Interactive associations of depression and sleep apnea with adverse clinical outcomes after acute myocardial infarction

OBJECTIVE: Depression and sleep apnea (SA) are common among patients with a recent acute myocardial infarction (AMI), and both are associated with increased risk for adverse outcomes. We tested the hypothesis that there is an interaction between them in relation to post-AMI prognosis. METHODS: Participants were patients with a recent AMI, 337 of them were depressed and 379 were nondepressed, who participated in a substudy of the Enhancing Recovery in Coronary Heart Disease (ENRICHD) clinical trial. SA was identified from Holter electrocardiogram by an algorithm that detects cyclic variation of heart rate. RESULTS: During a median follow-up of 25 months, 83 (11.6%) patients either died or experienced a recurrent AMI and 43 (6.0%) patients died. Among 94 patients with both depression and SA, these end points occurred in 25 (26.6%) and 20 (21.3%) at 3.9-and 6.9-times higher prevalence than predicted probabilities by ENRICHD clinical risk scores (p <.001 for both). In the patients with depression alone, SA alone, or neither, the prevalence was similar to the predicted probability. Depression and SA showed significant interactions in prediction of these end points (p = .02 and p = .03). SA independently predicted these end points in patients with depression (p = .001 and p <.001) but not in those without depression (p = .84 and p = .73). Similarly, depression independently predicted these end points in patients with SA (p <.001 for both) but not in those without SA (p = .12 and p = .61). CONCLUSIONS: Depression and SA are interactively associated with adverse clinical outcomes after AMI. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00313573.