A 68-year-old man presents to the emergency room with palpitations. He has a previous history of hypertension and syncope with pacemaker implantation 3 years ago:

• Underlying atrial tachycardia (red arrows) – may be atrial flutter
• Native complexes conducted with left bundle branch block
• VVI Pacing (blue arrows) with ventricular undersensing (pacing happens unnecessarily)