From:  Myxoedema coma with complete atrioventricular block: a case report

 Admission electrocardiographic features.

ParameterFinding
Atrial rateApproximately 41–42 beats/min
Ventricular escape rate on admission 12-lead ECGApproximately 13–14 beats/min
Bedside monitored ventricular rateApproximately 25–30 beats/min
AV relationshipComplete AV dissociation/Complete AV block
PR intervalNot assignable
QRS durationMarkedly wide, > 200 ms
Bundle-branch-block morphologyBroad, slurred idioventricular escape complexes; no typical RBBB or LBBB pattern
Limb-lead QRS voltageLow
Frontal QRS axisNo gross deviation apparent; precise numerical axis not assigned because of very low limb-lead voltage and archived-tracing quality
QT/QTcQT not reliably measurable because T-wave termination was indistinct and atrial deflections were superimposed; QTc not reported
Previous ECGNot available for reliable comparison

AV: atrioventricular; ECG: electrocardiogram; LBBB: left bundle-branch block; RBBB: right bundle-branch block.