By Onye G. Achilihu

Current science provides strong evidence supporting the benefits of regular exercise for primary and secondary prevention of cardiovascular diseases. However, athletes who may harbor latent cardiovascular abnormalities have a heightened risk of exercise-related sudden cardiac death.

Although reliable data does not exist in Nigeria, extrapolation can be made from data available in more advanced settings. Data from Italy show a 2.8fold greater risk of sudden cardiac death among competitive athletes when compared to non – athletes.

Why is a competitive athlete at greater risk of sudden cardiac death? Sudden Death in athlete results from intense physical exercise in the context of a hidden cardiovascular abnormality.

The exact mechanism may be due to abnormal heart rhythm resulting from increased activity of the sympathetic nervous system with high levels of adrenergic hormones acting on a vulnerable substrate. Contributing causes may include:

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Dehydration

Electrolyte Imbalance

Elevated temperatures

Increased platelet adhesiveness associated with exercise

Who is an athlete?

An athlete is a person engaged in regular physical training and participating in official competitive sports which emphasizes excellence,achievement and reward. Sudden cardiac death in athlete is difficult for the public to relate to because athletes are believed to be the healthiest segment of society.

Over the past several years, a number of high profile athletes have succumbed to death during sporting competition. Such elite athletes include our own Sam Okparaji who collapsed and died during a world cup qualifier with Angola in 1989 at the National Stadium Lagos. More recently,Chineme Martins suffered the same fate while playing for Nasarawa United.

While reading Segun Odegbami’s column on Saturday Vanguard of March 14, 2019, the following athletes were listed

Amir Angwe (Onikan Stadium, Lagos, 1995)

Charity Ikhidero, Benin 1997

Orobosa Adun

John Ikoroma

Emmanuel Ogoli

Causes Of Sudden Death in Athletes

In athletes, older than thirty-five years of age, 80% of sudden death is mostly due to atherosclerotic coronary artery disease, i.e. blockage in the blood vessels supplying the heart most due to cholesterol deposition which reduces blood flow during exercise, the plaque can rupture with increased platelet adhesiveness resulting from exercise. When this happens, the risk of heart attack can occur. If sufficient amount of heart muscle is damaged, death can occur.

In younger athletes, inherited and acquired cardiovascular anomalies are usually responsible. Cardiomyopathy, including hypertrophic Cardiomyopathy, arrythmogenic right ventricular Cardiomyopathy, is the most common cause of exercise – related death.

– Hypertrophic Cardiomyopathy is a primary disease of the heart muscle, transmitted through an individual’s genes. In an affected person, the heart muscle is abnormally thickened leading to a cascade of events which promote sudden death. The diagnosis is made by using electrocardiography and echocardiography. More than 90% of affected individuals have an abnormal electrocardiogram. The first manifestation of hypertrophic Cardiomyopathy may be sudden cardiac death

-Arrythmogenic Right Ventricular Cardiomyopathy has a prevalence of 1/1000 persons in the general population, it is due to mutation in the genes encoding certain proteins

-Congenital coronary artery anomalies which may include the origin or course of the blood vessels. These may result in abnormal electrical signals, reduced blood supply or compression by the great vessels during dynamic exercise.

Other structural anomalies which increases the risk of sudden death in an athlete include dissection/rupture of the aorta as may occur due to abnormal collagen which provides tensile strength to the blood vessels.

When this occurs, the blood vessels balloons out with increased propensity for rupture. Abnormalities of the heart valves, electrical cardiac abnormalities, blunt trauma to the chest, infections, and performance – enhancing drugs also contribute.

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Recommendations for competitive sports participation among athletes with potential causes of sudden cardiac death

All athletes with a proven diagnosis of the following condition should be excluded from competitive sports

– Structural Cardiac anomalies

– Electrical cardiac anomalies

– Acquired cardiac anomalies

– Strong family history of sudden death of undetermined cause

Primary and secondary prevention of sudden cardiac death in athletes

– Pre – participation screening should be mandatory to include:

• A detailed personal and family history
• Physical examination
• 12 – lead electrocardiogram
• Echocardiogram in some cases

These tests and their interpretations should be carried out by a highly trained cardiovascular physician because there can be an overlap between the physiological changes found in an athlete and what may be interpreted as abnormal on an electrocardiogram.

Automated External Defibrillators

In the event of cardiac arrest in an athlete, survival is improved by prompt recognition, the presence of trained medical personnel to initiate cardiopulmonary resuscitation and early access to an automated external defibrillator. Creation of emergency response plans at sports and athletic venues may improve the outcome of sudden cardiac events in athletes.

Summary

Sudden cardiac death (SCD) in an athlete is a rare yet highly visible tragedy that generates significant media attention and discussion among medical personnel, sports communities, and laypersons alike.

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The incidence of SCD is greater in athletes compared with their nonathletic counterparts due to increased risks associated with strenuous exercise in the context of a quiescent cardiac abnormality.

Numerous structural, electrical, and acquired cardiovascular abnormalities are capable of causing SCD, many of which can be identified during life and managed by lifestyle modifications, pharmacotherapy, and device therapy.

Strategies for the prevention of SCD, Including pre-participation cardiovascular screening, are endorsed by sports governing bodies, but mandatory pre-participation screening remains rare. Evaluation of athletes poses diagnostics difficulties, particularly differentiating between physiological adaptation to exercise, known asathlete’s heart, and cardiomyopathic processes capable of causing SCD.

*Achilihu, MD, FACC, is Fellow American College of Cardiology

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