It remains a difficult medical challenge to prevent the sudden cardiac death of athletes, typically defined as natural, unexpected death from cardiac arrest within one hour of the onset of collapse symptoms, excluding additional time on mechanical life support.[(Wider definitions of sudden death are also in use, but not usually applied to the athletic situation.) Most causes relate to congenital or acquired cardiovascular disease with no symptoms noted before the fatal event. The prevalence of any single, associated condition is low, probably less than 0.3% of the population in the athletes’ age group,and the sensitivity and specificity of common screening tests leave much to be desired. The single most important predictor is fainting or near-fainting during exercise, which should require detailed explanation and investigation.The victims include many well-known names, especially in professional soccer, and close relatives are often at risk for similar cardiac problems.
The causes of sudden cardiac death in young people can be different. In about two-thirds of cases, the coroner discovers during the autopsy that the death was due to a cardiac anomaly. For a variety of reasons, something – such as a structural heart defect – causes the heart to beat out of control. This abnormal heart rhythm is known as ventricular fibrillation. Some specific causes of sudden cardiac death in young people.
Arrhythmogenic right ventricular dysplasia (ARVD), or arrhythmogenic right ventricular cardiomyopathy (ARVC), is an inherited heart disease.
ARVD is caused by genetic defects of the parts of heart muscle (also called myocardium or cardiac muscle) known as desmosomes, areas on the surface of heart muscle cells which link the cells together. The desmosomes are composed of several proteins, and many of those proteins can have harmful mutations.
The disease is a type of nonischemic cardiomyopathy that involves primarily the right ventricle. It is characterized by hypokinetic areas involving the free wall of the right ventricle, with fibrofatty replacement of the right ventricular myocardium, with associated arrhythmias originating in the right ventricle.
ARVD can be found in association with diffuse palmoplantar keratoderma, and woolly hair, in an autosomal recessive condition called Naxos disease, because this genetic abnormality can also affect the integrity of the superficial layers of the skin most exposed to pressure stress.:513
ARVC/D is an important cause of ventricular arrhythmias in children and young adults. It is seen predominantly in males, and 30–50% of cases have a familial distribution.
Hypertrophic cardiomyopathy (HCM) is a condition in which a portion of the heart becomes thickened without an obvious cause. This results in the heart being less able to pump blood effectively. Symptoms vary from none to feeling tired, leg swelling, and shortness of breath. It may also result in chest pain or fainting. Complications include heart failure, an irregular heartbeat, and sudden cardiac death.
HCM is most commonly inherited from a person’s parents. It is often due to mutations in certain genes involved with making heart muscle proteins. Other causes may include Fabry disease, Friedreich’s ataxia, and certain medications such as tacrolimus. It is type of cardiomyopathy, a group of diseases that primarily affects the heart muscle.Diagnosis often involves an electrocardiogram, echocardiogram, and stress testing. Genetic testing may also be done.
Treatment may include the use of beta blockers, diuretics, or disopyramide. An implantable cardiac defibrillator may be recommended in those with certain types of irregular heartbeat. Surgery, in the form of a septal myectomy or heart transplant, may be done in those who do not improve with other measures. With treatment, the risk of death from the disease is less than one percent a year.
HCM affects about one in 500 people. Rates in men and women are about equal. People of all ages may be affected. The first modern description of the disease was by Donald Teare in 1958.
Dilated cardiomyopathy (DCM) is a condition in which the heart becomes enlarged and cannot pump blood effectively. Symptoms vary from none to feeling tired, leg swelling, and shortness of breath. It may also result in chest pain or fainting. Complications can include heart failure, heart valve disease, or an irregular heartbeat.
Causes include genetics, alcohol, cocaine, certain toxins, complications of pregnancy, and certain infections. Coronary artery disease and high blood pressure may play a role, but are not the primary cause. In many cases the cause remains unclear. It is a type of cardiomyopathy, a group of diseases that primarily affects the heart muscle. The diagnosis may be supported by an electrocardiogram, chest X-ray, or echocardiogram.
In those with heart failure, treatment may include medications in the ACE inhibitor, beta blocker, and diuretic families. A low salt diet may also be helpful. In those with certain types of irregular heartbeat, blood thinners or an implantable cardioverter defibrillator may be recommended. If other measures are not effective a heart transplant may be an option in some.
About 1 per 2,500 people are affected. It occurs more frequently in men than women. Onset is most often in middle age. Five-year survival rate is about 50%. It can also occur in children and is the most common type of cardiomyopathy in this age group.
