patients with av block during acute myocardial infarction had a significantly higher prevalence of left anterior descending coronary artery obstruction ( 91 versus 55 % , p less than 0.05 ) than did patients without av block and the obstruction preceded the exit of the first septal perforator branch in 73 % of cases with heart block and in 30 % of cases without block ( p less than 0.01 ) .
C0004245
av block
C0018794
heart block