Supernormal atrial conduction and its relation to atrial vulnerability and atrial fibrillation in patients with sick sinus syndrome and paroxysmal atrial fibrillation

Abstract

The purpose of this study was to evaluate prospectively the relationship between supernormal atrial conduction (SNC) and the atrial vulnerability to fibrillation in patients with sick sinus syndrome (SSS) and paroxysmal atrial fibrillation (PAF). Programmed atrial stimulation was performed in 32 age-matched control patients (group I), 26 with SSS but without tachyarrhythmias (group II), and 24 with both SSS and PAF (group III) to assess some determinants of atrial vulnerability, SNC, and atrial fibrillation inducibility. Supernormal atrial conduction was observed in 20 (63%) patients of group I, 12 (46%) patients of group II, and 5 (21%) patients of group III (group I vs group III; p < 0.002). The SNC zone was 46 ± 44 msec in group I, 36 ± 42 msec in group II, and 12 ± 24 msec in group III. (group I vs group III; p < 0.001). The absence of SNC showed a specificity of 89% and a positive predictive accuracy of 79% in predicting inducibility of atrial fibrillation. The sensitivity was 33% and the negative predictive accuracy was 52%. The SNC zone showed a significant inverse correlation with P wave duration ( r = −0.32; p < 0.003), intraatrial conduction time ( r = −0.28; p < 0.02), and maximum conduction delay ( r = −0.23; p < 0.05). The maximum decrease in conduction time during supernormal conduction showed a significant inverse correlation with P wave duration ( r = −0.27; p < 0.02), intraatrial conduction time ( r = −0.26; p < 0.02), and with the maximum conduction delay ( r = −0.27; p < 0.02). We conclude that the greater the atrial vulnerability and the greater the atrial conduction defects, the lower the occurrence of supernormal atrial conduction in the SSS. The absence of supernormal atrial conduction associated with atrial conduction defects may play an important role in the development of atrial fibrillation in patients with sick sinus syndrome and paroxysmal atrial fibrillation.