Atrial Fibrillation Is Associated With a Worse 90-Day Outcome Than Other Cardioembolic Stroke Subtypes

Abstract

Background and purpose: Patients with a cardioembolic stroke (CES) have worse outcomes than stroke patients with other causes of stroke. Among patients with CES, atrial fibrillation (AF) is a common comorbidity. Mounting data indicate that AF may be related to stroke pathogenesis beyond acute cerebral thromboembolism. We sought to determine whether AF represents an independent risk factor for stroke severity and outcome among patients with CES.

Methods: We retrospectively analyzed patients with acute hemispheric CES included in an academic medical center's stroke registry. CES was determined using the Causative Classification System of ischemic stroke. Multivariable logistic regression was used to determine whether AF was associated with 90-day outcome functional status.

Results: Our cohort included 140 patients. Of these, 52 had prevalent AF and 28 had incident AF diagnosed during their index hospitalization or within 90 days of hospital discharge. After adjustment for potential confounders or mediators, any AF (odds ratio, 2.51; 95% confidence interval, 1.03-6.33; P=0.049), infarct volume (odds ratio, 1.03; 95% confidence interval, 1.01-1.06; P=0.005), preadmission modified Rankin Scale score (odds ratio, 2.58; 95% confidence interval, 1.66-4.01; P<0.001), and admission National Institutes of Health Stroke Scale score (odds ratio, 1.17; 95% confidence interval, 1.08-1.28; P<0.001) remained associated with an unfavorable 90-day outcome (modified Rankin Scale score, 2-6).

Conclusions: AF is associated with an unfavorable 90-day outcome among patients with a CES independent of established risk factors and initial stroke severity. This suggests that AF-specific mechanisms affect CES severity and functional status after CES. If confirmed in future studies, further investigation into the underlying pathophysiological mechanisms may provide novel avenues to AF detection and treatment.

Keywords: atrial fibrillation; cerebral infarction; classification; outcomes research; risk factors; stroke.

Figure 1

Patient flow chart. AF=atrial fibrillation; CES=cardioembolic stroke mechanism; ESUS=embolic stroke of undetermined etiology; TIA=transient ischemic attack. *By 90-days.

Figure 2

Compared to patients without atrial fibrillation (AF), patients with AF had a significantly higher (A) CHA₂DS₂-VASc and (B) admission NIHSS score. In addition, AF patients had (C) a worse 90-day modified Rankin scale (mRS) score as well as worse 90-day mRS when adjusted for the baseline mRS (i.e., they had more frequent worsening of the mRS from baseline to 90-days). (D) There was no significant difference in the 90-day survival between patients with vs. without AF (in 6 patients with and 3 patients without AF the exact time to death could not be established and their time to death defined as 90-days). Boxes are median ± IQR, dotted lines indicate mean, whiskers indicate 10^th/90^th percentile and outliers are 5^th/95^th percentile. Mann-Whitney U test was used for comparisons of the CHA₂DS₂-VASc, NIHSS, 90-day mRS, and mRS-worsening from baseline to 90-days.