The findings about this inverse relationship were based on national health registries in Denmark.
Myocardial infarction (MI) survivors appear to have a reduced risk of Parkinson disease (PD) or secondary parkinsonism later in life, according to a new study released Wednesday in Journal of the American Heart Association.
The findings suggest an inverse relationship between cardiovascular risk factors and PD, said the authors, who conducted a nationwide population-based study based on health registries in Denmark.
It isn’t known what causes PD, but previous research has already shown that older age and men are more at risk. Some factors for worse cardiovascular outcomes, such as smoking, diabetes, higher blood pressure, and elevated cholesterol are linked with reduced risk of PD.
The risk of cardiovascular disease is higher in patients with PD, but the risk of PD in patients who have survived a heart attack is not known.
Although PD is a neurodegenerative disease, secondary parkinsonism has a number of other causes, including vascular processes, another disease of the nervous system, or medicines or illicit drug use.
The researchers examined health registries from the Danish National Health Service to compare the risk of PD and secondary parkinsonism in 183,019 patients who had a first-time heart attack between 1995 and 2016 and more than 909,000 controls matched for age, sex, and year of heart attack diagnosis.
Median (interquartile range) age at MI diagnosis was 71 (60-80) years; 62% of the population were men. Median follow-up time was 4.1 (25th-75th percentile, 0.7-9.6) years for patients with MI and 6.6 (25th-75th percentile, 2.9-11.6) years for the controls.
The difference in follow-up time stemmed from the competing risk of death after MI, as heart attack survivors had an expected higher prevalence of cardiovascular conditions and comorbidities. In addition, the MI group had slightly lower income and educational levels and higher levels of unemployment compared with controls.
After exclusions during the first year of follow-up, there were 131,396 heart attack survivors and 630,166 patients in the control group.
Cox regression analysis was used to compute adjusted HRs (aHRs) for PD and secondary parkinsonism, controlled for matching factors, and adjusted for comorbidities and socioeconomic factors.
After 21 years of follow-up, the cumulative incidence was 0.9% for PD and 0.1% for secondary parkinsonism in the MI cohort.
Surviving a heart attack was associated with a 20% decreased risk of PD and a 28% decreased risk of secondary parkinsonism compared with those in the general population. The aHR for PD was 0.80 (95% CI, 0.73-0.87), and the aHR for secondary parkinsonism was 0.72 (95% CI, 0.54-0.94).
However, there was a null association for heart attack survivors who were employed or had atrial fibrillation or flutter, alcoholism-related disease, and chronic kidney disease.
The authors said their study is the first to examine a link between MI and PD.
The study had several strengths, including its large size and use of a national population health database. Limitations include the observational design and the possibility of residual and unmeasured confounding.
Sundbøll J, Komjáthiné Szépligeti S, Szentkúti P, et al. Risk of Parkinson disease and secondary parkinsonism in myocardial infarction survivors.
J Am Heart Assoc. Published online February 16, 2022. doi:10.1161/JAHA.121.022768