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Cardiomyopathy
GMJ News knowledge hub · last reviewed August 2026 · Georgian Medical Journal
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Cardiomyopathy — primary structural and functional disease of the heart muscle not explained by coronary artery disease, hypertension or valvular disease — encompasses three clinically distinct entities: hypertrophic cardiomyopathy (HCM, the most common inherited cardiac condition at 1 in 500), dilated cardiomyopathy (DCM, the most common cause of heart transplantation in adults) and arrhythmogenic right ventricular cardiomyopathy (ARVC, a major cause of sudden cardiac death in young athletes) — collectively responsible for a disproportionate share of sudden cardiac death in people under 35 and the most common non-ischaemic indication for implantable cardioverter-defibrillator (ICD) and cardiac transplantation (WHO). Mavacamten (Camzyos) — FDA approved April 2022 — is the first cardiac myosin inhibitor and the first disease-modifying therapy specifically for obstructive HCM, reducing the pathological LVOT gradient by targeting the root cause (excess actin-myosin crossbridging) rather than managing symptoms downstream.
Key messages
HCM — 1 in 500 — most common inherited cardiac condition
Hypertrophic cardiomyopathy (HCM) affects approximately 1 in 500 people — the most prevalent inherited cardiac condition. MYBPC3 and MYH7 sarcomere gene mutations account for approximately 75% of genotype-positive cases. HCM is the most common cause of sudden cardiac death in competitive athletes under 35 in the USA.
Mavacamten (Camzyos) — first disease-modifying HCM drug (FDA 2022)
Mavacamten — a cardiac myosin inhibitor FDA-approved April 2022 — reduces the excessive actin-myosin crossbridging that causes left ventricular outflow tract (LVOT) obstruction in obstructive HCM (oHCM). EXPLORER-HCM Phase 3: 37% achieved primary endpoint vs 17% placebo. First drug that targets the root pathophysiology rather than managing symptoms downstream.
LVOT obstruction and the SAM-septal contact
In approximately 70% of HCM patients, hypertrophied septum + systolic anterior motion (SAM) of the mitral valve → LVOT obstruction → dynamic outflow gradient. Gradient worsens with: dehydration; vasodilators; Valsalva; standing (reduces preload). Classic auscultation: ejection systolic murmur that increases on standing and with Valsalva — the opposite of AS.
DCM — most common cause of cardiac transplantation
Dilated cardiomyopathy (DCM): dilated, poorly contracting LV (EF <50%) without coronary artery disease. Causes: genetic (TTN titin mutations — most common; LMNA — high arrhythmia/SCD risk); alcohol; viral myocarditis; peripartum; chemotherapy (anthracyclines); thyroid disease; idiopathic. Treatment: optimised GDMT (ACEI/ARNI + beta-blocker + MRA + SGLT-2i); CRT for LBBB; ICD; transplantation.
ARVC — exercise makes it worse
Arrhythmogenic right ventricular cardiomyopathy (ARVC): fibro-fatty replacement of the right ventricular free wall; desmosomal gene mutations (PKP2 most common). Epsilon wave on ECG; T-wave inversions V1-V4; late gadolinium enhancement on CMR. Crucially: exercise accelerates disease progression and arrhythmia risk. Strict restriction from competitive and strenuous sport is mandatory.
ICD vs sudden death — high-risk features in HCM
High-risk features for SCD in HCM requiring ICD consideration: prior cardiac arrest or sustained VT; massive LVH (wall thickness ≥30mm); family history of SCD; unexplained syncope; LV apical aneurysm; extensive late gadolinium enhancement (LGE >15% of LV mass); abnormal blood pressure response to exercise; non-sustained VT on Holter. HCM Risk-SCD calculator (ESC) estimates 5-year SCD risk.
Key statistics
MYBPC3 ~40%
most common HCM-causing gene mutation; MYH7 ~35%; together ~75% of genotype-positive
Nature Reviews CardiologyGDMT + ICD
cornerstone of DCM management; TTN and LMNA mutations require early ICD consideration
ESC Heart Failure GuidelinesCardiomyopathy types — relative prevalence and clinical outcomes
Source: ESC/ACC. HCM most common; DCM leads to most transplants; ARVC highest SCD risk in athletes.
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Cardiovascular diseaseHeart failure (DCM outcome)Atrial fibrillation (HCM complication)Myocarditis (DCM trigger)Cardiac amyloidosis (restrictive)Exercise and heart (ARVC risk)
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