Published on May 23rd, 2014
Relief for Patients with Hypertrophic Cardiomyopathy
Identification of patients with hypertrophic cardiomyopathy (HCM) can be difficult when the patient presents with little to no symptoms. We often encounter individuals who can easily be misdiagnosed or their symptoms overlooked by their physicians or themselves.
HCM is a genetic disorder that causes otherwise unexplained thickening of the heart muscle. Such patients have abnormally enlarged heart muscle cells, arranged in a disorganized pattern with fibrosis/scarring between the cells. Unlike hypertension and aortic valve stenosis, the increased left ventricular wall thickness is often heterogeneous. When the basal portion of the ventricular septum is disproportionately thickened, obstruction to ejection of blood through the outflow tract would produce a murmur, cause mitral valve regurgitation by pulling the anterior leaflet towards the septum and predispose the patient to symptoms of heart failure, syncope or chest pain.
HCM affects approximately 1 in 500 patients in the community. Some of these patients are at particularly high risk of sudden death or heart failure while others would suffer from one or more of the following:
- Exertional dyspnea (shortness of breath with activity)
- Orthopnea (shortness of breath lying down)
- Paroxysmal nocturnal dyspnea (shortness of breath during sleep)
- Angina (chest pain) – caused or worsened by exertion
- Lightheadedness (particularly on sitting or standing up)
- Syncope (fainting)
- Fatigue or lack of energy
- Edema (swelling in the legs and feet)
Patients with no or only minor symptoms generally have a better prognosis than those with more severe symptoms. However the severity of symptoms does not necessarily correlate with the extent of cardiac involvement or the risk of sudden death.
HCM is an inherited as an autosomal dominant trait. Symptoms may first appear during infancy or childhood, although they begin more commonly during the growth spurt of puberty, when left ventricular hypertrophy is accentuated. In a smaller percentage of cases, symptoms may not occur until later in life. If symptoms develop, they may vary in severity from one day to another.
Hypertrophic Cardiomyopathy: Diagnosis
Conventional testing for HCM includes electrocardiogram (ECG) and echocardiogram if the patient has a family history of the disease, has a heart murmur, or has symptoms suggestive of the condition. Further testing may be, however, needed to evaluate chest pain (exercise testing), palpitation (ambulatory ECG monitoring), and extent of myocardial fibrosis (cardiovascular magnetic resonance) or coronary artery disease (cardiac catheterization). First degree relatives of patients with HCM also require screening evaluation.
Patients with HCM can develop the following complications:
- Heart failure
- Heart block
- Infective endocarditis
- Increased risk of death due to sudden cardiac death, heart failure, or stroke
Hypertrophic Cardiomyopathy: Treatment
There is no cure for hypertrophic cardiomyopathy. However, several treatments are available to relieve the symptoms and decrease the risks associated with HCM.
Treatment may be aimed at prevention of sudden cardiac death, relief of left ventricular outflow tract obstruction, or alleviation of symptoms:
- Prevention of sudden cardiac death
- Implantable cardioverter-defibrillator (ICD)
- Relief of left ventricular outflow tract obstruction
- Medical therapy
- Calcium channel blockers
- Dual-chamber pacing with short atrioventricular delay
- Catheter-based therapy
- Alcohol septal ablation
- Surgical intervention
- Septal myectomy
- Mitral valve replacement
- Medical therapy
- Alleviation of symptoms
- Antiarrhythmic therapy
- Septal reduction procedures
- Electrophysiology procedures
- Chest pain
- Medical therapy
- Coronary artery angioplasty
- Heart failure
- Medical therapy
- Resynchronization therapy
- Ventricular assist devices
- Cardiac transplantation
The optimal treatment depends upon the individual situation. Many individuals are at low risk of sudden death and are asymptomatic and, thus, may not need any treatment during the early evaluation period.
Avoidance of dehydration – People with hypertrophic cardiomyopathy should try to maintain a steady fluid balance and avoid situations in which fluid is lost from the body and not adequately replaced (outdoor activity on a hot day, having fever, diarrhea or vomiting).
Activity restriction – Anyone with hypertrophic cardiomyopathy should talk to his/her healthcare provider about the safety of exercise. Most people with HCM are advised to avoid playing competitive sports, with the possible exception of some low-intensity sports (e.g., golf, billiards). Certain recreational sports are also not advised. These recommendations generally apply to all people with HCM.
Shortness of breath and chest pain – One or more medications may be used to treat the symptoms of shortness of breath and/or chest pain. Options include a beta blocker, a calcium channel blocker (verapamil or diltiazem), and/or disopyramide. These medications work to decrease the heart’s need for oxygen, improve the heart’s ability to fill with blood, improve blood flow to the heart, and decrease the obstruction of blood flow out of the heart.
If these treatments do not adequately relieve symptoms and there is significant obstruction to the flow of blood out of the left ventricle (left ventricular outflow tract obstruction), a procedure to reduce the obstruction may be recommended.
Arrhythmias – People with hypertrophic cardiomyopathy are at risk for irregular heart rhythms (arrhythmias). Although most arrhythmias do not cause symptoms, some can have serious consequences or even lead to sudden cardiac death. Therefore, testing for arrhythmias is important.
Procedures to relieve left ventricular outflow tract obstruction – Patients with hypertrophic cardiomyopathy who are severely symptomatic and who do not improve with medications may be advised to consider septal ablation or surgical treatment, such as myectomy.
Septal myectomy – Septal myectomy is the surgical removal of excess muscle from the thickened ventricular septum, the muscular wall between the left and right ventricles. The surgery is performed by opening the chest, placing the person on cardiopulmonary bypass (a heart lung machine), and removing excess tissue in the region of obstruction. Myectomy eliminates or improves symptoms in over 90 percent of patients with very low operative risk.
Nonsurgical septal reduction therapy – Ethanol ablation of the septum, also known as nonsurgical septal reduction therapy (NSRT), or transcoronary ablation of septal hypertrophy (TASH) involves injecting ethanol (alcohol) into the blood vessel supplying the upper part of the thickened septum. In this procedure, a cardiologist inserts an angioplasty catheter into an artery in the groin and threads it up to the base of the aorta. The catheter is passed into the left coronary artery to the branch that supplies the upper part of the septum. A small amount of ethanol is injected into this arterial branch. The ethanol causes a “controlled small heart attack”, resulting in death of muscle tissue supplied by the arterial branch. Over time, this damage will result in the upper part of the septum becoming thinner, reducing obstruction of blood flow from the left ventricle (left ventricular outflow obstruction). The procedure is successful in reducing obstruction of blood flow in 80 percent of cases.
Hypertrophic Cardiomyopathy: Prognosis
The long-term outcome for people with hypertrophic cardiomyopathy is generally good, especially in those diagnosed later in life. In symptomatic HCM, medical, device and surgical therapy have resulted in normalization of lifespan and improvement in quality of life for most patients. The vast majority of patients with HCM now have normal life expectancy without incurring any significant limiting symptoms or adverse disease complications.
The risk of cardiac complications varies among different families as well as among members within a given family. A major goal of the diagnosis and evaluation process is to identify those patients most likely to develop complications so that appropriate treatment can be provided. Genetic testing has allowed early detection of the disease and institution of preventive and life-saving measures that improve the outcomes of many affected individuals.