CASE: This is the case of a 35-year old male physician presenting with a 12-year history of palpitations despite oral metoprolol. He had reversible left hemiparesis with right hemispheric lacunar infarctions on computerized tomography scan. The 12-lead electrocardiogram (ECG) recorded during an episode of palpitations revealed wide QRS (0.16 s) tachycardia (heart rate=214 beats per minute) with left bundle branch block (LBBB) QRS morphology; no identifiable P waves; QS pattern in leads V1 to V4; RS pattern in leads V5 and V6; and a QRS axis at -1300. There were no AV dissociation; fusion and captured beats; and precordial QRS concordance. Electrophysiology studies (EPS) were performed. During programmed electrical stimulation (PES) at the right ventricular apex, sustained narrow QRS (0.10 s) tachycardia (168 bpm) was induced. Examination of the intracardiac atrial (A) and ventricular (V) electrograms during the tachycardia revealed a 1:1 AV relationship; closer A electrogram to the preceding A electrogram than the following V electrogram producing a short RP tachycardia (
DIAGNOSIS: FAT with acceleration-dependent functional LBBB based on a mechanism of triggered automaticity arising from the coronary sinus ostium.
TREATMENT AND OUTCOME: Radiofrequency ablation was applied on the identified arrhythymogenic atrial focus and effectively restored sinus rhythm and rendered the FAT non-inducible.