Plasma choline, smoking, and long-term prognosis in patients with stable angina pectoris.

BACKGROUND Plasma choline has been associated with cardiovascular disease and nonalcoholic steatohepatitis. DESIGN We sought to study relations of plasma choline and its metabolite betaine to long-term risk of acute myocardial infarction (AMI) and all-cause mortality according to smoking status, in patients undergoing coronary angiography for stable angina pectoris. METHODS Samples were obtained before angiography from 2568 patients who were subsequently randomized in the Western Norway B-Vitamin Intervention Trial (WENBIT). Hazard ratios (HR) were calculated using multivariate Cox-regression and p-values were reported for trends over quartiles. RESULTS Plasma concentrations of choline, but not betaine, were lower in smokers, and choline was positively associated with C-reactive protein and troponin T in nonsmokers, but not in smokers (p for interaction <0.03). During a follow up of 4.8 ± 1.4 (mean ± SD) years, 8.3% suffered from AMI and 6.1% died. In the total population, choline was not associated with AMI or all-cause mortality. However, comparing the highest vs. the lowest quartiles, plasma choline was associated with increased risk of AMI in nonsmokers (HR 2.63, 95% CI 1.56 to 5.51; p for trend = 0.013) and no risk in smokers (p for interaction < 0.001). Plasma choline significantly improved discrimination and reclassification when added to established cardiovascular risk factors. Plasma betaine was not associated with either endpoint. CONCLUSIONS In patients with stable angina pectoris, elevated plasma choline is associated with elevated troponin levels and increased risk of AMI in nonsmokers. These results motivate further research into the relation between choline metabolism, smoking, and atherothrombosis.