Association Between Unruptured Intracranial Aneurysms and Downstream Stroke.

Background and Purpose- Case reports suggest that unruptured intracranial aneurysms may serve as a nidus for thrombus formation and downstream embolic stroke. However, few data exist to support an association between unruptured aneurysms and ischemic stroke. Methods- We conducted a within-subjects case-control study of acute ischemic stroke patients prospectively enrolled in the Cornell Acute Stroke Academic Registry who had magnetic resonance imaging of the brain and arterial imaging of the head within 14 days of admission. Reviewers blinded to the study hypothesis ascertained the presence of aneurysms from the neuroradiologist's clinical report of the arterial imaging findings. McNemar test for paired data was used to compare the prevalence of unruptured aneurysms ipsilateral versus contralateral to the side of anterior circulation infarcts. Aneurysms of the anterior communicating artery or in the posterior circulation were not counted in the analysis. Results- Among 2116 patients registered in the Cornell Acute Stroke Academic Registry during 2011 to 2016, 1541 met our inclusion criteria, of whom 176 (11.4%; 95% CI, 9.8-13.0%) had an intracranial aneurysm. The prevalence of aneurysms did not differ on the side ipsilateral versus contralateral to the infarction (risk ratio [RR], 1.2; 95% CI, 0.9-1.5). There was no significant association between aneurysms and ipsilateral stroke in secondary analyses of the 1244 patients with stroke in a single anterior circulation territory (RR, 1.2; 95% CI, 0.8-1.9), the 619 patients with cryptogenic stroke (RR, 1.4; 95% CI, 0.9-2.0), or the 485 patients with cryptogenic stroke in a single anterior circulation territory (RR, 1.7; 95% CI, 0.8-3.3). Results were unchanged when counting only aneurysms >3 mm (RR, 1.2; 95% CI, 0.8-1.9) or 5 mm in diameter (RR, 1.2; 95% CI, 0.9-1.5). Conclusions- Contrary to our hypothesis, we found no significant association between unruptured intracranial aneurysms and ipsilateral ischemic stroke.

Incidence of Atrial Fibrillation in Patients With Recent Ischemic Stroke Versus Matched Controls.

Background and Purpose- It is unclear whether atrial fibrillation/flutter (AF) newly diagnosed after ischemic stroke represents a preexisting risk factor that led to stroke, an arrhythmia triggered by poststroke autonomic dysfunction, or an incidental finding. Methods- We compared AF incidence after hospitalizations for ischemic stroke, hemorrhagic stroke, and nonstroke conditions using inpatient and outpatient claims between 2008 and 2015 from a nationally representative 5% sample of Medicare beneficiaries. We used validated International Classification of Diseases, Ninth Revision, Clinical Modification ( ICD-9-CM) codes to identify AF-free patients hospitalized with ischemic or hemorrhagic stroke and matched them in a 1:1 ratio by age, sex, race, calendar year, vascular risk factors, and Charlson comorbidities. We then matched the combined stroke cohort in a 1:1 ratio to patients hospitalized for nonstroke diagnoses. We used survival statistics and Cox regression to compare postdischarge AF incidence among groups. Results- We matched 2580 patients with ischemic stroke, 2580 with hemorrhagic stroke, and 5160 patients with other conditions. The annual postdischarge AF incidence was 3.4% (95% CI, 3.1%-3.7%) after ischemic stroke, 2.2% (95% CI, 1.9%-2.4%) after hemorrhagic stroke, and 2.9% (95% CI, 2.6%-3.1%) after nonstroke hospitalization. Ischemic stroke was associated with a somewhat higher risk of AF than hemorrhagic stroke (hazard ratio, 1.5; 95% CI, 1.3-1.8) or nonstroke conditions (hazard ratio, 1.2; 95% CI, 1.1-1.3). The latter association attenuated in sensitivity analyses limiting the outcome to AF diagnoses made by cardiologists (hazard ratio, 1.1; 95% CI, 0.8-1.5) or limiting the outcome to a minimum of 2 AF claims on separate dates (hazard ratio, 1.2; 95% CI, 1.0-1.5; P=0.09). Conclusions- New diagnoses of AF were more common after hospitalization for ischemic stroke than after hospitalization for hemorrhagic stroke or nonstroke conditions, but all hospitalized patients had a substantial incidence of new AF diagnoses after discharge and differences were attenuated when using more stringent definitions.

Stroke Risk Following Takotsubo Cardiomyopathy.

BACKGROUND AND PURPOSE: Takotsubo cardiomyopathy, also known as stress cardiomyopathy, is an increasingly recognized cause of left ventricular dysfunction. Previously considered a benign disease, Takotsubo cardiomyopathy may be a risk factor of ischemic stroke based on recent small, single-center case series. The strength and temporal profile of this association remains uncertain. METHODS: We performed a cohort-crossover study using administrative claims data on all emergency department visits and acute care hospitalizations from 2005 to 2015 in California, New York, and Florida. We identified patients with Takotsubo cardiomyopathy, excluding those with a prior or concomitant stroke diagnosis. We compared the risk of ischemic stroke in the first year after Takotsubo cardiomyopathy to the risk of ischemic stroke in the second year after Takotsubo cardiomyopathy. Takotsubo cardiomyopathy and ischemic stroke were ascertained using previously validated ICD-9-CM codes. Absolute risks and odds ratios (OR) were calculated using McNemar test for matched data. RESULTS: Among 5283 patients with Takotsubo cardiomyopathy (mean age, 67 years; 92% female), we identified 49 ischemic strokes during the first year after Takotsubo cardiomyopathy versus 19 ischemic strokes during the second year after. The risk of stroke was significantly higher in the year after Takotsubo cardiomyopathy (absolute increase, 0.6%; 95% CI: 0.2-0.9; OR: 2.6; 95% CI: 1.5-4.6) as compared to the control period. CONCLUSION: We found a heightened risk of ischemic stroke in the year after a diagnosis of Takotsubo cardiomyopathy, although the absolute risk increase was small.