Sudden cardiac death: Recognizing warning signs

Sudden cardiac death (SCD), often described as a silent killer, refers to natural death due to an abrupt loss of cardiac activities. It happens when the heart stops beating or pumps insufficiently to maintain blood circulation. Once it occurs, a person may collapse within seconds, losing consciousness and breathing.

SCD has become a growing public health concern in China and worldwide. Each year, over 540,000 people die from SCD in China, according to data from the National Center for Cardiovascular Diseases (NCCD). 

Particularly alarming is the trend among younger populations: the proportion of cases among those aged 18 to 35 has risen sharply from 12% in 2015 to 28% in China in 2024.

Coronary artery disease and arrhythmia, also known as abnormal heart rhythm or irregular heartbeat, are leading contributors to SCD.

Compared with older adults, SCD in younger people is often more unpredictable and harder to detect. Older individuals are more likely to have chronic conditions such as hypertension or heart disease and long-term vascular changes. In contrast, cases among younger people tend to present with no prior medical history, few clear warning signs and rapid progression, making early intervention significantly more difficult.

This pattern may be closely linked to unhealthy lifestyle factors. Long-term sleep deprivation, chronic stress and irregular daily routines contribute to placing sustained strain on the cardiovascular system. In addition, habits such as smoking and excessive alcohol consumption further increase the risk.

Early warning signs: not always 'sudden'

Despite its name, sudden cardiac death is not always entirely without warning. In many cases, the body sends distress signals hours, days or even weeks in advance. Recognizing these early signs is critical for prevention.

Common warning symptoms include persistent chest pain or a feeling of tightness, palpitations or irregular heartbeat, shortness of breath, unexplained fatigue, dizziness and episodes of fainting or near-fainting. Some individuals may also experience cold sweats or nausea.

These symptoms are often overlooked or misattributed to fatigue or stress. However, experts emphasize that individuals experiencing any recurrent or unexplained cardiovascular discomfort should seek immediate medical evaluation. Early detection and treatment of heart disease remain the most effective way to reduce the risk of sudden cardiac death.

Prevention: reducing the risk before it strikes

It is important to take health check-ups, especially for those with risk factors such as hypertension, diabetes or a family history of heart disease. Tests, including electrocardiograms and echocardiograms, can help detect underlying abnormalities before they become life-threatening.

Lifestyle management is also key to preventing SCD. Maintaining regular sleep patterns, reducing chronic stress and avoiding prolonged fatigue are essential to protecting heart health.

It is recommended to maintain a balanced diet, favoring light and easily digestible foods while increasing the intake of whole grains, vegetables and fresh fruits rich in dietary fiber and vitamins. Reducing sugar consumption and limiting fried, processed and heavily preserved foods can further support cardiovascular health. Avoiding smoking and limiting alcohol intake can further reduce the risk.

Experts also caution against engaging in high-intensity exercise when the body is already fatigued, particularly after sleep deprivation or insufficient rest. Gradual training and awareness of one's physical limits are key, especially for those who have been inactive.

Emergency response

The first four to six minutes are widely regarded as the "golden window" for rescue when a sudden cardiac event does occur, as irreversible brain damage can begin shortly after the heart stops.

Bystanders should first check whether the person is responsive and breathing normally. If there is no response, bystanders should immediately call emergency services, start cardiopulmonary resuscitation and use the automated external defibrillator if available without delay.