Twelve-lead ambulatory ECG recording using a seven-electrode recorder: An alternative method for electrophysiological evaluation.

Introduction: Conventional three-lead ambulatory electrocardiogram recording (3L-AECG) is used for the quantitative diagnosis of arrhythmias. However, the lack of crucial information, such as QRS morphology and orientation, renders the 3L-AECG incomplete for planning electrophysiological interventions. The 12-lead AECG (12L-AECG) merges the temporal resolution 3L-AECG with the spatial resolution of the standard electrocardiogram (S-ECG). Although it provides more detail, it is not widely used. This study aimed to verify whether the seven-electrode 12L-AECG and S-ECG have similar waveforms.

Methods: A questionnaire consisting of 240 side-by-side comparisons (12 leads from 20 patients) was created. These consisted of a QRS registered using the 12L-AECG and a QRS from the same patient, registered using the S-ECG. The questionnaire was submitted to cardiologists trained in electrophysiology. For each comparison, the evaluator assigned "similar" or "different" depending on their own judgment.

Results: Five cardiologists completed the questionnaire, resulting in 1200 answers. The AECG-12 was similar to the ECG in 84.50 % of the instances (95 % confidence interval [CI] 83.20-86.50). The interobserver agreement was moderate (0.542, p < 0.001). The similarity between specific leads ranged up to 98 % (95 % CI 92.96-99.76). No significant differences were found among patients (p = 0.407).

Conclusion: The seven-electrode 12L-AECG and S-ECG produced comparable waveforms. This similarity supports the use of 12L-AECG for accurate arrhythmia tracking and assists in planning electrophysiological procedures.