A change in QRS morphology in right ventricular apical pacing: is it a red flag sign?

A 74-year-old man with symptomatic complete heart block underwent right ventricular apical permanent pacemaker implantation. The postoperative ECG showed, as expected, completely paced left bundle branch block QRS morphology. However, at the 2-month follow-up examination, his ECG showed paced right bundle branch block (RBBB) QRS morphology, although the patient was asymptomatic. On evaluation, pacemaker functioning was normal with no evidence of lead displacement. This case report highlights that RBBB morphology of paced QRS complex is not always a red flag sign.