Correlation between QTc interval and clinical severity of subarachnoid hemorrhage depends on the QTc formula used

Subarachnoid hemorrhage (SAH) frequently prolongs QT interval in the acute phase. The purpose of our study is to investigate whether the correlation between electrocardiographic corrected QT interval and the clinical severity of SAH depends on QTc formula used.

We retrospectively studied 52 consecutive subjects with nontraumatic SAH (extravasation of blood into the spaces covering the central nervous system that are filled with cerebrospinal fluid) who were admitted within the first day of SAH. QT intervals were measured on a standard 12-lead electrocardiography and corrected by Bazett and Hodges formulae. All patients were evaluated according to clinical condition on admission by Hunt-Hess grades. The patients were grouped in two different categories according to QT interval corrected by Bazett and Hodges and scored by Hunt-Hess (HH) grades.

Mean age of the study patients was 54 +/- 12 years and of those 31 (60%) were female. Mean values of heart rate and RR interval were 82 +/- 21 bpm and 777 +/- 163 msec, respectively. The mean QTc interval by Bazett and Hodges were 456 +/- 59 msec and 438 +/- 48 msec, respectively (P < 0.001). Twenty-three patients according to Bazett and fifteen according to Hodges had prolonged QTc. Correlation analyses showed relation between HH and QTc and prolonged QTc by Bazett (r = 0.278, P = 0.04 and r = 0.314, P = 0.024; respectively). There was no correlation between HH and QTc and prolonged QTc by Hodges (r = 0.204, P = 0.14 and r = 0.115, P = 0.41; respectively).

In our study, correlation between QTc interval and clinical severity of SAH depended on the QTc formula used.