On a December morning in Chennai, the beloved chief minister of Tamil Nadu suffered a ‘cardiac arrest’. Moments later, the reason for the chief minister’s death according to the crowd outside the Apollo Hospital in Chennai was asserted to be a ‘heart attack’. The two complicated failure mechanism terms were used interchangeably, owing to the obscurity of the definitions of the conditions. India’s largest TV channels too were unclear on what had happened, and beamed the wrong information on air before the dust settled. It is not uncommon for a person with minimal medical knowledge to get confused between the two conditions. Though the two sound similar, they are very different.
A heart attack, also called a myocardial infarction is a condition that happens when there is a sudden blockage of flow of blood flow to the heart. When there is decreased or no flow to a part of the heart, the area supplied by that particular artery starts dying, called infarction in the medical terminology. The heart is still beating and doing its work, but probably not as efficiently. The longer the part doesn’t receive blood, lesser are the chances for recovery of that part of the heart. The cardiologists call it a problem in the ‘plumbing’ system of the heart.
On the other hand, in a cardiac arrest, the heart suddenly stops beating. This is typically because of a problem in the ‘electrical’ system of the heart. As soon as the heart stops beating, there is no blood flow to the entire body, including the brain. If you ever witness someone who suddenly collapses, he may have only a few minutes before his body goes into irreversible damage. He/she needs immediate medical attention and you may need to start cardio-pulmonary resuscitation (CPR) till expert medical help arrives.
Though the two conditions are distinct, there is a correlation. In some cases of heart attack, the patient can have a cardiac arrest, but the most common cause of a cardiac arrest is heart attack. A cardiac arrest can also happen because of other conditions such as cardiomyopathies (disease of the muscles) and electrolyte abnormalities that can affect the electrical system of the heart.
Heart attack symptoms may include pain, dizziness, and shortness of breath, among others whereas a cardiac arrest leads to an almost instantaneous loss of consciousness. In simpler language, a heart attack is a circulation problem while a sudden cardiac arrest is an electrical problem.
Chances of survival
The chances of survival of a person suffering a cardiac arrest and heart attack vary distinctly. Although, survival depends on immediately getting CPR from someone nearby, almost 90 percent of people who suffer out-of-hospital cardiac arrests die. CPR, especially if performed in the first few minutes of cardiac arrest, can double or triple a person’s chance of survival.
Heart attacks, a bit less serious, don’t have such deadly statistics, since a blocked artery can be opened quickly with the right treatment. The treatment goal for a cardiac arrest is to facilitate the return of circulation and restore the electric rhythm, while for a heart attack, it is to reopen blocked arteries and restore blood flow. It is important to call for help and start CPR if someone has a cardiac arrest and take the patient to the hospital if having a heart attack.
(Dr Sameer Gupta FACC, FSCAI is an Interventional Cardiologist at the Metro Hospital in Noida and Umkal Hospital in Gurgaon. He hosts a weekly health awareness program on NDTV 24×7, ‘Doctors on Call’.)