Analysis of beat-to-beat variability of ventricular late potentials by a spectro-temporal technique in patients with Chagas´ disease

The aim of this paper is to analyze the beat-to-beat variability of ventricular late potentials (LP) in high resolution ECG (HRECG) records of patients with Chagas´ disease. In order to evaluate the LP activity, we propose a method which computes the bi-dimensional (2-D) cross-correlation between a template spectro-temporal (STM) of LP and the STM of each individual beat of the HRECG record. As LP detection parameter, we used the maximum value of the 2-D cross-correlation multiplied by a noise correction factor. The method was applied in HRECG records of eight Chagasic patients with high myocardial damage Our results show that three patients have a low beat-to-beat variability of the detection parameter, reflecting the presence of reproducible and stable LP in their HRECG records. However, the other five patients show a high or moderate variability of the detection parameter, reflecting the possible existence of beat-to-beat variable LP.