The clinical use of the MOGE(S) classification in the differential diagnosis between idiopathic hypertrophic cardiomyopathy and its phenocopies

Abstract

Aim . To determine the relation between idiopathic hypertrophic cardiomyopathy (HCM) and HCM phenocopies, as well as to study the etiological pattern of HCM phenocopies in patients of the North-Western region of Russia in different age groups. Material and methods . The study included 321 patients with left ventricular hypertrophy ≥15 mm according to an echocardiography. All the necessary clinical, laboratory and instrumental diagnostic methods for verification of HCM and HCM phenocopies was carried out. In the diagnosis, the MOGE(S) classification was used. Results . At a young age, idiopathic HCM accounts for 92% (n=62), HCM phenocopies — 8% (Danon disease (n=1 (2%)), isolated cardiac sarcoidosis (n=1 (2%)) and systemic AL amyloidosis (n=3(4%)). Idiopathic HCM is also found in the vast majority of middle-aged patients — in 85% of cases (n=86). HCM phenocopies (15%) were in isolated cardiac sarcoidosis (n=3 (3%)), systemic amyloidosis variants (n=12 (12%)) — AL amyloidosis with predominant cardiac injury (n=11,11%), hereditary transthyretin amyloidosis (n=1,1%). Of the 153 examined patients with HCM aged ≥60 years old, 85% (n=131) were diagnosed with idiopathic HCM. HCM phenocopies were detected in 15% of cases (n=22). In the etiological pattern of HCM phenocopies, transthyretin amyloidosis was 10%: non-hereditary transthyretin amyloidosis — 6% (n = 9), hereditary transthyretin amyloidosis — 4% (n=6); AL amyloidosis — 4% (n=6). In 1 patient, acromegalic cardiomyopathy (1%) was verified. In this article, we present 3 clinical cases that demonstrate the difficulty of differential diagnosis between idiopathic HCM and various HCM phenocopies. Conclusion . In all age groups, idiopathic HCM predominates. Lysosomal storage diseases classify as rare diseases. Isolated cardiac injury with amyloidosis and sarcoidosis is widely met but less often diagnosed. We determined a high frequency of isolated cardiac injury with amyloidosis under the age of 45 years. The etiological pattern of HCM phenocopies in the elderly is represented mainly by transthyretin cardiomyopathic amyloidosis of hereditary and non-hereditary variants.