APC RESISTANCE IN HIGH ELITE ATHLETES

Abstract

1587 Background: Resistance to activated protein C (APC) is the most prevalent hereditary risk factor for venous thrombosis. The prevalence is 2-8% in the general population of caucasian origin and around 40% in patients with a history of venous thrombosis. In more than 90% of the cases the reason for APC resistance is a point mutation in the factor V gene, resulting in a replacement of arginine at position 506 with a glutamine (factor V Leiden). Due to this replacement the inhibition of factor Va by APC is grossly impaired, resulting in a prothrombotic disposition. It is well known that elite athletes are exposed to several circumstantial factors known to contribute significantly to the risk of thrombosis: haemoconcentration following exercise, polycythaemia due to training at high altitude, traumata with consecutive immobilisation, long distance travels, oral contraceptives. Different case reports with effort thrombosis have been published. Methods: 173 elite athletes (German A-D cadre) were tested for in vitro APC response, expressed as APC ratio. Positive results with APC resistance were confirmed by molecular analysis of the factor V gene for the presence of the factor V Leiden mutation. Results: APC resistance was detected in 12 cases (11 heterozygote and 1 homozygote), corresponding to a prevalence of 6,9% in this population. Conclusion: The observed prevalence of 6,9% in this group of high elite athletes is within the range of reported prevalences for the general population from several authors. Based on the observed prevalence of APC resistance and the additional circumstantial risk profile, in our opinion screening for APC resistance among elite athletes is necessary to identify individuals at high risk and to take measures for preventing thrombosis specially for athletes who are homozygous carriers of the factor V Leiden mutation.