Prognosis of right bundle branch block and left anterior hemiblock after intracardiac repair of tetralogy of Fallot.

One hundred and forty-one survivors of intracardiac repair of tetralogy of Fallot (TOF), operated on between 1958 and 1972, were studied in order to document the incidence of right bundle branch block and left anterior hemiblock (RBBB and LAH) and to definite the late prognosis. RBBB and LAH occurred in 31 patients (22 per cent), all of whom have had complete follow-up. Transient complete heart block (CHB) occurred postoperatively in 2 patients; there were no other significant arrhythmias. Two late deaths have occurred, neither from arrhythmia (one from progressive congestive heart failure, and the other from attempted reclosure of a ventricular septal defect). The remainder of the patients are well an average of 76 months postoperatively (range, 144 to 12 months). The absence of late-onset CHB or sudden death in this series contrasts with the relatively high incidence of these events in some studies of RBBB and LAH after intracardiac repair of TOF. However, in those reports a history of transient postoperative CHB (indicative of trifascicular disease in this setting) can be found in 75 per cent of those who developed late-onset CHB or died suddenly. We conclude that the occurrence of RBBB and LAH after intracardiac repair of TOF does not of itself carry a bad late prognosis. The critical factor in a bad late prognosis in patients with ECG evidence of RBBB and LAH may be with ECG evidence of RBBB and LAH may be the history of transient postoperative CHB.