Medical Edge Newspaper Column

A Heart Condition Of The Young

April 10, 2006
DEAR MAYO CLINIC:
What is hypertrophic cardiomyopathy, and why are young, healthy athletes dropping dead from this disease? -- Rochester, Minn.

ANSWER:
Hypertrophic cardiomyopathy (HCM) is the abnormal thickening of heart muscle. It typically involves the septal muscle that separates the left ventricle (the heart's main pumping chamber) from the right ventricle. This thickening can impair the flow of blood into and out of the heart.

Though many patients are asymptomatic, others may experience shortness of breath, especially with activity or after eating; chest pain that occurs with exertion; temporary loss of consciousness; and irregular heartbeat. Sometimes HCM can result in sudden death, and it is the leading cause of death during athletic endeavors, accounting for dozens of fatalities each year.

HCM is relatively common, occurring in about one in 500 people in the general population and, most likely, it is just as common among serious athletes. Within the group of all HCM patients, the proportion of people who suddenly die is very small -- about 1 percent per year.

Risk factors for sudden death include extreme heart-muscle thickening, repeated fainting spells, abnormal blood pressure response to exercise, certain arrhythmias and a family history of sudden death. For people with these risk factors, an implanted defibrillator can avert potentially fatal incidents.

If an athlete -- or anyone else whose work entails extreme physical demands -- is diagnosed with HCM, doctors recommend that he or she retire from such activities, even if that person has an implanted defibrillator. By pursuing low-intensity aerobic exercise, other aspects of a healthy lifestyle and regular medical care, the vast majority of HCM patients need not fear premature death. The average life span of patients with HCM is similar to that of people without it.

When a doctor suspects HCM based on physical examination or electrocardiography, the diagnosis can be confirmed using echocardiography (echo), an ultrasound procedure that images the heart and can measure muscle thickness. Sometimes, a cardiac MRI may be necessary. Because HCM is thought to be a genetically transmitted disease, close relatives of patients with the condition should be tested, too.

The American Heart Association recommends that all athletes be given regular physical exams, during which the possibility of HCM may be detected. Some patient-advocate groups and individual sports leagues and organizations have adopted more rigorous screening standards. For example, some European countries require routine electrocardiograms (ECGs) for all athletes, and some U.S. universities perform echos on all incoming athletes.

Patients with symptomatic HCM may be put on medications such as beta-blockers or certain calcium channel blockers, which help by slowing the heart rate and improving blood flow through the heart chambers. While not a cure, such drugs can improve the patient's quality of life considerably.

More invasive treatments may be indicated for a minority of patients who continue to have symptoms. These include surgical myectomy (a portion of the excess muscle tissue is removed) and septal ablation (a nonsurgical catheterization procedure that uses chemicals to destroy some of that tissue). While both procedures have high success rates, myectomy is the "gold standard," preferred for its lower rates of complications and proven durability. Ablation is generally reserved for specific patients with multiple diseases, for whom surgery might pose increased risk.

While HCM tends to be underappreciated and overly feared, most patients have normal quality and duration of life. However, a small percentage are inherently at risk for sudden cardiac death, as are any HCM patients engaged in competitive sports. Awareness and careful evaluation are the keys to identifying and managing the disease in those individuals.

-- Steve R. Ommen, M.D., Hypertrophic Cardiomyopathy Clinic, Mayo Clinic, Rochester, Minn.