Cessation of Dual Antiplatelet Treatment and Cardiac Events After Percutaneous Coronary Intervention (PARIS): 2 Year Results From a Prospective Observational Study

Study Questions:

Does the risk of stopping dual antiplatelet therapy after percutaneous coronary intervention (PCI) change over time, and does the risk differ by indication for stopping dual antiplatelet therapy?


The PARIS (patterns of non-adherence to anti-platelet regimens in stented patients) registry is a prospective observational study of patients undergoing PCI with stent implantation in 15 clinical sites in the United States and Europe between July 1, 2009, and December 2, 2010. Adult patients (ages 18 years or older) undergoing successful stent implantation in one or more native coronary arteries and discharged on dual antiplatelet therapy were eligible for enrollment. Patients were followed up at months 1, 6, 12, and 24 after implantation. Prespecified categories for dual antiplatelet therapy cessation included physician-recommended discontinuation, brief interruption (for surgery), or disruption (noncompliance or because of bleeding). All adverse events and episodes of dual antiplatelet therapy cessation were independently adjudicated. The primary outcome of interest was major adverse cardiac events (MACE [composite of cardiac death, definite or probable stent thrombosis, myocardial infarction, or target lesion revascularization]).


A total of 5,018 patients who underwent PCI were included in this analysis. Over 2 years of follow-up, the overall incidence of any dual antiplatelet therapy cessation was 57.3%. Most recommended discontinuations (87%) were for a thienopyridine only (aspirin was almost always continued), whereas for most interruptions (290 [70%] of 412) and one half of disruptions (345 [50%] of 691), both a thienopyridine and aspirin were stopped. The overall 2-year MACE rate was 11.5%, most of which (74%) occurred while patients were taking dual antiplatelet therapy. Compared with those on dual antiplatelet therapy, the adjusted hazard ratio (HR) for MACE due to interruption was 1.41 (95% confidence interval [CI], 0.94-2.12; p = 0.10), and due to disruption was 1.50 (95% CI, 1.14-1.97; p = 0.004). Within 7 days, 8-30 days, and >30 days after disruption, adjusted HRs were 7.04 (95% CI, 3.31-14.95), 2.17 (0.97-4.88), and 1.3 (0.97-1.76), respectively. By contrast, with patients who remained on dual antiplatelet therapy, those who discontinued had lower MACE risk (HR, 0.63; 95% CI, 0.46-0.86). Results were similar after excluding patients receiving bare-metal stents and using an alternative MACE definition that did not include target lesion revascularization.


The investigators concluded that among patients undergoing PCI and discharged on dual antiplatelet therapy, cardiac events after dual antiplatelet therapy cessation depend on the clinical circumstance and reason for cessation, and attenuates over time. While most events after PCI occur in patients on dual antiplatelet therapy, early risk for events due to disruption is substantial irrespective of stent type.


Real-world data support the use of dual antiplatelet therapy among patients after PCI. Data such as these can confirm findings of randomized clinical trials, and also point out areas in need of further investigation. Further examination of such registries can identify clinical factors that may lead to inappropriate dual antiplatelet therapy cessation, and highlight patients at increased risk for adverse events.

Keywords: Myocardial Infarction, Follow-Up Studies, Platelet Aggregation Inhibitors, Ticlopidine, Pyridines, Europe, Angioplasty, Stents, Percutaneous Coronary Intervention, Registries, Blood Coagulation, Thrombosis, Confidence Intervals, Coronary Vessels, United States, Hemorrhage

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