Intermittent Interatrial Block in a Patient With Recurrent Transient Ischemic Attacks.

Interatrial block (IAB) is a conduction disorder linked to atrial fibrillation (AF) and ischemic stroke. Intermittent IAB, often triggered by premature atrial complexes (PACs), may precede AF and increase thromboembolic risk. We present a case of embolic stroke of undetermined source (ESUS) with intermittent partial IAB detected on ECG. Serial ECGs and Holter monitoring were analyzed. Intermittent partial IAB with dynamic P-wave changes was observed. No AF or alternative embolic source was identified. Intermittent IAB may indicate atrial vulnerability in ESUS. Recognizing subtle ECG changes could aid risk stratification and stroke prevention.