Many cases of<unk><unk><unk>  have no definite cause, it may be the result of various other problems.  A more extensive work-up is only indicated when PACs present with severe symptoms and complications.
Premature atrial contraction laboratory studies
Adams-Stokes syndrome electrocardiogram
Ventricular tachycardia echocardiography
Short QT syndrome electrophysiologic studies
Torsades de pointes electrocardiogram
Cardiomyopathy electrocardiogram
Pulseless electrical activity electrocardiogram
Right bundle branch block echocardiography