Most patients have little or no disability and a normal life expectancy [3]. Higher rates of morbidity or mortality are linked to the complications of the disorder, sudden cardiac death, progressive heart failure, cardiac dysrhythmia, and stroke due to emboli [3] [5] [7]. The initial presenting sign may be sudden cardiac death, particularly in preadolescents and adolescents [6]. Older individuals may also present with sudden cardiac death but more often they present with symptoms of cardiac dysfunction [3] [5] [8]. The clinical picture of hypertrophic cardiomyopathy varies greatly, from asymptomatic individuals to mildly disabling symptoms such as exercise intolerance and chest pain, to life threatening arrhythmias and heart failure [4][5]. Clinical presentation may even vary within the same family and/or phenotype [3] [5].

Signs and symptoms of hypertrophic cardiomyopathy include the following [1] [2] [3] [4]:

• Sudden cardiac death 
• Dyspnea (the most common presenting symptom)
• Dizziness
• Syncope and pre-syncope
• Angina
• Palpitations
• Orthopnea and paroxysmal nocturnal dyspnea
• Congestive heart failure

Sudden cardiac death generally occurs during exercise, usually in individuals with structural cardiac disease [10] [11]. It also may have a circadian distribution with deaths clustering in the morning and early evening [11] [14]. Dyspnea is the most common presenting symptom, occurring in as many as 90% of symptomatic patients [5] [8].
Angina is rare in children but common in adults [5]. It can occur without detectable coronary atherosclerosis [5] [10]. Increased myocardial oxygen consumption caused by ventricular hypertrophy resulting in endocardial ischemia, especially during exertion [5] [14]. Syncope is very common, resulting from inadequate cardiac output with exertion or from cardiac arrhythmia. It occurs more commonly in children and young adults [5]. It may identify patients at high risk for sudden cardiac death and indicates the need for an urgent workup and aggressive treatment [5] [10] [14]. Orthopnea and paroxysmal nocturnal dyspnea are early signs of congestive heart failure [3] [13].

Complications of hypertrophic cardiomyopathy include [3] [4] [5]:

• Congestive heart failure
• Ventricular and supraventricular arrhythmias
• Mitral valve prolapse and/or regurgitation
• Infective mitral endocarditis
• Atrial fibrillation with thrombus formation
• Sudden cardiac death

Sudden cardiac death is the most devastating consequence of hypertrophic cardiomyopathy [1] [3] [5]. It has the highest incidence in preadolescents and adolescents and is usually related to extreme exertion and ventricular fibrillation [3]. Hypertrophic cardiomyopathy can cause various arrhythmias, including atrial fibrillation, atrial flutter, ventricular ectopy, ventricular tachycardia, and ventricular fibrillation [4] [5]. Uncontrolled hypertension is seen in 37-56% of patients [5]. This comorbidity presents significant diagnostic and therapeutic problems [12]. Control of blood pressure is on of the primary goals of treatment [12].

Echocardiography is the primary means of diagnosing hypertrophic cardiomyopathy and determining optimal treatment and follow-up [2] [13]. Diagnosis is based on the presence of left ventricular hypertrophy [13] [14]. Ventricular wall thickness >/= 15 mm is indicative of the disorder with a wall thickness of more than 30 mm indicating a higher risk of sudden cardiac death [2] [13]. Congestive heart failure is seen in late stage hypertrophic cardiomyopathy [4] [5]. It is indicative of severe myocardial dysfunction and is the cause of disability and decreased quality of life [3].

Differential diagnoses:

• Aortic stenosis
• Restrictive cardiomyopathy, 
• Fabry Disease
• Glycogen storage disease type II
• Pediatric supravalvar aortic stenosis

• Asymptomatic

  HCM has a variable clinical presentation; ranging from asymptomatic to sudden death. The prevalence of HCM in the general population is 0.2% or 1/500, affecting males and females equally. [genedx.com]

  Risk stratification and prevention of sudden death Sudden death is the most common cause of death in HCM and occurs more often in young asymptomatic or only mildly symptomatic patients. [patient.info]

• Congestive Heart Failure

  We emphasize the need to consider hypertrophic cardiomyopathy in evaluating cases of congestive heart failure. [ncbi.nlm.nih.gov]

