Electrocardiographic Abnormalities and Serum Magnesium in Patients With Subarachnoid Hemorrhage

Abstract

Background and Purpose-ECG abnormalities and hypomagnesemia frequently occur after aneurysmal subarachnoid hemorrhage (SAH). Because hypomagnesemia is associated with several ECG abnormalities, we studied whether hypomagnesemia mediates ECG abnormalities after SAH. Methods-We prospectively studied a consecutive series of 62 patients admitted within 72 hours after aneurysmal SAH.A standard 12-lead ECG and serum magnesium measurement were routinely performed at admission. The relationship between serum magnesium and ECG abnormalities was assessed with linear regression analysis and the Mann-Whitney test in case of dichotomized ECG abnormalities. Results-Hypomagnesemia was present in 23 patients (37%), and 38 patients (61%) had a long QTc duration. Low serum magnesium was related to a long PR interval (Pϭ0.001) and a shorter QTc interval (Pϭ0.004). Adjustment for World Federation of Neurological Surgeons score, hydrocephalus, and the amount of cisternal and ventricular blood did not influence these relations. Conclusions-In patients with SAH, lower serum magnesium levels are related to less pronounced increase in the QTc interval. Although the direction of the relation was unexpected, decreased serum magnesium might be the missing link between SAH and ECG abnormalities.

The Insular Cortex and the Regulation of Cardiac Function

“…Hypomagnesaemia has been noted in SAH patients, who are the very stroke cases most likely to show ECG changes and cardiac arrhythmias. In a consecutive series of 62 patients hypomagnesaemia was associated with reduced QTc interval and could not account for the QTc prolongation seen in this series of SAH patients (37%) (326). There was also no association in this study, between serum potassium levels and ECG changes corroborating other reports (105).…”

Magnesium in Man: Implications for Health and Disease

“…Delayed cerebral ischemia (DCI) is the major cause of death and disability in patients that survive the first 24 h (126). Interestingly, patients with SAH often present with hypomagnesemia (531,532). Vasoconstriction is the main cause of DCI, and this may be enhanced when the patient is Mg 2ϩ deficient.…”

Acquired Long QT Interval: A Case Series of Multifactorial QT Prolongation

“…19 -23 The physiologic changes in myocardial conductivity caused by hypokalemia lead to decreased T-wave amplitude, T-wave inversion, STsegment depression, prominent U waves, and prolongation of the QT-U interval, which predisposes to ventricular tachycardia and TdP. 20 The ECG findings associated with hypomagnesemia often resemble those of hypokalemia, with widening of the QRS complex, ST-segment depression, and prominent U waves, 3,21 and may also include prolongation of the PR and QT intervals, peaking of the T waves, and other ST-segment and T-wave abnormalities. 21 Hypomagnesemia leading to QT-interval prolongation and ventricular arrhythmias, including TdP, has been documented as well.…”

“…20 The ECG findings associated with hypomagnesemia often resemble those of hypokalemia, with widening of the QRS complex, ST-segment depression, and prominent U waves, 3,21 and may also include prolongation of the PR and QT intervals, peaking of the T waves, and other ST-segment and T-wave abnormalities. 21 Hypomagnesemia leading to QT-interval prolongation and ventricular arrhythmias, including TdP, has been documented as well. 22 Hypocalcemia has also been reported to be a marginal cause of QT-interval prolongation and is thought to exert its effect by prolonging the action potential and repolarization time, although data regarding the association of hypocalcemia and LQT are more scarce than with hypokalemia and hypomagnesemia.…”