Coronary Sapsm, Prostaglandin and HLA Factors : SYMPOSIUM ON PATHOGENESIS OF CORONARY ARTERY SPASM

Abstract

To elucidate the contribution of prostanoids in coronary spasm, plasma levels of thromboxane B₂ (TXB₂0) and 6-keto PGF_1α at the coronary sinus and ascending aorta in 21 patients with variant angina were measured, as compared with findings in 20 with effort angina and 13 subjects with normal coronaries. In the coronary sinus blood, plasma TXB₂ in patients with effort angina exhibited statistically significant high levels, as compared with data in the controls. On the contrary, the data obtained from patients with variant angina were not statistically significant. However, eight patients whose coronary angiogram revealed more than 50% of coronary stenoses had statistically significant high levels of TXB₂ and other patients with normal coronaries or less than 50% of narrowing showed almost the same levels of TXB₂ as the controls. In contrast to TXB₂, the plasma levels of 6-keto PGF_1α in patients with variant angina were very low in both groups with variant angina. These data suggest that high levels of TXB₂ observed in patients with atherosclerotic coronaries may be an accelerating factor while low levels of prostacyclin may be an essential factor leading to spasm. HLA analysis of 23 patients with variant angina was performed to search for genetic factors, under the hypothesis that such may contribute to the low levels in prostacyclin. This preliminary study revealed statistically significant high frequencies of Bw52 and B-40 in the patients, as compared with frequencies among 152 normal Japanese. Genetic studies are ongoing in our clinic.