Raymond C.S. Seet

Prolonged Rhythm Monitoring for the Detection of Occult Paroxysmal Atrial Fibrillation in Ischemic Stroke of Unknown Cause

Atrial fibrillation (AF), commonly encountered in patients with ischemic stroke and transient ischemic attack (TIA), confers a 5-fold increased risk of ischemic stroke.1,2 AF-related strokes are associated with an ≈50% increased risk of disability and 60% increased risk of death at 3 months compared with strokes of other etiologies.3 Paroxysmal AF (PAF), a self-terminating recurrent form of cardiac arrhythmia that comprises between 25% and 62% of AF cases, may present as a brief single episode of arrhythmia or as clusters of abnormal rhythm of variable duration, sometimes evolving into a more persistent or permanent form.4 The self-terminating nature of PAF may lead to its underdiagnosis and consequent use of less effective treatment strategies (aspirin instead of oral anticoagulation) in poststroke patients. To address the underdiagnosis of PAF in patients with ischemic stroke and TIAs, several treatment guidelines have singled out the identification of PAF as an important goal after a stroke/TIA.5–8 The diagnosis of PAF, however, poses a challenge. Several features of AF (such as its brief duration, episodic frequency, and asymptomatic presentations) make its detection difficult and elusive to bedside screening measures, such as pulse monitoring and routine ECGs. To date, several studies have explored the use of prolonged noninvasive and invasive cardiac monitoring devices to identify AF but with variable success. After detection of AF, a cardioembolic mechanism is often inferred and anticoagulation occasionally prescribed for secondary stroke prevention. The routine use of cardiac monitoring to identify patients with PAF who will benefit from anticoagulation has been reported to be cost-effective.9 In this review, we provide an overview of the different methods of cardiac monitoring, summarize studies that investigated the incidence of PAF after stroke, and highlight gaps in our understanding of the pathogenic and prognostic significance of AF …

Paroxysmal Atrial Fibrillation in Cryptogenic Stroke: A Case-Control Study

BACKGROUND It is unclear if brief episodes of paroxysmal atrial fibrillation (PAF) detected by prolonged cardiac monitoring are an occult of cause of cryptogenic strokes (CS). We compared the incidence of PAF in patients with CS and patients with stroke of known cause (SKC) using prolonged ambulatory cardiac monitoring. METHODS We prospectively enrolled patients within 3 months of ischemic stroke to undergo noninvasive cardiac monitoring for 3 weeks. Primary end point was PAF detection independently confirmed by 2 blinded cardiologists. RESULTS The study consisted of 132 patients, 66 had CS and 66 had SKC. Episodes of PAF were detected in 16 of 64 (25%) patients with CS and 9 of 64 (14%) patients with SKC (P=.12). Duration and number of PAF episodes, PAF burden, and time of first PAF detection did not differ significantly between the 2 groups (P>.05 for all). In patients younger than 65 years, PAF was more common in the CS group (22% versus 3%; P=.07), whereas in patients 65 years or older, the rates of detection were similar (27% in CS versus 25% in SKC; P=.9). Among patients younger than 65 years with embolic imaging pattern, PAF was only observed in the CS group (21% versus 0%; P=.03). CONCLUSIONS Very short episodes of PAF are common in patients with CS and with SKC, but their pathogenic significance is unclear. Predominance of PAF in younger patients with CS and embolic infarct pattern suggests a causative role in these cases. More research is needed before prolonged cardiac rhythm monitoring can be recommended to guide anticoagulation in CS patients.

Safety of Intravenous Thrombolysis in Acute Ischemic Stroke Patients with Saccular Intracranial Aneurysms

BACKGROUND It is not known if the presence of unruptured intracranial aneurysms can increase the risk of hemorrhage after thrombolysis for acute ischemic stroke. The goal of our study was to evaluate the risk of hemorrhage after intravenous tissue plasminogen activator in acute stroke patients with intracranial aneurysms. METHODS This is a retrospective analysis of consecutive cases of patients with acute ischemic stroke who were treated with intravenous tissue plasminogen activator at Mayo Clinic between March 2002 and June 2011 and who were evaluated with invasive or noninvasive intracranial angiography. Univariate analyses were performed with the t, Chi-square, and Fisher exact tests where appropriate. RESULTS Intracranial angiograms were performed in 105 patients (85 magnetic resonance angiography, 19 computed tomography angiography, and 1 catheter arteriography). The mean age of the patients was 69 ± 14 years. The mean National Institutes of Health Stroke Scale score at admission was 8 ± 5. A total of 12 incidental saccular aneurysms were found in 10 (9.5%) patients, and all 10 of these patients were white. There were no subarachnoid hemorrhages during the hospital stay in any patient with or without intracranial aneurysm. The rates of symptomatic intracranial hemorrhage and 3-month clinical outcomes were similar in patients with or without intracranial aneurysms. CONCLUSIONS Intravenous thrombolysis was safe among our patients with acute ischemic stroke and incidental intracranial saccular aneurysm.

Thrombolysis outcomes among obese and overweight stroke patients: an age- and National Institutes of Health Stroke Scale-matched comparison.

