Factor V Q(506) (resistance to activated protein C) and prognosis after acute coronary syndrome

Factor V:Q(506) causing resistance to activated protein C (APC-resistance), is a risk factor for venous thrombosis. Some studies have indicated an ass ociation with arterial disease, especially in women. We investigated the pr evalence of the FV:Q(506) allele prospectively in 295 patients with acute c oronary syndrome. Mortality and myocardial infarction rate were evaluated a fter 30 days and after 2 years. The FV:Q(506) allele was found in 38 patien ts. In a Cox proportional hazards model, smokers carrying FV:Q(506) had a h igher risk of infarction or death within 30 days, compared to non-smokers w ith a normal genotype (relative risk 2.9 [95% Cl 1.2-7.0]). The difference remained significant after 2 years (relative risk 2.8 [95% Cl 1.2-6.5]). Th e effect of the FV:Q(506) allele on clinical outcome in acute coronary synd rome has not previously been described. Our results demonstrate a gene-envi ronment interaction between smoking and the FV:Q(506) allele, with an incre ased risk of early complications after an acute ischemic event.