Objectives and design: Leptin is involved in the regulation of bodyweight and metabolism in man and might also be involved in the pathophysiology of the insulin resistance syndrome, which is associated with the development of cardiovascular diseases. We tested whether leptin is a risk factor for acute myocardial infarction (AMI) in a nested case-referent study.
Subjects and methods: Sixty-two men with first-ever AMI were identified who, prior to AMI, had participated in population-based health surveys in Northern Sweden. Referents were matched for sex, age, date and type of health survey, and geographical region. Blood pressure, body mass index (BMI) and the presence of smoking, diabetes and hypertension were recorded. Total cholesterol, apolipoprotein A-1 (apo A-1), apolipoprotein B (apo B), plasminogen activator inhibitor (PAI-1), insulin, and leptin were analysed in stored samples. Their influences on first-ever AMI were analysed by conditional logistic regression analysis.
Results: Men with first-ever AMI had higher BMI, plasma insulin and leptin, and diastolic blood pressure than the referents. Furthermore, they had lower plasma apo A-1 and were more often smokers. Smoking, high leptin, PAI-1 and cholesterol, and low apo A-1 levels were significant risk factors for first-ever AMI in univariate analysis. High leptin (OR 8.97; 95% CI: 1.73-46.5) and cholesterol (OR 5.18; 95% CI: 1.34-20.0) levels remained significant risk factors for AMI in a multivariate model. High apo A-1 was protective (OR = 0.13; 95% CI: 0.03-0.55). The combination of high leptin and low apo A-1 was associated with a particularly pronounced increased risk for AMI.
Conclusion: Plasma leptin strongly predicts first-ever AMI. Our data support the hypothesis that leptin is an important link in the development of cardiovascular disease in obesity.