Sudden Death and Genetically Inherited Heart Disease

November 08, 2022
There has been a spate of sad news stories of athletes who have lost their lives while running, tragically affecting the lives of their families and loved ones they leave behind. News stories such as these tend to come in waves, so in my position as an expert in cardiology and genetics, I wanted to cast some light over the subject of genetically inherited heart disorders.

Many runners have been fortunate enough to receive timely treatment as soon as they experience symptoms, often being saved by a rapid transfer to a hospital for treatment. However, there are a number of runners who have tragically lost their lives at a relatively young age, who have not undergone sufficient screening, treatment, or prevention. In truth, sudden death is not exclusive to runners as this condition can affect people playing any sports, including badminton, tennis, basketball, or football. Indeed, you have probably heard news stories every now and again, be they from Thailand or abroad, that state heart disease as a major cause of death despite sudden death being quite a rare occurrence that only affects around 1 in every 50,000–100,000 people each year. Nevertheless, the fact that this condition can strike down people in their physical prime, who have no history of heart disease – be they professional athletes or amateurs – means that the public tend to take notice, resulting in more concern for athletes or even members of the general public.

We can distinguish between the causes of sudden cardiac death according to age, with athletes under 35 years most likely to be affected by myocardium, arrhythmia that may or may not be caused by myocarditis, and congenital coronary artery disease. On the other hand, athletes over 35 who die suddenly are usually found to have experienced an ischemic heart attack. Nonetheless, one of the main factors behind athletes suffering this event is a condition associated with genetics called hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is a condition that affects up to 1 in every 500 people, with most people affected by it having no idea that they have this underlying condition. Many will have never experienced symptoms, while others may have noticed a tightness in the chest alongside other symptoms, such as tiring easily, palpitations, faintness, or loss of consciousness, which could have developed at a very young age and continued into adolescence and beyond. Some cases will have noticed symptoms when exercising, when dehydrated, or after a heavy meal as the part of the heart (left ventricle) affected by this condition is responsible for transporting blood to the brain and other vital organs. The condition increases the size of the left ventricular wall, thereby reducing the chamber size of the heart. This can lead to an obstruction of blood flow in some cases, resulting in blood being cut off from vital organs. Most athletes with this condition are completely unaware of it as they think their symptoms must be a result of their intense exercise routine, and because those symptoms tend to go away once they stop exercising, before coming back when they restart. In addition to the thickening that affects the septum between to two ventricles, this condition has been found to cause myocardial scarring or fibrosis, which has the potential to cause arrhythmia or cardiac arrest. Worryingly, there are some instances where athletes may not experience much thickening of the heart muscles and therefore have no symptoms despite the presence of the condition.

In terms of diagnosis, medical staff will make inquiries into the patient’s history and perform an echocardiogram (ECG) to assess basic heart function. The results can then be used to inform any subsequent screening, which helps provide a risk assessment for sudden death as well as informing recommendations regarding tailored exercise regimen for each individual. This is vital information as some cases may not be suited to playing intense sports and they can be warned about this. However, they may still be able to partake in other sports that are less strenuous, and which can be used to alleviate stress.

With regard to treatment, there are several techniques that can help to alleviate symptoms, including a coronary artery angiography or heart surgery used to reduce the thickness of the muscle. Additionally, innovations in the field of genetics mean we can now offer medication specifically targeted at treating this condition, called cardiac myosin inhibitors. As such, those with this condition have now a range of options when compared to times gone by, with many of the techniques available today capable of helping patients live a normal life.

Interestingly, this condition is a genetic disease that is caused by the presence of genes associated with the proteins which are the main ingredients of the heart muscle and which can be passed on from generation to generation. Nowadays, there are a whole host of genetic screening techniques available, meaning that an appointment with a specialist to undergo genetic counseling to determine which techniques are most useful for each individual. This screening will be able to identify family members who share the same genes but for whom disorders are yet to develop. This then can be used as a form of risk assessment for those disorders or conditions. Moreover, we can use these screening techniques to advise couples who are planning on starting their own family.

To conclude, those starting off on an exercise regime should be vigilant for the aforementioned symptoms, being careful to build up intensity gradually, but stopping immediately and seeking medical consultation should any of the following symptoms occur: tightness in the chest, faintness, or loss of consciousness. Furthermore, people deemed at high risk, including those with a family history of hypertrophic cardiomyopathy or a sudden death in the family, should consult a doctor to undergo heart screening before starting any such regimen. This is especially important for athletes with intense training programs, such as marathon runners, because this screening will look into their family history and involve special diagnostics, such as an ECG or EKG, to ensure doctors can make the correct recommendations on how to proceed. This may also mean referring patients to a genetic specialist, who can offer advice or the available screening techniques used to analyze their risk of inheriting a heart disorder.
Information sourced from the Thailand Medical Genetics and Genomics Association (MGGA). Article written by Polakit Teekakirikul, M.D., cardiologist and medical geneticist at Bumrungrad International Hospital.

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