How much worse can it get? Ventricular fibrillation complicating complete heart block with junctional escape rhythm

This is a case of a 60-year-old female with a history of diabetes mellitus, hypertension and right breast carcinoma for which she underwent mastectomy, chemotherapy, and radiation therapy nine years earlier. She presented to the oncology clinic for a routine follow-up, and was only on oral hypoglycemic medications and amlodipine for treatment of hypertension. On physical examination, she had a heart rate of 30 bpm and blood pressure of 184/78 mm Hg. Her physical examination was otherwise unremarkable apart from variable intensity of the first heart sound. An ECG was obtained, and it showed a complete atrioventricular block with a sinus rate of 100 beats per minute, a junctional escape rhythm of 33 bpm and a corrected QT interval of 428 milliseconds. Her ECG seven months earlier was unremarkable. Laboratory investigations including serial cardiac enzymes and thyroid function tests were normal. Echocardiogram showed normal left ventricular systolic function and no significant abnormalities. Cardiac CT scan showed normal coronaries. While awaiting pacemaker implantation, the patient was noted to have episodes of non-sustained polymorphic ventricular tachycardia (VT) followed by sustained VT that degenerated into ventricular fibrillation (VF) (Figure 1). Prompt defibrillation was performed with a biphasic shock of 200 Joules (Figure 2). A temporary pacemaker was inserted and followed by implantation of a dual chamber pacemaker without complications.