Faculty Bibliography

Background and Purpose- The risk of arterial ischemic events after intracerebral hemorrhage (ICH) is poorly understood given the lack of a control group in prior studies. This study aimed to evaluate the risk of acute ischemic stroke and myocardial infarction (MI) among patients with and without ICH. Methods- We performed a retrospective cohort study using claims data from Medicare beneficiaries from 2008 to 2014. Our exposure was acute ICH, identified using validated International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. Our primary outcome was a composite of acute ischemic stroke and MI, whereas secondary outcomes were ischemic stroke alone and MI alone. We used Cox regression analysis to compute hazard ratios during 1-month intervals after ICH. Sensitivity analyses entailed exclusion of patients with atrial fibrillation and valvular heart disease. Results- Among 1 760 439 Medicare beneficiaries, 5924 had ICH. The 1-year cumulative incidence of an arterial ischemic event was 5.7% (95% CI, 4.8-6.8) in patients with ICH and 1.8% (95% CI, 1.7-1.9) in patients without ICH. After adjusting for potential confounders, the risk of an arterial ischemic event remained significantly increased for the first 6 months after ICH and was especially high in the first month (hazard ratio, 6.7 [95% CI, 5.0-8.6]). In secondary analysis, the risk of ischemic stroke was increased in the first 6 months after ICH (hazard ratio, 6.1 [95% CI, 3.5-9.3]) but the risk of MI was not (hazard ratio, 1.6 [95% CI, 0.3-2.9]). In sensitivity analyses excluding patients with atrial fibrillation and valvular heart disease, the association between ICH and arterial ischemic events was similar to that of the primary analysis. Conclusions- In a large population-based cohort, we found that elderly patients with ICH had a substantially increased risk of ischemic stroke in the first 6 months after diagnosis. Further exploration of this risk is needed to determine optimal secondary prevention strategies for these patients.

The R code used for the data analysis and simulations in our manuscript (Díaz et al. 2018) had two errors, which we have corrected.

Background Mobile stroke units (MSUs) reduce time to intravenous thrombolysis in acute ischemic stroke. Whether this advantage exists in densely populated urban areas with many proximate hospitals is unclear. Methods and Results We evaluated patients from the METRONOME (Metropolitan New York Mobile Stroke) registry with suspected acute ischemic stroke who were transported by a bi-institutional MSU operating in Manhattan, New York, from October 2016 to September 2017. The comparison group included patients transported to our hospitals via conventional ambulance for acute ischemic stroke during the same hours of MSU operation (Monday to Friday, 9 am to 5 pm). Our exposure was MSU care, and our primary outcome was dispatch-to-thrombolysis time. We estimated mean differences in the primary outcome between both groups, adjusting for clinical, demographic, and geographic factors, including numbers of nearby designated stroke centers and population density. We identified 66 patients treated or transported by MSU and 19 patients transported by conventional ambulance. Patients receiving MSU care had significantly shorter dispatch-to-thrombolysis time than patients receiving conventional care (mean: 61.2 versus 91.6 minutes; P=0.001). Compared with patients receiving conventional care, patients receiving MSU care were significantly more likely to be picked up closer to a higher mean number of designated stroke centers in a 2.0-mile radius (4.8 versus 2.7, P=0.002). In multivariable analysis, MSU care was associated with a mean decrease in dispatch-to-thrombolysis time of 29.7 minutes (95% CI, 6.9-52.5) compared with conventional care. Conclusions In a densely populated urban area with a high number of intermediary stroke centers, MSU care was associated with substantially quicker time to thrombolysis compared with conventional ambulance care.

OBJECTIVE:To determine whether cerebrovascular risk factors are associated with subsequent diagnoses of Parkinson disease, and whether these associations are similar in magnitude to those with subsequent diagnoses of Alzheimer disease. METHODS:This was a retrospective cohort study using claims data from a 5% random sample of Medicare beneficiaries from 2008 to 2015. The exposures were stroke, atrial fibrillation, coronary disease, hyperlipidemia, hypertension, sleep apnea, diabetes mellitus, heart failure, peripheral vascular disease, chronic kidney disease, chronic obstructive pulmonary disease, valvular heart disease, tobacco use, and alcohol abuse. The primary outcome was a new diagnosis of idiopathic Parkinson disease. The secondary outcome was a new diagnosis of Alzheimer disease. Marginal structural Cox models adjusting for time-dependent confounding were used to characterize the association between exposures and outcomes. We also evaluated the association between cerebrovascular risk factors and subsequent renal colic (negative control). RESULTS:Among 1,035,536 Medicare beneficiaries followed for a mean of 5.2 years, 15,531 (1.5%) participants were diagnosed with Parkinson disease and 81,974 (7.9%) were diagnosed with Alzheimer disease. Most evaluated cerebrovascular risk factors, including prior stroke (hazard ratio = 1.55; 95% confidence interval = 1.39-1.72), were associated with the subsequent diagnosis of Parkinson disease. The magnitudes of these associations were similar, but attenuated, to the associations between cerebrovascular risk factors and Alzheimer disease. Confirming the validity of our analytical model, most cerebrovascular risk factors were not associated with the subsequent diagnosis of renal colic. INTERPRETATION:Cerebrovascular risk factors are associated with Parkinson disease, an effect comparable to their association with Alzheimer disease. ANN NEUROL 2019;86:572-581.

OBJECTIVE:Atrial cardiopathy without atrial fibrillation (AF) may be a potential cardiac source of embolic strokes of undetermined source (ESUS). Atrial volume is a feature of atrial cardiopathy, but the relationship between atrial volume and ESUS remains unclear. METHODS:We compared left atrial volume among ischemic stroke subtypes in the Cornell Acute Stroke Academic Registry (CAESAR), which includes all patients with acute ischemic stroke at our hospital since 2011. Stroke subtype was determined by neurologists per the TOAST classification and consensus ESUS definition. Left atrial volume index (LAVI) was obtained directly from our echocardiography image system (Xcelera, Philips Healthcare). We used t-tests and analysis of variance for unadjusted comparisons and targeted minimum loss-based estimation for comparisons adjusted for demographics and comorbidities. RESULTS:increase in LAVI was associated with a 4.4% increase in ESUS probability (95% CI, 2.3%-6.4%). Results were similar after excluding patients with AF during post-discharge heart-rhythm monitoring. INTERPRETATION:We found larger left atria among patients with ESUS versus non-cardioembolic stroke. There was significant overlap in left atrial size between ESUS and non-cardioembolic stroke, highlighting that many ESUS cases are not cardioembolic.