New onset of AV-nodal reentrant tachycardia (AVNRT) in the elderly- an uncommon diagnosis?
Authors: Grosse A , Borisov G , Kirsch K , Alothman O , Surber R , Geller JC , Schulze PC , Raffa S 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Arrhythmias in elderly patients (pat) are common. In this subset of pat, atrial fibrillation is by far the most frequent sustained arrhythmia but not the only one. Clinical, ECG and electrophysiological (EP) features of AV-nodal reentrant tachycardia (AVNRT) have rarely been described in the elderly, and this represents the aim of the current study.

Methods
At 2 EP-centres in Germany, data from all pat undergoing an EP-study (EPS) and diagnosed with AVNRT between January 2018 and May 2021 were collected and analysed. Pat &gt; 65 years constituted the study population.

Results
During the study period AVNRT was diagnosed in a total of 329 pat. 93 pat (28%) were &gt; 65 years and represent the study population [median age 74 (65-89) years, 48% female]. In the majority (85%), the duration of symptoms was short (&lt; 1 year), 14 pat had symptoms of paroxysmal tachycardia for longer than 10 years. Most of the pat (n=88, 94%) had at least one ECG-documentation. In SR, the PR interval was relatively long [median 180 (120-380) ms)]. In 84% of pat, sustained AVNRT [median cycle length (CL) 400 (270-800) ms] was induced during EPS. In the remaining pat, at least 2 typical AV-nodal-echo beats were induced. Slow pathway (SP) ablation/modification was performed in all but one patient presenting with a very long baseline PR-interval, low antegrade Wenckebach-point (WP) and very slow AVNRT. In this case, the pat was treated with ß-blocker after pacemaker (PM) implantation. In 3 additional pat, PM implantation was necessary after ablation due to intermittent high-degree AV-block. In comparison to the rest of the study population, these four pat had a longer baseline PQ interval [median 275 (IQR 248- 303) ms vs. 180 (IQR 160- 192) ms], a longer baseline AH interval [median 207ms (IQR 185- 234) ms vs. 95 (IQR 80- 107) ms], a lower baseline antegrade WP CL [median 510 (IQR 435- 645) vs. 390ms (IQR 355- 470) ms], and a longer tachycardia CL [TCL 557 (IQR 454- 661) ms vs. 400 (IQR 364- 443) ms; p value &lt;0,01 for all comparisons]. The overall complication rate (other than AV block) was low (2 pat with AV fistula treated conservatively) and comparable to the one described in younger pat.

Discussion
Elderly pat also have AVNRT, there are a slight differences in physiology (i.e. relatively long baseline PR-interval and TCL, likely due to changes of the conduction system with aging), and as in young pat, ablation is curative treatment with similar (low) complication rate. A subset of pat, characterized by longer PR- and AH-intervals, lower WP and longer TCL may be at higher risk for AV-block after SP modification. Whether this is due to pre-existing damage or to posterior location of the FP remains unknown.
SP ablation is safe and effective even in elderly pat. In pat presenting with EP characteristics presumptive of a baseline impairment of the conduction properties of the FP, ablation of the FP could be attempted to avoid postprocedural high degree AV block.