  We emphasize the need to consider hypertrophic cardiomyopathy in evaluating cases of congestive heart failure. Related Topics Loading Related Articles [doi.org]

  Orthopnea and paroxysmal nocturnal dyspnea are early signs of congestive heart failure. [symptoma.com]

  Congestive Heart Failure This is a common feature of all late stage cardiomyopathies when the muscles of the heart become too weak to pump enough blood to the body for normal function. [childrenscardiomyopathy.org]

• Surgical Procedure

  Surgical Myomectomy - A surgical procedure that removes the thickened area of the heart and relieves the obstruction. Automatic Implantable Cardiac Defibrillators (AICD) - Stops a potentially lethal arrhythmia. [urmc.rochester.edu]

  In this review we discuss the evolution of surgical procedures to relieve obstruction and review modern surgical approaches. [ncbi.nlm.nih.gov]

  Your care may include: Medications Surgical procedures Arrhythmia management Heart failure treatments Learn more about HCM treatment options [ohsu.edu]

  What Surgical Procedures Are Used to Treat Hypertrophic Cardiomyopathy? Surgical procedures used to treat HCM include: Septal myectomy. [webmd.com]

• Dyspnea

  The most common symptoms experienced by patients with HCM are dyspnea with exercise, orthopnea, paroxysmal nocturnal dyspnea, palpitations, episodes of lightheadedness, chest pain, fatigue or swelling of the ankles. [heartdisease.about.com]

  AHCM can occur with varied presentations such as chest pain, palpitations, dyspnea, syncope, atrial fibrillation, myocardial infarction, embolic events, ventricular fibrillation, and congestive heart failure. [ncbi.nlm.nih.gov]

• Exertional Dyspnea

  A 10-month female infant who experienced cough, fever, aggressive exertional dyspnea, and recurrent cyanosis was admitted to our hospital. [ncbi.nlm.nih.gov]

  The subsequent limited cardiac output and secondary increase in pulmonary venous pressure result in exertional dyspnea. [archivesofpathology.org]

  Patients who experience symptoms as a consequence of HCM have a clinical course that evolves along one or more pathways: progressive heart failure with exertional dyspnea; fatigue and chest pain; occasional evolution to end-stage phase; AF; and sudden [anesthesiology.pubs.asahq.org]

• Chest Pain

  Patients with obstructive HCM have a difficult time with activity due to shortness of breath, chest pain or lightheadedness. [urmc.rochester.edu]

  Apical HCM can lead to drug-refractory chest pain. [ncbi.nlm.nih.gov]

  This can cause symptoms of chest pain during exercise and makes the person more prone to life-threatening abnormal heart rhythms such as ventricular tachycardia or ventricular fibrillation. [mottchildren.org]

• Heart Disease

  Her mother and first-born son had died of heart disease at the ages of 65 and 16 years, respectively. Four of her 8 siblings had died suddenly of unknown cause or of heart disease, and 2 others of cerebral infarction by the 7th decade. [ncbi.nlm.nih.gov]

  Heart disease: a textbook of cardiovascular medicine. 5th ed. Philadelphia, PA: WB Saunders; 1997. [bestpractice.bmj.com]

  Hypertrophic cardiomyopathy is any disease of the heart muscle in which the heart loses its ability to pump blood effectively. [beaumont.edu]

• Heart Murmur

  To our knowledge, this is the first case in which heart murmurs associated with a diastolic paradoxical jet flow have been clearly described. [ncbi.nlm.nih.gov]

  These sounds include an abnormal heartbeat or a heart murmur. [medstarwashington.org]

  A heart murmur is a sound made in the heart as blood is flowing through an abnormal valve or abnormal heart muscle. [acsm.org]

• Mitral Valve Prolapse

  Because none of these symptoms is unique to HCM, the condition is often misdiagnosed as exercise-induced asthma, mitral valve prolapse, or anxiety/depression. [columbiasurgery.org]

  Because the symptoms of HCM mimic those in many other conditions, it is often misdiagnosed as exercise-induced asthma, mitral valve prolapse, or anxiety/depression. [columbiacardiology.org]

  Complications of hypertrophic cardiomyopathy include: Congestive heart failure Ventricular and supraventricular arrhythmias Mitral valve prolapse and/or regurgitation Infective mitral endocarditis Atrial fibrillation with thrombus formation Sudden cardiac [symptoma.com]

