The effects of alcohol on coagulation and fibrinolytic factors: a controlled trial - PubMed

Content

Light-to-moderate alcohol intake is associated with a reduced incidence of ischaemic cardiovascular events, whilst heavy alcohol intake can predispose individuals to stroke. Alcohol-induced changes in coagulation and fibrinolysis may be relevant and are the subject of this controlled trial of varying alcohol intake in 55 predominantly beer-drinking men. Following 4 weeks stabilization maintaining usual drinking habits, participants were randomized to either continue usual alcohol intake or to restrict alcohol by changing to low alcohol beer for 4 weeks. In a final 4 week period, they crossed over to low or usual alcohol intake, respectively. Comparing combined low and usual alcohol periods, an increase in mean weekly alcohol intake from 92 to 410 ml (mean daily intake from 13 to 58 ml) was associated with a decrease in plasma fibrinogen (by 11%, P < 0.001) and platelet count (3%, P < 0.05), but increases in factor VII (7%, P = 0.001), tissue plasminogen activator (tPA; 16%, P = 0.01) and plasminogen activator inhibitor-1 (PAI-1; 21%, P < 0.001). The ratio, tPA/PAI-1, fell from 0.50 to 0.44 (P = 0.02) confirming the relatively greater increase in PAI-1 with alcohol consumption. Two lipid-associated natural anticoagulants, tissue factor pathway inhibitor and beta 2-glycoprotein-I, did not change. The substantial reduction in plasma fibrinogen with alcohol intake may well contribute to the apparent protection alcohol confers against ischaemic coronary and cerebral events. The increase in factor VII and relatively greater increase in PAI-1 than tPA with alcohol intake may attenuate this benefit and indeed may sufficiently predispose individuals to thrombosis to contribute to the increased incidence of ischaemic stroke seen in heavier drinkers. The balance of anticoagulant and procoagulant and fibrinolytic effects in any individual may vary depending on quantity and type of alcoholic beverage ingested, as well as on genetic and other variables, all of which merit further study.

Summary
A controlled trial investigated the effects of varying alcohol intake on coagulation and fibrinolysis in 55 predominantly beer-drinking men. After a 4-week stabilization period, participants were randomized to either maintain their usual alcohol intake or switch to low alcohol beer for another 4 weeks, followed by a crossover period. Results showed that increasing weekly alcohol intake from 92 to 410 ml led to a significant decrease in plasma fibrinogen (11%) and platelet count (3%), while factor VII, tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) increased. The tPA/PAI-1 ratio decreased, indicating a greater increase in PAI-1 with alcohol consumption. The reduction in plasma fibrinogen may explain the protective effects of light-to-moderate alcohol intake against ischaemic cardiovascular events. However, the increase in factor VII and PAI-1 could counteract these benefits, potentially increasing the risk of thrombosis and ischaemic stroke in heavy drinkers. The study highlights the complex interplay of anticoagulant and procoagulant effects influenced by the type and amount of alcohol consumed, suggesting further research is needed to understand these dynamics.