Myocardial Infarction After Epilepsy Onset: A Population-based Retrospective Cohort Study

Introduction: Cardiovascular comorbidities of epilepsy such as hypertension, hyperlipidemia, and diabetes are associated with myocardial infarction (MI). Little data on the development of subsequent cardiovascular disease (CVD) in persons with epilepsy (PWE) are available, with inconsistent findings regarding the association between epilepsy and subsequent MI. A higher risk of MI among adults (without prior MI) following epilepsy diagnosis compared with that among controls was hypothesized.

Methods: This retrospective cohort study used statewide hospital and emergency department (ED) encounter data from 2000-2013 for South Carolina residents aged >18 years without prior MI at the onset of epilepsy, or the first encounter for controls. Persons with epilepsy were compared with 1) persons with migraine (PWM), whose neurological condition has characteristics similar to epilepsy; and 2) persons with isolated lower extremity fracture (PWLF). Subsequent MI was defined as a diagnosis of MI after the first clinical encounter for epilepsy, migraine, or lower extremity fracture (LEF); the association was evaluated with Cox proportional hazard modeling methods.

Results: In this study, 2.2% of PWE, 0.6% of PWM, and 1.2% of PWLF had a subsequent MI. Persons with epilepsy were significantly more likely to be non-Hispanic Black (NHB), be covered by Medicaid, and reside in a rural or low income area compared with PWM and PWLF. Specific cardiovascular disease risk factors were more prevalent in PWE than in PWM and PWLF. After adjustment, the hazard of subsequent MI in PWE was 48% higher than in PWM (hazard ratio (HR) = 1.48; 95% confidence intervals (CI) = 1.31-1.67) and 24% higher than in PWLF (HR = 1.24; 95% CI = 1.10-1.39). The hazard of MI increased with increasing age and number of additional comorbidities and was higher in males, those living in rural areas, and those with specific cardiovascular risk factors.

Conclusion: Persons with epilepsy had moderately elevated risk of subsequent MI compared with PWM or PWLF. The association between epilepsy and MI needs to be further investigated, and clinical care of PWE should include evaluation and management of risk factors for MI.