Stroke after MI
By Ethan Cumbler, MD
Witt BJ, Ballman KV, Brown RD Jr, et al. The incidence of stroke after myocardial infarction: a meta-analysis. Am J Med. 2006 Apr;119(4):354.e1-9.
Stroke and myocardial infarction (MI) share many of the risk factors leading to atherosclerosis, including hypertension, hyperlipidemia, diabetes, tobacco abuse, and age. Logically, patients at risk for one event would also be at risk for the other, yet this interaction appears to be more complex. The study by Witt, et al., aims to elucidate the rate of in-hospital stroke in patients initially admitted with an MI.
The authors analyzed 22 observational studies of myocardial infarction that recorded the incidence of cerebrovascular accidents after acute MI. Clinical trials were excluded from the analysis in order to provide representation of an unselected population. Of the trials reviewed, 11 were included in the analysis of in-hospital strokes, three for the 30-day time point, and two for the one-year time point. The other trials used different time points and were not included in the analysis. The patients had a mean age ranging between 59 and 72.7 years, and all had a predominance of males. The rate of in-hospital stroke was 11.1 events per 1,000 hospitalizations. This incidence rose to 12.2/1,000 at 30 days and 21.4/1,000 at one year.
Plausible hypotheses for why the rate of cerebrovascular accident would be particularly high in the post-MI period include the potential for localized wall motion dysmotility or low flow leading to intracardiac thrombosis, event-related arrhythmia, or procedure-related embolic events. The studies from which this meta-analysis was derived were not designed in such a way for a causal relationship to be identified. However, age, diabetes, hypertension, prior stroke, anterior location of MI, atrial fibrillation, heart failure, and nonwhite race were all found to have an association with increased risk for stroke. Interestingly, angina on presentation was associated with an apparent decreased risk, theorized to potentially be due to ischemic preconditioning.
While this study shares the usual limitations of meta-analyses of observational studies, the authors have done an excellent summation of the data available including both English and non-English language articles in the analysis. Notably, the review included studies spanning more than 25 years and, thus, included data from studies done in the era prior to modern therapy for cardiac ischemia including potent antiplatelet and statin therapy. The three studies with in-hospital time points started in the 1990s had a lower average rate of stroke, which may reflect the effect of more potent anti-platelet agents used in today’s therapy for acute coronary syndromes.
The implication for the hospitalist is to recognize that patients admitted for MI are at high risk for stroke during the index hospitalization. A low threshold for suspicion of a cerebrovascular event needs to be maintained for post-MI patients with new neurologic symptoms. Future studies will be needed to address the risk/benefit of anticoagulation in high-risk patients for stroke following a myocardial infarction.
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Predicting PE in the ED Using Revised Geneva Score
By Jeffrey Carter, MD
Le Gal G, Righini M, Roy PM, et al. Prediction of pulmonary embolism in the emergency department: the revised Geneva score. Ann Intern Med. 2006 Feb 7;144(3):165-171.
Introduction: Pulmonary embolism remains a common life-threatening disorder with imperfect diagnostic modalities and strategies. Much of the current literature focuses on the development and validation of clinical probability assessments that identify low-risk patients who can be safely managed without invasive testing or lung scanning.