Hypertrophic cardiomyopathy is caused by an abnormality of heart muscle, usually caused by a genetic mutation of a sarcomeric protein, that results in disrupted myocardial alignment known as myocardial disarray. The result is regional hypertrophy with variable involvement of myocardium. Hypertrophy of the basal septum, adjacent to the left ventricular outflow tract (LVOT), may result in outflow obstruction.
Presenting symptoms are variable, and many patients remain asymptomatic for decades. When symptoms develop, they are often associated with LVOT obstruction and may include dyspnea, palpitations, syncope, or sudden cardiac death. HCM can be diagnosed at any stage of life. It is the most common cause of sudden cardiac death in young athletes.
I42.2 – Other hypertrophic cardiomyopathy
233873004 – Hypertrophic Cardiomyopathy
- Aortic stenosis – The murmur does not change with position or Valsalva; usually seen after age 50.
- Hypertensive heart disease – No murmur is noted; not usually seen in young adults; wall thickness on echocardiography is usually less than 15 mm.
- Mitral regurgitation – High-pitched holosystolic murmur best heard at the apex.
- Ventricular septal defect – Holosystolic murmur radiating all over precordium. History of congenital heart disease or myocardial infarction may be present.
- Subaortic membrane – No change in murmur with physiological maneuvers.
- Supravalvular aortic stenosis – No change in systolic murmur with physiological maneuvers; associated with Williams syndrome.
- Aortic coarctation – Higher blood pressure in upper extremities; radio-femoral delay; systolic murmur or continuous murmur may be heard.
- Cardiac amyloidosis – Low voltage on ECG; restrictive physiology is noted on echocardiography.