Ever since a 31-year-old software professional from Bengaluru, Aman Deep Singh Jagade, died of a suspected cardiac arrest on August 9 while completing a 21-km half-marathon at Nandi Hills, I have been flooded with questions. How can a young, seasoned athlete, used to running long distances, suffer a sudden cardiac event?
It can seem surprising that someone who appears fit and healthy and has even passed a routine medical check-up could suffer sudden cardiac arrest during endurance sport. The reason is that standard screenings, such as a basic ECG, blood-pressure measurement, or routine physical examination are designed to identify common warning signs, not every possible heart abnormality. Some structural or electrical problems can remain hidden, while the extreme physical demands of long-distance running can act as a trigger in a person who is otherwise unaware of an underlying vulnerability.
One important issue is that early coronary artery disease can remain silent. A person may have plaque developing in the coronary arteries without experiencing symptoms, and routine examinations may not detect it. Even a stress test can sometimes appear normal if the disease has not yet significantly restricted blood flow.
Some structural heart conditions can also go unnoticed. For example, hypertrophic cardiomyopathy, in which the heart muscle becomes abnormally thickened. Certain congenital abnormalities of the coronary arteries may not always be obvious during a routine physical examination.
There are also heart conditions that primarily affect the heart’s electrical system rather than its structure. Certain inherited rhythm disorders can cause dangerous arrhythmias even when the heart looks structurally normal. These conditions may not be identified during a routine check-up and sometimes require more specialised cardiac or electrophysiological assessment.
A marathon places an enormous and sustained demand on the cardiovascular system. For several hours, the heart must maintain a high cardiac output to deliver oxygen-rich blood to working muscles. This prolonged workload can place considerable stress on the heart, particularly when combined with dehydration, heat, fatigue, or an individual’s underlying susceptibility.
Among the conditions doctors consider in sudden cardiac death in younger people are cardiomyopathies — diseases of the heart muscle that can affect its structure, pumping ability or electrical stability. One of the best known is hypertrophic cardiomyopathy. Often inherited, it causes abnormal thickening of the heart muscle. The degree and pattern of thickening can vary considerably, and some people remain completely unaware that they have the condition. Others may experience breathlessness, chest discomfort, palpitations, dizziness or fainting, particularly with exertion. In some individuals, however, there may be no warning at all before arrhythmia (irregular heartbeats) occurs. This makes the heart’s electrical activity so chaotic or fast that the heart can no longer pump blood effectively and its electrical impulses shut down.
Cardiomyopathies are mostly inherited. And the condition does not necessarily have to appear in every generation. A person can carry a disease-associated genetic variant but show few or no clinical manifestations.
A strong family history of premature coronary disease, inherited cholesterol disorders, smoking, diabetes, hypertension and other risk factors can bring coronary disease into consideration even in a younger person.
Electrolyte disturbances can add another layer of risk. Significant changes in sodium and other electrolytes can interfere with the heart’s normal electrical activity. Both severe dehydration and excessive fluid intake can potentially contribute to dangerous electrolyte imbalances that interfere with normal heartbeats, which is why appropriate hydration during endurance events is important.
Finally, the combination of intense exertion, a very high heart rate, and a surge of stress hormones such as adrenaline can increase the heart’s electrical instability. In someone with an underlying heart condition or vulnerable coronary plaque, this intense physiological stress may help trigger a serious arrhythmia or another acute cardiac event.
Certain patterns deserve medical attention, particularly when they occur during exercise. Watch out for chest pain or pressure with exertion, fainting or near-fainting while exercising, recurrent dizziness during intense activity, unexplained racing or irregular heartbeats and breathlessness that is disproportionate to the level of exertion.
A fainting episode during exercise, in particular, should not simply be written off as exhaustion without appropriate assessment.
There is no universal battery of tests that every marathoner needs. The person should definitely do an echocardiogram, which assesses heart chambers, wall thickness, pumping function and other structural features. A CT angiogram is needed to map the extent of plaque in the arteries.
Exercise testing can reveal abnormalities that are not evident at rest and may help assess symptoms during exertion. Holter or longer rhythm monitoring is useful when palpitations, fainting or intermittent arrhythmias are suspected.
Years of endurance training genuinely change the heart. The chambers can enlarge. The heart can pump more blood with each beat. Resting heart rate can fall considerably. There can also be physiological changes in heart-muscle thickness. This is commonly called the athlete’s heart.
It is not a disease. It is the heart adapting to sustained physical training. This is why interpreting an athlete’s ECG or echocardiogram requires context — including the athlete’s sport, training history, symptoms, family history and the pattern of cardiac adaptation.
A marathoner is extraordinarily fit. But fitness is not a cardiac diagnosis.
(Dr Shetty is lead cardiologist and medical director, Sparsh Hospital, Bengaluru)
