Menu

What is hypertrophic cardiomyopathy?

I must confess I am somewhat of a reality TV junkie, and although I can’t claim that I have watched every season, "Survivor" is still my favorite after something like 30 seasons on the air. In the season just ended in early December, one of the competitors had to withdraw from the contest when his teenaged athlete son became very ill with a heart condition that ultimately required he undergo a heart transplant. It is possible that the young man had a condition called cardiomyopathy.  Fortunately, his transplant team found an excellent donor heart and he is recovering well, but to be so young and have such a catastrophic life threatening illness has certainly changed his life.

Although we don’t see a large number of cardiomyopathy cases, it is really not that unusual of a disease in the population, and even though it is seen in all age groups, our pilot population is skewed toward the 50 and over end of the spectrum. Hypertrophic cardiomyopathy (HCM) is a subset of the disease and can present with either no or very mild symptoms including shortness of breath, fatigue, and palpitations in the chest, with escalating symptoms of chest pain, fainting, and worsening arrhythmias that could lead to sudden death. 

Therein lies the rub for the FAA from a regulatory certification standpoint. You will recall that the FAA’s job as the guardians of safety of the National Airspace System requires that they assess medical conditions on the basis of risk that the condition could result in a pilot experiencing a subtle or sudden incapacitation in flight. Now, we know that the incidence of medical incapacitation in flight is extremely rare, but that is another discussion.

In the presence of a diagnosis of cardiomyopathy, the FAA is concerned about how the disease can bring about a couple of things. One is a significantly reduced ejection fraction (EF), the calculated volume of blood that the left ventricle, the heart pump, can “eject” into the aorta to adequately supply the body’s demand for nutrients and oxygen. In non-diseased hearts, the “normal” ejection fraction is 50 percent or greater. When the EF drops below 40 percent, the FAA’s “cut point” for certification, an airman will most likely be denied certification until the heart recovers well enough for the EF to climb above 40 percent.

The other scary thing about HCM is the propensity for the heart’s electrical system to begin to do weird things that result in abnormal heart rhythms that, in the worst-case scenarios result in a loss of pumping ability, but this time, the problem is electrical and not “mechanical.” The arrhythmia that leads to the worst outcome is ventricular fibrillation, in which the heart muscle has no organized rhythm and contractions of the muscle are so poor that no blood is being circulated. Sustained ventricular fibrillation has a very poor prognosis, and out-of-hospital arrhythmias of this type are often fatal. Ventricular fibrillation and sustained ventricular tachycardia, a rapid heart rate that puts the heart into overdrive, are typical rhythms seen in the worst cases of cardiomyopathy.

When the FAA reviews an airman’s medical history, among the tests that will be required are a standard exercise treadmill stress test or a stress echocardiogram; an M Mode/2D echocardiogram that visualizes the function of the heart muscle as well as the valves in the heart—the aortic, mitral, pulmonary, and tricuspid; and a 24-hour Holter monitor to evaluate the heart rate and rhythm. A detailed review of the patient’s symptoms, including a review of the family history because HCM often has genetic characteristics, are important parts of the evaluation.

The ejection fraction number is somewhat elusive depending upon the testing used to calculate the percentage. Probably the most reliable measurement is done using an established workhorse procedure called an exercise MUGA. This test seems to have a higher “sensitivity” and therefore produces the most accurate measurement of what the ejection fraction number actually is. Although a stress test or stress echo can produce a calculated ejection fraction, it may be a conservative number, so if you have an evaluation for cardiomyopathy and the ejection fraction is low, once your heart has healed and recovered sufficiently, you might ask your cardiologist to order you a MUGA to submit to the FAA.

Portrait of Gary Crump, AOPA's director of medical certification with a Cessna 182 Skylane at the National Aviation Community Center.
AOPA NACC (FDK)
Frederick, MD USA

Gary Crump

Gary is the Director of AOPA’s Pilot Information Center Medical Certification Section and has spent the last 32 years assisting AOPA members. He is also a former Operating Room Technician, Professional Firefighter/Emergency Medical Technician, and has been a pilot since 1973.

Related Articles