Telemedicine application for predicting ventricular arrhythmia and sudden cardiac death by the analysis of phase synchronization in heart failure patients

The approach consists of an application of the Hilbert-Huang transform to decompose an empirical time series into a number of intrinsic mode functions (IMFs), calculation of instantaneous phase of the resultant IMFs, and the statistics of synchronization. Our telemedicine server collected the 24-hour ambulatory ECGs (RhythmPattern, SzivLeso) and analyzed the data. The study population (age 67.3±8.2 years) consists of 97 heart failure patients with EF <; 0.35, where frequent (>; 4000/24 hours) ventricular ectopic beats were found. The ECG monitoring was repeated in every month with a mean follow-up was 36.4 months. The number of synchronization (NSy), its length (ASy), were compared in patients with and without ventricular tachycardia (VT+: number of patients 21, VT-: 76); with and without sudden cardiac death (SCD+: 11, SCD-: 86). The dichotomization cutoff points that maximized the hazard ratio obtained from the Cox regression model were: NSy: 18.4/24hour; ASy: 69.3 minute; SI: 0.39.