Lessons to learn from sudden cardiac deaths

Lt Gen BN Shahi (retd)

Cardiologist and Former Director General, Armed Forces Medical services

The sudden death of young or middle-aged celebrities such as actor Sidharth Shukla, singer KK, producer Raj Kaushal and comedian Raju Srivastava has attracted the attention of the public in our country. Undoubtedly, it has caused a devastating effect, both psychological and economic, on the affected families, and society at large. It is tragic to lose a person at the height of his or her career. The deaths have also triggered a debate around burnout, stress, depression and other mental health issues.

More than 90 per cent of sudden natural deaths result from heart-related diseases. Although many heart disorders increase the risk of sudden cardiac death (SCD), the presence of previous heart disease is not necessary. Sudden cardiac death may be the first manifestation of overt heart disease.

Preceding symptoms such as palpitations, chest pain, fainting or breathlessness may suggest heart-related causes, but are not specific. Terminal consequences of any acute or chronic insult to the heart leads to dangerous rhythm disturbances, ending in cardiac arrest due to ventricular fibrillation (VF).

The USA reports approximately 4 lakh out-of-hospital sudden cardiac deaths per year. The data for India is not available. Important causes of SCD may be considered under two broad categories: with or without underlying structural diseases of the heart.

Among the structural heart abnormalities, the main cause is the narrowing or blockage of coronary arteries supplying blood to the heart muscle due to deposition of fatty materials in the lumen of the artery. This is called atherosclerosis. Sudden rupture or fissure in the fatty plaques in blood supply to the heart muscle precipitates dangerous irregularity of heart rhythm called ventricular tachycardia, which soon degenerates into VF and cardiac arrest. Severe stress, both physical and mental, combined with non-specific plaque inflammation contributes to plaque rupture and fissure. Also, those having suffered heart attacks (myocardial infarction) with gross damage to the heart muscle (left ventricular dysfunction), associated with irregular heartbeats, are potential candidates for sudden cardiac deaths.

Primary diseases of the heart muscle such as hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) and arrhythmic right ventricular dysplasia (ARVD) are also important causes of sudden cardiac deaths. These diseases are related to genetic abnormalities, present both in men and women. The HCM is the most common cause of sudden death in young individuals, especially among athletes and those doing vigorous exercises. The ARVD is a substrate in approximately 1 per cent of the sudden deaths in the adult population. Unexplained loss of consciousness heralds sudden death. Diagnosis of HCM and ARVD can be arrived at through simple tests such as ECG and echocardiography.

Heart valve diseases, particularly critical aortic valve stenosis, due to congenital, rheumatic or calcific degeneration of the valve may lead to sudden cardiac death while doing vigorous physical exercise due to cardiac arrhythmia. Surgical replacement of the valve or non-surgical procedures such as transcatheter aortic valve implantation are effective.

Acute inflammation of the heart muscle mostly due to a virus, including coronavirus, may also lead to cardiac arrest and death during physical exercise. Congenital anomalies in blood vessels to the heart muscle such as the origin of the left coronary artery from the pulmonary artery, although not common, may cause cardiac arrest and sudden death during exercise in adolescents and adults, unless surgically corrected.

Among the causes present in structurally and apparently normal hearts, congenital channelopathies such as long or short QT syndrome and brudaga syndrome are important causes of sudden deaths during sleep, physical exercise, swimming and exposure to sudden loud noise. The Wolff-Parkinson-White syndrome due to the existence of abnormal conducting pathways in the heart may rarely cause sudden death due to dangerous arrhythmia. Radio-frequency ablation of abnormal pathways cures the problem.

Other rare causes of sudden death in structurally normal hearts are catecholaminergic polymorphic ventricular tachycardia and idiopathic ventricular fibrillation. Very rarely, a blunt injury to the chest over the heart region can also induce sudden cardiac death.

Overt or occult coronary artery disease, smoking, high blood pressure, diabetes, high blood cholesterol, strong family history of sudden death and acute mental stress (spousal death is an example) are considered high-risk markers and should be addressed optimally to prevent SCD.

Early detection and evaluation of coronary artery disease are essential. High-risk individuals such as smokers, diabetics and those with a family history of sudden cardiac deaths must have routine cardiac checkups, including ECG, echocardiogram, stress test and, if needed, coronary angiography. Lifestyle changes and the use of cardioprotective drugs such as beta-blockers, antiplatelets and lipid-lowering agents must be instituted on a long-term regular basis. The amount of exercise which a heart-disease patient can do safely should be prescribed by a cardiologist or physician.

In appropriate cases, coronary angioplasties and bypass surgery may be performed to reduce the risk of sudden cardiac death. Advanced device therapy like cardiac resynchronisation therapy, implantable cardioverter-defibrillator and radiofrequency ablation are very effective in improving cardiac function and controlling life-threatening rhythm disturbances and sudden cardiac arrest.

Many victims of sudden cardiac arrest survive if immediate cardiopulmonary resuscitation (CPR) and automated external defibrillators are available on the spot. The national health policy should include a simplified CPR training programme for all able-bodied citizens, particularly school and college students. Automated external defibrillators should be available at public places such as railway stations, airports, shopping malls and fitness centres. 

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