Double Antiplatelet Therapy Reduces Risk of Short- and Long-term Stent Thrombosis
Risk of thrombotic events may be greatest in the short term following stenting.
Patients who maintained double antiplatelet therapy reduced their risk of short- and long-term stent thrombosis following stenting; patients taking clopidogrel were 11 times less likely to experience a thrombotic event in the first six months following stenting.
In the Milan/Siegburg/Naples Experience, research conducted by Alaide Chieffo, MD, of the San Raffaele Scientific Institute in Milan, Italy, and colleagues found that the overall rate of thrombosis was low (58 thromboses in 3,021 patients).
Of these thromboses, 42 occurred in the first six months following stenting. In the 16 long-term thromboses, nine occurred in patients taking clopidogrel, and seven in patients who had discontinued therapy.
In the first 30 days, 97% of patients were on double antiplatelet therapy. The rate of thrombosis in this group was 0.9% compared with 4.2% among patients who were not on dual antiplatelet therapy (Table).
Through the first 180 days after stenting, eight of the 439 patients who had discontinued clopidogrel had thrombosis, compared with 34 of 2,582 patients who were on dual therapy. After 180 days, the event curves were comparable, suggesting the most significant risk associated with discontinuing therapy was in the early period, Chieffo said.
Patients with chronic renal insufficiency, with lesions in the left descending artery, who had an intraaortic pump or who were taking GPIIb/IIIa inhibitors at baseline were more likely to experience stent thrombosis.
Other predictors of stent thrombosis included prior brachytherapy and left ventricular ejection fraction less than or equal to 30%.
Researchers could not determine whether the thrombotic events reflected a failure of the stent or were caused by the development of new vulnerable plaques inside the stent that did not allow the development of restenosis. 