  Mitral regurgitation is a common finding in patients with HCM and appears on cine MRAs as a signal void in the left atrium during ventricular systole. It may be associated with mitral valve prolapse (see the images below). [emedicine.com]

  1.4:1 Mitral valve prolapse and mitral regurgitation Decreased midaortic flow Partial systolic closure of the aortic valve in midsystole Other imaging modalities that may be useful include the following: Chest radiography Radionuclide imaging Cardiac [emedicine.medscape.com]

• Systolic Murmur

  Outflow tract obstruction may cause a systolic murmur at the left sternal edge, radiating to the aortic and mitral areas. Most patients with left ventricular outflow murmurs also have mitral regurgitation. [patient.info]

  An early peaking, harsh diamond shaped systolic murmur starts at the beginning of systole and ends well before the second heart sound. A fourth heart sound gallop is also present in diastole as you can readily see on the wave form tab. [easyauscultation.com]

  Patients with a left ventricular outflow tract (LVOT) obstruction may have additional signs such as an ejection systolic murmur that is classically louder with the Valsalva manoeuver. [radiopaedia.org]

• Dizziness

  Others may experience shortness of breath, dizziness, palpitations or chest discomfort. Some patients experience problems in the heart’s electrical system resulting in life-threatening heart rhythms (arrhythmias). [spectrumhealth.org]

  HCM symptoms can include: Chest pain Shortness of breath Dizziness Fainting You may be able to manage your symptoms with medication. We also provide the following treatment options for patients with HCM symptoms. [heart.uvahealth.com]

  Illustration depicting the difference between a normal heart and hypertrophic cardiomyopathy Symptoms include shortness of breath, chest discomfort, palpitations, fatigue, dizziness or passing out. [barnesjewish.org]

  The major symptoms are shortness of breath, dizziness or fainting, chest pain, and cardiac arrhythmias. [columbiasurgery.org]

There are no specific laboratory blood tests required for the evaluation of hypertrophic cardiomyopathy [13] [14]. Definitive diagnosis is genetic testing for mutant genes [1] [3]. Genetic testing, though diagnostic for the condition, is currently expensive and may not yet be widely available [1]. It is becoming more accessible and is the only means of identifying the specific phenotype involved [1] [3] which can be helpful in determining optimal treatment regimes and complication prevention strategies.

Two-dimensional (2-D) echocardiography is diagnostic and cost-effective in identifying hypertrophic cardiomyopathy [5] [13]. Identification of left ventricular wall thickening is diagnostic for the condition [13] [14]. An accurate and complete family history is necessary for the diagnosis of genetic cardiomyopathy [1] [5]. The family history should include at least 3 generations including the incidence of heart disease demographics, medical information, age of onset and patterns of inheritance [1].

Other studies that may be useful include the following [3] [4] [5]:

• Chest radiography
• Cardiac magnetic resonance imaging to localize hypertrophy, especially when echocardiography is questionable.
• Radionuclide imaging with thallium or technetium shows myocardial perfusion defects.
• Doppler echocardiography to detect mitral regurgitation.
• Holter monitoring and show various cardiac arrhythmias.
• Cardiac catheterization is not required for the diagnosis, but may be useful to assess outflow obstruction, cardiac hemodynamics, and left ventricular and coronary anatomy. It is also when invasive therapy is suggested.
• Exercise echocardiography to assess left ventricular function, exercise tolerance, and left ventricular outflow tract gradients during exercise [13] [14]. This may help to determine the risk of complications in patients with hypertrophic cardiomyopathy [13] [14]. A patient’s function during exercise echocardiography may have a role in risk assessment for patients [14]. 
• Tissue Doppler imaging can differentiate hypertrophic cardiomyopathy from other causes of left ventricular hypertrophy [13]. 
• Electrophysiology study using electrical stimulation to identify conduction abnormalities [13].

