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Homocysteine lowering and cardiovascular events after acute myocardial infarction
Kaare Harald Bønaa1, Inger Njølstad, Per Magne Ueland
1Institute of Community Medicine, University of Tromsø, Tromsø, Norway. kaare.bonaa@stolav.no
Insights
B vitamin treatment, including folic acid and vitamin B12, did not reduce cardiovascular events after heart attack. Combined B vitamin therapy showed a trend toward increased risk, and is not recommended for secondary prevention.
Area of Science:
- Cardiology
- Nutritional Science
- Clinical Trials
Background:
- Elevated homocysteine levels are a known risk factor for cardiovascular disease.
- This study investigated the effectiveness of B vitamin supplementation for secondary prevention in patients post-myocardial infarction.
Purpose of the Study:
- To determine if homocysteine-lowering treatment with B vitamins (folic acid, B12, B6) reduces recurrent cardiovascular events after acute myocardial infarction.
- To assess the safety and efficacy of different B vitamin combinations in secondary cardiovascular prevention.
Main Methods:
- A randomized, double-blind, placebo-controlled trial involving 3749 patients within seven days of acute myocardial infarction.
- Patients received daily treatments of folic acid, vitamin B12, vitamin B6, or placebo in a factorial design.
- The primary endpoint was a composite of recurrent myocardial infarction, stroke, or sudden cardiac death over a median follow-up of 40 months.
Main Results:
- Folic acid plus vitamin B12 significantly lowered homocysteine levels by 27% but did not reduce the primary endpoint risk (RR 1.08, P=0.31).
- Vitamin B6 monotherapy showed no significant benefit for the primary endpoint (RR 1.14, P=0.09).
- Combined folic acid, vitamin B12, and vitamin B6 treatment showed a trend toward increased risk (RR 1.22, P=0.05).
Conclusions:
- B vitamin treatment, including folic acid and vitamin B12, is ineffective for preventing recurrent cardiovascular disease after acute myocardial infarction.
- Combined B vitamin therapy demonstrated a potential for harm, suggesting it should not be recommended for this patient population.
- Further research may be needed to clarify the role of B vitamins in cardiovascular health, but current evidence does not support their use for secondary prevention post-MI.
Background:
Homocysteine is a risk factor for cardiovascular disease. We evaluated the efficacy of homocysteine-lowering treatment with B vitamins for secondary prevention in patients who had had an acute myocardial infarction.
Methods:
The trial included 3749 men and women who had had an acute myocardial infarction within seven days before randomization. Patients were randomly assigned, in a two-by-two factorial design, to receive one of the following four daily treatments: 0.8 mg of folic acid, 0.4 mg of vitamin B12, and 40 mg of vitamin B6; 0.8 mg of folic acid and 0.4 mg of vitamin B12; 40 mg of vitamin B6; or placebo. The primary end point during a median follow-up of 40 months was a composite of recurrent myocardial infarction, stroke, and sudden death attributed to coronary artery disease.
Results:
The mean total homocysteine level was lowered by 27 percent among patients given folic acid plus vitamin B12, but such treatment had no significant effect on the primary end point (risk ratio, 1.08; 95 percent confidence interval, 0.93 to 1.25; P=0.31). Also, treatment with vitamin B6 was not associated with any significant benefit with regard to the primary end point (relative risk of the primary end point, 1.14; 95 percent confidence interval, 0.98 to 1.32; P=0.09). In the group given folic acid, vitamin B12, and vitamin B6, there was a trend toward an increased risk (relative risk, 1.22; 95 percent confidence interval, 1.00 to 1.50; P=0.05).
Conclusions:
Treatment with B vitamins did not lower the risk of recurrent cardiovascular disease after acute myocardial infarction. A harmful effect from combined B vitamin treatment was suggested. Such treatment should therefore not be recommended. (ClinicalTrials.gov number, NCT00266487.).
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