Association of Antimitochondrial Antibody With Right Atrial Low Voltage and Sick Sinus Syndrome

BACKGROUND: Antimitochondrial antibodies (AMAs), well known as markers of primary biliary cholangitis, are increasingly recognized in cardiac disease. Their potential association with right atrial (RA) abnormalities and sick sinus syndrome (SSS) remains unclear. CASE SUMMARY: We report three AMA-positive patients with atrial arrhythmia and RA involvement. Two patients demonstrated extensive RA low voltage on electroanatomic mapping, and one patient showed impaired atrial sensing and pacing consistent with SSS. Left ventricular involvement was variable. One patient developed myositis, indicating systemic autoimmune manifestations. DISCUSSION: These cases suggest a potential link between AMA positivity, RA low voltage, and SSS, even in the absence of left ventricular dysfunction. AMA may confer selective RA vulnerability through mitochondrial or immune-mediated pathways, highlighting the need for further investigation.