The natural history of atrioventricular conduction defects in acute myocardial infarction

Abstract

Of 446 patients admitted to the Coronary Care Unit, 54 (11.5 per cent) developed A-V conduction disturbance with a mortality rate of 33 per cent. Twenty-nine had complete heart block with a mortality rate of 45 per cent. There were three times as many patients with inferior infarction than anterior infarction and their mortality rate was only one third that of the latter. Approximately one third of those patients who developed first degree heart block progressed to complete heart block, and about one third of those who developed second degree heart block developed complete heart block. In those with first degree heart block, the site of infarction and time of onset was of no value in predicting those patients who might progress to complete heart block. It is suggested that the prophylactic insertion of an endocardial pacing catheter prior to the development of complete heart block is of little value in patients with inferior infarcts, but may be of value in those with anterior infarcts who develop first degree block.