• Left Axis Deviation

  ECG: Findings also may include right or left axis deviation, conduction abnormalities, sinus bradycardia with ectopic atrial rhythm and atrial enlargement. Voltage criteria for LVH alone are nonspecific and are often seen in normal young adults. [patient.info]

  Electrocardiography demonstrated sinus rhythm; left axis deviation; right atrial enlargement; right bundle branch block; T-wave inversions on leads I, aVL, and V1-V6; and positive R wave on lead aVR (Fig. 1B). [ekjm.org]

  The electrocardiogram is abnormal in over 95% of cases; the most common abnormalities include high precordial QRS voltages, secondary repolarization abnormalities (ST segment depression, T wave inversion), left axis deviation, and deep, narrow so-called [radiopaedia.org]

• Lateral Q Wave

  These may mimic prior myocardial infarction, although the Q-wave morphology is different: infarction Q waves are typically > 40 ms duration while septal Q waves in HCM are < 40 ms. Lateral Q waves are more common than inferior Q waves in HCM. [lifeinthefastlane.com]

• Inferior Q Wave

  These may mimic prior myocardial infarction, although the Q-wave morphology is different: infarction Q waves are typically > 40 ms duration while septal Q waves in HCM are < 40 ms. Lateral Q waves are more common than inferior Q waves in HCM. [lifeinthefastlane.com]

• Short PR Interval

  >0.44 s in men and >0.46 in women Premature ventricular beats or more severe ventricular arrhythmia Supraventricular tachycardia, atrial flutter, or atrial fibrillation Ventricular preexcitation: short PR interval ( First-degree (PR ≥0.21 s, not shortening [doi.org]

• ST Elevation

  In this report, we aimed to present a patient referred to our clinic with complaints of chest pain and electrocardiography findings who had been misdiagnosed as non-ST elevation acute coronary syndrome. [kosuyoluheartjournal.com]

• T Wave Inversion

  His electrocardiogram exhibited a biphasic T wave in lead V2 with ST depressions in leads V3-V6 with deep symmetrical T-wave inversions in these leads as well. His troponin was negative and the patient was taken for cardiac catheterization. [ncbi.nlm.nih.gov]

  The classic ECG finding in apical HCM is giant T-wave inversion in the precordial leads. [lifeinthefastlane.com]

  Investigations Electrocardiogram (ECG): most patients have an abnormal ECG, although electrocardiographic features are nonspecific and include LVH, ST segment changes and T-wave inversion. [patient.info]

• Left Ventricular Hypertrophy

  Left ventricular hypertrophy is rare in children with TNNT2 mutations. Left ventricular hypertrophy is absent in the minority of adults, but most have an abnormal ECG. [ncbi.nlm.nih.gov]

  Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disorder characterized by unexplained left ventricular hypertrophy (increased heart muscle thickness), myocyte disarray (disorganized cardiac cells) and fibrosis. [brighamandwomens.org]

  Left ventricular diastolic dysfunction may lead to compensatory left atrial hypertrophy, with signs of left atrial enlargement (“ P mitrale “) on the ECG. [lifeinthefastlane.com]

Early identification and appropriate treatment of individuals with hypertrophic cardiomyopathy is imperative [4]. The management of patients with hypertrophic cardiomyopathy has change over the past 20 years, particularly with the development of implantable cardiac defibrillators (ICDs) and alcohol septal ablation [7]. To improve quality of life current recommendations for the treatment suggest a step-wise incremental approach [7]. This means the use of therapies to maintain control and prevent complications with the least amount of medication and/or least invasive surgical intervention in order to minimize the risk for adverse effects [5] [7].

The aim of treatment is to decrease the occurrence and risk of sudden cardiac death, alleviate out-flow obstruction, control hypertension, and prevent congestive heart failure and cardiac disability [5] [7]. Of greatest importance to any therapy is early identification of patients and immediate institution of effective medical and/or surgical intervention [4].
The staged approach may include [5] [7]:

• Pharmacotherapy including antihypertensive medications (beta blockers, calcium channel blockers), and anti-arrhythmia drugs
• Minimally-invasive surgical procedures (pacemaker implantation)
• Invasive surgery (mitral valve replacement, left ventricular myomectomy)

Medication

The purpose of medication therapy is to reduce the pressure gradient across the left ventricular outflow tract or reduce the occurrence of arrhythmias [3]. Medications commonly used in the treatment of hypertrophic cardiomyopathy include [3] [4] [5]:

