Background: Although coexistence of atrioventricular conduction disturbances with sick sinus syndrome (SSS), so-called binodal disease (BND), is a frequently encountered disorder, its clinical significance and electrophysiological characteristics remain unknown.
Methods and results: One hundred and seven patients with SSS were divided into BND (n=30) and N-BND groups (n=77). Sinus cycle length, sinus node recovery time (SRT), sino-atrial conduction time (SACT), the number of isolated sinus node electrograms, atrio-His (AH) interval, His-ventricular (HV) interval, intra-atrial conduction time (PA intervals) and QRS width were measured. In addition, the prevalence of bundle-branch block was obtained. The parameters of sino-atrial and intra-atrial conduction were significantly longer in the BND group: SRT (5,070+/-2,628 vs 3,122+/-1,856 ms, p<0.05), SACT (115+/-30 vs 87+/-21 ms, p<0.05), PA intervals (56+/-13 vs 41+/-8 ms, p<0.05). The BND group was more likely to have atrial fibrillation than the N-BND group (83.3% vs 53.2%, p<0.01). HV interval, QRS width and the prevalence of associated bundle-branch block did not differ between the 2 groups.
Conclusion: BND patients not only had sino-atrial and atrioventricular node dysfunction, but also widespread atrial conduction disturbances. Thus, in the clinical setting BND should be categorized as severe SSS.