Complete heart block complicating acute myocardial infarction.

Complete heart block (CHB) developed in 10.3% of patients with acute myocardial infarction (MI). It was more frequent among patients with inferior myocardial infarction compared to anterior myocardial infarction, but the mortality was significantly high among patients with anterior MI who developed CHB. A new classification into primary (P) and secondary (S) CHB is suggested by the sequence of events. The incidence and mortality of SCHB was significantly high when compared to the incidence and mortality of PCHB. Wide QRS complexes, a heart rate of less than 60/min, and syncopal attacks were the grave prognostic signs. Progression from a lesser degree of AV block and regression of CHB to a lesser degree of AV Block were both observed in 25.8% cases. Circulatory failure in the form of shock, hypotension, congestive heart failure, and left ventricular failure, alone or in combination was a factor in 17 of the 22 patients who died. Four of 5 patients who underwent transvenous pacing also died.