How common is heart attack in young adults? Is there a need to worry?

Most people are under the impression that heart attacks only occur in people who are older. This is a misconception. Acute heart events also occur among young people - specifically those under the age of 50. Understandably, when such events occur, a sense of panic occurs.

This is called catastrophic thinking, a topic I had written about earlier. The solution to catastrophic thinking is to examine all the background facts before jumping into a conclusion.

This article is written to examine the facts around young onset heart attacks, with special focus on how commonly they occur. Links are included to my prior articles on related topics including CPR, treadmill test and heart-healthy diet. A summary is provided at the end.

What is a heart attack?
A heart attack or acute coronary syndrome occurs when blood flow to the heart muscle is suddenly impaired. This occurs either from a progressive narrowing of coronary arteries from atherosclerosis or from rupture or erosion of a plaque which was already present inside these blood vessels, leading to clotting, and blockage of blood flow. When muscle cells die from continued lack of oxygen supply, it is called a myocardial infarction.

Commonly triggered by unaccustomed exertion, it can also occur without prior warning.

Cardiac arrest, a commonly misused term, refers to stopping of the heart, somewhat like a water pump stalling due to a power cut. One of the common underlying reasons is a myocardial infarction. Abnormal heart rhythms due to multiple causes could lead to a cardiac arrest. Thus, a cardiac arrest can also occur from reasons beyond coronary artery disease, such as drowning. Therefore, such individuals need not always have blocked coronary arteries. A detailed discussion is beyond the scope of this article.

A person undergoing a sudden cardiac arrest often collapses on to the ground, unable to respond or breathe properly. It is important to do CPR (cardiopulmonary resuscitation) to immediately resuscitate such a person. This has to be continued until the patient reaches the hospital. Without CPR, there will be no blood flow to the brain; permanent brain damage will occur within minutes. My article on how anyone can become a lifesaver has details, including links to CPR videos.

Who is more likely to develop a heart attack?
The INTERHEART study proves that the same risk factors are linked with heart attacks around the world.

Even though a heart attack is more likely to occur in someone with the traditional coronary risk factors such as smoking, diabetes, hyperlipidaemia, sedentary lifestyle, obesity, hypertension and family history of heart disease, it can also occur in people without these conditions.

The focus of this article is to distinguish between these two categories of heart attacks, and attempt to estimate the odds of developing such a complication at a young age.

What percentage of deaths from heart attacks occur below 50 in India?
It is estimated that 50% of deaths from coronary heart disease in India occur below the age of 50. This information is published in the WHO paper ‘Burden of disease in India by National Commission on Macroeconomics and Health’.

While this statement might seem scary, it is important to look at the big picture before jumping into pessimistic conclusions.

There are two caveats which explain this observation.

1) Unlike western nations where the average age of the population is in the mid-40s, India is a young country where the vast majority of individuals are young - with an average age of only 28.4. In fact, approximately 75% of India’s population is below the age of 40. As a result, the total number of diseases - including heart disease - will be relatively higher in this age group.

Naturally, the average age of a person with heart disease will also be lower in India. That is one of the reasons why it is often claimed that “Indians develop heart disease at a younger age”. This is somewhat like saying, “all people in India are 28 years old”.

2) Death reporting in India is not a uniform process. All deaths are not certified or registered. It varies between urban and rural regions as well as between states. Overall, most large hospitals are located in urban areas. Therefore, deaths that occur in urban settings are more likely to be correctly recorded and reported. In contrast, a death occurring at home in a remote village might not necessarily be classified according to the correct cause. Thus, it is possible that many of the deaths occurring in older age groups from cardiac causes are not included in this calculation.

What are the odds or risk of developing a heart attack by age group in India?
A landmark paper was published in 2011 by CR Soman, Raman Kutty and others in Asia Pacific Journal of Public Health, looking at seven villages in Kerala over a period of five years covering a population of 161,942 people, examining 4271 deaths, classifying them as objectively as possible.

The authors have published the rate of coronary heart disease deaths in each age group, see table below.

The authors report that the chance of death from coronary heart disease in the age group 35 to 44 years was 59 per 100,000 persons among men, and 17 per 100,000 for women. From the table, it can be seen that this rate increases with each decade. This proves that the chance of developing a heart attack increases with age.

Thus, although the individual risk or rate of heart attacks is lower among younger adults, the total number of individuals in this age group is large. Hence, the total number of events is also large. This was highlighted in the population pyramid above.

What is the importance of Dr CR Soman’s paper from Kerala?
All research studies are not equal; some are closer to the truth than others.

