[Congenital isolated complete atrioventricular block: long-term experience with 38 patients]

The management of patients with isolated congenital complete heart block is controversial, and indications for cardiac pacing are not clearly defined. In the present study we report our long-term experience in the management of patients with this disease.

Thirty-eight consecutive patients aged 2 days to 28 years (mean age 10 years) were studied and followed up for 130 +/- 57 months (range 18 to 274). They underwent an extensive evaluation including history, physical examination, electrocardiography and echocardiography; thirty-seven patients had Holter monitoring and exercise test. Electrophysiologic study was performed in 24 patients.

Twenty-two patients were asymptomatic, sixteen had symptoms as syncope or presyncope (7 patients), marked exercise intolerance (1 patient), presyncope and marked exercise intolerance (1 patient), heart failure (1 patient), mild dyspnea on exertion (6 patients). Electrocardiograms showed a narrow QRS in all patients. Holter monitoring showed a marked bradycardia (awake heart rate < or = 55 beats/min in infants, < or = 40 beats/min in children and adults) in 15 patients and junctional pauses of > 3 seconds in 9 of them. The exercise test showed a markedly reduced exercise tolerance in 2 patients and exercise-induced complex ventricular arrhythmias in 3 patients. Echocardiography showed a structurally normal heart and a normal left ventricular function in all patients. The electrophysiologic study always showed a suprahisian site of block. Twenty patients (53%) underwent cardiac pacing at a median age of 14 +/- 10 years and were followed up for 110 +/- 59 months (range 18 to 253) after pacing; prophylactic pacing was performed in 10 patients. Indications for cardiac pacing were: syncope or presyncope (7 patients), presyncope and marked exercise intolerance (1 patient), neonatal heart failure (1 patient), marked exercise intolerance (1 patient), neonatal marked bradycardia (2 patients), marked bradycardia with junctional pauses of > 3 seconds and/or complex ventricular arrhythmias (7 patients), complex ventricular arrhythmias (1 patient). No death occurred during the follow-up. In 9 of 20 patients who had cardiac pacing, indication for this procedure appeared during the follow-up (development of symptoms, marked bradycardia and/or complex ventricular arrhythmias). Complications of pacing were infrequent (9 complications in 7 patients) and mainly occurred in the first years of our experience. At present 12 patients have an atrioventricular sequential pacing and 8 have a rate-responsive ventricular one. All patients who had pacing showed an improvement of exercise tolerance; 11 of them underwent exercise test after pacing which showed a significant increase in exercise duration (from 11.1 +/- 1.9 to 15.3 +/- 1.1 min, p < 0.01). In the 3 patients with complex ventricular arrhythmias we observed their suppression after atrioventricular sequential pacing. At present 35 patients are asymptomatic and 3 have mild dyspnea on exertion.

Our results confirm that patients with isolated congenital complete heart block often have symptoms and/or signs of electric instability without symptoms. Cardiac pacing relieves symptoms and improves working capacity. Although in this study we are not able to draw conclusions on the therapeutic value of prophylactic pacing, our favourable follow-up results suggest that this therapeutic approach may prevent complications.