The Effect Of Hypomagnesemia To QTc Interval And T Peak-End Interval

Background and purpose:Electrolytes disturbance is the common cause for acquired long QT syndrome(ALQTS).It is obvious that hypokalemia and hypocalcemia will prolong the QT interval.However,the effect of hypomagnesemia on the QT interval is still inconsistent.Borys Surawicz has demonstrated that hypomagnesemia has no relationship with QT interval by laboratory research.This finding has not been proved in the investigations of human beings.In the meanwhile,several case reports have been published showing that hypomagnesemia could widen the QT interval and further result in ventricular arrhythmias(VT),torsade de pointes(TdP)and ventricular fibrillation(VF).T-peak to end interval(Tpe),reflecting the transmural dispersion of repolarization,is the independent predictor for malignant arrhythmias.To our knowledge,no studies have been carried out on the relationship between hypomagnesemia and Tpe inerval.We aimed to investigate the association of hypomagnesemia with QT interval and Tpe interval.Methods:37 in-hospital patients with hypomagnesemia among 2011.4-2016.3 were recruited in the study.QT interval,QTp interval and Tpe interval of precordial lead(V1-V6)were measured,and heart rate-corrected QT interval(QTc),heart rate-corrected QTp interval(QTp-c)and heart rate-corrected Tpe interval(Tpe-c),Tpe interval dispersion andTpe/QT were calculated.The values derived from the ECGs would then be compared between the patients with hypomagnesemia and them with normal magnesium level.Results:Patients with hypomagnesemia vs.them with normal magnesium level:there was statistical significance of HR(81±15 vs.76±13,P<0.01),QTc interval(428.7±25.2 vs.422.7±24.0,P<0.05)?Tpe-max interval(90.0±15.7 vs.85.7±13.8,P<0.05)?Tpe-maxc interval(104.5±17.4 vs.96.4±16.2,P<0.01)?Tpe interval dispersion(19.4±13.5 vs.14.6±10.1,P<0.05)? Tpe/QT(0.24±0.04 vs.0.23±0.04,P<0.01)between the two groups.there was no statistical significance of QTp-c interval(326.6±31.7 vs.327.3±31,P>0.05)between the two groups.Conclusions:1.Patients with hypomagnesemia had longer QTc interval ? Tpe interval and Tpe-cinterval,and bigger Tpe interval dispersion and Tpe/QT.2.Patients with hypomagnesemia had prolonged QTc interval,which was mostly caused by the widening of the Tpe interval.