Six Versus Twelve Months of Dual Antiplatelet Therapy After Drug-Eluting Stent Implantation in ST-Elevation Myocardial Infarction - DAPT-STEMI

Contribution To Literature:

The DAPT-STEMI trial showed that among patients who remain event-free at 6 months following PPCI with a ZES for STEMI, cessation of DAPT at the 6-month mark vs. continuing for an additional 6 months (12 months total from stent implantation) is noninferior for clinical outcomes at 2 years.

Description:

The goal of the trial was to assess the safety and efficacy of 6 vs. 12 months of dual antiplatelet therapy (DAPT) in patients presenting with ST-segment elevation myocardial infarction (STEMI) and undergoing primary percutaneous coronary intervention (PPCI) with a second-generation drug-eluting stent (DES).


Study Design

Patients with STEMI and undergoing PPCI with a second-generation DES (zotarolimus-eluting stent [ZES]) were randomized in a 1:1 fashion to either 6 months (n = 433) or 12 months of DAPT (n = 437).

  • Total number of enrollees: 1,496
  • Duration of follow-up: 1 year
  • Mean patient age: 60 years
  • Percentage female: 23%
  • Percentage with diabetes: 14%

Inclusion criteria:

  • Age 20-85 years
  • PPCI with second-generation ZES
  • Event free at 6 months (no MI, stent thrombosis, target vessel or lesion revascularization, or stroke/bleeding requiring DAPT discontinuation)

Exclusion criteria:

  • Intolerance to aspirin, prasugrel, ticagrelor, heparin, bivalirudin, zotarolimus, or everolimus 
  • Planned elective surgical procedure necessitating interruption of DAPT during the first 6 months after the procedure
  • Need for oral anticoagulation
  • History of stent thrombosis
  • DES in main left coronary artery
  • Active bleeding, known bleeding diathesis, or known coagulopathy
  • Oral anticoagulant therapy with Coumadin derivative
  • Malignancies or other comorbidity
  • Pregnancy

Other salient features/characteristics:

  • Prior MI: 5%
  • P2Y12 inhibitor at start of trial: clopidogrel: 42%, prasugrel: 30%, ticagrelor 29%
  • Infarct vessel: left anterior descending: 41%, right coronary artery: 41%
  • Average number of treated vessels: 1.08
  • Total stented length: 29 mm

Principal Findings:

The primary outcome, all-cause mortality, MI, revascularization, stroke, and TIMI major bleeding at 18 months for 6-month vs. 12-month DAPT, was 4.8% vs. 6.6%, p for noninferiority = 0.004, p for superiority = 0.26.

  • All-cause mortality: 0.7% vs. 1.4%, p = 0.33
  • MI: 1.8% vs. 1.8%, p = 0.97
  • TIMI major bleeding: 0.2% vs. 0.5%, p = 0.58

Secondary outcomes for 6-month vs. 12-month DAPT:

  • Stent thrombosis: 0.7% vs. 0.9%, p = 0.72
  • Target lesion failure: 1.2% vs. 1.8%, p = 0.42

Interpretation:

The results of this trial indicate that among patients who remained event free at 6 months following PPCI with a ZES for STEMI, cessation of DAPT at the 6-month mark vs. continuing for an additional 6 months (12 months total from stent implantation) is noninferior for clinical outcomes at 2 years. The trial was underpowered to assess individual safety endpoints. These are thought-provoking results, and while they may not change practice or guidelines immediately, they indicate the need for additional clinical trials in this area. The most recent American College of Cardiology/American Heart Association DAPT guidelines indicate that a 6-month duration may be reasonable among patients undergoing PCI for stable angina.

References:

Presented by Dr. Elvin Kedhi at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2017), Denver, CO, November 1, 2017.


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