The Association of Serum Magnesium Levels and QT Interval with Neurological Outcomes After Targeted Temperature Management

Abstract

Targeted temperature management (TTM) is associated with corrected QT (QTc) prolongation and decrease in serum magnesium (Mg) levels that may lead to recurrent ventricular arrhythmia and poor neurological outcomes. We aimed to evaluate the association between QTc interval and Mg levels during TTM with neurological outcomes. We reviewed the electrocardiograms of 366 patients who underwent TTM during the induction, maintenance, and rewarming phase after cardiac arrest. We reviewed the association of change in QTc interval, and Mg levels with neurological outcomes. In total, 71.3% of the patients had a significant increase in QTc interval defined as >60 ms or any QTc >500 ms during TTM. Poor neurological outcome was associated with persistent prolongation of QTc after rewarming (507 vs. 483 ms, p = 0.046) and higher Mg levels at presentation (2.08 ± 0.41 mg/dL, p = 0.014). Supplemental Mg did not have any significant change in their QTc. Patients with prolonged QTc during TTM should be promptly evaluated for QTc-prolonging factors given its association with worse neurological outcomes. The inverse correlation between Mg levels and poor neurological outcomes deserves further investigation.

Keywords: QTc interval; cardiac arrest; hypomagnesemia; neurological outcomes; targeted temperature management.