The time interval from the initiation of the P-wave to the start of left atrial appendage ejection flow: Does it reflect interatrial conduction time ?

Recurrence of atrial fibrillation is more common in patients with atrial conduction delay. In the present study, we evaluated whether findings obtained from transesophageal echocardiography (TEE), a semi-invasive method, correlate with those from an invasive method, electrophysiologic study (EPS), in measuring interatrial conduction time. Methods and Results: We compared two methods of calculating interatrial conduction time in a group of 33 patients. The origin of the P-wave on the surface electrocardiogram (ECG) was taken as the onset of atrial activation. The time interval from this point to the commencement of the left atrial appendage ejection flow (P-LAA) was measured by TEE. Meanwhile, simultaneous recordings of the left atrial appendage were obtained with a catheter positioned in the LAA, and an invasive interatrial conduction time was measured from the origin of the surface's earliest P-wave (I-IACT). The mean I-IACT (46.27 +/- 13.25 ms) correlated strongly with the mean P-LAA (49.91 +/- 12.72 ms; r = 0.839, P < 0.0001). Conclusion: The interatrial conduction time can be estimated with a relatively noninvasive method using P-LAA measurements. This technique can be applied widely in predicting AF recurrence, and appropriate therapy may be applied