Hypertensive patients with carotid artery plaque exhibit increased platelet aggregability

Platelets play an important role in myocardial infarction and ischemic stroke events, but whether platelet aggregability is related to early stage arteriosclerosis remains unclear.

We used a novel platelet counting system which makes it possible to detect spontaneous platelet aggregation, to evaluate the relationship between platelet aggregability and carotid artery arteriosclerosis in 125 outpatients with primary hypertension (46-73 years old: 65 men, 60 women). All subjects underwent carotid artery ultrasonography to determine whether plaque was present and to estimate intima-media thickness.

Patients with carotid artery plaques (Plaque(+), n=63) were older and had higher systolic blood pressures than patients without plaques (Plaque(-), n=62), but no significant differences in sex, body mass index, diastolic blood pressure, plasma concentrations of glucose, total cholesterol, triglyceride, lipoprotein cholesterol, fibrinogen or the platelet count in whole blood were observed between Plaque(+) and Plaque(-) groups. Plaque(+) subjects showed greater spontaneous platelet aggregability and platelet aggregation induced by 2 microM or 0.5 microM of ADP or 0.3 microM of epinephrine than the Plaque(-) group. When age and systolic blood pressure were matched (n=52 in both groups), the Plaque(+) subjects exhibited greater platelet aggregability than the Plaque(-) subjects. Platelet aggregation induced by 2 microM of ADP showed statistical significant positive correlation coefficients with age, HbA1c and diastolic blood pressure.

Our results indicate that hypertensive patients with carotid artery plaque have increased platelet aggregability. A prospective study is recommended to clarify whether this increase in platelet aggregability promotes the progression of arteriosclerosis.