Haemorheologic studies in patients with reduced coronary vasodilator capacity but normal coronary angiogram (syndrome X)

The cause of syndrome X, i.e. typical angina, positive exercise test, normal coronary angiogram, normal resting cardiac function, but reduced coronary vasodilator capacity is still unknown. The purpose of the study was to investigate blood fluidity as a possible cause of syndrome X. Haematocrit, plasma viscosity, erythrocyte aggregation, and erythrocyte deformability were examined in 14 patients with syndrome X (group 1), 24 patients with typical angina, positive exercise test, but normal coronary vasodilator capacity (group 2), and 37 patients with atypical chest pain and normal coronary arteries (control group). Coronary vasodilator capacity was determined by the argon method. Compared with normals, patients with syndrome X showed an elevated plasma viscosity (1.31 ±0.05 mPas vs l.26±0.04 mPas, 2P>001), an elevated erythrocyte photometric aggregation index (141 ±27% vs 100 ±23%, 2?>001) and a reduced erythrocyte filterability (0.51 ±0.12 vs 0.66 ± 0.09, 2P > 0.01). Significant differences in the haemorheologic parameters between group 1, group 2 and the control group, however, were not detected. Multiple regression analysis did not reveal a significant relationship between coronary vasodilator capacity and the haemorheologic parameters tested. The data suggest that the reduction in coronary vasodilator capacity in patients with syndrome X cannot be attributed to haemorheologic alterations.