The difference between sudden cardiac death and myocardial infarction.

Written by Xie Zhi Hong
Cardiology
Updated on February 21, 2025
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Sudden cardiac death refers to the sudden death of a patient caused by various heart diseases. The most common causes include malignant arrhythmias such as ventricular fibrillation and ventricular tachycardia, severe bradycardia, significant valvular dysfunction, or the sudden occlusion of the coronary arteries leading to death. Myocardial infarction, on the other hand, refers to the sudden cessation of blood supply to the heart vessels, causing myocardial death and leading to arrhythmias or valvular dysfunction, which presents a range of symptoms in patients. Myocardial infarction can result in death in 30% of patients, but with medical intervention, the mortality rate can significantly decrease. Therefore, in cases of sudden cardiac death, the patients are already deceased. However, the mortality rate from myocardial infarction under natural circumstances is relatively high, reaching 30%. With current medical interventions, the rate of mortality due to sudden cardiac death can be reduced to less than 10%.

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Written by Chen Guang Yin
Cardiology
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Is sudden cardiac death hereditary?

The majority of sudden cardiac deaths are caused by acute and extensive myocardial infarction, with some caused by malignant arrhythmias. Coronary atherosclerotic heart disease has a genetic history. Patients with such a family history, especially those with early-onset heart disease family history—that is, a family history of heart disease before the age of 50—should be given high attention. Heart disease has a genetic predisposition, and since sudden cardiac death is a type of heart disease, it also has a genetic predisposition.

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Written by Xie Zhi Hong
Cardiology
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The main cause of sudden cardiogenic cardiac arrest

70% of sudden cardiac deaths are caused by arrhythmias, often referred to as malignant arrhythmias, with the most common ones being ventricular tachycardia and ventricular fibrillation. A small portion is caused by severe bradycardia. This condition is generally seen in patients with structural heart diseases, such as acute myocardial infarction, severe dilated cardiomyopathy, hypertrophic cardiomyopathy, or patients in the late stages of valvular insufficiency or stenosis. It can also occur in patients with severe electrolyte disturbances, who are prone to malignant arrhythmias.

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Written by Chen Guang Yin
Cardiology
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Will there be any sequelae from cardiogenic sudden death?

So, sudden cardiac death is firstly a sudden event. Whether there are sequelae depends greatly on whether timely rescue was administered at the time of the cardiac arrest. If effective cardiopulmonary resuscitation is given within a short time, generally within 4-6 minutes, then the patient's vital signs including consciousness might gradually recover, and it's possible that no severe sequelae will remain. However, if the rescue is not timely, it's possible for the heartbeat and breathing to be restored but not consciousness, leading to brain death and a vegetative state. This is a possibility.

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Written by Zhang Yue Mei
Cardiology
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Does sudden cardiac death have a connection with overwork?

Sudden cardiac death is directly related to overexertion, particularly in individuals with coronary heart disease, congenital heart disease, rheumatic heart disease, viral myocarditis, and heart rhythm disorders, especially those accompanied by heart failure. Excessive strain can increase the burden on the heart, exacerbate heart failure, lead to arrhythmias, and in severe cases, result in sudden death. Therefore, patients with structural heart disease must follow a doctor's guidance to routinely use effective medications for treatment, rest adequately, avoid overexertion, and maintain a low-fat, low-salt diet to minimize factors that increase cardiac load and prevent the occurrence of sudden death.

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Written by Chen Guang Yin
Cardiology
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The difference between cardiogenic sudden death and cerebrogenic sudden death.

The concept of sudden cardiac death exists, but there doesn't seem to be an equivalent term for "sudden brain death." For instance, if a large cerebral hemorrhage occurs and the patient dies within a very short time, this is referred to as death due to cerebral hemorrhage, not sudden death. Sudden death is characterized by death occurring unexpectedly within just a few minutes. The main difference between these, I think, is time. Sudden cardiac death happens very quickly and unexpectedly, which is why it's termed sudden death. In the case of brain-related issues, such as a significant cerebral hemorrhage, especially in the brainstem, it can compress the vital centers, leading to rapid respiratory and circulatory failure, and eventually death. Compared to sudden cardiac death, there is a slight delay in brain-related deaths; they don't occur as swiftly, and I believe the major difference lies in the timing.