An Association Between the Prolonged Heart Rate-corrected QT Interval and Global Functional Outcome in Patients with Subarachnoid Hemorrhage

ABSTRACT

PURPOSE: Autonomic dysfunctions after subarachnoid hemorrhage (SAH) may lead to various arrhythmias, electrocardiographic abnormalities, and myocardial dysfunction. Prolongation of the heart rate-corrected QT (QTc) interval is frequently observed in patients with SAH. The aim of this study was to examine the associations between the QTc interval and global functional outcome in patients with SAH. METHODS: We studied 413 adult patients admitted via the emergency department within 48 hours after the onset of spontaneous SAH from January 2007 to December 2011. Among 413 patients with SAH, there were 154 male and 258 female patients whose mean age was 58.8+/-12.4 years. QT intervals were measured by standard 12-lead electrocardiography (ECG) and corrected by Bazett formulae. The QTc interval were considered prolonged at >450 ms in men and >470 ms in women. Outcomes were assessed using the length of hospital stay and the Modified Rankin scale (MRS) at discharge. RESULTS: One or more repolarization abnormalities occurred in 61.9% of patients. The most frequently observed ECG abnormality was QTc prolongation (54.9%), followed by non-specific ST-T changes(16.2%), ST-depression(9.2%), T-wave inversion(11.4%), U-wave(2.7%), and ST-segment elevation(1.7%). No correlations were found between age, sex, body mass index (BMI), location of aneurysm, and QTc interval. Multiple logistic regression analysis showed a relationship between prolonged QTc and Hunt Hess grades (p=0.012) in men, length of hospital stay (p=0.038) in women, Fisher grade (p=0.001), and MRS (p=0.006, p=0.011) in both. CONCLUSION: The prolonged QTc interval is more frequently observed in patients with severe hemorrhage and an unfavorable functional outcome (MRS 4-6) in SAH patients.