Case Report
A 73-year-old man with a history of non-ischemic dilated cardiomyopathy and receiving cardiac resynchronization therapy (CRT, Boston Scientific) implantation in 2021, was admitted to our hospital for chest distress, shortness of breath after activity, paroxysmal palpitations and bilateral pitting oedema for 2 weeks. The patient complained of dyspnea and dizziness during paroxysmal palpitations. Echocardiography revealed the left ventricular dilatation and the decreased left ventricular systolic function with ejection fraction (EF) of 31%. Ambulatory ECG monitoring later revealed recurrent episodes of pacemaker-mediated arrhythmia (PMA) with a right bundle branch block (RBBB) pattern (Figure 1). In total, 51 episodes were recorded (episodes lasted from 10 seconds to 20 minutes), most of which corresponded to the patient’s symptoms of dyspnea and dizziness. Of note, most episodes of PMA were following a premature atrial contraction (PAC) accompanied by the appearance of ventriculoatrial (VA) conduction with no prolongation of atrioventricular (AV) delay.
What accounts for the PMA with RBBB pattern? How to manage this PMA?