Electrophysiological properties in patients undergoing atrial compartment operation for chronic atrial fibrillation with mitral valve disease

AIMS: Surgical treatment for atrial fibrillation is now feasible inselective cases. The aim of this study was to assess the electrophysiologicalproperties of patients undergoing atrial compartment operationfor chronic atrial fibrillation. METHODS AND RESULTS: Electrophysiological studies were performed in 20 mitral valvepatients with atrial fibrillation who had been maintained insinus rhythm for more than 1 year after atrial compartment operation.Intra-cardiac recording and programmed electrical stimulationwere performed in various atrial compartments. The parametersstudied included sinus node function, atrial conduction andrefractoriness, atrioventricular conduction function and induciblearrhythmias if any. Intra-cardiac recordings showed that therhythm was of sinus origin in all cases, with the earliest atrialactivity located in the high right atrium. The mean sinus cyclelength was 750±110 ms, AH time 106±29 ms, andHV time 53±7 ms. The sinus node function was normal in18 patients (90%), and only two patients had prolonged sinusnode recovery and sino-atrial conduction. The right atrial appendagecompartment was driven by the sinus node in all patients. However,the conduction time from the high right atrium to the rightatrial append age compartment was markedly prolonged in 12 of15 patients (80%) undergoing the three-compartment operationin which an incision was placed between the high right atriumand right atrial appendage compartments. On the other hand,the electrical activities in the left atrial compartment weremuch more varied. In 13 of 20 patients (65%), the left atrialcompartment was driven by the sinus node; 11 of the 13 patientshad a normal or mildly prolonged conduction time (ranged 75to 146 ms), whereas two patients had a marked delay in conduction(200 ms and 266 ms, respectively). In the remaining seven patients,the left atrial compartments were dissociated from the restof the heart; five of them had a quiescent left atrium, onea fluttering left atrial rhythm, and one a slow left atrialrhythm. The effective refractory period was longer in the leftatrial compart ment (242±47 ms) as compared to that ofthe high right atrium (224±26 ms, P<0·01) andright atrial appendage compartments (219±25 ms, P<0·01).Programmed electrical stimulation could not induce atrial fibrillationin any patient, whereas two patients had inducible atrial flutterand three repetitive atrial responses. CONCLUSION: (1) Atrial compartment operation does not impair sinus nodefunction in most cases. (2) Elimination of atrial fibrillationwhile maintaining the electrical connection between differentatrial compartments is feasible.