Causes of Sudden Cardiac Death During Exercise

Sport is a double-edged sword. On the one hand, the benefits of exercise for cardiovascular health are well known, but on the other hand, exercise can increase the risk of sudden cardiac death (SCD) in individuals with known or undiagnosed cardiovascular disease. SCD is rare but still a troubling issue. There are many examples that some famous professional athletes have experienced, but these only show the surface of the true phenomenon, which is quite broad to include amateur athletes.

 

SCD during exercise is defined as death that occurs during or within one hour after stopping exercise. There are 92% of cases occur during sports activities, 7.4% within 30 minutes after stopping sports, and only a few within 30-60 minutes after stopping sports.

 

Comparison of Athletes and Non-athletes
Athletes have a 2.8 times higher risk of experiencing SCD compared to non-athletes, most of which are caused by undetected cardiovascular disease. However, it should be noted that exercise is not the sole cause of a higher risk of SCD, but rather a combination of intense physical activity in athletes with underlying cardiovascular disease, which can cause arrhythmias or disturbances in the rhythm of the heartbeat, causing cardiac arrest.

 

Causes of SCD in Athletes <35 years
Annually, SCD occurs in 1–3/100,000 competitive athletes <35 years of age worldwide. In athletes aged <35 years, the main causes include hypertrophic cardiomyopathy or thickening of the heart muscle, and right-sided arrhythmogenic heart disease.

 

Other causes of SCD during exercise include: congenital abnormalities in the anatomy or shape of the coronary arteries; commotio cordis caused by a blunt blow to the chest, for example being hit by a ball; infection or inflammation of the heart muscle or myocarditis; abnormal heart pump function in diastolic cardiomyopathy; leaky or blocked heart valves such as mitral valve prolapse and aortic stenosis; rupture of the great vessels in aortic rupture, etc.

 

Causes of SCD in Athletes >35 years
While the main cause of sudden cardiac death in athletes aged> 35 years is coronary heart disease. The frequency of sudden cardiac death in this population ranges from 1/15,000 to 1/50,000, mainly in males. In most cases, the sufferer previously showed symptoms. In contrast, in athletes <35 years, only 30% reported prior symptoms. There is a 40-60% reduction in the number of deaths or deaths in cases caused by cardiovascular disease with moderate-intensity exercise three or more times a week. It should also be noted that the benefits of regular exercise outweigh the risks of SCD in the elderly.

 

Pathophysiology of SCD
From a pathophysiological point of view, sudden cardiac death can occur mechanically or electrically (arrhythmic). Mechanically it can be in the form of decreased heart function due to acute blockage of blood circulation or cardiac tamponade, namely the presence of excess water in the lining of the heart, shock due to massive bleeding such as rupture or rupture of the extrapericardial aorta, gastrointestinal or gastrointestinal bleeding, or due to adrenal septic apoplexy. However, in more than 90% of cases, the mechanism is electrical (arrhythmic), with acute cardiac pump failure caused by asystole (no electrical activity on the electrocardiogram or EKG) or ventricular fibrillation (rapid, irregular heartbeat).