Background: Blood platelets are related to coronary atherogenesis. Platelets secrete serotonin (5-hydroxytryptamine) which has several effects on the vascular wall and promotes thrombogenesis, mitogenesis, and proliferation of smooth muscle cells. Serotonin may therefore be one of the factors involved in the development of coronary artery disease (CAD). We have assessed serotonin among conventional predictors for CAD in patients undergoing coronary angiography for chest pain or clinically suspected angina pectoris.
Methods and results: Of 121 consecutive male patients (mean age 65, range 41 to 90 years) undergoing angiography, 96 had coronary artery stenosis and 25 had normal angiograms. Serotonin, blood platelet count, and conventional biochemical risk factors for CAD were determined in the morning the day before the angiography. High serotonin (cut-point 1000 nmol/L) was significantly associated with CAD with an odds ratio (OR) of 3.4 (95% confidence interval 1.2 to 9. 8). The corresponding OR for smokers was 4.8 (1.9 to 12.2); hypercholesterolemia (>7 mmol/L), 2.9 (1.1 to 7.6); high platelet count (cut-point 325 10(9)/L), 3.0 (1.0 to 9.5); and family history of heart disease, 2.3 (1.0 to 5.2). After adjustment with conventional risk factors, the OR for CAD was 3.8 (1.1 to 13.1), comparing high and low values of serotonin. The relation between serotonin and CAD was strengthened only when patients <70 years (n=82) were included in the analysis. In this age group, the occurrence of cardiac events during a mean of 3.7 years of follow-up was significantly associated with high serotonin values.
Conclusions: The study suggests that serotonin is associated with coronary artery disease and occurrence of cardiac events, particularly in younger age groups. This association seems to persist after adjustment for conventional risk factors.