Trends and Impact of Early Medical Complications in Acute Ischemic Stroke: Data from the Austrian Stroke Unit Registry.

Introduction Early medical complications following acute ischemic stroke (AIS) are common and might increase post-stroke morbidity and mortality. This study aimed to evaluate trends in the prevalence of early medical complications over almost two decades and their impact on three-month functional outcome and mortality. Methods A total of 181,704 AIS patients from the Austrian Stroke Unit Registry (2006-2024) were analyzed. Early medical complications included decompensated heart failure, cardiac arrythmia, sepsis, pneumonia, urinary tract infection (UTI), deep vein thrombosis, and pulmonary embolism. Functional outcomes were assessed using the modified Rankin Scale (mRS) after three-months, with favorable outcome defined as mRS ≤1. Associations between early medical complications and mRS were analyzed using multivariable Poisson regression models. Results Among all patients, 16,279 (9.0%) had early medical complications. Pneumonia (4.2%), UTI (2.9%), cardiac arrhythmia (1.4%), and decompensated heart failure (1.4%) were most common, with significant declines in prevalences over time. Admission NIHSS scores decreased, and the use of intravenous thrombolysis and mechanical thrombectomy increased. Decompensated heart failure (RR = 1.85, 95% CI 1.73-1.97, p <0.001), sepsis (RR = 1.75, 95% CI 1.53-1.99, p <0.001), pulmonary embolism (RR = 1.67, 95% CI 1.33-2.10, p <0.001), and pneumonia (RR = 1.64, 95% CI 1.57-1.72, p <0.001) were significantly associated with three-month mortality. Furthermore, the complications least associated with a favorable outcome were pneumonia (RR = 0.36, 95% CI 0.32-0.41, p <0.001), decompensated heart failure (RR = 0.38, 95% CI 0.32-0.46, p <0.001), and sepsis (RR = 0.59, 95% CI 0.45-0.77, p <0.001). The effect sizes didn't change significantly through the observed years. Conclusions This study observed a significant reduction in the prevalence of early medical complications after acute ischemic stroke. Especially decompensated heart failure, pneumonia, sepsis, and pulmonary embolism continue to substantially affect mortality and functional outcome in AIS patients.