What Are Genetic Cardiomyopathies?
Cardiomyopathies is an umbrella term constituting a diverse group of heart diseases characterized by the structural and functional disorders of the myocardium (cardiac of heart muscles). Genetic cardiomyopathies are cardiomyopathic conditions that are caused by genetic mutations. The mutations can influence the structure and function of the heart and affected muscle, impacting the heart’s ability to pump oxygen-rich blood efficiently from the heart. There are various types of genetic cardiomyopathies, including dilated, restrictive, and hypertrophic.
What Is the Etiology of Genetic Cardiomyopathies?
The etiology of the genetic or inherited cardiomyopathies is chiefly linked to mutations in specific genes like TTN, MYH7, MYBPC3, or TNNT2. These genes play a crucial role in the cardiac muscle's structure and function. Such genetic mutations can be inherited from one or both parents, resulting in a genetic predisposition for developing cardiomyopathies. Genetic cardiomyopathies constitute various types associated with respective genetic changes. One such type is caused by mutations in the gene encoding the proteins of the sarcomere. The sarcomere is known as the contractile unit of the cardiac muscle cells. Another type of genetic cardiomyopathy can be associated with a mutation in the genes responsible for regulating muscular contraction and other significant cellular functions.
What Are the Types of Genetic Cardiomyopathies?
Cardiomyopathy, in general, can be acquired or inherited. However, genetic cardiomyopathies are typically inherited. The primary types of cardiomyopathy are as follows.
Dilated Cardiomyopathy:
Genetic dilated cardiomyopathy or familial dilated cardiomyopathy is a genetic form of cardiomyopathic heart disease. This condition occurs when the cardiac muscle becomes thin and fragile in at least one of the heart's four chambers. This results in the dilatation or enlargement of the open area of the chamber. This makes it harder for the heart to pump efficient blood. The heart, in turn, attempts to compensate for this malfunction. The heart will inadvertently increase the amount of blood pumped, resulting in further and severe degrees of thinning of the cardiac muscle. This manifests a significant frailty of the cardiac muscle, potentially resulting in heart failure over time.
The inherited dilated cardiomyopathy usually takes a severe start to manifest the symptoms of health problems. Hence, the cardiac manifestations tend to start in the mid-adulthood stage, but it is determined to occur at any period ranging from infancy to adulthood. Not every person with the genetic dilated cardiomyopathy experiences the same degree of severity. It seems to be negotiable even among family members. In addition to the usual symptoms like shortness of breath, arrhythmias (irregular heartbeat), fatigue, fainting, and swelling of the legs, some people could encounter acute (sudden) cardiac death as the very first sign. Such individuals are symptomatic; otherwise, this is the first serious sign.
Hypertrophic Cardiomyopathy:
The inherited hypertrophic cardiomyopathy is a heart disease that results from a hypertrophy or thickening of the cardiac muscle. The cardiac muscle thickening generally involves the interventricular septum. The interventricular septum disunites the heart's left ventricle (lower left chamber) and the right ventricle (the right lower chamber). In certain cases, there can be a restrain and obstruction of the blood flow resulting from interventricular septum thickening. This could result in cardiac murmurs (abnormal heart sounds during a heartbeat) and other associated impacts. In other cases, there will be less efficiency in pumping blood rather than a physical impediment to the blood flow.
The inherited or familial hypertrophic cardiomyopathy is more likely to occur in adolescence or young adulthood. However, people can witness it during any event in life. The symptoms are typically variable among the family members. Many people experience no symptoms, while others suffer shortness of breath, chest pain, chest palpitations, dizziness, lightheadedness, and syncope (fainting), specifically during physical performance.
At times, this condition could induce serious complications. It can induce arrhythmias, and that might be life-threatening. Arrhythmias refer to an abnormal heart rate. Hence, this condition precipitates the risk of sudden cardiac death, even without alarming or no signs. The clinical findings suggest that a small group of people with inherited hypertrophic cardiomyopathy develop heart failure, potentially requiring heart transplantation.
What Are the Common Symptoms Associated With Genetic Cardiomyopathies?
A substantial number of people with genetic cardiomyopathies stay asymptomatic. Moreover, the initial stages of cardiomyopathy show no signs or symptoms. People tend to experience the symptoms as the condition progresses over time.
The potential signs and symptoms associated with genetic cardiomyopathy include the following.
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Shortness of breath with rest or activities.
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Abdominal bloating due to accumulation of fluid.
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Rapid, pounding, and fluttering heartbeat.
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Chest discomfort.
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A robust pressure in the chest.
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Dizziness.
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Fainting.
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Lightheadedness.
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Fatigue.
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Cough while lying down.
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Swelling of the extremities.
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Swelling of the ankles and feet.
In some people, the condition worsens, manifesting severe degrees of symptoms. On the contrary, the condition stays mild even for a longer time in other people.
How Is Genetic Cardiomyopathy Addressed?
The specified genetic mutation is identified through genetic testing. It aids in the recognition of nature and the inheritance pattern. Managing genetic cardiomyopathy involves a combination of lifestyle, medical, and surgical interventions. Medications are usually prescribed for the relief of symptoms and the improvement of heart function. They include beta-blockers and angiotensin-converting enzyme (CE) inhibitors. In certain cases, pacemakers or implantable devices might be recommended to regulate heart rhythm. Healthcare professionals consider heart transplantation in severe cases, manifesting advanced heart failure and marked impairment in heart function.
Prognosis:
The prognosis of genetic cardiomyopathies varies based on the specific type and genetic mutations involved. These conditions, affecting the heart muscle, can lead to heart failure, arrhythmias, and other complications. The outlook is influenced by factors such as the severity of symptoms, age at onset, and the effectiveness of medical interventions. While some individuals may experience a relatively stable course with appropriate management, others, especially those with early-onset and more severe forms, may face a less favorable prognosis.
Conclusion:
Genetic cardiomyopathies are a pivotal cause of sudden death in all age ranges. Hence, genetic testing is regarded as a beneficial method for familial screening, contributing to individual prognostic insight. Obtaining a family history of at least three generations is crucial for all people suspected of primary cardiomyopathy. Moreover, a visit with the genetic counselor can also provide a genetic evaluation. Therefore, clinical or genetic screening is essential for every first-degree relationship of the patient with genetic cardiomyopathy.
