Plasma viscosity and haematocrit in the course of acute myocardial infarction

Plasma viscosity and haematocrit were determined in 44 patients with acute myocardial infarction on the 1st, 2nd, 3rd and 10th day of hospitalization. The highest haematocrit value for the entire group was found on the 1st day of acute myocardial infarction-43.3 SD±4.6% declining progressively to 38.8 SD±3.5% on the 10th day (P<0.001). Plasma viscosity for the entire group was normal on the first day of acute myocardial infarction (1.44 SD±0.10cp) and started to increase on the second day (1.51 SD±016 cp, P<0.001). A relationship was found between reinfarction or death (17 patients) occurring during hospitalization and changes in haematocrit and plasma viscosity. In this group plasma viscosity rose to 1.63 SD±0.19 cp on the second day of acute myocardial infarction (P<0.001 vs plasma viscosity value on the first day). This elevation persisted on the third day. Haematocrit values in this group were 47.9 SD±3.6% on the first day of acute myocardial infarction declining progressively and significantly afterwards. In the remaining patients both plasma viscosity and haematocrit were normal and did not change. No correlation of plasma viscosity and haematocrit were found when tested for other clinical complications, sex, age, maximal creatine phosphokinase values and coronary risk factors. We suggest that variations in haematocrit and plasma viscosity during acute myocardial infarction exist in a group of patients in whom reinfarction or death occurs. The changes in haematocrit and plasma viscosity precede the complications by 4-8 days. It is possible that the early elevation of haematocrit and plasma viscosity during acute myocardial infarction may initially aggravate coronary microcirculatory blood flow and thus contribute to the later occurrence of reinfarction or death.