Objective:

To determine the composition of acute ischemic strokes (AIS) before and during the pandemic at a comprehensive stroke center in Colorado (USA).

Background:

The overall composition of stroke subtype is typically stable within biogeographical groups. Whether the COVID-19 pandemic impacted stroke etiology is still being investigated, but most studies have been performed outside the USA.

Design/Methods:

This retrospective cohort study of adults (≥18) with AIS evaluated stroke subtype using TOAST classification: 1) large artery atherosclerosis; 2) cardioembolic; 3) small vessel occlusion; 4) other known etiology; 5) cryptogenic stroke. Comparisons were made between the pre-COVID period (1/1/2019 – 12/31/2019) vs. the COVID period (3/1/2020 – 3/1/2021) using Pearson chi-square tests for stroke subtype, demographics (age, sex, race, comorbidities), stroke severity (NIHSS ≥21), and clinical outcome (discharge mRS ≥3).

Results:

There were 2,130 patients with AIS: Pre-COVID (n=1,034) and COVID (n=1,096). Patients admitted during the COVID period were significantly more likely to have cryptogenic strokes (25.6% vs. 31.8%, p=0.002) and less likely to have stroke subtypes of large artery atherosclerosis (17.6% vs. 12.1%, p<0.001) and small vessel occlusion (10.1% vs. 7.7%, p=0.05). There were no differences in the rate of cardioembolic stroke (36.2% vs. 35.7%, p=0.82) and other known etiology (10.4% vs. 12.7%, p=0.11) by time period. Patients admitted during the COVID period were more likely to be female (43.9% vs. 51.0%, p=0.001), have atrial fibrillation (17.2% vs. 21.2%, p=0.02), have more severe strokes (9.8% vs. 12.7%, p=0.01), and have worse outcomes compared to patients admitted pre-COVID (53.5% vs. 60.9%, p=0.003).

Conclusions:

In the setting of a widespread pandemic, stroke etiology, demographics, and clinical outcomes can shift dramatically. During COVID-19, these changes included more cryptogenic strokes, more strokes among females and patients with atrial fibrillation, more severe strokes, and worse outcomes. Whether there has been a lasting shift is currently being investigated.