Original articles

Interventional cardiology

Dual antiplatelet therapy for more than 12 months after percutaneous coronary intervention: insights from the Guthrie PCI Registry

K J Harjai, C Shenoy, P Orshaw, J Boura

Guthrie Clinic, One Guthrie Square, Sayre, Pennsylvania, USA

^{Correspondence to} Dr K J Harjai, Cardiac Catheterization Laboratories, Guthrie Health System, One Guthrie Square, Sayre, Pennsylvania 18840, USA; harjai_kishore{at}guthrie.org

Objective: To assess the impact of dual antiplatelet (DAP) therapy of >12 months on long-term death and myocardial infarction (MI) after percutaneous coronary intervention (PCI).

Design, setting and patients: Prospective, single-centre, observational study of 1859 consecutive patients who underwent successful PCI of a native coronary artery and survived event-free for at least 12 months.

Main outcome measures: Combined end point of death or non-fatal MI determined by survival analysis and propensity-adjusted multivariable Cox regression. Similar analyses were performed in the two stent subsets: bare metal stents (n = 835), drug-eluting stents (n = 1024); and three high-risk subsets: diabetic patients (n = 486), patients presenting with MI (n = 713), and those with ACC/AHA type C lesions (n = 717).

Results: Baseline characteristics were as follows: mean (SD) age 64 (12) years, male 69%, diabetic 26%, presentation with MI 38%, mean (SD) ejection fraction 49 (12)%, mean (SD) vessel diameter 3.1 (0.5) mm. Duration of DAP was 27 (11) months in "DAP >12 months" and 4.1 (4.1) months in "DAP 12 months" (p<0.001). At a median follow-up of 3.4 years after PCI, "DAP >12 months" vs "DAP 12 months" had similar incidence of death or MI (9.4% vs 10.3%, log-rank p = 0.83). After multivariable adjustment, DAP therapy >12 months was not associated with lower incidence of death or MI than DAP therapy 12 months (adjusted HR = 1.01; 95% CI 0.74 to 1.37, p = 0.95). Analysis of each of the five predefined subsets showed similar results.

Conclusions: In patients who undergo successful native coronary PCI and survive event-free for at least 12 months, continuation of dual antiplatelet therapy beyond 12 months does not confer long-term protection from death or MI.

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