What is HCM?

HCM is an autosomal dominant inherited disease, meaning that if just one parent carries the pathogenic gene, each child has a 50% chance of inheriting the condition. While many patients have a family history of HCM, some cases result from spontaneous genetic mutations.

HCM can occur at any age, affecting infants, adolescents, and the elderly. Since some individuals exhibit no obvious symptoms, the condition is often discovered incidentally during routine check-ups or family screenings.

HCM is generally classified into two main types, based on whether the hypertrophy causes obstruction of blood flow:

Obstructive HCM (oHCM): The most common type, accounting for approximately 60–70% of all HCM cases. Abnormal thickening of the interventricular septum can obstruct the left ventricular outflow tract (LVOT) during contraction, making it difficult for blood to flow into the aorta. Symptoms may include chest tightness, shortness of breath, fainting, and, in severe cases, sudden cardiac death.

Non-obstructive HCM: Representing around 30–40% of cases, this type does not involve significant LVOT obstruction. However, the thickened myocardium can still impair diastolic function, leading to reduced exercise tolerance, arrhythmias, or heart failure. In some patients, the hypertrophy is localized to the apex of the heart, the mid-ventricular region, or presents in a diffuse pattern, which may be difficult to detect through routine auscultation.

Additionally, there are special forms of HCM that involve myocardial fibrosis, restrictive physiology, or myocardial bridging. These variants are more complex and typically require advanced imaging modalities such as cardiac MRI for accurate diagnosis and evaluation.

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Hypertrophic Cardiomyopathy