Differentiation of poor R wave progression of old anteroseptal myocardial infarction from that due to emphysema.

The R/S ratio was calculated in all the six conventional precordial leads in 27 cases of emphysema and 23 cases of old anteroseptal myocardial infarction, all having poor R wave progression in the precordial leads. An R/S ratio greater than or equal to 3.5 in lead V5 was found to be most sensitive (87%), specific (83%) and accurate (85%) in differentiating poor R wave progression of old anteroseptal myocardial infarction from that due to emphysema.