Interpreting a prominent R wave in V1 is an exercise in differential diagnosis. The clinician must be able to list the causes. Here’s the list:
Left ventricular ectopy
Right ventricular hypertrophy
Acute right ventricular dilation (acute right heart strain)
Type A Wolff-Parkinson-White syndrome
Posterior myocardial infarction
Progressive muscular dystrophy
Misplaced precordial leads
Right bundle branch block
You’ll make fewer mistakes if you keep this list in mind when confronted with an electrocardiogram which displays an R wave in V1 of greater amplitude than the S wave.
Via the American Journal of Emergency Medicine.