[Limitations of ventricular late potentials in atrial fibrillation]

It is generally admitted that the chaotic atrial activation in atrial fibrillation makes analysis of ventricular late potentials uninterpretable. However, some workers have contradicted this affirmation. The authors performed signal averaged electrocardiogram in 17 patients with atrial fibrillation before cardioversion for external D.C. shock. The recording was repeated 15 minutes after restoration of sinus rhythm. None of the patients had complete bundle branch block in atrial fibrillation or sinus rhythm. Analysis was made with a band pass filter of 40 Hz and to a final noise level of 0.3 microV. The positivity of late ventricular potentials was confirmed by the presence of at least 2 of the usual 3 criteria: an averaged QRS duration > 120 ms, a RMS 40 < 20 microV and a LAS > 40 ms. The mean duration of the averaged filtered QRS complex was 122 ms in atrial fibrillation and 112 ms in sinus rhythm, a non significant decrease of 9%. The mean value of the RMS 40 was 24 microV before cardioversion versus 29 microV after restoration of sinus rhythm, a significant increase of 19% (p < 0.05). Finally, the mean duration of the LAS in atrial fibrillation was 45 ms, decreasing to 35 ms in sinus rhythm, a significant reduction of 22% (p < 0.05). In atrial fibrillation, 10 patients had ventricular late potentials (2 positive criteria) and 7 had no ventricular late potentials. In sinus rhythm, on the other hand, 6 patients were positive and 11 negative.(ABSTRACT TRUNCATED AT 250 WORDS)