Evidence for a role of serotonin in initiation of coronary arterial thrombosis in dog and man.

We report recently published results in dogs by Torr et al. in which the accumulation of platelet thrombi in canine coronary arteries was abolished by the specific serotonin 5HT2 receptor antagonist, ritanserin. The serotonin blockade by ritanserin also prevented the re-establishment of thrombi by adrenaline infusion. 61 humans with critical coronary artery stenoses shown by coronary angiography were divided into control and serotonin antagonist (31 ketanserin administration) groups. While awaiting coronary artery bypass grafting or angioplasty, 7 of the subjects in the control group had coronary arterial occlusions, 4 of whom died. The only occlusion in the serotonin antagonism group occurred in a subject who died suddenly after 2 years of study. The probability of the occlusion rate in subjects subjected to serotonin antagonism being the same as that of the control subjects was less than 0.0245, by Fisher's exact test. It is concluded that serotonin may be as important in mediating coronary thrombosis in man as it is in animals.