• Beta-adrenergic blocking agents decrease heart rate lowering myocardial oxygen consumption and reduce the myocardial ischemia. Metoprolol (Lopressor, Toprol XL) is the drug of choice in the treatment of obstructive and non-obstructive hypertrophic cardiomyopathy. Most frequently used drug is Verapamil (Calan, Isoptin, Verelan).
• Calcium channel blockers are alternatives to beta blockers. They decrease the gradient across the left ventricular outflow tract. These agents are more effective in improving exercise performance. 
• Antiarrhythmic medications alter the electro-conductive mechanisms that cause arrhythmias. Sotalol (Betapace, Sorine) is a class III antiarrhythmic blocks K+ channels, and lengthens the QT interval. may be helpful in converting atrial fibrillation. Currently, the only drug shown to reduce the incidence of arrhythmogenic sudden cardiac death is amiodarone (Cordarone).
• Anticoagulants, such as Warfarin (Coumadin, and Jantoven), are used to prevent thromboembolic complications of hypertrophic cardiomyopathy.

Two thirds of patients with outflow obstruction who are symptomatic can be managed long term with medical treatment alone [3].

Surgery

• Pacemaker Implantation: Permanent pacing for conduction blocks is recommend in patients with significant resting or provoked left ventricular outflow obstruction and some cardiac arrhythmias [3] [4]. This treatment does not necessarily reduce the risk of ventricular arrhythmias and sudden death [3] [6]. It should be used as adjunctive therapy along with antihypertensive and antiarrhythmic medications [3].
• Surgical septal myectomy: Research indicates that myectomy should be the primary treatment for severely symptomatic young patients with obstructive hypertrophic cardiomyopathy who do not respond to drug therapy [7] [13]. Research has shown that approximately 22% of patients with left ventricular outflow obstruction will require septal reduction therapy [12]. Those undergoing any of the procedures have significant improvement in function [12].
• Catheter septal ablation using ethanol infusion destroys myocardium of the left anterior descending artery inducing a therapeutic infarction of the interventricular septum [3] [13]. This decreases the septal thickening and reduces the left ventricular outflow obstruction [13] [14]. It acts in the same way as a surgical myomectomy, but is less invasive [3] [7]. For patients over 40 years of age and not eligible for surgery because of comorbidities, alcohol septal ablation is preferred therapy to reduce obstruction and symptoms [13]. In many centers, this is the preferred procedure for hypertrophic cardiomyopathy [7].
• Radiofrequency catheter ablation of AV node can treat atrial fibrillation in some cases [7]. 
• Implantable cardioverter defibrillator (ICD) is used to prevent sudden cardiac death due to arrhythmia [3] [6] [12]. This device automatically detects and treats arrhythmias using bradycardia or tachycardia pacing, low-energy cardioversion, or high-energy shock defibrillation [6] [7]. It has been life-saving and has been shown superior to antiarrhythmic drug therapy [6]. 
• Mitral valve replacement is used only for patients with severe mitral regurgitation leading to congestive heart failure or severe pulmonary hypertension [7].

Follow-up

Activity restrictions may include total abstinence from competitive athletic activities and strenuous physical exertion, such as heavy lifting, lifting weights, and snow shoveling [2] [5] [7]. These restrictions should apply if [5] [6]:

• Significant outflow gradient
• Significant ventricular or supraventricular arrhythmia
• Marked left ventricular hypertrophy
• History of sudden death in relatives with hypertrophic cardiomyopathy
• Identified malignant genotype
• Young age (< 30 years)
• Abnormal blood pressure response to exercise
• History of syncope, particularly in children

Consultations indicated in hypertrophic cardiomyopathy [5]:

• Cardiologist 
• Cardiothoracic surgeon 
• Geneticist

Patient and family education:

• Family members should learn cardiopulmonary resuscitation [6]. 
• Patient and family should be referred for psychosocial counseling. 
• Any blood relative of an individual with known hypertrophic cardiomyopathy should have an urgent echocardiography and genetic testing [1] [2] [13]. 

The overall survival of patients with hypertrophic cardiomyopathy is similar to that of the general population [3] [7]. Most patients are asymptomatic. In many the first indication of the disease may be sudden cardiac death, usually from ventricular tachycardia or fibrillation [4] [5]. Death from hypertrophic cardiomyopathy is often sudden, unexpected, and usually associated with sports or vigorous exertion [3].

