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?