Activated protein-C resistance [APC] as a risk factor for thrombosis in cerebral and myocardial infarction

ABSTRACT

Activated protein-C. [APC] resistance is referred to poor anticoagulant response to activated protein C. It is a strong risk factor for the genesis of venous thrombosis. To evaluate its role in the pathogens is of arterial thrombosis, APC sensitivity ratio [APC-SR] was estimated in 40 healthy control subjects without history of thrombosis, and in 40 subjects with arterial thrombosis before the age of 45 years. [20 subjects with myocardial infarction and 20 with cerebral infarction]. In addition, protein C, protein S, antithrombin III activity, thrombomodulin [TM], prothrombin time [PT] and partial thromboplastin time [PTT] were also measured.The study revealed that the lower limit of normal APC-SR was 1.8, below which we found 15 positive cases for APC resistance among our patients [9 cases with myocardrial infarction and 6 cases with cerebral infarction] and non in control subjects. A statistically significant decrease in APC-SR [P < 0.01] was found in all patients with arterial thrombosis [2.18 +/- 0.22] as compared to control group [2.84 +/- 0.52] and in APC positive patients [1.69 +/- 0.44] as compared to each of APC negative patients [2.67 +/- 0.62], all patients with thrombosis [2.18 +/- 0.22] and control group [2.82 +/- 0.52]. There was no significant difference in APC-SR between APC positive stroke and APC positive myocardial infarction. PTT was significantly decreased in APC positive patients as compared to control and APC negative subjects [P <0.01]. Other parameters of study did not show any siginificant difference between different groups and subgroups of study. Significant positive correlation was found between APC-SR and PTT in all patients of this study [r = 0.408, P < 0.05].Smoking was found to increase the relative risk of thrombosis among APC positive cases by about 2 folds, while hypertension increases this relative risk by 3 folds than normotensive APC positive cases. We can conclude that APC resistance may be a strong risk factor for premature arterial thrombosis [before 45 years] and the risk of thrombosis among APC positive cases increases with smoking and hypertension