Background: Several case reports of myocardial infarction in patients with factor XII deficiency have been published. In the present study we investigated the prevalence of this condition.
Methods: Factor XII activity (one-stage clotting assay), fibrinogen (derived method), and lipoprotein (a) (enzyme-linked immunosorbent assay) were measured in the plasma of 426 consecutive patients with coronary heart disease awaiting cardiac surgery.
Results: Among the 426 patients, 44 (10.3%) were found to be moderately deficient in factor XII (factor XII activity 17-50%, antigen 15-57%). The prevalence of factor XII deficiency was significantly higher (P < 0.0001) among patients with coronary heart disease than among 300 healthy blood donors (2.3%). Among coronary heart disease patients with this deficiency, elevated levels of fibrinogen, lipoprotein (a), and blood pressure were no more prevalent than in those without the deficiency; nor were cigarette smoking or a positive family history of thromboembolism more prevalent.
Conclusions: Coronary heart disease patients showed a 10% prevalence of factor XII deficiency. However, the pattern of atherosclerotic risk factors did not differ between patients with or without the deficiency.