No association of APC resistance with myocardial infarction.

Resistance to activated protein C (APC resistance) due to the factor V mutation 506 Arg-->Gln (factor V Leiden) is the most prevalent inherited risk factor for venous thromboembolism. Its association with arterial thromboembolic disease, however, is still controversial. In the present study we found no difference between the prevalence of APC resistance (assessed by the ratio of the aPTT with and without added APC) in 134 non-anticoagulated survivors of myocardial infarction and that in 100 controls of similar age and sex distribution (2.2% and 2.0%, respectively). Patients showed a significantly higher median value for the aPTT ratio than controls (2.85 and 2.66, respectively), a fact we could not explain by our data.