Case Report: A 14-year-old girl presented with sudden onset of pre-excited atrial fibrillation with a rapid ventricular response. She was hemodynamically stable and was treated with a procainamide bolus which converted the rhythm to sinus. She had a past medical history of hypertrophic cardiomyopathy and WPW syndrome with multiple accessory pathways diagnosed four years back. At that time she underwent successful ablation of a two rapidly conducting accessory pathways in the right antero-lateral and left lateral AV groove. She had a third midseptal to antero-septal pathway; however, this pathway was not ablated at the time, due to the relative proximity to AV node, the limited antegrade conduction properties, and the lack of retrograde conduction. She was treated with atenolol.
The patient had a strong family history of heart disease. Her mother had WPW syndrome and HCM and had atrial fibrillation at 12 years of age. She subsequently had placement of an ICD. Her maternal uncle, who was previously healthy, died suddenly at the age of 32 years. Also, her maternal cousin has WPW syndrome.
Considering the past history of WPW and evidence of pre-excitation on ECG, she underwent electro-physiological testing. Three accessory pathways (right postero-septal, right lateral and midseptal) were mapped. Both right sided pathways were successfully ablated. The midseptal pathway demonstrated delayed elimination (10 – 15 seconds) with application of radiofrequency energy, though this was soon followed by accelerated junctional rhythm requiring termination of the lesion. Her postoperative course was remarkable for the development of a variety of AV conduction findings. On post-op day 4, she developed sinus rhythm with first degree AV block and no evidence of ventricular pre-excitation. Two days later, this progressed to compete AV block. The following day, her AV node conduction returned, though there was still no evidence of pre-excitation. On post op day 9, ventricular pre-excitation was once again evident. She underwent implantation of a dual chamber ICD in view of the episode of high grade AV block and history of syncope in the setting of hypertrophic cardiomyopathy. Genetic testing was demonstrated the patient to be heterozygous in the PRKAG2 gene coding for a missense mutation defined as c.1589 A>G.
Discussion: Mutations in PRKAG2 gene that regulates the ?2 subunit of the AMP dependent protein kinase have been associated with the development of AV accessory pathways, cardiac hypertrophy and conduction system abnormalities. We describe an adolescent female affected by the disease who experienced multiple life threatening arrhythmias and AV nodal block before placement of an ICD (Implantable cardioverter defibrillator). We aim to reiterate the importance of early recognition of this entity and possible placement of ICD early in the course of management to prevent catastrophic arrhythmias and possible sudden cardiac death.