Elevated level of plasma homocysteine in patients with slow coronary flow

Elevated plasma levels of homocysteine are currently considered a major, independent risk factor for cardiovascular diseases. Recently, several investigators have suggested that even mild elevation in plasma homocysteine level can severely disturb vascular endothelial function and subsequently impair coronary blood flow. Accordingly, we investigated plasma homocysteine level in patients with slow coronary flow.

Study population included 53 patients with angiographically proven normal coronary arteries and slow coronary flow in all three coronary vessels (group I, 21 females, 32 males, mean age=48+/-9 years), and 50 subjects with angiographically proven normal coronary arteries without associated slow coronary flow (group II, 22 females, 28 males, mean age=50+/-8 years). Coronary flow rates of all patients and control subjects were documented by Thrombolysis In Myocardial Infarction frame count (TIMI frame count). All patients in group I had TIMI frame counts greater than two standard deviations above those of control subjects (group II) and, therefore, were accepted as exhibiting slow coronary flow. The mean TIMI frame count for each patient and control subject was calculated by adding the TIMI frame counts for each major epicardial coronary artery and then dividing the obtained value into 3. Plasma homocysteine level was measured in all patients and control subjects using commercially available homocysteine kits.

There was no statistically significant difference between two groups in respect to age, gender, hypertension, diabetes mellitus, hyperlipidemia and cigarette smoking (p>0.05). Plasma homocysteine level of patients with slow coronary flow were found to be significantly higher than those of control subjects (15.5+/-5.7 vs. 8.7+/-4.2 microM/l, respectively, p<0.001). Moreover, we found a significant positive correlation between plasma homocysteine level and mean TIMI frame count (r=0.660, p<0.001).

We have shown that patients with slow coronary flow have raised level of plasma homocysteine compared to control subjects with normal coronary flow. This data suggests that elevated level of plasma homocysteine may play a role in the pathogenesis of slow coronary flow.