Patients who present at a younger age, particularly infants and young children, have a much higher mortality rate and a much greater degree of ventricular hypertrophy [5]. They are symptomatic earlier in the disease course, most likely because they have more malignant genotype [4] [5]. Early diagnosis is needed in order to initiate treatment before the advent of sudden cardiac death or progressive cardiac dysfunction and disability [4] [5]. A diagnosis of hypertrophic cardiomyopathy is not always ominous and is compatible with normal lifespan [3].

Hypertrophic cardiomyopathy (HCM) is a genetic disorder inherited as autosomal dominant pattern or sporadic [1] [3]. The estimate of the prevalence of the disorder varies between sources with some reporting it to be rare and others as a common disease [8] [9] [10]. Studies of outpatients referred for echocardiographic evaluation report that hypertrophic cardiomyopathy is an uncommon disease occurring in only 0.5% of this population [10]. Other sources reporting the same numbers consider the incidence to be a common occurrence [8] [9]. Prevalence in the general population is not known [9] [10].

Familial hypertrophic cardiomyopathy is a heterogeneous genetic disease as the genetic defects can occur at more than one location [1] [2]. The presence of the gene mutation in one parent results in a 1:2 chance of each child inheriting the gene and therefore the disease. If both parents have the mutation their children have a 3:4 chance of having the disorder [1]. A minority of cases may be caused by spontaneous mutations [1] [2]. The genetic error has been found to be a mutation on one of a variety of genes responsible for producing sarcomeric proteins [2] [5]. Alterations in these proteins result in abnormalities in cardiac development and cardiomyopathy [2] [3] [4].

Hypertrophic cardiomyopathy is typically diagnosed when patients present with unexplained left ventricular hypertrophy [5] or with sudden cardiac death [4]. Further characteristics of hypertrophic cardiomyopathy include outflow tract obstruction, diastolic dysfunction, arrhythmias, stroke, infective endocarditis and sudden cardiac death [2] [4]. Detection of patients at high risk of sudden cardiac death is difficult [7].

Hypertrophic cardiomyopathy can be classified as obstructive or non-obstructive types [2] [5]. The obstructive form is due to obstruction of the left ventricular outflow tract. Hypertrophy occurs in left ventricle usually the interventricular septum. This results in an obstruction to the outflow of blood from the left ventricle [2]. The non-obstructive form of the disorder may show defects in the atrioventricular (AV) node or sinoatrial (SA) node and result in cardiac arrhythmias [2]. Hypertrophic cardiomyopathy is the leading cause of sudden cardiac death in preadolescent and adolescent children [3] [14]. These events are generally due to a cardiac arrhythmia, usually ventricular fibrillation [6].

Symptoms of hypertrophic cardiomyopathy include [3] [4] [5] [6]:

• Sudden cardiac death
• Syncope and pre-syncope
• Dizziness
• Angina
• Palpitations
• Dyspnea
• Orthopnea
• Paroxysmal nocturnal dyspnea
• Congestive heart failure

Some individuals are asymptomatic and go undiagnosed throughout their lives [5]. Treatment for the disorder is aimed at controlling and minimizing the cardiac complications of the abnormalities of the heart. Antihypertensive and anti-arrhythmia medications are useful in decreasing ventricular outflow issues and cardiac arrhythmias [5] [7] [12]. Surgical interventions, SA node obliteration, intercardiac pacing, or implantable cardioverter defibrillator, can be helpful in correcting arrhythmias and preventing sudden cardiac death [4] [6] [7].

Hypertrophic cardiomyopathy is an uncommon condition with prevalence of only 0.05-0.2% of the outpatient population referred for echocardiography [4] [10]. Incidence in the general population is unknown [9]. Evidence of the disease found by echocardiography occurs in approximately 25% of first-degree relatives of patients with hypertrophic cardiomyopathy [1] [10] [13].

The genetic inheritance pattern of hypertrophic cardiomyopathy is autosomal dominant so no sex predilection should occur [1] [9]. However, it is slightly more common in males than in females [9]. This may be due to other confounding factors. Hypertrophic cardiomyopathy usually presents at a younger age in females and they tend to be more symptomatic and more likely to be disabled by their symptoms than males [9].

