Traditional and new electrocardiographic predictors of non-sustained polymorphic ventricular tachycardia caused by drug-induced long QT syndrome

Abstract

Aim. To identify electrocardiographic (ECG) predictors of drug-induced non-sustained polymorphic ventricular tachycardia (PVT).Material and methods. The study included 110 patients with ischemic heart disease and /or arterial hypertension and cardiac arrhythmias who were taking class III antiarrhythmic drugs (amiodarone or sotalol). According to the presence or absence of the drug-induced QT interval prolongation (Bazett) (greater than 450 ms in men and greater than 470 ms in women), the patients were divided into 2 groups: «LQTS» (n=64) and «Non LQTS» (n=46). According to the presence or absence of non-sustained PVT, patients with drug-induced LQTS were additionally divided into the «PVT» (n=17) and «Non PVT» (n=47) groups. All patients underwent clinical, laboratory and instrumental examinations, which included taking anamnesis, physical examination, echocardiography, Holter monitoring, general clinical laboratory examinations, 12-lead ECG recording before and while taking antiarrhythmic drugs.Results. In the «LQTS» group of patients, PVT was significantly more common than in the «non LQTS» group (p=0.017). When analyzing the baseline ECG parameters recorded before the initiation of antiarrhythmic therapy, no significant differences were found between the groups except for a greater QT interval dispersion in the group of patients with LQTS and non-sustained PVT compared with patients without LQTS (p=0.03). While receiving antiarrhythmic therapy, patients with LQTS and non-sustained PVT had a longer duration of the QT interval (p<0.05), as well as the duration of the corrected QT and JT intervals (p<0.001) compared with group of patients without LQTS and subgroup without non-sustained PVT. The values of the parameters of the balance of depolarization and repolarization of the ventricular myocardium (iCEB and iCEBc) were significantly higher in patients with LQTS and non-sustained PVT (p<0.001). Based on the results of the analysis of contingency tables, the most effective predictor of non-sustained PVT was an iCEBc value ≥5.81 (OR=7.294, 95% CI [4,245-11,532]). According to the results of one-way ROC-analysis, the iCEBc value ≥5.81 demonstrated high sensitivity (94.1%) and specificity (84.9%), as well as a fairly high area under the ROC-curve (0.901).Conclusions. Our results indicate that the value of the corrected index of the cardioelectrophysiological balance ≥5.81 can be used in the prediction of non-sustained PVT in patients with QT interval prolongation induced by amiodarone and sotalol in addition to the existing ECG parameters.