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15-Year ECG Evolution of Interatrial Block and Effects of Atrial Septal Pacing
Yuko Matsui1, Satoshi Higuchi2, Kensuke Kikuchi1
1Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
Background:
Interatrial block (IAB) reflects atrial remodeling and an arrhythmogenic substrate; however, its long-term progression is poorly characterized.
Case Summary:
An 87-year-old woman with recurrent atrial tachyarrhythmias and sinus node dysfunction demonstrated progressive P-wave prolongation from 120 to 160 ms over a 15-year period, evolving from partial to atypical advanced IAB with a triphasic morphology. Intracardiac mapping revealed extensive biatrial scarring and markedly delayed interatrial conduction. High right atrial septal pacing shortened the P-wave duration to 126 ms and was followed by sustained freedom from atrial arrhythmias.
Discussion:
This case provides to our knowledge the first documentation of long-term electrocardiographic progression from partial to atypical advanced IAB, offering insights into the natural history and underlying mechanisms of IAB. High atrial septal pacing improved interatrial conduction and may suppress atrial arrhythmias even in the setting of advanced atrial remodeling, highlighting the clinical importance of recognizing atypical IAB patterns.
Take-Home Messages:
Long-term electrocardiographic follow-up captured the progression of IAB in a single patient. High atrial septal pacing optimized interatrial conduction and helped maintain sinus rhythm in a markedly remodeled atrium.
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