In general, hypertrophic cardiomyopathy has occurrence peaks in two age groups with highest incidence in the second and third decade of life [9]. However, hypertrophic cardiomyopathy can present at any age [5] [9]. Reported annual mortality rates in patients with hypertrophic cardiomyopathy are 1% to 3-6%, and have significantly improved over the past 40 years [3]. The risk of sudden death in children is as high as 6% per year [3].

Hypertrophic cardiomyopathy is a genetic disease [1] that is due to defects in one or more of the genes encoding for the sarcomeric proteins, such as myosin heavy chain, actin, tropomyosin, and titin [2] [3] [8]. The risk for mortality and degree of cardiac hypertrophy vary with the specific genotype [3]. Alterations in sarcomeric proteins cause changes in to cardiac musculature. Abnormal calcium kinetics and abnormal calcium fluxes result in an increase in intracellular calcium concentration, which may produce hypertrophy and cellular disarray [2]. Myocardial hypertrophy and disorganization of the muscle fibers result in the abnormal myofibrillar architecture [2] [3]. This may also cause in abnormal coronary arteries with reduction in the size of the lumen and thickening of the vessel walls [2]. Muscle fiber abnormality in hypertrophic cardiomyopathy most often occurs in the ventricular septum and causes extensive fibrosis of the walls of the heart [2] [3]. This occurs in more than 80% of cases [2]. As a result of these abnormalities in cardiac musculature the following findings may occur [2] [3]:

• Abnormal systolic motion of the mitral valve
• Left ventricular hypertrophy
• Left atrial enlargement
• Small ventricular chamber size
• Septal hypertrophy
• Mitral valve prolapse and mitral regurgitation
• Decreased mid-aortic flow
• Partial systolic closure of the aortic valve in midsystole

A narrowing of the left ventricular outflow tract occurs in many patients with hypertrophic cardiomyopathy [2] [3] [5]. The narrowing is caused by the asymmetry and hypertrophy of the septum and possibly by an abnormal location of the mitral valve [5]. Cardiac arrhythmias are common due to fibrosis of the septum. The septum may be at least 4-6 mm thicker than normal for each age group and thicker than the posterior wall [2] [3]. In more than 80% of cases of sudden cardiac death the cause is ventricular fibrillation [5] [8].
Common electrocardiographic findings include ST-T wave abnormalities and left ventricular hypertrophy, axis deviation (right or left), conduction abnormalities (P-R prolongation, bundle-branch block), sinus bradycardia with ectopic atrial rhythm, and atrial enlargement [13] [14].

Genetic testing can and screening of first-degree relatives can be used to identify asymptomatic family members of the index case [1] [2]. Electrocardiography following this determination may help to reduce sudden cardiac death and complications in these individuals [13] [14]. Patients must abstain from strenuous and competitive athletic activity and physical exertion [10] [11]. However, since many individuals are asymptomatic and undiagnosed this is not an efficient preventive measure for sudden cardiac death [11].
Cardiovascular screening before competitive sports participation has been reported to reduce the frequency of unexpected sudden death from hypertrophic cardiomyopathy [1] [9]. But large-scale screening of athletes may not be feasible or cost-effective [1] [11]. Screening individuals before participation in exercise may reduce exercise associate symptoms [1] [9] [11]. High-risk patients should be excluded from certain activities and possible prodromal symptoms should be evaluated immediately. All fitness personnel should be trained for emergencies [11]. Early identification of at risk individuals is imperative to prevent complications such as ventricular obstruction, cardiac dysfunction, arrhythmias, stroke, infective endocarditis and sudden cardiac death [5].

Hypertrophic cardiomyopathy (HCM) is a genetic disorder [1] [2] [3]. It is characterized by myocardial hypertrophy resulting in cardiac dysfunction occurring in without an obvious precipitating cause [2] [3] [4]. Its symptomatology and presentation varies widely and may often be asymptomatic [5] [4]. It is the leading cause of sudden cardiac death, particularly among children and adolescents (especially young athletes) [1] [3] [6]. This is the most distinctive presentation of the disorder.

Hypertrophic cardiomyopathy is a progressive disease that worsens with age if left untreated [3]. Congestive heart failure may occur in the late stages of the disorder [2]. Management is aimed at controlling the underlying cardiac conditions with medication and/or surgical intervention [5] [7]. Although the condition cannot be prevented, early identification and treatment of individuals at risk can prevent the complications of the condition [4] [5]. Since this is a familial genetic disease, screening of close blood relatives of affected patients is the beat means of doing this [1]. Cardiac evaluation of athletes before they participate in strenuous physical activity and sports is recommended but may not be financially feasible [1] [4].

