[ Preventive Measures ]
The Heart of the Matter: Genetic Heart Tests Play a Growing Role in Saving Lives
Published: Tuesday, February 19, 2013 at 4:03 a.m.
Last Modified: Tuesday, February 19, 2013 at 4:03 a.m.
It took Kevin Kirkpatrick three decades to learn the cause of his exhaustion, recurring illness and shortness of breath. The diagnosis he finally received — and some timely genetic testing — possibly saved his daughter's life.
KNOW YOUR HISTORY
Medical experts agree that a good family history is the best starting point for determining if you or anyone in your family is a good candidate for genetic testing. The surgeon general provides a template for taking a family history at hhs.gov/familyhistory/.
Kirkpatrick has arrythmogenic right ventricular dysplasia/cardiomyopathy, or ARVD. The condition causes an abnormal heartbeat, or arrhythmia, due to a progressive replacement of normal heart tissue with fat and scar tissue. The gene mutation that causes it has a 50 percent probability of being passed from parent to child.
With that knowledge, the 54-year-old father from Cleburne, Texas, insisted on having his daughter, Maudie, then 14, tested. Maudie had been suffering from a shortness of breath that her doctors had mistaken for asthma and allergies. After she tested positive, she received medications and an implantable cardioverter defibrillator.
That device has already shocked her heartbeat back to normal more than once. She might have died without it.
ARVD is one of several heart conditions known to have a genetic component. Genetic testing is playing an increasingly important role in preventing sudden cardiac arrest, says Dr. Richard Wu, director of the electrophysiology lab and heart rhythm clinic at UT Southwestern Medical Center, who treats the Kirkpatricks.
Doctors are still learning how to best interpret the results of genetic testing, but already they say the potential to save lives is great.
"Some of these tests have only become commercially available and covered by insurance six or seven years ago," says Wu, who also serves as an associate professor of internal medicine at the University of Texas-Southwestern, which launched its Medical Genetics Program five years ago; the program is part of the Department of Molecular Genetics, which dates to the 1970s.
In the past, it's been said that the first symptom of sudden cardiac arrest is usually the last, because it so often results in death. Now, if one family member has a heart condition with a genetic component, others also can be tested, then treated pre-emptively, if necessary.
"Someone may have a mutation and have no outward display until their 30s," Wu says. "If a patient is thinking about having children, we can do a screening to see if her children might develop it."
Dr. David Edwards, an electrophysiologist in advanced heart care at the Heart Hospital Baylor Plano, was instrumental in opening a new on-site genetics clinic in October.
Edwards cautions that interpreting results can be challenging in this relatively new field. Some genetic tests, such as the one for long QT, an arrhythmia, can have an accuracy rate of as high as 90 percent.
In other conditions, such as hypertrophic cardiomyopathy, a thickening of the heart muscle, mutations may lurk in a larger pool of possible genes. Also, while tests may reveal common family mutations, not all mutations may be dangerous or harmful. Sometimes even an expert might have to make a diagnosis based on probabilities rather than certainties, he says.
"There's a whole new level of information available, but it can give you a false sense of security because the results are rarely black and white," Edwards says.
Testing costs can range from a few hundred dollars to a few thousand dollars, but it is almost always covered by insurance when the testing is indicated, according to Laura Panos, one of the genetic counselors at the Heart Hospital Baylor Plano.
A blood draw is all that is usually needed, although sometimes a saliva or buccal sample will do, she notes. A buccal sample is obtained by using a swab to collect cheek cells or mouthwash to loosen cheek cells, which are then spit into a container.
The first and most important thing anyone can do is to gather a good family history that lists the age at which each family member died and the cause of death, experts agree. It turns out that there was a red flag for a genetic component in the Kirkpatrick family, although no one had been tested for ARVD, Kevin Kirkpatrick says. One aunt died of heart disease in her 50s, as did his sister this past fall at 52.
Now 20, Maudie calls herself as lucky. Her father agrees, but is still stricken by the memory of his daughter at a volleyball game when she was 14, and she, in her own words "felt paralyzed but ... aware of the whole situation."
When asked to recall the moment, he cannot speak. The words, when they emerge, come out haltingly.
"As a parent sitting in those stands, watching your child collapse and turn pale with purple lips — you can't even articulate what that does to you. I don't remember much. I was sitting and the next thing I knew I was on the court beside her. People told me I jumped over the railing. We were fortunate our daughter survived because she had her ICD. Had she not had that, it might have been a much different story."
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