Dual Antiplatelet Therapy for More Than 12 Months after Percutaneous Coronary Intervention: Insights from the Guthrie PCI Registry

Kishore J Harjai ^1*, Chetan Shenoy ², Pamela Orshaw ¹ and Judy Boura ³

¹ Guthrie Clinic, United States
² Duke University Medical Center, United States
³ William Beaumont Hospital, United States

^* To whom correspondence should be addressed. E-mail: kharjai{at}aol.com.

Accepted 4 June 2009

Abstract

Objective: Assess the impact of dual antiplatelet (DAP) therapy >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 2 stent subsets: bare-metal stents (n=835), drug-eluting stents (n=1024); and 3 high-risk subsets: diabetics (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 age 64±12 years, male 69%, diabetic 26%, presentation with MI 38%, ejection fraction 49±12%, mean 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<0.0001). 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%, 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; CI 0.74-1.37, p=0.95). Analysis of each of the 5 pre-defined subsets revealed similar results.

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