When Paying Attention Pays Back: Missense Mutation c.1006G>A p. (Val336Ile) in PRKAG2 Gene Causing Left Ventricular Hypertrophy and Conduction Abnormalities in a Caucasian Patient: Case Report and Literature Review.

PRKAG2 cardiomyopathy is a rare genetic disorder that manifests early in life with an autosomal dominant inheritance pattern. It harbors left ventricular hypertrophy (LVH), ventricular pre-excitation and progressively worsening conduction system defects. Its estimated prevalence among patients with LVH ranges from 0.23 to about 1%, but it is likely an underdiagnosed condition. We report the association of the PRKAG2 missense variant c.1006G>A p. (Val336Ile) with LVH, conduction abnormalities (short PR interval and incomplete right bundle branch bock) and early-onset arterial hypertension (AH) in a 44-year-old Caucasian patient. While cardiac magnetic resonance (CMR) showed a mild hypertrophic phenotype with maximal wall thickness of 17 mm in absence of tissue alterations, the electric phenotype was relevant including brady-tachy syndrome and recurrent syncope. The same variant has been detected in the patient's sister and daughter, with LVH + early-onset AH and electrocardiographic (ECG) alterations + lipothymic episodes, respectively. Paying close attention to the coexistence of LVH and ECG alterations in the proband has been helpful in directing genetic tests to exclude primary cardiomyopathy. Hence, identifying the genetic basis in the patient allowed for familial screening as well as a proper follow-up and therapeutic management of the affected members. A review of the PRKAG2 cardiomyopathy literature is provided alongside the case report.

Real-world candidacy to mavacamten in a contemporary hypertrophic obstructive cardiomyopathy population.

AIMS: In the EXPLORER-HCM trial, mavacamten reduced left ventricular outflow tract obstruction (LVOTO) and improved functional capacity of symptomatic hypertrophic obstructive cardiomyopathy (HOCM) patients. We sought to define the potential use of mavacamten by comparing real-world HOCM patients with those enrolled in EXPLORER-HCM and assessing their eligibility to treatment. METHODS AND RESULTS: We collected information on HOCM patients followed up at 25 Italian HCM outpatient clinics and with significant LVOTO (i.e. gradient ≥30 mmHg at rest or ≥50 mmHg after Valsalva manoeuvre or exercise) despite pharmacological or non-pharmacological therapy. Pharmacological or non-pharmacological therapy resolved LVOTO in 1044 (61.2%) of the 1706 HOCM patients under active follow-up, whereas 662 patients (38.8%) had persistent LVOTO. Compared to the EXPLORER-HCM trial population, these real-world HOCM patients were older (62.1 ± 14.3 vs. 58.5 ± 12.2 years, p = 0.02), had a lower body mass index (26.8 ± 5.3 vs. 29.7 ± 4.9 kg/m2 , p < 0.0001) and a more frequent history of atrial fibrillation (21.5% vs. 9.8%, p = 0.027). At echocardiography, they had lower left ventricular ejection fraction (LVEF, 66 ± 7% vs. 74 ± 6%, p < 0.0001), higher left ventricular outflow tract gradients at rest (60 ± 27 vs. 52 ± 29 mmHg, p = 0.003), and larger left atrial volume index (49 ± 16 vs. 40 ± 12 ml/m2 , p < 0.0001). Overall, 324 (48.9%) would have been eligible for enrolment in the EXPLORER-HCM trial and 339 (51.2%) for treatment with mavacamten according to European guidelines. CONCLUSIONS: Real-world HOCM patients differ from the EXPLORER-HCM population for their older age, lower LVEF and larger atrial volume, potentially reflecting a more advanced stage of the disease. About half of real-world HOCM patients were found eligible to mavacamten.