PLASMA-FIBRINOGEN LEVEL IS NOT ELEVATED IN YOUNG-ADULTS FROM FAMILIESWITH PREMATURE ISCHEMIC-HEART-DISEASE

Several epidemiological studies have found that the plasma fibrinogen level is a risk factor for ischemic heart disease (IHD), similar in im portance to the serum cholesterol level. A family history of IHD is al so a significant risk factor for IHD, statistically independent of the serum cholesterol level. Whether the familial risk for IHD is related to genetic control of the fibrinogen level is unknown. Estimates of t he genetic contribution to the variance in plasma fibrinogen levels va ry markedly. We previously found elevated levels of cholesterol and fa ctor VII in young subjects with a familial history of premature IHD. I n the present study we chose to measure fibrinogen, factor VII antigen , and total cholesterol levels in 43 asymptomatic first-degree relativ es (<50 years old) of patients with premature IHD and in 43 age- and s ex-matched asymptomatic young adults at low risk of IHD. No subjects i n either group were smokers. The mean plasma fibrinogen level of the h igh-risk group (259 mg/dL) did not differ significantly from that of t he low-risk group (250 mg/dL; p>0.4). In contrast, the high-risk group had significantly higher mean factor VII antigen (p<0.001) and mean s erum cholesterol (p<0.0001) than the low-risk group. These data argue against the hypothesis that genetic determination of the plasma fibrin ogen level is a common pathophysiological mechanism responsible for fa milial risk of IHD.