ECG abnormalities in predicting secondary cerebral ischemia after subarachnoid haemorrhage.

BACKGROUND: Electrocardiographic (ECG) abnormalities frequently occur after subarachnoid haemorrhage (SAH), and have been linked with poor outcome. The pathogenesis behind this relation is unclear. We hypothesized that cardiac dysfunction may contribute to the development of delayed cerebral ischemia (DCI) and investigated if electrocardiographic repolarization abnormalities on admission, representing this cardiac dysfunction, are related to DCI. We also assessed the additional value of ECG characteristics to establish prognosticators for clinical outcome (WFNS, age and Hijdra score).
METHOD: In a series of 121 consecutive patients with aneurysmal SAH we related individual repolarization-like ECG changes (ST and T-wave changes, QTc prolongation, a U-wave) to the occurrence of DCI by means of Cox proportional hazard modelling and to poor outcome (death or dependence) with logistic regression analysis. We used ROC curves to assess the additional prognostic value of the most important ECG characteristics to established prognosticators.
FINDINGS: Only ST segment depression had a statistically significant relationship with the occurrence of DCI (HR 2.4 [95%CI 1.2-4.9]) in univariate analysis. In a similar analysis ST-elevation (OR 4.9; [95%CI 0.99-24.0]), ST-depression (OR 10.6; [95%CI 2.3-48.8]), T-wave inversion (OR 2.5; [95%CI 1.1-5.5]) and ischemic like ECG abnormalities (OR 8.3; [95%CI 3.0-22.2]) were significantly related to poor outcome. In multivariate models with extension of these ECG characteristics for establishing prognosticators the AUC of the ROC improved from 0.81 to 0.84.
CONCLUSIONS: ECG abnormalities did not contribute to the prediction of DCI and have limited value in prognosticating poor outcome. The occurrence of DCI is not the explanation of this relationship between ECG characteristics and outcome.