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Homocysteine and myocardial infarction
B Israelsson1, L E Brattström, B L Hultberg
1Department of Medicine, University of Lund, Malmö General Hospital, Sweden.
Insights
High plasma homocysteine levels were observed in men who experienced myocardial infarction (MI) before age 55. Low folate and vitamin B12 may contribute, suggesting homocysteine as a potential risk factor for heart attack.
Area of Science:
- Cardiovascular Medicine
- Clinical Biochemistry
- Nutritional Science
Background:
- Myocardial infarction (MI) in younger men often lacks conventional risk factors.
- Elevated plasma homocysteine is a suspected contributor to cardiovascular disease.
Purpose of the Study:
- To investigate plasma homocysteine levels in men with premature MI and low conventional risk.
- To explore the relationship between homocysteine, B vitamins, and methionine metabolism in these patients.
Main Methods:
- Case-control study matching MI patients with healthy controls on key cardiovascular parameters.
- Measurement of fasting plasma total homocysteine, erythrocyte folate, and serum vitamin B12.
- Assessment of homocysteine response to methionine loading.
Main Results:
- 24% of men with premature MI exhibited high fasting plasma homocysteine.
- High homocysteine correlated negatively with folate and vitamin B12 levels.
- Methionine loading revealed potential homocystinuria heterozygosity in a subset of patients.
Conclusions:
- Elevated plasma homocysteine may be a risk factor for myocardial infarction in men with a low conventional risk profile.
- Reduced remethylation due to low B vitamin status could contribute to hyperhomocysteinemia.
- Further investigation into homocystinuria as a risk factor is warranted.
Abstract:
Five (24%) subjects out of a group of 21 men, 48-58 years old (mean 54), who had suffered their first myocardial infarction (MI) before the age of 55 and with a low risk profile vis-à-vis conventional risk factors in a health screening preceding the MI, had abnormally high total plasma homocysteine values in the fasting state when investigated within 1-7 years (mean 3) after their MI. The patient group was exactly matched with 36 control subjects for sex, age, diastolic blood pressure, smoking, and serum concentrations of cholesterol and triglycerides. Total plasma homocysteine was negatively correlated to both erythrocyte folate and serum vitamin B12, and vitamin concentrations below the median of the normal distribution were found in the five with high plasma homocysteine content, indicating a possible involvement of reduced remethylation of plasma homocysteine to methionine. After methionine loading, in 3 of the patient group (14%) homocysteine levels exceeded mean +2 SD for controls, which may indicate heterozygosity for homocystinuria. Results are consistent with the hypothesis that a high plasma homocysteine content may be a risk factor for MI.