According to a 2007 study by Caimi et al., the blood of young adults remains hyperviscous after 3 and 12 months following an acute myocardial infarction (AMI), or heart attack, despite a positive clinical course. Cardiovascular risk factors, their influence on blood flow, and corresponding coronary lesions were studied in a group of 96 patients aged less than 46 years with recent acute myocardial infarction. Compared to 52 control subjects, patients had significantly higher low shear and high shear blood viscosity and significantly lower blood filterability and erythrocyte deformability at baseline. Differences in viscosity were not influenced by hematocrit, which did not vary between the groups. Blood properties of patients did not change significantly in the months following the heart attack, even though some risk factors were modified after the event (many patients stopped smoking; hypertension and diet were carefully controlled). These subjects showed a hyperviscosity syndrome that was not influenced by the number of risk factors (tobacco smoking, hypertension, diabetes, hypercholesterolemia, and family history of coronary artery disease). Hyperviscosity was only slightly more evident in patients with more coronary damage.
Forty-one of the patients were re-examined after 3 and 12 months, and it was found that no significant variation in blood properties emerged in comparison with initial values. Blood viscosity was not significantly different among the patients with various levels of coronary damage, with the exception of blood viscosity at a shear rate of 225 s-1, which was higher in AMI subjects with 2-3 vessel disease in comparison with those without coronary stenosis, and blood viscosity at a shear rate of 0.51s-1, which was higher in AMI subjects with 2-3 vessel disease in comparison with those with 1 vessel disease (p < 0.05 for all). Although some authors consider acute myocardial infarction as an autonomous disease in young adults, these results suggest that hyperviscosity syndrome observed at the initial stage is not simply an acute reaction to a heart attack, persists during subsequent months following the heart attack, and is not influenced by intervention on modifiable risk factors alone.
Caimi G, Valenti A, Lo Presti R. Acute myocardial infarction in young adults: evaluation of the haemorheological pattern at the initial stage, after 3 and 12 months. Ann Ist Super Sanita. 2007;43(2):139-143.