Hypertrophic Cardiomyopathy and Ventricular Pre-Excitation. Description of a Clinical Case

The patient is an 18-year-old young man suffering from cardiomyopathy due to a mutation c.1598>Gp (His530Arg) in the PRKAG2 gene, diagnosed in childhood and characterized by progressive increase in ventricular parietal thicknesses (Figure 1). This pathology represents a metabolic cardiomyopathy due to glycogen storage with a characteristic phenotype: massive hypertrophy, conduction disorders (pre-excitation) (Figure 2)., supraventricular tachyarrhythmias and frequent presence of accessory pathways. In this specific case, despite mildly symptomatic for heart failure, the patient showed a significant structural evolution (2017: 11 y.o, 10 mm; 2021, 14 y.o, 30 mm) for this reason, he underwent a dual-chamber implantable automatic defibrillator (ICD) in primary prevention. At last assessment in 2025 (18 y.o.), the patient presented 50 mm of thicknesses. In the last months, the device has documented two episodes of high-frequency supraventricular tachyarrhythmia, both recognized as ventricular tachycardia. The first episode resulted in the delivery of an inappropriate shock, while the second was interrupted by anti-tachycardia pacing (ATP) (Figure 2). This behaviour is consistent with the pathophysiology of PRKAG2 syndrome, in which the abnormal atrioventricular conduction and the possible presence of accessory pathways can confound the device's discrimination algorithms, increasing the risk of inappropriate treatments Considering the arrhythmic events and the severe structural phenotype, an electrophysiological study (SEF) with mapping and possible ablation of abnormal pathway was planned in order to reduce the recurrence of tachyarrhythmias and prevent further inappropriate shocks. At the same time, given the marked hypertrophy, the progressive nature of the disease and the high risk of evolution to advanced heart failure, the patient was sent to transplant evaluation. A family with the same mutation, described above, showed a severe prognosis for decompensation and the need for transplantation. This case represents an example of the management complexity of PRKAG2-related storage cardiomyopathies and the importance of a multidisciplinary approach between clinical cardiologists, electrophysioly and heart failure experts.Figure 1 Figure 2 Figure 3