Hematocrit and coronary heart disease.

Hematocrit values of patients with acute myocardial infarction have been reported by some workers to be higher than those found in controls; this has been denied by others. In these reported studies important postural, postprandial, age and stress effects have not been considered. In the present investigation hematocrits of healthy and coronary subjects were determined under the same "standard basal" conditions, in the morning hours, fasting or after a light breakfast, and in sitting position; patients studied had no acute illness or distress. A mean hematocrit of 49.1 +/- 2.4% was observed in 66 men with chronic coronary disease and of 46.8 +/- 3.2% in 68 healthy controls of the same age and sex, the difference being highly significant. The increased hematocrit and plasma viscosity in coronary patients creates significantly higher whole blood viscosity than that observed in healthy controls. This hemodynamic factor may be responsible for the development of clinical symptoms of coronary heart disease and possibly of the basic vascular disease itself.