CONGRESS ABSTRACT

A 66-year-old Caucasian woman presented for outpatient evaluation due to elevated blood pressure levels at home (approximately 220/120 mmHg) and a significant family history of long QT syndrome. The index case in the family appeared to be her sister, investigated following an ECG showing markedly prolonged QT interval and a family history of sudden cardiac death. The patient underwent genetic analysis, revealing a positive mutation in KCNQ1. She was currently on treatment with Levotiroxina for recently discovered hypothyroidism.The ECG showed sinus rhythm with a heart rate of 85 bpm, signs of left ventricular hypertrophy, particularly Sokolow (SV1 + RV6 70 mm) and Peguero Lo Presti (SD + SV4 50 mm). The QTc interval was 515 ms (Bazett). Echocardiography revealed severe left ventricular hypertrophy (SIVd 14 mm; PWd 12 mm; LVMi 128 g/m2; RWT 0.5) with normal overall systolic function (EF 60%). No significant valvular pathologies were observed, and the right ventricle appeared normal in size and function.The hypertrophy was attributed to uncontrolled severe arterial hypertension. However, the identification of a prolonged QT interval in a patient with a strong family component (Schwartz score 4, high probability) led to genetic testing, confirming a mutation in KCNQ1. As the patient was asymptomatic with a low risk of major arrhythmias over the next 5 years (1-2-3-LQTS-risk score 2.77%), she entered follow-up and received beta-blocker therapy, specifically nadolol, combined with other antihypertensive medications.This clinical case describes an entire family with LQTS1 (type 1) positive for KCNQ1 mutation, exhibiting phenotypic manifestations distinct from those reported in the literature. Notably, there was a prevalence in females, and the condition was incidentally discovered during a routine checkup conducted for unrelated reasons, without any history of major arrhythmias.Long QT syndrome (LQTS) is characterized by a prolonged QT interval, predisposing individuals to life-threatening arrhythmias leading to syncope and sudden death. Mutations in genes encoding ion channels account for 75% of LQTS cases. LQTS1, associated with a ‘loss-of-function’ mutation in the KCNQ1 gene, represents one of the three genetic subtypes. LQTS1 typically manifests with arrhythmias in childhood, with a male predominance. Adrenergic triggers are crucial precipitants for arrhythmic events