ISOLATED CONGENITAL COMPLETE ATRIOVENTRICULAR-BLOCK IN ADULT LIFE - APROSPECTIVE-STUDY

Background The prognosis of congenital complete atrioventricular block (CCHB) is usually considered favorable in adults. This belief is base d on studies comprising a limited number of patients and with rather s hort observation times. In the present study, the natural history of t he disease was investigated by a prospective follow-up through decades of adult life of patients with a large group having well-defined CCHB without structural heart disease. Methods and Results The diagnostic criteria of CCHB proposed by Yater were applied. Patients registered a s having CCHB in 1964, supplemented by younger patients all without sy mptoms during their first 15 years of life, were selected. The study w as limited to patients with isolated, complete, permanent block. An in terview was conducted with all patients and clinical follow-up data ob tained. There were finally 102 patients, 61 women and 41 men. In Novem ber 1994, the time of observation, after the age of 15 years in surviv ors, was between 7 and 30 years. The mean age at follow-up or at death was 38 years, median age 37 years, and range 16 to 66 years. Stokes-A dams (SA) attacks occurred in 27 patients, in 8 with a fatal outcome. The first attack was fatal in 6 of these 8 patients. Nineteen survived and a pacemaker (PM) was implanted thereafter. Another 8 patients rec eived a PM because of repeated fainting spells, and 27 others have had a PM implanted for other reasons such as fatigue, effort dyspnea, diz ziness, ectopies during exercise tests, mitral regurgitation, and a lo w ventricular rate (VR). VR decreased with age, with a mean rate at 15 years of 46 beats per minute (bpm), at 16 to 20 years of 43 bpm, at 2 1 to 30 years of 41 bpm, at 31 to 40 years of 40 bpm, and after 40 yea rs of age of 39 bpm. SA attacks occurred in all 7 patients with prolon ged QT(c) time. Low VR at rest or at work, presence of bundle-branch b lock pattern, low working capacity, and ectopies at rest and/or during effort were not statistically significant risk factors. SA attacks oc curred in 6 patients without any of these signs. Mitral regurgitation developed in 16 patients and 4 died. A PM reduced the risk of death. A change to a lower degree of block occurred in 6 patients. Conclusions Prophylactic PM treatment is recommended even for symptom-free adults with CCHB because of the high incidence of unpredictable SA attacks w ith considerable mortality from first attacks, a gradually decreasing VR, significant morbidity, and a high incidence of ''acquired'' mitral insufficiency.