Heart block in acute myocardial infarction: prognostic factors and role of transvenous catheter pacemaker.

A prospective study was carried out to determine the prognostic factors in patients with second-degree and complete heart block following acute myocardial infarction and to re-examine the indications for artificial transvenous pacing. Of the 117 consecutive patients with proved acute myocardial infarction, 15 developed advanced heart block (second degree and complete). The presence of the following factors, either alone or in combinations, were attended with poor prognosis: preceding Stokes-Adams syndrome, cardiogenic shock, congestive heart failure, complications secondary to cardiac arrest, anterior infarction and wide QRS complex. In the nine cases requiring artificial transvenous pacemaker because of Stokes-Adams attacks, congestive heart failure or frequent multifocal ventricular ectopic beats, there were five deaths. The remaining six patients, who were without complications and were not paced, all survived; these patients had normal QRS duration with heart rates above 60 per minute. This study indicates that prophylactic transvenous catheter insertion in acute heart block does not appear justified unless specific indication(s) arise. Postmortem studies revealed significant narrowing of all the major coronary vessels in all five fatalities. The overall mortality in this series of cases of acute heart block was 33%.