Heart condition is usually asymptomatic

Q: My son's pediatrician just ordered a heart ultrasound test to see if his heart is too muscular. I was so upset that I didn't understand all the things the pediatrician said. Please tell me about this condition. Should my other kids get tested?

A: It is important that you understand what is going on with the health of your kids. I am sure your pediatrician would be pleased to explain everything again, as well as to answer your questions, so definitely talk with him or her. Based on your description, it sounds like your pediatrician is suspicious of hypertrophic cardiomyopathy (HCM).

HCM is a condition where the heart muscle becomes too thick; a typical diagnostic criterion is a 15-millimeter or greater left ventricle thickness. Most cases of HCM are inherited. In fact, there are over 100 different possible mutations to any one of 10 different genes that can cause this condition, making this the most common genetic heart disease and affecting 1 in 500 people.

Most people with HCM have no symptoms; instead it is discovered when a heart ultrasound (echocardiogram) is done for other reasons or for screening purposes. If the heart muscle becomes thick enough, however, it can actually block the blood from being able to leave the heart. If this happens, the patient can have symptoms of poor heart output including chest pain, shortness of breath with exertion, heart failure or fainting, as well as irregular heart rhythms and even sudden death.

HCM is often suspected due to these symptoms, especially in an adolescent, or because a certain type of heart murmur (a whishing sound your health care provider can hear with their stethoscope) is found on physical exam.

Since HCM is usually an inherited condition, anyone with a family history of it who has symptoms that could be related to the condition should get a full evaluation including an echocardiogram and a stress test. More so, even asymptomatic close family members of someone with this condition should be screened. Typical recommendations for this screening are:

• A thorough history and physical (H&P) exam for kids less than 12
• H&P exam as well as an echocardiogram annually for those 12 to 18
• H&P exam and an echocardiogram at least every five years for those over 18

HCM can have severe complications, including an increased risk of developing heart failure or an irregular heart beat, as well as a 0.1 percent to 0.7 percent risk of sudden death per year. Risk factors that make sudden death more likely include a history of fainting, a history of a type of irregular heart beat called ventricular tachycardia, abnormal blood pressure response to exercise, a very thickened heart muscle (over 30 millimeters) or having a history of cardiac arrest.

Patients with no symptoms may not require treatment, although avoiding intense sports or other situations that can exacerbate their condition may be recommended. For those with symptoms or those who their treating clinician feel will benefit from treatments, the first line of treatment is certain medications that reduce the forcefulness of the heart squeeze, such as beta blockers. Other medications are sometimes used as well.

Although only a minority of patients with HCM have symptoms, of those with severe symptoms over 10 percent do not respond to medications. These patients may be referred for surgery to cut away the thickened muscle. This open heart procedure has a high success rate, although not without some risk. Between 1 percent and 4 percent of patients die from the procedure, and up to 10 percent have their heart conduction system affected and subsequently require a pacemaker.

A new, less invasive therapy has been developed where a catheter is introduced through the blood vessels then up to the heart so alcohol can be injected directly into the area of thickened heart muscle to destroy some of it. This approach seems to be almost as effective as surgery, and seems to have similar mortality rates. It may be especially useful for those patients who are not good surgical candidates. However, problems with the heart conduction system after this procedure are more common than after the surgical procedure, and 10 percent to 30 percent of patients subsequently require a pacemaker.

Since HCM is a potentially life-threatening hereditary condition, people with a close relative with HCM, as well as those with symptoms or physical exam findings, should see their health care provider to determine if they need screening.

Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at DrHersh@juno.com.