similar outcomes [for] 12 and 30 months [of therapy], then there will be even more enthusiasm toward trials like SECURITY,” he said. “But on the other hand, if the DAPT trial suggests that 30 months is superior to 12 months, that would really challenge how we move forward with these [shorter duration] antiplatelet therapy studies.”
1. Colombo A, Chieffo A, Frasheri A, et al. Second-generation drug-eluting stent implantation followed by 6- versus 12-month dual antiplatelet therapy: the SECURITY randomized clinical trial. J Am Coll Cardiol. 2014;64:2086-2097.
2. Holmes DR Jr. Art and science [editorial]. J Am Coll Cardiol. 2014;64:2098-2100.
- The study was sponsored by Fondazione Evidence, a nonprofit organization that received grants from Biosensors, Medtronic, and Terumo.
- Drs. Colombo and Holmes report no relevant conflicts of interest.
- Dr. Kandzari reports receiving research and grant support from Abbott Vascular, Biotronik, Boston Scientific, and Medtronic and consulting honoraria from Boston Scientific and Medtronic.