Prominent R wave in lead V1: Electrocardiographic differential diagnosis

Tall lead V1 (tall RV1), defined as an RIS ratio equal to or greater than 1, is not an infrequent occurrence in emergency department patients. This electrocardiographic finding exists as a normal variant in only 1% of patients. Physicians should therefore be familiar with the differential diagnosis for this important QRS configuration.

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
Hypertrophic cardiomyopathy
Progressive muscular dystrophy
Dextrocardia
Misplaced precordial leads
Right bundle branch block
Normal variant

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.

Taken from article in American Journal of Emergency Medicine