Association of Antimitochondrial Antibody with Right Atrial Low Voltage and Sick Sinus Syndrome (JACC Case Reports May 2026)-Article: Association of Antiimitochondrial Antibody with Right Atrial Low Voltage and Sick Sinus Syndrome

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This case series reports three patients with positive antimitochondrial antibodies (AMA) who showed right atrial (RA) electrical abnormalities and arrhythmias. The authors investigated whether AMA, best known as a marker of primary biliary cholangitis, might also be linked to cardiac disease, especially RA low voltage (RA-LV) and sick sinus syndrome (SSS).<br /><br />Patient 1 was a woman with recurrent atrial tachycardia and preserved left ventricular function. Repeat ablation revealed extensive RA-LV, and AMA testing was positive. Patient 2 was a man with heart failure, atrial fibrillation, reduced left ventricular ejection fraction, and extensive RA-LV on mapping; AMA was positive, and he also had signs of possible AMA-associated myopathy. Patient 3 was a woman with exertional dyspnea and SSS. During pacemaker implantation, atrial sensing and capture were poor, and pacing later failed, consistent with severe RA dysfunction; AMA was positive despite preserved left ventricular function.<br /><br />Across the cases, left ventricular involvement varied, but RA abnormalities were consistent. The authors suggest AMA may be associated with selective RA vulnerability, possibly through mitochondrial dysfunction and/or immune-mediated injury, particularly affecting the sinoatrial node and atrial myocardium. They propose that RA-LV may be an early marker of AMA-related cardiac involvement, even before left ventricular dysfunction appears.<br /><br />The report concludes that AMA testing may be useful in patients with unexplained SSS or RA-LV, and that larger prospective studies are needed to confirm the association and clarify mechanisms.

Meta Tag

Concept Antimitochondrial Antibody

Concept Right Atrial Low Voltage

Concept Sick Sinus Syndrome

Concept Cardiac Involvement

Concept Atrial Arrhythmia

Keywords

antimitochondrial antibodies

right atrial low voltage

sick sinus syndrome

atrial arrhythmia

right atrial dysfunction

primary biliary cholangitis

sinus node dysfunction

atrial tachycardia

atrial fibrillation

mitochondrial dysfunction

Antimitochondrial Antibody

Right Atrial Low Voltage

Sick Sinus Syndrome

Cardiac Involvement

Atrial Arrhythmia