A tale of two cities: A retrospective observational cohort study of the impact of COVID-19 on acute stroke presentation, timing, and outcomes.

OBJECTIVES: The purpose of this study was to identify the impact of COVID-19-related "shelter in place" restrictions on stroke metrics in two metropolitan Texas cities, Austin and San Antonio. MATERIALS AND METHODS: Data was derived from stroke quality metric registries and compared between two treatment periods: (1) during the state's COVID-19 "shelter in place" restriction period, and (2) the corresponding period during the previous year for Austin and San Antonio, Texas. Primary outcomes include the dichotomized process measures of time last known well (TLKW) to arrival, arrival to brain imaging initiation, and arrival to administration of thrombolytic therapy. Secondary outcomes are clinical endpoints: independent ambulation at discharge, discharge to home, and in-hospital mortality. RESULTS: Austin patients were older and presented with less-severe strokes. San Antonio patients were more likely to be Hispanic, suffer from a large vessel occlusion, and have independent ambulation at discharge (adjusted odds ratio, 2.04; 95% confidence intervals, (1.25-3.37). Within-city analyses revealed a trend toward increased TLKW to arrival in Austin and San Antonio during COVID-19. During COVID, Austin patients had decreased length of stay (LOS) while a higher proportion of San Antonio patients had a favorable outcome (discharged home & independent ambulation). CONCLUSIONS: Longer TLKW to hospital arrival during COVID did not impact arrival-to-imaging, arrival-to-treatment times nor patient outcomes, even in patients at higher risk for stroke. Future studies should continue to assess the impact of COVID-19 on stroke care and outcomes pre- and post-introduction of the COVID-19 vaccine, and as infectivity rates spike or recede.

Decrease in Stroke Diagnoses During the COVID-19 Pandemic: Where Did All Our Stroke Patients Go?

Despite the evidence suggesting a high rate of cerebrovascular complications in patients with SARS-CoV-2, reports have indicated decreasing rates of new ischemic stroke diagnoses during the COVID-19 pandemic. The observed decrease in emergency department (ED) visits is unsurprising during this major crisis, as patients are likely to prioritize avoiding exposure to SARS-CoV-2 over addressing what they may perceive as mild symptoms of headache, lethargy, difficulty speaking, and numbness. In the central and south Texas regions where we practice, we suspect that patient admission, treatment, and discharge volumes for acute stroke treatment have decreased significantly since COVID-19-related shelter-at-home orders were issued. Symptoms of stroke are frequently noticed by a family member, friend, or community member before they are recognized by the patients themselves, and these symptoms may be going unnoticed due to limited face-to-face encounters. This possibility emphasizes the importance of patient education regarding stroke warning signs and symptoms during the current period of isolation and social-distancing. The south Texas population, already saddled with above-average rates of cardiovascular and cerebrovascular disease, has a higher stroke mortality rate compared to Texas and U.S. averages; however, the number of patients presenting to EDs with acute ischemic stroke diagnoses is lower than average. In our viewpoint, we aim to present the relative literature to date and outline our ongoing analyses of the highly affected and diverse stroke populations in San Antonio and Austin, Texas, to answer a simple question: where did all our stroke patients go?

Importance of atrial surface area and refractory period in sustaining atrial fibrillation: testing the critical mass hypothesis.

OBJECTIVE: The critical mass hypothesis for atrial fibrillation (AF) was proposed in 1914; however, there have been few studies defining the relationship between atrial surface area and AF. This study evaluated the effect of tissue area and effective refractory period (ERP) on the probability of sustaining AF in an in vivo model. METHODS: Domestic pigs (n = 9) underwent median sternotomy. Epicardial activation maps were constructed from bipolar electrograms recorded from form-fitting electrode templates placed on the atria. Baseline ERPs were determined. ERP was lowered with a continuous infusion of acetylcholine (0.005-0.04 mg/Kg/min) until AF could be sustained after burst pacing. The atria were sequentially partitioned using bipolar radiofrequency ablation. ERPs were lowered using acetylcholine until AF could be sustained in each subdivision of atrial tissue. Each subdivision was further divided until AF was no longer inducible. At study completion, the heart was excised and the surface area of each section was measured. RESULTS: Over a range of ERPs from 75 to 250 ms, the probability of AF was correlated with increasing tissue area (range, 19.5-105 cm(2)) and decreasing ERP. Logistic regression analysis identified shorter ERP (P < .001) and larger area (P = .006) as factors predictive of an increased probability of sustained AF (area under the curve of the receiver-operator characteristic = 0.878). CONCLUSIONS: The probability of sustained AF was significantly associated with increasing tissue area and decreasing ERP. These data may lead to a greater understanding of the mechanism of AF and help to design better interventional procedures.

Chronic performance of a novel radiofrequency ablation device on the beating heart: Limitations of conduction delay to assess transmurality.

OBJECTIVE: The creation of consistently transmural lesions with epicardial ablation on the beating heart has represented a significant challenge for current technology. This study examined the chronic performance of the AtriCure Coolrail device (AtriCure Inc, West Chester, Ohio), an internally cooled, bipolar radiofrequency ablation device designed for off-pump epicardial ablation. The study also examined the reliability of using acute intraoperative conduction delay to evaluate lesion integrity. METHODS: Seven swine underwent median sternotomy. The right atrial appendage and inferior vena cava were isolated with a bipolar radiofrequency clamp. Linear ablation lines were created between these structures with the AtriCure Coolrail. Paced activation maps were recorded with epicardial patch electrodes acutely before and after ablation and after keeping the animals alive for 4 weeks. The conduction time across the linear ablation was calculated from these maps. The lesions were histologically evaluated with trichrome staining. RESULTS: Only 76% of cross-sections of Coolrail lesions were transmural, and only 1 of 12 ablation lines was transmural in every cross-section examined. Mapping data were available in 5 of the animals. Significant conduction delay was present after the creation of each line of ablation acutely; however, after 4 weeks, conduction time returned to preablation values, demonstrating lack of transmurality. CONCLUSIONS: The AtriCure Coolrail failed to reliably create transmural lesions. Although the Coolrail was able to create acute conduction delay, its failure to transmurally ablate the atrial myocardium left gaps along the length of the lesion, which resulted in neither chronic conduction block nor delay across any line of ablation.