Deceleration capacity alterations before Non-Sustained Ventricular Tachycardia episodes in post myocardial infarction patients

While Non-Sustained Ventricular Tachycardia (NSVT) can be characterized as innocent in healthy persons, such arrhythmias in post-infarction patients can be associated with an increased risk for Arrhythmic Sudden Cardiac Death (SCD). The Autonomic Nervous System (ANS) may influence the electrical status before fatal arrhythmias initiations. In this work we study the differences between the behavior of Deceleration Capacity (DC) of heart rate before the onset of NSVT and in the rest of the signal. Twenty (20) patients having presented NSVT episodes are examined. Nine (9) of them have been classified as high risk for SCD after 16 months of follow up, while the rest (11) have been considered as low risk. For each NSVT episode the 30 min period before the episode and the 150 min period exactly before this period were compared. Windowed analysis was performed. Mean values showed that DC is reduced before NSVT episodes in both high and low risk patients. High risk patients presented lower mean values for DC compared to the low risk.