BACKGROUND Whether obese and overweight stroke patients respond differently to intravenous thrombolysis is unclear. The purpose of this study is to determine the influence of obesity and risk components of metabolic syndrome to stroke recovery in patients undergoing intravenous thrombolysis. METHODS Outcomes after recombinant tissue plasminogen activator treatment were compared between obese (body mass index [BMI] >30 kg/m(2)), overweight (BMI 25-30 kg/m(2)), and normal weight (BMI <25 kg/m(2)) patients. The association between BMI, risk components of the metabolic syndrome, and dose of recombinant tissue plasminogen activator per kilogram of body weight to stroke outcomes were assessed in a multivariable model. RESULTS A total of 169 patients (mean age 75 years; baseline National Institutes of Health Stroke Scale score 11) were included. No differences in the frequency of symptomatic intracranial hemorrhage and poor functional recovery were observed among obese, overweight, and normal weight patients. A linear trend toward worse stroke recovery was observed in patients with a greater number of metabolic risk components (P for trend .043). By contrast, there were no significant associations between the number of risk components of metabolic syndrome with respect to symptomatic intracranial hemorrhage. Using stepwise regression analyses, age, baseline stroke severity, and the number of risk components of the metabolic syndrome accounted for 52% variation in functional recovery after intravenous thrombolysis. CONCLUSIONS Acute stroke outcomes do not differ between obese and overweight patients undergoing intravenous thrombolysis. The number of metabolic risk components contributes more significantly to functional recovery following intravenous thrombolysis.

Bleeding complications associated with warfarin treatment in ischemic stroke patients with atrial fibrillation: a population-based cohort study.

BACKGROUND Bleeding events are the major obstacle to the widespread use of warfarin for secondary stroke prevention. Previous studies have not examined the use of risk stratification scores to estimate lifetime bleeding risk associated with warfarin treatment in a population-based setting. The purpose of this study is to determine the lifetime risk of bleeding events in ischemic stroke patients with atrial fibrillation (AF) undergoing warfarin treatment in a population-based cohort and to evaluate the use of bleeding risk scores to identify patients at high risk for lifetime bleeding events. METHODS The resources of the Rochester Epidemiology Project Medical Linkage System were used to identify acute ischemic stroke patients with AF undergoing warfarin treatment for secondary stroke prevention from 1980 to 1994. Medical information for patients seen at Mayo Clinic and at Olmsted Medical Center was used to retrospectively risk-stratify stroke patients according to bleeding risk scores (including the HAS-BLED and HEMORR2HAGES scores) before warfarin initiation. These scores were reassessed 1 and 5 years later and compared with lifetime bleeding events. RESULTS One hundred patients (mean age, 79.3 years; 68% women) were studied. Ninety-nine patients were observed until death. Major bleeding events occurred in 41 patients at a median of 19 months after warfarin initiation. Patients with a history of hemorrhage before warfarin treatment were more likely to develop major hemorrhage (15% versus 3%, P = .04). Patients with baseline HAS-BLED scores of 2 or more had a higher lifetime risk of major bleeding events compared with those with scores of 1 or less (53% versus 7%, P < .01), whereas those with HEMORR2HAGES scores of 2 or more had a higher lifetime risk of major bleeding events compared with those with scores of 1 or less (52% versus 16%, P = .03). Patients with an increase in the HAS-BLED and HEMORR2HAGES scores during follow-up had a higher remaining lifetime risk of major bleeding events compared with those with no change. CONCLUSIONS Our findings indicate high lifetime bleeding risk associated with warfarin treatment for patients with ischemic stroke. Risk stratification scores are useful to identify patients at high risk of developing bleeding complications and should be recalculated at regular intervals to evaluate the bleeding risk in anticoagulated patients with ischemic stroke.

Risk Factors and Consequences of Atrial Fibrillation with Rapid Ventricular Response in Patients with Ischemic Stroke Treated with Intravenous Thrombolysis

Atrial fibrillation (AF) is associated with rapid ventricular response (RVR) that increases myocardial demand and blood pressure instability. We investigated the incidence, risk factors, and outcomes of RVR among patients with ischemic stroke receiving treatment with intravenous (IV) recombinant tissue plasminogen activator (rtPA). Consecutive patients with AF who received IV rtPA within 3 hours of symptom onset were included. Vascular risk factors, stroke characteristics, and outcome measures were compared between patients who developed RVR and those who did not. Eighty patients with AF (mean age, 79 years; 46% men) who underwent rtPA treatment were studied. Nineteen (24%) of these patients developed RVR and were treated with IV rate-controlling medications. A bimodal pattern of distribution was observed in the occurrence of RVR, with the first peak occurring within 12 hours of stroke onset and the second peak occurring 24-48 hours after onset. Compared with the patients without RVR, those with RVR stayed a median duration of 1.2 days longer in the intensive care unit (P = .048). There were no differences in functional recovery and hemorrhagic outcomes between the patients with RVR and those without RVR. We observed a 16-hour delay in the resumption of antiarrhythmic medications (either at previous or reduced dosage) in the patients who subsequently developed RVR (median time from stroke onset, 29 hours vs 13 hours; P = .040). Our findings suggest that a delay in the resumption of rate-control medications in patients with AF may result in RVR and prolong the use of intensive care resources.