What is hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy is a rare genetic disorder that affects the production of sarcomeric proteins important in the normal development of heart musculature. Its incidence in the general population is unknown because many with the defective gene are asymptomatic. The occurrence in patients seen in out-patient cardiac care is only 0.2 to 0.5%.
This disorder is the primary cause of sudden cardiac deaths, especially in children, adolescents, and young athletes. Long-term effects of the abnormal heart development include progressive heart failure and abnormal cardiac rhythm.

What are the symptoms of hypertrophic cardiomyopathy?

Symptoms of hypertrophic cardiomyopathy include:

• Sudden cardiac death
• Shortness of breath especially with exertion
• Fainting and near-fainting
• Dizziness
• Angina (chest pain)
• Palpitations
• Decreased blood pressure with standing
• Congestive heart failure

What causes hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy is a genetic disorder inherited from one or both parents and results in abnormal musculature of the heart. There are no known predisposing factors for the gene mutations.

How is it diagnosed?

Hypertrophic cardiomyopathy is suspected when the patient presents with one or more of the clinical symptoms of the disorder, especially sudden cardiac death in young children and adolescents. Clinical diagnosis can be made using a two-dimensional electrocardiograph. Definitive diagnosis is made by genetic analysis for the presence of the gene mutation.

What are the complications?

• Congestive heart failure
• Cardiac arrhythmias
• Mitral valve abnormalities (prolapse and/or regurgitation) causing decreased heart function
• Endocarditis
• Formation of blood clots and emboli
• Sudden cardiac death

How is it treated?

Hypertrophic cardiomyopathy is treated by controlling and preventing the complications of the disorder. Medications are used to control high blood pressure and heart arrhythmias which interfere with cardiac function. Ventricular fibrillation, a dysrhythmia that is not conducive with life, is the primary cause of sudden cardiac death. It can be treated with anti-arrhythmia medications, but the implantation of an implantable cardioverter defibrillator (ICD) is the most effective treatment. Other surgical procedures such as mitral valve replacement, therapeutic obliteration of faulty conduction pathways, and repair of obstructions to blood flow through the heart may be necessary in patients with severe cardiac disease.

How can hypertrophic cardiomyopathy be prevented?

There are currently no known means of preventing the inheritance of the hypertrophic cardiomyopathy gene abnormality. Early identification and treatment of the disorder help to prevent and/or limit the complications of the disease. Individuals known to have hypertrophic cardiomyopathy should not participate in strenuous sports and physical activity.
Screening and evaluation with electrocardiography of athletes may be helpful in preventing sudden cardiac death associated with sports. Evaluation and genetic testing of blood relatives of any one diagnosed with the abnormality is recommended.

1. Colombo MG, Botto N, Vittorini S, Paradossi U, Andreassi MG. Clinical utility of genetic tests for inherited hypertrophic and dilated cardiomyopathies. Cardiovasc Ultrasound. 2008;6:62-72.
2. Morimoto S. Sarcomeric proteins and inherited cardiomyopathies. Cardiovasc Res. 2008;77(4):659-66. 
3. Maron BJ. Hypertrophic cardiomyopathy: a systematic review. JAMA. 2002;287(10):1308-20. 
4. Soor GS, Luk A, Ahn E, Abraham JR, Woo A, Ralph-Edwards A, Butany J. Hypertrophic cardiomyopathy: current understanding and treatment objectives. J Clin Pathol. 2009;62(3):226-35. 
5. Soor GS, Luk A, Ahn E, Abraham JR, Woo A, Ralph-Edwards A, Butany J. Hypertrophic cardiomyopathy: current understanding and treatment objectives. J Clin Pathol. 2009;62(3):226-35. 
6. You JJ, Woo A, Ko DT, Cameron DA, Mihailovic A, Krahn M. Life expectancy gains and cost-effectiveness of implantable cardioverter/defibrillators for the primary prevention of sudden cardiac death in patients with hypertrophic cardiomyopathy. Am Heart J. 2007;154(5):899-907. 
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