A pacemaker implantation is not indicated in the case of reversible high-degree sinus node dysfunction (SND) and atrio-ventricular blocks (AVB). However, it is still unknown whether these reversible automaticity/conduction disorders may recur in some patients at follow-up, in the absence of reversible cause.

This single center retrospective study aimed to determine the incidence and predictive factors of pacemaker implantation at follow-up and after reversible symptomatic high degree SND or AVB.

Based on medical electronic files codes, we identified patients who were hospitalized in our cardiac intensive care unit between January 2003 and December 2020 for reversible high-degree conduction or SND and who were discharged alive and without pacemaker implantation (PPM) from the hospital. Acute myocardial infarctions and post cardiac surgery patients were excluded. We categorized the patients according to the need of PPM at follow-up for non-reversible SND/AVB.

Of the 93 patients included, 26 patients (28%) were readmitted for PPM at follow-up after hospital discharge. Among baseline characteristics, compared to patients who did not had SND/AVB recurrence, those with further PM implantation only differed by more frequent previous hypertension (70% vs. 46%, P=0.031). Not the etiology and neither the type of conduction/automaticity disorder differed between the two groups. However, recurrence of the conductive disorder was significantly associated with the presence of conduction blocks (Complete bundle branch block or left bundle branch hemiblock) on ECG at discharge (36% in patients without PPM vs. 68% in PPM patients, P=0.012).

Almost one third of the patients discharged alive from the hospital after a reversible SND/high degree AVB needed a pacemaker implantation at follow-up. Complete bundle branch block or left bundle branch hemiblock on discharge ECG after recovery of normal AV and/or sinus node function was associated with a greater risk of recurrence leading to pacemaker implantation.