Abstract
Hypertrophic cardiomyopathy (HCM) is the most frequent genetic disease of the myocardium, with a prevalence of 1:500 cases in the general population. The salient feature is a hypertrophy, symmetrical or not, of the walls of the left ventricle (mainly the septum, but also less typical locations, such as the apex or the infero-lateral wall), not linked to abnormal load conditions. HCM is mostly an autosomal dominant inherited disease with incomplete penetrance and variable expressivity, mainly linked to mutations in genes coding for sarcomeric proteins. Several studies have shown an up-regulation of the ACE-2 gene, perhaps indicative of a compensatory anti-hypertrophic and anti-fibrotic response of the myocardium, in hypertrophic cardiomyopathy. Being the ACE-2 receptor target of the SARS-CoV-2 virus, these patients may have an increased risk of infection and a worse outcome.
A 47-year-old man, with no known comorbidities, was hospitalized in our Emergency Medicine Department for bilateral SARS-CoV-2 pneumonia. Noninvasive mechanical ventilation c-PAP (FiO2 60%, PEEP 7.5 cmH2O) was started for hypoxemic respiratory failure and an ECG showed diffuse ventricular repolarization abnormalities suggestive of left overload (asymmetric negative T waves V4–V6, in I, II, and aVL, flat in aVF. Figure 1), with a deep Q wave in III. The patient was asymptomatic for chest pain and equivalents and D-dimer and indices of myocardionecrosis were normal. Echocardiographic evaluation was performed, with evidence of marked asymmetric concentric hypertrophy of the left ventricle (interventricular septum: 16 mm), without significant anomalies in segmental kinetics, noteworthy valvulopathies, and pericardial effusion. The family and personal medical history were negative for syncope, sudden cardiac death, and resuscitated cardiac arrest and the estimated risk of sudden cardiac death at 5 years (HCM Risk-SCD) was <4% (1.33%). The diagnostic hypothesis of non-obstructive hypertrophic cardiomyopathy was advanced. During hospitalization, ECG monitoring showed no sustained ventricular arrhythmias and the patient remained asymptomatic for dyspnoea, chest pain, and equivalents. Subsequent echocardiograms showed no new changes. A progressive weaning from oxygen support was carried out and, after 30 days, the patient was discharged to home fiduciary isolation, with optimal cardiological therapy and indication to study with cardiac magnetic resonance to the negativization of the nasal swab for SARS-CoV-2. MRI, performed about 2 months later, confirmed the suspicion of hypertrophic cardiomyopathy, with no signs of late enhancement in T1-weighted sequences (Figure 2). The patient was then referred to a genetic study and cardiological follow-up, still in progress.
Incomplete Penetrance and Variable Expressivity: Hallmarks in Channelopathies Associated with Sudden Cardiac Death
