Increased thromboxane A2 generation and altered membrane fatty acid composition in platelets from patients with active angina pectoris.

Lipid composition of platelet membranes and thromboxane A2 (TxA2) generation by platelets were investigated in eighty-seven anginal patients (forty-two with resting angina in active phase and forty-five with effort stable angina or rest angina in inactive phase) and in forty-five clinically healthy subjects of similar age. All subjects were on the same dietary regimen and the adherence to diet was checked by analysis of red blood cell lipids. Platelets from active angina patients produced more TxA2 than platelets from both inactive patients and controls (p less than 0.001). Moreover patients with active angina had higher arachidonic acid (AA, p less than 0.001) and lower eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) levels in phosphatidylcholine (PC, p less than 0.001), than inactive patients and controls. AA and EPA changes in membrane PC significantly correlated with TxA2 production (p less than 0.001) but not with coronary pathoanatomy. Plasma lipids, content of cholesterol, total phospholipids (and their saturated and unsaturated fatty acids) and the different phospholipid fractions in platelet membrane were not different in the three groups. Present results indicate that in platelets from anginal patients phospholipid fatty acid composition is at least in part independent of plasma composition and that in active angina there are modifications leading to increased TxA2 formation and possibly contributing to the occurrence of ischemic attacks.