A patient with inferior acute myocardial infarction with grade II ischaemia. A patient with inferior acute myocardial infarction with grade II ischaemia. (A) There is ST elevation in II, III and aVF and V5–V6. The J/R ratio is less than 0.5 in all leads. (B) A patient with inferior acute myocardial infarction and grade III ischaemia. There is ST elevation in leads II, III, and aVF with a J/R ratio >0.5 in leads III and aVF (see text). Y Birnbaum, and B J Drew Postgrad Med J 2003;79:490-504 Copyright © The Fellowship of Postgraduate Medicine. All rights reserved.