Long-Term Risk of Stroke in Myocardial Infarction Survivors
What are the risks of ischemic stroke, intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH) in patients with a myocardial infarction (MI) compared with the general population?
A nationwide population–based cohort study was conducted using Danish medical registries from 1980 to 2009 to identify all patients with a first-time inpatient diagnosis of MI. The stroke risk of the group with MI was compared to sex- and age-matched controls for cumulative stroke risks and adjusted stroke rate ratios.
Over the 29-year period, there were 258,806 patients with an MI and 1,244,773 persons from the general population. Comorbidities were higher in the MI group including congestive heart failure, atrial fibrillation and flutter, hypertension, diabetes, and chronic kidney disease. For patients with MI, the cumulative stroke risks after 1-30 years were 12.6% for ischemic stroke, 1.2% for ICH, and 0.24% for SAH. During the first 30 days after MI, there was a significant 30-fold increase in adjusted stroke rate ratio for ischemic stroke and 15-fold for SAH. The adjusted stroke rate ratio remained increased during 31-365 days (3-fold for ischemic stroke, 2-fold for ICH, and 1.5-fold for SAH). During the ensuing 1-30 years, ischemic stroke risk gradually declined by decade, but remained increased for ischemic stroke (1.6) and decreased to near unity for ICH and SAH.
An MI was a risk factor for all stroke subtypes during the first year of follow-up, but only for ischemic stroke thereafter.
The decline in ischemic stroke at the end of the first decade and in the second decade coincided with use of aspirin post-MI. The authors speculated that the decrease in risk of ischemic versus hemorrhagic strokes during the last study decade may have been due to use of dual antiplatelet therapy for 1 year after MI followed by life-long aspirin.
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