Overall, long-term survival after the Mustard or Senning operation is good, but late arrhythmias remain a concern. Whether postoperative electrophysiological investigations can identify patients at risk of developing serious arrhythmias is unknown. In this study, 16 children who underwent electrophysiological study after the Mustard or Senning operation for complete transposition (the combination of a concordant atrioventricular and a discordant ventriculo-arterial connexion) were followed up for one month to 9 years (mean 4.33 years) after this investigation. At the electrophysiological study, sinus nodal dysfunction was diagnosed in 9 16 patients, and abnormalities of atrial conduction and refractoriness in 7 13. During follow-up, 7 children developed clinical evidence of the sick sinus syndrome. When considering corrected sinus node recovery time as the only electrophysiological parameter, the sensitivity of predicting sick sinus syndrome from the electrophysiological study was 42%, and specificity 66%. The sensitivity increased to 71% if additional electrophysiological criteria of sinus node dysfunction were included, such as sinuatrial conduction time or sinus node entrance block, but specificity dropped to 55%. Atrioventricular conduction disturbances were rare. Thus, abnormalities at electrophysiological studies after the Mustard or Senning operations are frequent, but identification of patients at risk of developing sick sinus syndrome remains difficult. © 1990.
