Evaluate for underlying pathology
ECG
Labs
CBC
Chemistry
Troponin
PT/PTT
CBC
Chemistry
Troponin
PT/PTT
Prolongation of the PR interval (first degree AV block) AND
Right bundle branch block AND
Either left anterior fascicular block or left posterior fascicular block
Right bundle branch block AND
Either left anterior fascicular block or left posterior fascicular block
ECG will show more atrial complexes than ventricular complex indicating high grade heart block
Right budle branch block + extreme left axis deviation (left anterior fascicular block) + atrioventricular heart block
Trifascicular Block
Differential includes ischemic events, electrolyte abnormalities, and medication overdoses in addition to rheumatologic conditions[1][2]
Digital block
Anterior MI
Cervical spine clearance
Rheumatic fever
Nerve and regional blocks 
Myocarditis