Laboratory findings predicting sudden cardiac arrest and ventricular tachycardia include elevated level of Natriuretic peptides—B-type (BNP) or  N-terminal pro-BNP as the marker of myocardial stress and fibrosis in heart failure disease, highly sensitive troponin T indicating cardiomyocyte injury, screening about hypokalemia, hypomagnesemia and also  toxic level of digoxin, cocaine, tricyclic antidepressant.
Ventricular tachycardia laboratory findings
Atrial flutter laboratory findings
Right bundle branch block laboratory findings
Atrial fibrillation laboratory findings
Atrioventricular block laboratory findings
Premature atrial contraction laboratory findings
Second degree AV block laboratory findings
Pulseless ventricular tachycardia laboratory findings