The relation between plasma fibrinogen, blood hematocrit and exercise ST segment depressions in hyperlipoproteinemia.

In order to study whether the high frequency of exercise ST segment depressions found in primary asymptomatic hyperlipidemia were due to increased plasma fibrinogen levels and blood hematocrit and consequently higher blood viscosity these parameters were determined in fifty-four consecutive hyperlipidemic subjects. Mean plasma fibrinogen as determined by polymerization time was increased in hyperlipidemia. It did not differ between groups with and without exercise ST segment depressions. Mean hematocrit was normal in both men and women. Men with exercise ST segment depressions had lower mean hematocrit than those without (p less than 0.01). The findings speak against the view that the exercise ST segment depressions found in asymptomatic subjects with hyperlipoproteinemia should be due to increased blood viscosity. The most probable cause is a premature, subclinical atherosclerosis.