Protein C and/or protein S deficiency and occurrence of stent thrombosis: a hitherto unrecognized association.

OBJECTIVE: To study the prevalence of protein C and/or protein S deficiency in patients of stent thrombosis and correlate its association with the event, if any.
BACKGROUND: Stent thrombosis is the Achilles heel of percutaneous coronary intervention (PCI) and has been associated with so many predisposing factors that if one analyzes all patients undergoing PCI, one or more such factors would be present in almost every patient; however, its incidence remains no more than 1-2%. We hypothesized a preexisting prothrombotic state, or tendency, in a small proportion of patients that possibly plays a key role in its occurrence.
METHODS: We analyzed the prothrombotic tendency of individual patients by studying protein C and protein S levels. Thirteen patients presenting with stent thrombosis and 24 age- and sex-matched controls were studied.
RESULTS: Protein S was found to be deficient in 11 of 13 patients (84.6%) of stent thrombosis and in only 4 of 24 patients (16.7%) in matched controls (P < 0.001), while protein C was found deficient in 2 of 12 patients (16.7%) of stent thrombosis, and 1 of 24 patients (4.2%) in matched controls (P = 0.25) and either protein C or protein S was deficient in 11 of 13 (84.6%) of stent thrombosis and 5 of 24 (20.8%) controls (P = <0.001). Low protein S levels were strongly associated with stent thrombosis (odds ratio 3.04, 95% confidence interval 1.34-4.7) with sensitivity 0.73 and specificity of 0.91.
CONCLUSIONS: Protein S deficiency is strongly correlated to the occurrence of stent thrombosis, a fact that has hitherto not been recognized and needs further evaluation. ©2010, Wiley Periodicals, Inc.