Frequently Asked Questions
What is Hypertrophic Cardiomyopathy?
Hypertrophic Cardiomyopathy (HCM) is a genetic disease, occurring in 1 in 500 individuals. Although more common than initially thought, it is hard to diagnose and may be quite subtle, and therefore most patients are unaware of any problem until they develop symptoms. Making it even more difficult to diagnose is the fact that symptoms may develop early, in the teenage years, or much later in life. And, despite being a genetic disease, many patients may not be aware of a family history of the disease. Unfortunately, there is no reliable genetic test that can make the diagnosis in all cases, leaving physicians to rely on their own specialized expertise and experience with the disease process. For this reason, diagnosis and management of HCM is increasingly being performed by specialized Centers of Excellence with large patient volume.
The basic problem in this disease is an abnormality of the heart muscle fibers themselves. The muscle is rendered inefficient, and as a result becomes larger and larger in an effort to compensate. The effect is a markedly thickened heart muscle. In some cases, the thickening is disproportionate, affecting the wall between the two ventricles (septum) more than the free walls. Such patients are prone to obstruction of blood flow out of the heart (left ventricular outflow tract obstruction or LVOT obstruction) and a leaking heart valve (mitral regurgitation or MR) and more severe symptoms. The latter patients are termed Hypertrophic Obstructive Cardiomyopathy (HOCM), to differentiate them from patients without LVOT obstruction.
Who gets HCM?
HCM is a genetic disease, transmitted predominantly in an autosomal dominant fashion. This means that if a parent has the disease, then 50% of the children will carry the gene as well. However, even if a child gets the same gene, there is still no way of telling whether the child will develop thickening or symptoms. Thus, it may appear that the disease skips generations at times, when in fact it has not. Such children should be screened with an echocardiogram every five years to evaluate for the development of thickening. And, any symptoms of palpitations or lightheadedness, shortness of breath or chest pain, should be taken seriously.
What are the symptoms of HCM?
Patients with HCM may develop a variety of symptoms, including lightheadedness, passing out, shortness of breath, chest pain or palpitations (racing heart). Symptoms may occur on exertion, or even when the patient is not doing anything physical.
Lightheadedness or Passing Out
Patients with HCM are at increased risk of sudden death, at a rate of 1%-2% per year. Because of the muscle abnormality, the heart is irritable and may trigger abnormally fast heart rhythms, which drop the blood pressure to dangerous levels that do not support life. Lightheadedness or passing out is particularly worrisome, and should be evaluated thoroughly at a specialized center. Lightheadedness and passing out may also be related to LVOT obstruction. In these cases, medical therapy and other procedures may improve the symptoms.
Shortness of Breath
Patients with HCM can develop heart failure; that is, a backup of fluid in the lungs and legs. This occurs because the heart cannot pump out the requisite amount of blood. Moreover, some patients with HCM develop a leaky valve (mitral regurgitation or MR), compounding the shortness of breath. Finally, those with severe LVOT obstruction are particularly affected, and may not be able to walk even a few feet without shortness of breath.
Because the muscle thickens, it requires more blood. Therefore, even if patients don’t have artery blockages (atherosclerosis) they may still get typical heart-attack-type chest pain (angina). Moreover, patients with HCM are not immune to typical coronary disease, and can develop heart blockages like others of similar age, especially if they have the typical risk factors of smoking, diabetes, high blood pressure and high cholesterol. There is also evidence that patients with HCM may have abnormal coronary blood flow on the microscopic level, and thus overall blood flow may be compromised even though the larger arteries of the heart appear normal.
HCM can cause a variety of irregular heartbeats (arrhythmias), from simple “extra beats” to atrial or ventricular tachycardias and fibrillation. Those with palpitations may benefit from further testing.
How can you treat HCM?
Fortunately, most symptoms respond to lifestyle changes and appropriate medical therapy. However, in some cases, medication doses are high, and may result in side effects at times. At Winthrop, your cardiologist will help find a regimen that agrees with you, while minimizing symptoms. For those who continue to have severe symptoms despite medication, there are other options, including pacemaker placement, alcohol septal ablation or surgical myectomy.
HCM symptoms can be improved by staying hydrated. This means drinking 3-5 tall glasses of water every day and avoiding products that can cause dehydration, such as alcohol, caffeine and tea. In addition, patients should avoid strenuous aerobic exercise, which may trigger abnormal rhythms.
A variety of medications are available for HCM. The most commonly utilized are a class called beta-blockers, which help the heart relax, minimize obstruction to blood flow and alleviate mitral regurgitation, thereby decreasing symptoms. Other medications, such as calcium-channel blockers and disopyramide may be utilized in certain patients. Finally, for patients with certain rhythm disorders and palpitations, anti-arrhythmic medications such as amiodarone and blood thinners such as coumadin may be options.
In some patients, placement of a permanent pacemaker may improve symptoms. This device allows precise contraction sequence of the various chambers of the heart, and may minimize the outflow obstruction, as well as improve the efficiency of the heart. Studies indicate that permanent pacemakers seem to work particularly well in older patients.
Alcohol Septal Ablation
For those with severe symptoms, alcohol septal ablation may be performed to decrease the amount of obstruction (LVOT obstruction) within the heart. This procedure, performed by an interventional cardiologist, was first described almost 20 years ago and is performed in the cardiac catheterization laboratory. Under mild sedation, a small amount of alcohol is injected into the small area of heart muscle causing the obstruction. Almost immediately, there is a reduction in obstruction in properly selected patients, with continued improvement of symptoms over the ensuing two years, at which point it plateaus. Over 90% of patients show significant improvement in symptoms. Patients stay in the hospital 3-4 days for monitoring. The main risks of the procedure include the possibility of needing a permanent pacemaker and rare occurrences of stroke, heart attack or death. Older patients, and those with other medical problems, are particularly well-suited for this procedure.
Performed for over 40 years, surgical myectomy is a type of open-heart surgery whereby a portion of the thickened septum is removed physically in order to reduce obstruction to blood flow out of the heart (LVOT obstruction). As opposed to alcohol septal ablation, surgical myectomy is particularly well-suited for younger patients and those with valve disease or other coronary disease — such as coronary atherosclerosis — for whom surgery is required for valve replacement or repair or coronary artery bypass surgery. Appropriately selected patients have dramatic improvement that can persist for many years, similar to alcohol septal ablation. Patients typically stay in the hospital for 5 days, and require rehabilitation for another 1-2 weeks. The main risks include stroke, heart attack, permanent pacemaker and death, in addition to risks of infection and bleeding associated with bypass and mechanical ventilation. However, as most patients with HCM are young and otherwise healthy, these risks are typically much less than one would expect in patients who undergo coronary bypass surgery (CABG).
Implantable Defibrillator (ICD)
In patients deemed to be at higher risk for sudden death, an ICD may be offered. This device is placed under the left shoulder and is similar to a permanent pacemaker. In fact, the ICD can function as a pacemaker, but also functions as a mini “shock box” that constantly monitors heart rhythm and determines whether there is a lethal arrhythmia. Such arrhythmias are shocked back to normal immediately, thereby saving the patient’s life. In order to determine the need for an ICD, your Winthrop cardiologist may schedule certain tests, such as a Holter monitor or exercise stress test (treadmill test).