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

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 non-sustained 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.