Extended early meets late for assessment of conduction block along an ablation line.

PURPOSE: The purpose of the study was to investigate the usefulness of the extended early meets late (EEML) feature of the HD Coloring software for confirmation of bidirectional block along an ablation line.

METHODS

A single-center prospective observational study of consecutive patients with atypical atrial flutter or persistent atrial fibrillation submitted to catheter ablation including linear lesions from January 2019 to June 2020, with confirmation of bidirectional block across ablation lines assessed with the feature EEML and a multipolar catheter was conducted. Patients were divided into two groups - those with versus those without bidirectional block - and different EEML thresholds were analyzed to assess which one had the better sensitivity and specificity to predict block.

RESULTS

During the 24-month enrollment period, a total of 94 patients were included (50% males, mean age of 64 ± 10 years, 60% with structural heart disease) - 55 patients with versus 39 patients without confirmed a bidirectional block. Activation maps were performed during atrial pacing, with a median number of 1340 (interquartile range 1135-2060) points acquired in 11 ± 3 min, and a mean mapped cycle length of 287 ± 51 ms. The EEML feature was highly useful in detecting bidirectional block along ablation lines, with a 25% threshold value showing the highest discriminative performance (area under the curve of 0.93), 95% sensitivity and 92% specificity in predicting block.

CONCLUSIONS

The EEML feature of the HD Coloring software is a useful addition to the CARTO mapping system for assessment of block across an ablation line. The threshold value of 25% is the most accurate.