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A relatively new sub-specialty of cardiology is helping people with a family history of certain serious heart problems understand their risk of developing the same conditions and how to prevent them. Called cardiogenetics, the service is usually only available at advanced heart centers like MedStar Washington Hospital Center, which opened the first program in the Washington metropolitan area. But during the field’s short history, cardiogenetics has already demonstrated its value in identifying some inherited heart syndromes and improving, even saving, the lives of individuals with genetic-based heart disease.
That’s because some very specific and dangerous heart problems are known to have strong genetic components. Yet until now, we’ve had to rely on clinical findings, EKGs and imaging to diagnose and treat such conditions—most often, after symptoms have surfaced and the damage has already begun. In contrast, cardiogenetics gives us a new type of tool that can actually help predict the likelihood of developing the disease, allowing us to make pre-emptive strikes before problems arise.
Cardiogenetic Testing—When and Why
Despite the prevalence of cardiovascular disease in the United States, cardiogenetic testing is only used for a subset of conditions. Testing is most often recommended because of a suspicious finding on a patient’s EKG or other test, his or her symptoms, or personal or family history. Red flags include fainting or palpitations during exercise, a diagnosis of heart failure at age 40 or younger, multiple family members with the same heart condition, or an incidence of sudden, unexpected death in the family.
To date, the conditions most suitable for cardiogenetic testing are a few specific structural and electrical abnormalities that can produce fatal irregularities in the heart’s rhythm, including hypertrophic cardiomyopathy (HCM) and long QT syndrome (LQTS). Anyone with an inherited heart disease like HCM or LQTS may face a 50/50 chance of passing this genetic error on to their children.
Hypertrophic cardiomyopathy, an abnormal thickening in the walls of the heart muscle that restricts blood flow and weakens the heart, may result in ventricular fibrillation, a fatal arrhythmia. Quite common, HCM occurs in roughly 1 out of every 500 people and is the leading cause of sudden cardiac death in people 30 and younger, in which the heart suddenly stops beating, without warning.
If an individual is found to have a defective HCM gene, we can then screen family members to determine who, if anyone, is at increased risk for the condition and needs close follow-up for early identification of disease and intervention. If the genetic error is discovered in a child, for instance, precautions might include frequent monitoring, an echocardiogram every few years and other safety measures, such as avoiding competitive sports. Conversely, a negative finding frees parents and kids from increased vigilance, life-style restrictions, and worry…at least for HCM.
How it Works
Cardiogenetic testing is extremely simple for the patient, as it only involves collection of blood or saliva samples. Then the tricky part begins, as specialists work to find potential molecular changes that indicate—or, more often, suggest—the presence of the genetic material responsible for the disease.
There are three possible outcomes:
- Positive: a genetic error is causing the patient’s disease or symptoms.
- Negative: there is no evidence of a genetic mutation.
- Inconclusive: something genetically unusual is discovered, but science does not yet understand the relationship between the mutation and the disease; i.e., the genetic variation could be harmless or harmful.
If tests identify a genetic disorder, recommendations range from avoiding certain things (like some common medications, strenuous exercise or excessive alcohol consumption) to watchful waiting to the prompt initiation of medical, electrophysiological or surgical treatment.
Fortunately, we have the full array of proven and promising treatments available, multiple experts in every aspect of cardiac care and a certified genetic counselor in cardiology who can help guide patients and families in their decisions.
Knowledge is Power
As scientists continue to learn more about the genetic basis for heart disease, the field of cardiogenetic testing will evolve as well. Until then, interpretation is often as much art as science.
Because of the field’s newness and complexity, current consensus guidelines advise that cardiogenetic testing only be carried out by dedicated centers, like ours, that offer genetic counseling before and after testing. That assures that patients and family members understand the various implications of results and options so they can make fully informed decisions.
Meanwhile, a patient’s best bet to defeat or minimize hereditary disease, of any type, is to be aware of his or her family’s medical history. In the presence of arrhythmias, congestive heart failure or cardiac arrest, ask your physician whether cardiogenetics testing might be appropriate for you. Results can help you eliminate, postpone or reduce the effects of genetic conditions or, if negative, reassure you that you’re not following in your family’s footsteps. Either way, knowledge is power!
Listen to Dr. O’Donoghue’s podcast interview about cardiogenetics.