There are other causes of sudden cardiac death in young people. These include structural abnormalities of the heart, including unrecognized congenital heart disease and abnormalities of the heart muscle. Other causes are inflammation of the heart muscle, which can be caused by viruses and other diseases. In addition to the long QT syndrome, there are other abnormalities of the heart’s electrical system, such as Wolff-Parkinson-Whyte Syndrome, Brugada Syndrome, Arrhythmogenic Cardiomyopathy, which can cause sudden death.
Long QT syndrome (LQTS) is a condition which affects repolarization of the heart after a heartbeat. This results in an increased risk of an irregular heartbeat which can result in palpitations, fainting, drowning, or sudden death. These episodes can be triggered by exercise or stress. Other associated symptoms may include hearing loss.
Long QT syndrome may be present at birth or develop later in life. The inherited form may occur by itself or as part of larger genetic disorder. Onset later in life may result from certain medications, low blood potassium, low blood calcium, or heart failure. Medications that are implicated include certain antiarrhythmic, antibiotics, and antipsychotics.Diagnosis is based on an electrocardiogram (EKG) finding a corrected QT interval of greater than 440 to 500 milliseconds together with clinical findings.
Management may include avoiding strenuous exercise, getting sufficient potassium in the diet, the use of beta blockers, or an implantable cardiac defibrillator. For people with LQTS who survive cardiac arrest and remain untreated, the risk of death within 15 years is greater than 50%. With proper treatment this decreases to less than 1% over 20 years.
Long QT syndrome is estimated to affect 1 in 7,000 people. Females are affected more often than males. Most people with the condition develop symptoms before they are 40 years old. It is a relatively common cause of sudden death along with Brugada syndrome and arrhythmogenic right ventricular dysplasia. In the United States it results in about 3,500 deaths a year. The condition was first clearly described in 1957.
Wolff–Parkinson–White syndrome (WPWS) is a disorder due to a specific type of problem with the electrical system of the heart which has resulted in symptoms. About 40% of people with the electrical problem never develop symptoms. Symptoms can include an abnormally fast heartbeat, palpitations, shortness of breath, lightheadedness, or syncope. Rarely cardiac arrest may occur. The most common type of irregular heartbeat that occurs is known as paroxysmal supraventricular tachycardia.
The cause of WPW is typically unknown. A small number of cases are due to a mutation of the PRKAG2 gene which may be inherited from a person’s parents in an autosomal dominant fashion. The underlying mechanism involves an accessory electrical conduction pathway between the atria and the ventricles. It is associated with other conditions such as Ebstein anomaly and hypokalemic periodic paralysis. Diagnosis is typically when an electrocardiogram (ECG) show a short PR interval and a delta wave. It is a type of pre-excitation syndromes.
WPW syndrome is treated with either medications or radiofrequency catheter ablation. It affects between 0.1 and 0.3% in the population. The risk of death in those without symptoms is about 0.5% per year in children and 0.1% per year in adults. In those without symptoms ongoing observation may be reasonable. In those with WPW complicated by atrial fibrillation, cardioversion or the medication procainamide may be used. The condition is named after Louis Wolff, John Parkinson, and Paul Dudley White who described the ECG findings in 1930.
Brugada syndrome (BrS) is a genetic disorder in which the electrical activity within the heart is abnormal. It increases the risk of abnormal heart rhythms and sudden cardiac death.Those affected may have episodes of passing out. The abnormal heart rhythms seen in those with Brugada syndrome often occur at rest and may be triggered by a fever.
About a quarter of those with Brugada syndrome have a family member who also has the condition. Some cases may be due to a new genetic mutation or certain medications. The most commonly involved gene is SCN5A which encodes the cardiac sodium channel. Diagnosis is typically by electrocardiogram (ECG), however, the abnormalities may not be consistently present. Medications such as ajmaline may be used to reveal the ECG changes. Similar ECG patterns may be seen in certain electrolyte disturbances or when the blood supply to the heart has been reduced.
There is no cure for Brugada syndrome. Those at higher risk of sudden cardiac death may be treated using an implantable cardioverter defibrillator (ICD). In those without symptoms the risk of death is much lower, and how to treat this group is less clear. Isoproterenol may be used in the short term for those who have frequent life-threatening abnormal heart rhythms, while quinidine may be used longer term. Testing people’s family members may be recommended.
The condition affects between 1 and 30 per 10,000 people. It is more common in males than females and in those of Asian descent. The onset of symptoms is usually in adulthood. It is named after the Spanish cardiologists Pedro and Josep Brugada who described the condition in 1992. Their brother Ramon Brugada was the first to describe one potential genetic cause in 1998.