More Than 1 in 10 Patients Discontinue Antiplatelet Therapy Early

More than 1 in 10 patients who receive a drug-eluting stent (DES) prematurely stop taking antiplatelet therapy, researchers report in a study published in the January 15, 2011, issue of the American Journal of Cardiology. Within the first year after the procedure, discontinuation of aspirin, clopidogrel, or both drugs was associated with an increase in adverse events including death and stent thrombosis.

Researchers led by Roberta Rossini, MD, PhD, of Ospedali Riuniti di Bergamo (Bergamo, Italy), retrospectively analyzed 1,379 patients who received sirolimus-eluting or paclitaxel-eluting stents at 2 Italian centers from June 2005 to March 2008. Early discontinuation was defined as withdrawal of aspirin and/or clopidogrel within the first 12 months, and late discontinuation referred only to aspirin withdrawal after 12 months.

Early discontinuation occurred in 8.8% of patients and late discontinuation in 4.8%. Bleeding events were the most frequent cause of early discontinuation, while surgery was the most frequent cause of late discontinuation.

Anticoagulants, Diabetes Predict Discontinuation

Factors that predicted early discontinuation of 1 or both agents included in-hospital major bleeding, oral anticoagulant use at discharge, and lack of a statin prescription, whereas the only independent predictor of late discontinuation was previous stroke. Looking at each drug separately, aspirin discontinuation was tied to oral anticoagulants, while clopidogrel cessation was associated with diabetes, serum creatinine level at admission, statins at discharge, and oral anticoagulants at discharge.

The cumulative incidence of MACE (death, MI, destabilizing symptoms leading to hospitalization, and nonfatal stroke) as well as the rate of Academic Research Consortium-defined definite, probable, or possible stent thrombosis were greater in patients who discontinued antiplatelet therapy early compared with those who did not. Similarly, overall mortality and cardiovascular death also were more frequent in conjunction with early cessation (table 1).

Table 1. Cumulative Events According to Antiplatelet Compliance

Among patients with stent thrombosis, 22% had prematurely stopped either aspirin or clopidogrel and 16.0% had stopped clopidogrel. However, 43% were still on dual antiplatelet therapy at the time of their event.

Timing Matters

Similar to the overall study, Kaplan-Meier curves showed that patients who discontinued their medications early had a greater incidence of death than those who stopped late or not at all. MACE, stent thrombosis, and death were most common when discontinuation occurred within the first 30 days. A quick break from antiplatelet therapy lasting less than 5.5 days, however, did not have any negative effect, because most MACE events occurred outside of that time frame.

Patients with late discontinuation from aspirin, meanwhile, had a trend toward higher MACE and stent thrombosis and a significantly greater incidence of MI and nonfatal stroke than those who continued taking aspirin as indicated. However, there were no significant differences in cardiovascular death and overall death for those who stopped aspirin after 1 year.

The study authors point out that failure to comply with prescribed therapy “is a marker of overall medical noncompliance, which might have accounted for some of the excess mortality and MACE we observed.” Even so, they conclude, “ongoing investigations specifically powered to understand the prognostic implications of extending thienopyridine therapy will provide more insights into this topic.”

Source:Rossini R, Capodanno D, Lettieri C, et al. Prevalence, predictors, and long-term prognosis of premature discontinuation of oral antiplatelet therapy after drug eluting stent implantation. Am J Cardiol. 2011;107:186-194.

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