Tachycardia burden in stroke unit is associated with functional outcome after ischemic stroke

Background: Stroke unit care is associated with decrease in mortality and improvement in neurological outcome in patients with acute stroke. Heart rate is a commonly monitored variable in the stroke unit. However, little is known about tachycardia burden in the stroke unit and its association with outcome. Aims: To investigate the effects of tachycardia burden in the stroke unit on functional outcome in patients with acute ischemic stroke. Methods: We collected data from 246 patients with acute ischemic stroke admitted to our stroke unit between July 2013 and June 2014. Tachycardia burden was defined as duration of heart rate over 95 per minute divided by the total monitoring time, using the heart rate data sampled every 1 min. We divided the study population into quartiles of tachycardia burden and analyzed their association with poor three-month functional outcome (modified Rankin Scale score of ≥3). Results: Among included patients (age, 67.4 ± 12.8; male, 53.7%), tachycardia burden was 0.7% (median, interquartile range [0.1-5.7%]). The patients with higher tachycardia burdens were older, more likely to have higher stroke severity, cardioembolic etiology, atrial fibrillation, fever, pneumonia, higher initial glucose level, and higher white blood cell count. As compared with the lowest quartile (<0.1%), the highest quartile of tachycardia burden (≥6.0%) was significantly associated with poor outcome (adjusted odds ratio, 5.10; 95% confidence interval, 1.38-18.90; p = 0.01) after adjustment for covariates. Conclusions: Patients with increased tachycardia burden during stroke unit stay have poor functional outcome. Countermeasures against worsening factors might be utilized for patients with increased tachycardia burden.