P7 INJECTABLE LOOP RECORDER IMPLANTATION IN CHILD WITH DANON SYNDROME AND VENTRICULAR EXTRASYSTOLES

Abstract

Abstract Introduction Danon syndrome is a rare X–linked storage disorder caused by mutation of the LAMP2 gene, which is expressed in the heart with hypertrophic cardiomyopathy, heart failure and arrhythmias. Clinical case Little C. comes to our observation at the age of 3 years for ventricular extrasystoles. The maternal grandmother died suddenly at the age of 36, with the autopsy of hypertrophic cardiomyopathy being found. The mother, who died at the age of 28 from heart failure, was suffering from Danon syndrome with non–obstructive hypertrophic cardiomyopathy with dilatative evolution, episodes of atrial fibrillation and sustained ventricular tachycardia, WPW syndrome, already subjected to ICD implantation and on list for cardiac transplantation. The little girl presents a normal echocardiogram at our first evaluation; Holter documents numerous isolated, monomorphic ventricular extrasystoles. Genetic analysis is started to ascertain the presence of the germline mutation in the LAMP2 c.928G>A gene (related in the literature to Danon disease). During the follow–up the patient, always asymptomatic for syncope and / or palpitations, presents the appearance of slight concentric hypertrophy of the left ventricle; to Holter persistence of monomorphic, non–repetitive ventricular extrasystoles. At the age of 5, injectable loop recorder implantation is performed. The procedure is well tolerated and with no complications. The sensing of the R wave (1.03 mV) was great. Beta–blocker therapy is also undertaken. At remote monitoring, some false episodes of tachyarrhythmias due to double counting due to the presence of high voltage T waves are observed in the first month after the implant; after reprogramming the gain, false alarms do not occur. Over the course of about 3 years, monitoring with loop recorder allowed to document the absence of sustained brady and tachyarrhythmias. At the clinical follow–up, a reduction in the arrhythmic burden was observed, with almost total disappearance of ventricular extrasystoles. Conclusions The loop recorder implant is a safe and reliable procedure in pediatric age for the monitoring of patients at arrhythmic risk who do not have indication for defibrillator implantation. Danon syndrome is expressed phenotypically with hypertrophic cardiomyopathy in the second to third decade of life; it is, therefore, necessary to identify paediatric subjects who may be most at risk of sudden arrhythmic events.