Non Sustained Ventricular Tachycardia Episodes Detected in the Memory of Antibradycardia Pacemakers in the Absence of Known Arrhythmogenic Disease

Aims: Patients with disturbances of current generation and/or propagation are treated with the implantation of an antibradycardia pacemaker. These devices have incorporated innovative programs for the detection of tachyarrhythmic episodes with sufficient memory for ECG recordings. Our research team confirmed and investigated further this new observation looking for the presence of Unexpected Complex Ventricular Ectopy in the absence of systolic ventricular dysfunction.
Methods: We interrogated the pacemakers from 144 patients with either no-known organic heart disease or stable coronary disease and normal left ventricular systolic function ( male:62%, mean age:77±10,mean LVEF:55%,VVI:25%, DDDR:75%). The underlying diseases were: Sinus Node Disease: 68%, Second degree Atrio-Ventricular block (AVB): 13%, Third degree AVB: 27%, Bifascicular AVB: 0.7%, Trifascicular AVB: 1.4%, Atrial fibrillation: 43%. During the last year, we interrogated the pacemakers searching for non sustained ventricular tachycardia (NSVT) episodes in their memory.
Results: For a mean period of 5.3±6.1 years after the implantation, the interrogation revealed NSVT episodes in 53 patients (37%) with a mean number of 10±5 QRS complexes in a row. When Signal Averaged ECG (SAECG) was performed after temporary low rate VVI pacing mode programming, 22 patients out of these 53 (41%) had Late Potentials.
Conclusions: In elderly patients treated with an antibradycardia pacemaker a significant proportion of them presented with subclinical NSVT despite the absence of any systolic ventricular dysfunction. Senile ventricular fibrosis could explain such findings. The clinical significance of the observed complex ventricular arrhythmia in this elderly population without any evidence of systolic ventricular dysfunction remains unknown.