Analysis of QTc Prolongation Related to Arrhythmia in Patients with Aconitine Intoxication

ABSTRACT

PURPOSE: This study examined the association between the prolongation of heart rate-corrected QT (QTc) and arrhythmia in patients with aconitine intoxication. METHODS: A 13-year retrospective study of patients with aconitine poisoning treated at emergency departments between March 2002 and May 2013 was conducted. The EKGs obtained within 4 hours after the ingestion of aconitine were analyzed to measure the QT and QTc intervals. The QT interval was manually measured and QTc was obtained using Bazett's formula. The patients were divided into a normal QTc group and a prolonged QTc group (prolonged QTc interval defined as >450 ms in men and >470 ms in women). General characteristics, clinical features, laboratory results, and abnormal EKG findings of the two groups were compared. RESULTS: Forty-one patients were enrolled in this study. The mean QTc intervals of the normal QTc group (n=20) and prolonged QTc group (n=21) were 446.4+/-18.2 ms and 500.6+/-18.1 ms, respectively. The prolonged QTc group had a significant presence of arrhythmia compared with the normal QTc group. Arrhythmia occurred in two of the 20 normal QTc group patients and 17 of the 21 prolonged QTc group patients (p<0.001). Premature ventricular contractions were observed in one normal QTc patients and in 17 prolonged QTcpatients (p<0.001). Ventricular arrhythmias were the most common arrhythmia in both groups. A bundle branch block occurred in 12 patients, all from the prolonged QTc group (p<0.001). Eleven of 12 patients with a bundle branch block had their electrocardiogram return to normal. CONCLUSION: A prolonged QTc interval within 4 hours after ingestion of aconitine is a significant predictor of arrhythmia. Serial measuring of the QTc interval is recommended to predict arrhythmia.