What Is the Most Accurate and Simple Method to Assess Block Through the Cavotricuspid Isthmus?

The determining factor in allowing the effective elimination of typical atrial flutter by catheter ablation has clearly been the progressive refinement of procedural endpoints (Table 1). In our own experience, three clear transitions, demarcated by progressive reductions in the recurrence rates for this arrhythmia, have been evident. Beginning with a high recurrence rate when flutter termination and noninducibility were considered sufficient endpoints, the demonstration of cavotricuspid isthmus block based on septal and lateral right atrial activation sequences reduced recurrence rates to about 12%. Further refinement with the routine use of local electrogram-based criteria [1], mapping double potentials supplemented with differential pacing [2], has led to an additional reduction in recurrence rates to < 5%.