Follow-up of the family with congenital absence of sinus rhythm

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In 1960, Bacos et al 1 reported their investigation of a family with a “congenital familial nodal rhythm.” They examined 2 brothers, 1 age 50 (IV-10, Figure 1), and the other age 42 (IV-14, Figure 1), with atrioventricular (AV) junctional bradycardia and intermittent atrial fibrillation (AF). Except for an enlarged pulmonary artery, the cardiovascular examination (including cardiac catheterization) disclosed no abnormal findings. The family history suggested that the condition was inherited from their mother (III-9, Figure 1), who lived to age 71 but was known to have slow heart rate and AF during the last 20 years of her life. The survey of the remaining family performed by the investigators 1 suggested that this was a dominant autosomal trait with an extremely high degree of penetrance. The investigators suspected a congenital absence of the sinus node but recorded occasional bradycardia with P waves believed to be of sinus origin. The 2 aforementioned brothers had 2 sisters (IV-12 and IV-15, Figure 1), who also had “nodal bradycardia” in childhood and documented paroxysms of AF, with an onset late in the third decade in 1, and in the fourth decade in the other. One of the 4 siblings (IV-14, Figure 1), was not married and had no offspring, but the remaining 3 had a total of 4 daughters (V-3, 5, 6, 7, Figure 1), all of whom had slow “nodal rhythm.” One of these daughters had a son (VI-3, Figure 1), born in 1958, in whom “nodal rhythm” was suspected at birth. As a result of their family survey, Bacos et al 1 made a number of predictions regarding the expected natural course of the existing and the subsequently born members of this family. They were expected to manifest slow heart rate and regular rhythm since birth but the childhood and development were to be normal. Subsequently, they were to experience transient palpitations beginning in their late 20s or early to mid-30s, and finally to develop an established AF requiring chronic treatment. Furthermore, the prophecy offered an excellent prognosis for longevity. The present communication updates the condition of the family with this unusual disorder after 27 years and compares the actual course of events with that predicted by Bacos et al. 1