PMC8376443_01
(a) ECG of patient 1 on day 5 ICU admission showing CHB with ventricular escape rhythm rate approximately 50 bpm. (b) ECG of patient 1 on day 8 admission showing ST elevation in lead AVR and ST depression at leads 1, AVL, II, AVF, V5, and V. (c) ECG of patient 1 on day 8 admission showing ventricular tachycardia and subsequently pulseless electrical activity (not recorded).
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ICU admission, the patient was noted to be in complete heart block on cardiac telemetry monitoring.  Figure 1(a) shows that a 12-lead electrocardiogram performed confirmed the diagnosis of CHB with a ventricular rate of approximately 50 bpm. Immediate laboratory investigations including thyroid function, cardiac biomarkers, and electrolytes were unremarkable. ECG showed ST elevation in AVR with global ST depression (Figure 1(b)). Shortly after, the patient deteriorated further and developed ventricular tachycardia (Figure 1(c)) and passed away later that day following a failed cardiopulmonary resuscitation (CPR).
PMC8376443_02
ECG for patient 2 on day 7 of admission showing CHB with ventricular rate approximately 35 bpm.
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He was also noted to have bradycardia with cardiac telemetry monitoring which revealed a CHB with occasional sinus pause, and the 12-lead ECG showed a CHB (Figure 2).
PMC8376443_03
(a) ECG on admission for patient 3 showing sinus tachycardia. (b) ECG for patient 3 on day 5 admission showing complete heart block CHB with narrow QRS, suggesting distal AV node focus as origin of escape rhythm.
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ECG on admission (Figure 3(a)) showed sinus tachycardia at 167 bpm, normal intervals, normal axis, and absence of ischemic findings. On day 5 of admission to ICU, intermittent complete heart block was seen on telemetry for less than 24 hours and 12-lead ECG showed a CHB with narrow QRS, suggesting distal AV node focus as origin of escape rhythm (Figure 3(b)).