QT variability before premature ventricular contraction as a short term predictor of non sustained ventricular tachycardia in chronic heart failure

Background – Myocardial repolarization lability before and after premature ventricular complex (PVC) has been recently suggested as a potential marker of malignant ventricular arrhythmias. We therefore sought to investigate possible different behavior of QT and Tpeak-Tend (Te) interval variability index (VI) when calculated before and after a PVC with respect a non-sustained ventricular tachycardia (nsVT). Method and Results – QTVI, TeVI and other short-term repolarization indexes were calculated before and after PVC (PVC group) as well as before and after nsVT (nsVT group). QTVI and TeVI before PVC were significantly lower in the nsVT group than PVC group (p<0.05), whereas QTVI and TeVI differences resulted significantly higher in the nsVT than the counterpart (p<0.01). At multivariate logistic regression analysis, low QTVI and TeVI values before PVC were significantly associated to higher risk of imminent nsVT (QTVI: OR, 6.44; 95% CI, 1.33-31.18, p<0.05; TeVI: OR, 6.87; 95% CI, 1.25-37.72, p<0.05). Conclusion – QTVI and TeVI before PVC seem be predicative for imminent nsVT. Further studies needed to assess possible utility of these findings for monitoring patients with chronic heart failure at high risk of sudden cardiac death.