• Myocardial Infarction
• Interventional Techniques & Devices Clinical Trials

Hyo–Soo Kim, MD, Seoul National University Hospital, Seoul, South Korea, reported results from a study that compared double– with triple–dose antiplatelet therapy (DAPT vs TAPT) in acute coronary syndrome (ACS) patients who were undergoing percutaneous coronary intervention (PCI), which showed no difference in net clinical outcomes between the two treatment regimens after 1 month.

The Harmonizing Optimal Strategy for Treatment of Coronary Artery Stenosis – Safety & EffectiveneSS of Drug–ElUting Stents & Antiplatelet Regimen [HOST–ASSURE; NCT01267734] trial was a 2 × 2 factorial design trial that compared the safety and long–term effectiveness of coronary stenting, the everolimus–eluting stenting system, and the zotarolimus–eluting stenting system, as well as the short term efficacy and safety of TAPT, adding cilostazol to standard aspirin + clopidogrel dosing, versus DAPT with aspirin + higher–dose clopidogrel. The presentation by Prof. Kim focused only on the results of the comparison of the two antiplatelet regimens.

The HOST–ASSURE study comprised 3750 subjects who were undergoing PCI with drug–eluting stents (DES) at 40 centers in South Korea. Subjects were randomized in a 1:1 fashion to either TAPT (aspirin 100 mg daily, clopidogrel 75 mg daily, cilostazol 200 mg loading–dose followed by 100 mg twice daily) or DAPT (aspirin 100 mg daily, clopidogrel 150 mg daily). All patients were loaded with 300 mg of aspirin and 300 to 600 mg of clopidogrel prior to PCI. Patients with a left ventricular ejection fraction <25%, cardiogenic shock, or symptomatic heart failure were excluded from the study. The hypothesis that was being tested was that the net clinical outcome at 1 month with TAPT would be noninferior to that with DAPT. The net clinical outcome was defined as a composite of cardiac death, nonfatal myocardial infarction (periprocedural or spontaneous), definite or probable stent thrombosis, stroke, or PLATO major bleeding. The noninferiority margin was set at 0.75% absolute. In other words, the study had 90% power to show that the rate of the net clinical outcome in patients who were assigned TAPT was not more than 0.75% higher than with DAPT, assuming that no difference in rates between the regimens truly existed.

Patients were well balanced between treatment assignments. The mean age was 63 years; one–third of subjects were women, one–third was diabetic, and one–third of subjects were current smokers. Approximately 50% of patients presented with an acute coronary syndrome (unstable angina or non–ST–segment elevation myocardial infarction [NSTEMI]), and 10% presented with STEMI. Concomitant use of beta–blockers (68%), statins (85%), and ACEI/ARB (65%) was frequent.

Thirty–five days after randomization, 1.44% of DAPT and 1.22% of TAPT–treated patients experienced the primary endpoint (ie, an absolute risk difference in favor of TAPT of 0.22%; p<0.001 for noninferiority; HR, 0.85; 95% CI, 0.49 to 1.48; p=0.57 for superiority). There were no significant differences between treatment groups when data were analyzed as individual risk components (all incidence rates were <1%), nor were there any differences in the rates of target lesion or vessel revascularization. Platelet reactivity (VerifyNow P2Y₁₂ Assay) was significantly (p<0.001) higher after clopidogrel loading and at the end of the study for patients who received the DAPT regimen.

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