Familial or hereditary heart diseases are a group of conditions with a genetic origin that affect the large arteries or the heart. We speak of cardiomyopathies if the structure of the heart muscle is altered (hypertrophic, dilated, or arrhythmogenic cardiomyopathy) and of channelopathies if the alteration occurs in the heart's electrical system (Brugada syndrome, long QT syndrome).
The genetic origin of these diseases means they can be present in several members of the same family. This implies that, once a disease is diagnosed in a particular patient (called the index case), it is necessary to rule out the presence of the disease in other family members. This study is called family screening , and its importance lies, among other reasons, in the fact that many of these diseases, in their most severe manifestations, can increase the risk of sudden death, making early diagnosis essential to identify those family members who may be at risk.
This does not mean that all family members should be tested. Screening should be done sequentially : it would begin with the first-degree relatives of the index case , that is, parents, siblings, and children; if a new case is detected, then those first-degree relatives who were not previously included in the screening (those who are not related to the index case) would be tested, and so on.
To illustrate it more clearly: imagine that a cousin (our mothers are sisters) has been diagnosed with hypertrophic cardiomyopathy: we do not have to be studied, at least initially. First of all, their parents must be studied; If her mother was positive, our mother would have to be tested next, and only if she was positive, it would be our turn. Altering the order of the study of family members entails many problems and generates more confusion than certainty.
Once the need for testing has been established due to a first-degree relative with a patient diagnosed with heart disease, we may encounter two situations : the index case has a genetic test with an identified mutation , or the test was negative or was not performed . In the first case, a genetic test should be carried out to determine if the relative being studied carries the mutation. If not, the study is complete for them; if they do carry the mutation, they should be studied in depth to determine whether or not they have developed the disease, which should be repeated periodically as this can change over time. It is important to emphasize that carrying a mutation does not necessarily mean that the disease will develop, nor that if it does, it will manifest in the same way as in the index patient, since in addition to the genetic component, there are other factors that can affect the development of the pathology. It is also necessary to stress that, in cases where a mutation has been identified, the study should be carried out in a unit specializing in familial heart disease.
In the second scenario , when no mutation has been identified, the initial evaluation can be carried out in a general cardiology consultation and will consist, at least, of an electrocardiogram (ECG) and an echocardiogram. Depending on the condition, it may be necessary to expand the evaluation with other tests such as exercise stress testing, Holter ECG monitoring, or cardiac magnetic resonance imaging (MRI). In certain circumstances, such as Brugada syndrome or long QT syndrome, a drug challenge test may be required. In any of these cases where further evaluation is necessary, your general cardiologist will refer you to the appropriate unit. It is important to note that, if the evaluation is negative, it is sometimes necessary to repeat it periodically over the years. This will be discussed with you during your consultation, taking into account the specific condition (for example, a patient screened for hypertrophic cardiomyopathy at age twenty with an initial negative result may develop the condition later).
In summary : we should see a cardiologist for evaluation if a first-degree relative has been diagnosed with an inherited heart condition . The initial assessment can be done in a general cardiology clinic , and from there, we will be referred, only if necessary, to a specialized familial heart disease unit. It is crucial to bring the reports from the index case to the first consultation.
By Dr. Alvaro Lozano