We have long known that ischemic stroke is a devastating complication following myocardial infarction (MI). Stroke incidence has been previously reported by numerous clinical trials, but is limited by the narrow group of patients selected for the trial, which precludes extrapolation to the population seen in day-to-day practice. Besides, treatment of acute MI has undergone paradigm shifts with the introduction of in-hospital interventions and drugs for secondary prevention. The influence of these modern treatments on the risk of stroke was unknown.
Kajermo and colleagues examined trends of stroke incidence after an MI, and its predictors. Using a national registry, patients admitted with a first MI to cardiac ICUs in Sweden from 1998-2008 were included. They then identified patients who subsequently developed an ischemic stroke. 2.1% of acute MI patients developed an ischemic stroke within 30 days. Over time, the incidence decreased significantly with rates during 2007-2008 being 2%, compared to 2.2% during 1998-2000. This decrease was attributed to the increased utilization of PCI, statins, ASA and P2Y12-inhibitors. The study confirmed other variables that have previously been shown to increase stroke risk such as prior stroke, age, female sex, diabetes and atrial fibrillation.
This is the largest study (n=173,233) that has examined this question in an unselected population. Although you would suspect that the stroke etiology was likely cardioembolic from an LV thrombus, there was no association between in-hospital anticoagulation and stroke occurrence. In fact, the association of MI secondary prevention treatments with stroke reduction would suggest that stroke etiology is related to pathophysiological players common to both MI and stroke, such as atherosclerosis and platelet activation. Similarly, one would have thought that an invasive interventional procedure (PCI) would be associated with higher stroke risk. However, PCI decreased this risk and is possibly related to early revascularization reducing myocardial infarct volume and the subsequent development of heart failure/atrial fibrillation, thereby reducing stroke.
Congratulations are due to the cardiology community for rigorous, effective implementation of early revascularization and secondary prevention.