Temporal Beat-to-Beat Variability of Repolarization Changes Predict Non-Sustained Ventricular Tachycardia in Ischemic Heart Disease Patients

Abstract

Beat-to-beat variability of repolarization (BVR) is a promising marker of increased arrhythmia risk. BVR analysis could improve non-invasive risk stratification and may be valuable in the management and prevention of ventricular tachycardia (VT). We investigated the temporal evolution in BVR before spontaneous nonsustained ventricular tachycardia (nsVT) in patients with Ischemic Heart Disease (IHD). 24h Holter recordings from 20 IHD patients were collected prior to implantable cardioverter-defibrillator (ICD) implantation. After R-peak detection, Q-wave onset and T-wave offset were determined with a semi-automated template matching technique. The QT-annotation was manually verified and adjusted if necessary. Episodes of nsVT were semi-automatically identified and BVR was assessed at time points 1, 5 and 30 minutes prior to nsVT, and at a fixed moment during sleep (03:00am). Resting BVR, measured at 03:00am, was 7.26 ± 3.88 ms and was significantly (p<0.05) higher at 5 minutes (14.40 ± 7.61 ms) and 1 minute (18.01 ± 6.48 ms), but not at 30 minutes (8.90 ± 4.93 ms) prior to nsVT. These preliminary results reinforce the value of BVR analysis in the risk stratification of IHD patients; and identify a novel prediction method of impending VT that could be used for real-time analysis and monitoring.