My CCU attending asked me to, if nothing else, remember 3 causes of a tall R wave in V1. In my diligence I have indeed remembered nothing else. What’s in your differential?


3 things to consider with a tall R wave in V1 (R/S ratio >= 1):

posterior MI (tall R waves V1-V3, ST depressions V1 & V2, upright T’s V1-V3; try posterior leads)
pre-excitation syndromes (ie. WPW; PR < 0.12 seconds, QRS > 0.11 seconds, delta wave)
RVH (seen in chronic lung disease, MR, pulmonary stenosis)

Most common: RBBB (rsR’, QRS >= 0.12 seconds, wide S in leads 1, V5, V6)

Other causes include right heart strain (PE), hypertrophic cardiomyopathy, normal variant (1% of patients; dx of exclusion)

Here is a zebra:
Tall R waves in leads V1 to V3
Rangadham Nagarakanti, MD and D. Luke Glancy, MD
Proc (Bayl Univ Med Cent). 2010 Oct; 23(4): 432–433.


Prominent R wave in lead V1: electrocardiographic differential diagnosis.
Mattu A, Brady WJ, Perron AD, Robinson DA.
Am J Emerg Med. 2001 Oct;19(6):504-13.