Electrocardiographic and Arrhythmic Manifestations of End-Stage Atrial Myopathy in Patients With Longstanding Persistent or Permanent Atrial Fibrillation: A 3-Patient Case Series

BACKGROUND Advanced atrial remodeling, often associated with atrial fibrosis, may be accompanied by severe atrial electrical dysfunction and a range of electrocardiographic and arrhythmic manifestations. Data on the clinical features of this process are limited. CASE REPORT We report 3 patients with end-stage atrial myopathy and longstanding persistent or permanent atrial fibrillation (AF). One patient with extensive biatrial scar developed recurrent low-amplitude atrial tachycardias after AF ablation. Two patients demonstrated progression from AF to atrial standstill with junctional rhythms. In both patients, serial ECGs showed loss of fibrillatory activity, and device interrogation demonstrated absent atrial sensing and capture. One patient underwent pacemaker implantation without atrial lead placement, due to the absence of atrial sensing or capture on electrophysiology mapping. Important coexisting substrates for atrial remodeling included hypertrophic cardiomyopathy, mitral valve disease, and prior cardiac surgeries. CONCLUSIONS Patients with longstanding persistent or permanent AF may demonstrate distinct findings suggestive of advanced atrial myopathy, including loss of fibrillatory waves on ECG, low-amplitude atrial tachycardias, atrial standstill, junctional rhythms, absent atrial sensing or capture on device interrogation, and extensive atrial scarring on electrophysiology mapping. Recognition of these clinical manifestations may provide insight into advanced atrial remodeling and potentially inform AF ablation and atrial pacing strategies. Further studies are needed to better define the mechanisms, prevalence, and clinical significance of these findings.