Magnetic Resonance Features of a Recent Catheter Ablation of Left Posterior Fascicular Ventricular Tachycardia.

A 71-year-old male patient with a past medical history of hypertension, hyperlipidemia, and chronic kidney disease stage II presented with a complaint of intermittent palpitations for three months and was found to have wide complex tachycardia on the electrocardiogram (ECG). The patient was given adenosine and amiodarone, following which he underwent synchronized cardioversion at 150 Joules followed by 200 Joules without successful conversion. He was subsequently initiated on lidocaine drip at the rate of 1 to 4 mg/minute to maintain adequate rhythm control, which converted him to sinus rhythm and relieved his symptoms. An eventual assessment with an electrophysiology study identified the presence of incessant left ventricular tachycardia (VT). The mechanism was confirmed to be left posterior fascicular ventricular tachycardia (LPF-VT). Successful mapping and ablation for the LPF-VT were achieved. Post-procedure cardiac MRI showed two small areas of near-transmural delayed enhancement. These areas are associated with nulled areas in the inferolateral wall at the left posterior His-Purkinje fascicle. This case highlights fascicular VT as a separate clinical entity, with its characteristic ECG features and acute MRI features after ablation.