Exercise-induced platelet aggregation in angina and its possible prevention by β1-selective blockade

Abstract

Moderate exercise increased platelet aggregability of 12 middle-aged men with stable angina pectoris: the mean ADP threshold fell from 4.58 +/- 0.63 to 3.18 +/- 0.41 microM, P less than 0.01. Exercise did not, however, alter platelet aggregability in 12 healthy matched controls. Physical effort approximately doubled the plasma levels of adrenaline and noradrenaline in patients as well as in controls. Under the same conditions the cAMP content of platelets fell in the angina group from 20.86 +/- 1.86 to 17.78 +/- 1.71 pmol 10(-9) platelets, P less than 0.01, while there was no change in control levels. The fall of cAMP could account for the observed increase in platelet aggregability. We speculate that the increased aggregability of platelets in the exercising anginal subjects represents an imbalance between prostacyclin release and haemodynamic changes. The beta 1-selective blocker metoprolol, in usual therapeutic dosages, prevented the observed platelet changes probably by minimizing the haemodynamic disturbances and stimulating release of prostacyclin.

Relation Between Platelet Response to Exercise and Coronary Angiographic Findings in Patients With Effort Angina

“…Indeed, despite the enhanced platelet reactivity at baseline, patients with NCAs exhibited a significant reduction in platelet reactivity after exercise, whereas CAD patients, in agreement with previous studies, [1][2][3][4][5] showed a significant increase.…”

“…A careful clinical history, including risk factors for CAD and drug therapy, was recorded from each patient. Patients with any of the following conditions were excluded: (1) myocardial infarction or unstable angina in the previous 6 months; (2) anticoagulant therapy; (3) previous coronary angiography; (4) previous revascularization procedures (surgical or percutaneous); and (5) variant angina.…”

“…[1][2][3][4] This can occur even at low workloads and independently of whether myocardial ischemia is induced or not during exercise. 5 In a recent study, we found that in contrast to well-matched CAD patients, those with cardiac syndrome X (effort angina, positive exercise test, and angiographically normal coronary arteries) display a decrease in platelet reactivity after exercise.…”

Treadmill exercise in claudicants on aspirin results in improved antioxidant status but only minimal platelet activation

“…Studies of moderate or sub-maximal exercise yielded conflicting results varying from suppressed platelet function through to elevated activity [14,16,17]. In CAD, there is evidence to suggest an association between exercise and increased platelet activity although the relationship between exercise intensity and platelet activation is not well defined [18][19][20][21]. However, other work has shown that exercise has no effect on platelet function [22], and at least one study suggests a reduction in platelet activity in CAD patients with exercise [23].…”

Antiplatelet and Antileukocyte Effects of Cardiovascular,Immunomodulatory and Chemotherapeutic Drugs

“…The 1 -selective blocker MET, in usual therapeutic dosages, prevented the observed platelet changes in exerciseinduced platelet aggregation in angina probably by minimising the haemodynamic disturbances and stimulating release of prostacyclin [87]. However, MET prevented the increase of platelet aggregability and the decrease of intracellular cAMP during exercise stress in patients with stable angina pectoris [88].…”