Systematic review of thienopyridine discontinuation and its impact upon clinical outcomes.

The optimal length of clopidogrel therapy in patients with acute coronary syndromes or in those who have undergone percutaneous coronary intervention (PCI) remains controversial. We therefore sought to determine the risk of both perioperative and premature discontinuation of clopidogrel. PubMed and EMBASE databases were searched January 2000 through March 2010 for articles written in English and reporting adverse clinical events following discontinuation of clopidogrel. Studies of perioperative clopidogrel cessation are mostly observational, but do suggest a hazard for adverse cardiac events. This appears to be especially high in the first month after PCI, but it is unclear whether there is a 'safe' window. Studies of 'premature' clopidogrel discontinuation, although mostly retrospective and statistically flawed, suggest that the first 6 months after stenting are highest risk; discontinuation with drug-eluting stents (DESs) is probably higher risk than with bare metal stents, but most studies are of DESs alone. There are no randomized trials sufficient to determine the optimal length of clopidogrel therapy; future randomized clinical trials may provide more clarity.