On the Relationships Between Anti-bradycardia Pacing after Premature Ventricular Contraction, and Pacing Associated Tachyarrhythmias

Background: Anti-bradycardia pacing, available on implantable cardioverter defibrillators (ICD), has been recently associated, in a few cases, to ventricular tachyarrhythmias (VT) onset. Aim: Contribute to understanding the pacing associated tachyarrhythmias (PAT) by examining and interpreting differences due to comparison between PAT and non-PAT episodes retrieved from patients that experienced at least one PAT episode. Methods: From 67 patients, a pool of 187 VT episodes was retrieved: 21 PAT and 28 non-PAT episodes from 8 patients are analysed. Three phases of the intracardiac electrograms are examined: (i) Pre-VT phase, immediately preceding VT-onset & lasting 20 seconds, is characterized by its heart cycle (HC-PreVT), prevalence of premature ventricular contraction (PVC PREV ), prevalence of paced beats (P PREV ); (ii) VT initiation phase is characterized by coupling interval (CI) and prematurity index (PI), and (iii) the VT episode characterized by VT-cycle and prevalence of non-treated VTs (NTVT PREV ). Results: 90% of PAT episodes immediately follow a PVC. PAT episodes are associated to HC-PreVT significantly higher (p<0.001), a greater PVC PREV (p<0.001) and P PREV (p<0.001), a smaller PI (p<0.001). Conclusion: Results indicate that moderation or inhibition of anti-bradycardia pacing after PVC could significantly reduce the number of PAT episodes.