Are sleep complaints an independent risk factor for myocardial infarction?

To investigate whether subjective sleep complaints are an independent predictor of myocardial infarction (MI) in a community of older adults and to gain clues as to why the association between sleep complaints and incident MI exists.

Using longitudinal data from the Piedmont study on 2960 adults aged 65 or older who were free of symptomatic heart disease at baseline, we screened 19 potential confounders to determine if any, alone or in combination, could explain the observed relationship between incident MI and sleep complaints.

During the three-year follow-up period, there were 152 incident MIs. Restless sleep (incidence density ratio (IDR) = 1.58, 95% confidence interval (CI) = 1.11, 2.24) and trouble falling asleep (IDR = 1.68, 95% CI = 1.09, 2.60) predicted incident MI after adjusting for age, gender, and race. IDRs were not substantially impacted by controlling for smoking, blood pressure, diabetes or obesity. After adjustment for education, number of prescription medicines, self-rated health, and depression score, all IDRs were nullified. In particular, self-rated health and depression were strong independent risk factors for MI.

A subjective sleep complaint increases the likelihood of a first MI in older adults without overt coronary heart disease (CHD) independently of classic coronary risk factors and appears to be a marker for a syndrome of depression and malaise that may have a causal relationship to MI.