A sudden cardiac arrest is not the same as a heart attack

Popular Bollywood singer KK was merely 53 when he suddenly died after performing at a concert at Kolkata this week. As I flipped through news posts today, I noticed that some news headlines say he died of a heart attack while other headlines say the cause of the death was a sudden cardiac arrest. A sudden cardiac arrest is not the same as a heart attack. 

For the benefit of my readers, let me try and make it clear why the two terms cannot be used interchangeably. Also, we need to remind ourselves that just two steps taken as an emergency measure could have increased the chances of KK's survival. 

Singer KK was merely 53 years old when he suddenly died after a concert on 31 May 2022. Could prompt emergency measures have prevented the casualty? 

The heart is a muscular pump that pushes blood into different parts of the body through a network of blood vessels. The heart muscles get their nutrition and oxygen supply through blood vessels called coronary arteries. 

What causes the heart to beat? The heart beats due to contraction and relaxation of its muscles.  Different parts of the heart contract and relax when an electrical signal passes through them like a wave. This wave-like signal is generated in the right upper chamber of the heart and then passes to its other areas. 

Simply put, a heart attack is when the blood flow to a part of the heart is blocked as one or more of the coronary arteries or their branches is blocked. 

In contrast, a sudden cardiac arrest (SCA) is when the heart does not beat normally and suddenly stops beating because the wave-like electrical signal that generates heart beats is disrupted. 

Heart attack represents a problem in the circulation of oxygen-rich blood to parts of the heart whereas an SCA represents a problem with the electrical signalling that makes the heart beat. 

Heart attack

When an artery in the heart is blocked due to cholesterol or fat deposits or due to a blood clot, oxygen-rich blood does not reach the specific area of the heart that the artery supplies. 

If the blocked artery is not reopened quickly or a bypass route is not created, the cells in the part of the heart which is normally supplied by that artery start to die due to lack of oxygen. If the person goes without treatment for a longer duration, more areas of the heart get less oxygen and nutrition and more cells die. 

'Myocardium' means the muscle tissues of the heart. "Infarction" means the death of tissue due to loss of blood supply. Now you know why a heart attack is also called a 'myocardial infarction' or simply 'MI'!

Symptoms of a heart attack or MI can be immediate and intense but more often, the symptoms start slowly and persist for hours, days, or weeks before the intense chest pain we often associate with a heart attack. 

Common symptoms of a heart attack include chest discomfort, discomfort in other parts of the upper body, shortness of breath, cold sweat, nausea, and breathlessness. Men and women can have different symptoms suggestive of a heart attack. 

If you notice any of these warning signs, and even if you are not sure this is a heart attack, please call emergency. Every second matters. Consult a cardiologist even if the symptoms do not persist for long. 

The cardiologist will run a few tests to confirm if it was a heart attack and then, treat the blockage to prevent future heart attacks.

Sudden Cardiac Arrest

An SCA occurs suddenly without much warning. It occurs when either the heart stops beating completely or when the heart is not beating sufficiently to pump blood to different parts of the body. 

Like I explained before, heart beats are a result of the contraction and relaxation of the heart muscles.

An electrical impulse generated inside the right upper chamber of the heart travels to other parts of the heart. As this impulse passes through different parts of the heart, it causes a wave of contractions and relaxations. As a result, the heart beats and pumps the blood. 

When there is a disruption in these electrical impulses, the heart stops beating or beats insufficiently. The heart is unable to push blood to the brain, lungs, and other parts. When the brain is deprived of oxygen, within seconds, the person loses consciousness and you may not be able to feel their pulse. Death can occur within minutes if the person does not receive immediate care. 

The Link

Though an SCA is not a heart attack, the two are linked. 

SCA may occur after a heart attack or during the recovery from a heart attack. 

Most heart attacks do not lead to SCA but when an SCA occurs, a heart attack is a common cause. An SCA may occur due to a heart attack or due to other causes as well. 

Other causes of sudden cardiac arrest

A sudden cardiac arrest may also ocur due to inherited abnormalities in the signal pathway that causes the heart to beat.

It can also occur due to abnormalities or dysfunction of the heart muscles. The medical term for this is 'cardiomyopathy'. Alcohol consumption, obesity, fibrotic diseases and inflammations can increase the risk of cardiomyopathies. 

Heart failure, valve disorders and some congenital abnormalities can also increase the risk of SCA.

How can you help?

When you see some one showing symptoms suggestive of a heart attack or an SCA, do not waste any time. 

Call emergency immediately. 

That's 911 if you are in USA . 

If you are in India, call 102 for ambulance service. 

A person having a heart attack may still be breathing and talking. They do not need a cardiopulmonary resuscitation (CPR). But they still need to be sent to the hospital immediately. So, call emergency or ambulance service. 

In contrast, if the person is not breathing and has become unconscious, it is probably an SCA. Call emergency and start hands-only CPR immediately. Even if you are alone with the person, you can start hands-only CPR. 

1. Call emergency. 

2. Start CPR immediately. 

In case of a heart attack, follow step 1. In case of an SCA, follow steps 1 and 2  without delay. These two steps can increase the chances of survival. Cardiac arrest is reversible if CPR is done within minutes. 

Continue the CPR till professional help arrives. With swift action, you can help revive a person from cardiac arrest.  

CPR uses chest compression to mimic heart beats and forces blood into different body parts. It keeps enough oxygen in the lungs and gets it to the brain till normal heart rhythm is restored by professional emergency service providers. 

When the professional emergency service providers arrive, they may use an electric defibrillator to send an electrical impulse to the heart. This electric shock provides an external electrical signalling that can get the heart to beat on its own once again. 

It's an emergency!

You do not need to be professionally trained to do a CPR. 

If you see someone falling down unconscious, without wasting time, just bend down and try to wake them up. Check if they are breathing. If they do not seem to be breathing and you do not feel their pulse. start CPR immediately. 

While kneeling beside them, use both your hands to press on the middle of their chest. Push hard at a rate of about 100-120 times a minute. Keep doing that till help arrives. You can continue CPR for about 10 minutes without stopping in between. 

Here are a few helpful videos that tell you how to do a hands-only CPR while waiting for an ambulance to arrive. 

• A 1-minute video by the American Heart Association that gives you just the basics about hands-only CPR
• A nearly 2.5-minute video  of cardiologist Late Dr. KK Aggarwal showing you the details and some alternative ways to do a CPR in case you cannot use both your hands. 

If you found this post helpful, do leave me a comment. 

If you have seen a person revive from an SCA due to prompt action, tell us about it.