We studied the levels of
thromboxane B2 (TXB2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), platelet aggregability,
beta-thromboglobulin and
platelet factor 4 in 30
coronary artery disease (CAD) patients and 21 normal subjects during exercise. During treadmill exercise, 13 of 30 CAD patients reported
chest pain. We administered a selective
thromboxane synthetase inhibitor (OKY-046) for 2 weeks to 10 CAD patients with exercise-induced
chest pain and studied its effects. At rest, the plasma TXB2 levels and platelet aggregation were significantly lower in normal subjects than in CAD patients, and there was no difference between CAD patients with and without exercise-induced
chest pain. On treadmill testing, plasma TXB2 levels and platelet aggregation increased significantly only in the CAD patients with exercise-induced
chest pain. Plasma
6-keto-PGF1 alpha levels in normal subjects were significantly higher than those in CAD patients both at rest and during exercise. After administration of
OKY-046, mean exercise time increased significantly from 7.5 to 8.6 min (p less than 0.001). Plasma TXB2 level and platelet aggregation decreased significantly after
OKY-046 administration both at rest and during exercise. These results suggest that a marked increase in TXA2, with only a minimal change in PGI2, during exercise may contribute to exercise-induced
myocardial ischemia, and that
OKY-046 is useful in the treatment of CAD patients.