Diffuse generalized phenotype of hypertrophic cardiomyopathy: genetic spectrum and surgical correction

Introduction. Hypertrophic cardiomyopathy (HCM) is characterized by clinical and genetic heterogeneity. Age of manifestation, clinical and anatomical phenotypes of HCM vary significantly. This study discusses genetic causes and reconstructive surgery results for patients with particular intracardiac phenotype - diffused generalized HCM (DG-HCM). Methods: personal and familial medical history, general examination, 12-lead resting ECG, 24-hour ECG Holter monitoring, transthoracic and transesophageal EchoCG, cardiac MRI with gadolinium enhancement. A ten-gene panel was sequenced by IonTorrent PGM. Mutational screening in patients with suspected multisystemic diseases was performed by Sanger sequencing. Results: 170 patients with obstructive HCM (oHCM) requesting genetic counseling and surgical correction of HCM were evaluated. We distinguished particular DG-HCM subtype of oHCM (diffuse hypertrophy of IVS, LV free walls, papillary muscles displaced towards the LV apex) in 34 patients; 31 out of 34 underwent open heart reconstructive surgery. Patients with DG-HCM were younger at the time of surgery, had higher risk of SCD, and connective tissue dysplasia of the mitral valve. Hemodynamics normalization was observed in 1, 3, and 5 years after surgery. Eighteen ICDs were implanted; five patients experienced appropriate shocks. The genetic spectrum was enriched up to 30% by multisystem disorders. Mutations in "sarcomeric" genes were detected in 15%. Conclusion: Intracardiac phenotype of HCM may correlate with genetic cause and long-term prognosis. DG-HCM phenotype accounts for 20% oHCM patients and indications for open-heart surgery. Extended myectomy with parietal resection of papillary muscles and correction of mitral valve insufficiency provides long-term benefits for DG-HCM patients. Multisystem disorders in patients with DG-HCM should be of special attention. Study was supported by research project FURG-2024-0004.