Dementia and mortality after myocardial infarction: a Danish nationwide study
M Pilavci, M Blenkov, H Christensen, C H Garred, C Sindet-Pedersen, M Elmegaard, L Kober, C Torp-Pedersen, M Schou, D M ChristensenAbstract
Background and purpose
Ischemic heart disease and dementia share several risk factors, suggesting shared underlying pathophysiological mechanisms related to cardiometabolic disease. Given the increasing focus on dementia as a potential manifestation of the cardiometabolic disease spectrum, we investigated the association between a first-time myocardial infarction (MI) and the risk of dementia together with the risk of mortality.
Methods
Using Danish nationwide registries, we included all patients with a first-time MI without dementia from 1 January 1999 to 31 December 2023. Each patient was matched in a 1:2 ratio with controls without MI and dementia, by sex, birth year and index date. Patients were followed until diagnosis of dementia, death or end of study. We assessed the risk of all-cause dementia and mortality, using the Aalen-Johansen estimator to account for competing risk and censoring.
Results
A total of 174,772 patients with first-time MI and 349,500 controls were included (median age 69 years and 65% males). During the first years after MI, the risk of dementia was slightly higher in patients with MI compared to controls (1-year risk: 0.86% [95% CI: 0.81-0.90] versus 0.76% [95% CI: 0.74-0.79]). However, long-term risk of dementia appeared lower in patients with MI compared with controls likely due to the higher competing risk of mortality in patients with MI (Figure 1). Mortality was consistently higher among patients with MI, with 1- and 20-year risk of 16.36% (95% CI: 16.12-16.53) and 65.10% (95% CI: 64.77-65.43) versus 3.42% (95% CI: 3.36-3.48) and 52.59% (95% CI: 52.35-52.83) in controls.
Conclusion
First-time MI was associated with an elevated early risk of dementia. However, this association reversed over time with increasing age, as the competing risk of mortality became more dominant in patients with MI. Further investigation is needed to understand the trajectory after MI and to evaluate whether intensified risk factor management may reduce the risk of dementia.