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Why Do Heart Attacks Happen?

Medically reviewed by John Paul Abrina, MD · Oncology · Davao Doctors Hospital

Written by Kip Soliva · Updated Jul 27, 2022

Why Do Heart Attacks Happen?

Why do heart attacks happen?

Heart attacks are one of the most common and most dangerous types of cardiovascular diseases. According to the World Health Organization (WHO), 85% of the cardiovascular disease-related deaths in 2016 are caused by heart attack and stroke. Many people fear heart attacks because they can strike at any time, and can put a person’s life at risk.

Heart attacks, also called myocardial infarction, is a medical emergency that is characterized by reduced blood flow to the heart. 

why do heart attacks happen

Why Do Heart Attacks Happen?

Coronary Heart Disease

Why do heart attacks happen? One primary cause of heart attacks is the condition called coronary heart disease.

Coronary heart disease, also known as ischemic heart disease,  is a condition where the flow of oxygen-rich blood to the heart is suddenly reduced or disrupted. Coronary heart disease is primarily caused by the build-up of plaque in the coronary arteries.

Plaque is composed of cholesterol deposits which can cause the arteries to become narrowed. This process of plaque accumulating inside the arteries is called atherosclerosis

Plaque can build up over the years in the arteries, and doesn’t have to cause health problems right away. However, during a heart attack, plaque can break off the surface of the artery and rupture, causing a blood clot to form in the coronary arteries. 

why do heart attacks happen

Coronary Artery Spasm

A coronary artery spasm, also called a vasospastic angina, variant angina, or Prinzmetal’s angina, is a condition wherein one of the coronary arteries spasms or constricts. The spasm causes the blood flow to the heart to become disrupted or reduced significantly. If an artery spasms long enough, it may cause a heart attack.

Coronary artery spasms can occur to anyone, but most usually happens to smokers. Although experts are unsure about the exact cause of coronary artery spasms, other possible causes  include:

  • Drugs, such as cocaine.
  • Being exposed to extremely cold temperatures.
  • Undergoing extreme stress or pain.

Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA)

In some very rare cases, a heart attack can occur even without any blockages in the artery. This is referred to by doctors as something called a myocardial infarction with non-obstructive coronary arteries (MINOCA). 

Heart attacks caused by MINOCA are found to be more common in those who are younger, or women. Studies have also shown that those who suffer from heart attacks caused by MINOCA are those who are less likely to possess any of the heart attack risk factors such as high cholesterol or triglycerides levels. 

Although more studies are being done to decipher why people have heart attacks without any clots or blockages, experts have found out that MINOCA can be caused by:

  • Coronary Artery Spasms.
  • Microvascular Coronary Disease: This condition is characterized by reduced oxygen and blood flow to the heart due to the narrowing of the smaller branches of blood vessels that are linked to the coronary arteries.

Spontaneous Coronary Artery Dissection (SCAD)

Why do heart attacks happen to those without any symptoms?

In some instances, rare conditions can lead to heart attacks. SCAD is one such rare condition. It happens due to a tear in one of the blood vessels located in the heart. This condition is considered a medical emergency, and can be fatal in some cases.

Am I at Risk of having a Heart Attack?

A risk factor is defined as a type of behavior or condition that increases one’s risk of developing a certain disease. The risk factors can be developed into three categories, namely:

Non-modifiable risk factors cannot be changed, these include traits or characteristics that every person is born with. Non-modifiable risk factors of heart attacks are the following:


People with family members who have suffered heart attacks in the past are more at risk of suffering from heart attacks. Similarly, if someone in your family has a heart condition, then you are also more at risk of acquiring that disease and having a heart attack.


Usually, heart attacks happen to people older than 65 years old. Men who are older than 45 and women over the age of 55 are more at risk of suffering from a heart attack.

Modifiable Risk Factors include behaviors or conditions that can still be changed. These include:


The chemicals found in cigarettes can increase one’s risk of several diseases, including coronary heart disease which may lead to heart attack.

Exposure to secondhand smoke can also increase one’s risk of suffering from a heart attack.

Higher than normal triglyceride levels

Having too much bad cholesterol or low-density lipoprotein (LDL) cholesterol in your bloodstream can contribute to the narrowing of blood vessels, this can reduce the blood supply of the heart.

  • Diabetes: Those suffering from diabetes are also at risk of a heart attack, due to the lack of the chemical called “insulin” which is produced by the pancreas.
  • Obesity: Obesity is one of the leading causes of various diseases, including diabetes and hypertension which are both linked to an increased risk of heart attack.
  • Not enough exercise: Exercise is one way you can reduce your risk of various cardiovascular diseases, which can lower your chances of suffering from a heart attack.

Key Takeaways

Heart attacks are primarily caused by blockages or clots that can form in the coronary arteries, which are mainly responsible for supplying blood and oxygen to the heart. Necessary lifestyle changes must be made in order to reduce your risk of suffering from a heart attack.

Learn more about heart attacks here. 


Hello Health Group does not provide medical advice, diagnosis or treatment.

Medically reviewed by

John Paul Abrina, MD

Oncology · Davao Doctors Hospital

Written by Kip Soliva · Updated Jul 27, 2022

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