Does the Magnitude of the Electrocardiogram QT Interval Dispersion Predict Stroke Outcome?

Background: QT dispersion, maximal inter-lead difference in QT interval on 12-lead ECG, measures cardiac repolarization abnormalities. Data are conflicting whether QT dispersion predicts adverse outcome in acute ischemic stroke patients. Aims: Determine if QT dispersion predicts: (a) short-term clinical outcome in acute ischemic stroke, and (b) stroke location (insular vs non-insular cortex). Methods: Admission ECGs from 412 consecutive patients with acute stroke symptoms from two university-based stroke centers were reviewed. QT dispersion was measured. A neuroradiologist reviewed brain imaging for insular cortex involvement. Favorable clinical outcomes at discharge were modified Rankin Score of 0-1, discharge National Institutes of Health Stroke Scale score < 2, and discharge to home. Multiple logistic regression was performed for each outcome measure and to determine the association between insular infarct and QT dispersion. Results: Of 145 subjects in the final analysis: median age=65 years (interquartile range 56,75); male 38%, black 68%, median QT dispersion =78 msec (interquartile range 59,98), median admission National Institutes of Health Stroke Scale score=4 (IQR 2,6). QT dispersion did not predict short-term clinical outcome for modified Rankin Score (OR=1.001, 95%CI 0.99-1.01 p=0.85), National Institutes of Health Stroke Scale at discharge (OR=0.994, 95%CI 0.98-1.01, p =0.30), or discharge disposition (OR=1.001, 95%CI 0.99-1.01, p =0.81). Insular cortex involvement did not correlate with QT dispersion magnitude (OR=1.009, 95%CI 0.99-1.02, p=0.45). Discussion: We could not demonstrate that QT dispersion is useful in predicting short term clinical outcome at discharge in acute ischemic stroke. Further, the magnitude of QT dispersion did not predict insular cortical stroke location.