Secondary prevention with homocysteine-lowering B-vitamins does not reduce risk of death or major cardiovascular events, according to the WENBIT study.

In the Western Norway B-vitamin intervention trial, a total of 3,090 patients with angiographically verified (established) heart disease, mainly stable angina pectoris and 2 or 3 vessel coronary artery disease, were randomly allocated to four groups to receive a daily oral dose of either folate (with vitamin B12) and vitamin B6, folate (with vitamin B12), vitamin B6 or placebo. During a median follow-up time of 38 months, there were no significant differences in risk of death or major cardiovascular events between the intervention groups.

The participants were randomised when undergoing coronary angiography at Haukeland (Bergen) or Stavanger University Hospitals in Western Norway from 1999 to 2004. The groups did not differ significantly regarding age, gender, clinical, laboratory or angiographic findings, cardiovascular risk factors or concomitant medication. Study patients received conventional treatment, including acetylsalisylic acid (90%), statins (89%) and beta-blockers (77%). Mean age at randomisation was 61.8 years and 20.5 % of participants were women.
 

There is no mandatory folate fortification of foods in Norway. Mean homocysteine levels at baseline were 10.8 µmol/L. In the groups receiving folate, homocysteine was lowered by 28%, and remained unaltered in the non-folate groups. A total of 422 participants experienced at least one event classified as the composit primary end point, defined as death (all cause), non-fatal myocardial infarction, unstable angina pectoris or non-fatal thromboembolic stroke.

The survival analyses calculating time to the first primary end point, revealed no significant differences between the groups receiving folate or not (p=0.35) or between the groups who received vitamin B6 or not (p=0,23).

Our findings are in concordance with, and add further evidence to, previous trials that have failed to prove that homocysteine-lowering intervention with folate supplementation reduces risk of death or progression of cardiovascular disease in patients with established cardiovascular disease. Furthermore, there were no effects of vitamin B6 treatment. At this time, B-vitamin supplementation is not justified as secondary prevention in cardiovascular disease.