The value of this study is that it was conducted from the ground upwards - systematically observing a large population over a few years, covering all age groups and demographic segments.

This study is methodologically different from a retrospective analysis of heart attacks that were recorded at a hospital. A hospital receives patients from various segments of the population, and data from a hospital need not necessarily reflect the true picture in the community.

In developing countries, all individuals do not have equal access to hospitals - which tend to be concentrated in urban areas. Older people living in remote rural areas have limited access due to multiple reasons. In contrast, younger people tend to migrate to urban areas in search of work, and therefore have easy access to hospitals. As a result, younger cases get overrepresented in a hospital’s database.

Unequal or skewed access to hospital care can confound the demographic picture when heart disease rates are measured at a hospital, as was seen in the multinational INTERHEART study, where older age groups were almost certainly underrepresented in developing countries.

Likewise, measuring heart disease rates among migrants to developed nations is confounded by skewed age pyramids, with the older generation of many migrants staying back in the home country. This generates a false impression that such populations have younger onset of heart disease than the host country.

What is the risk for someone in their forties dying from a heart event?
Risk is estimated as a rate, which is a fraction. A rate has a numerator (number of observed events) and a denominator (the size of the observed population)

According to Dr CR Soman’s study, the rate is 59 per 100,000 people per year, or 1: 1700.

In plain English this means that 99,941 people out of 100,000 will not die from a heart attack. In other words, this is an extremely rare outcome in this age group.

How commonly could this happen to someone in the same age group, who has no coronary risk factors?
A large study from Canada published in the Journal of the American Heart Association in 2019 addressed this question. The authors looked at 12,519 patients who developed acute coronary events below the age of 50, and found that 8% of these individuals did not have any risk factors.

The overall rate of coronary events in the study was 50 per 100,000 people every year among men below age 50, and 20 per 100,000 for women < 55 years.

In the Canada study, for those without risk factors among people below age 50, the rate was 4 per 100,000.

As 8% of coronary events occur without risk factors in the below 50 age group, we can assume that 99,996 people out of 100,000 will not develop such an event.

In other words, the individual risk of a person without risk factors to develop a coronary event at a young age is immensely rare, at 1: 20,000.

How many such events could be occurring in Kerala in young age groups?
If we applied the above published figures to Kerala’s population, specifically to people in the 35-45 age group, the following numbers can be arrived at.
Of a total population of 3.6 crore, the percentage in that age segment is 15%.
That translates to 54,00,000 people.
Overall rate = 59/100,000
Total estimated events per year = 59 x 54 = 3186
Total events among those with no risk factors = 3186 x 8% = 255

What about a treadmill test?
A commonly asked question in this context is whether to go for a specialised heart investigation such as a treadmill ECG test.

Unlike a urine pregnancy test that always shows either a positive or negative result, heart investigations can sometimes be inaccurate and misleading. When done without the right clinical indication, the test might show a false positive result - that is even in the absence of heart disease. This leads to long-lasting anxiety, and unnecessary further invasive tests.

The test could also give a false negative result by failing to detect heart disease, falsely reassuring the person. The solution is to undergo these tests only at the direction of a doctor, after assessment of individual risk profile. My article on treadmill tests covers this topic in detail.

How has the pandemic affected heart events?
There is evidence of greater risk of heart events occurring for at least a year following COVID-19, likely because this virus affects the inner lining of blood vessels. While there is no preventive medication advised, it is safer to avoid strenuous exercises during the months following SARS-CoV2 infection. Routine activity need not be restricted.

Summary
All deaths are tragic. But when people hear about apparently healthy young individuals dying suddenly from a heart attack, it is common to feel a sense of panic that it could happen to anyone at any time. This is called catastrophic thinking. The solution is to look at facts and figures, and calculate the actual probability.

After analysing the above published papers, it is clear that the chance (rate) of such an event occurring in a person under 50 is extremely small. Among all such events, 8% occur in people with no known risk factors. The following table lists the risks of a few conditions, for comparison.

In other words, not all heart attacks are preventable. But this should not stop us from doing what we can to reduce our individual risk. Avoiding tobacco and excessive alcohol use, maintaining a physically active lifestyle with regular exercise, adequate sleep and reasonably healthy diet specifically avoiding trans fats and excess salt intake are important. The topics of cooking oils and cholesterol were covered in detail in my earlier articles.

Knowing one’s numbers (health parameters) such as weight, blood pressure, sugar, lipid profile and discussing these with the family doctor are important.

Further reading

Catastrophic thinking: why we consider the worst-case scenario. Article by Dr Rajeev Jayadevan

https://www.onmanorama.com/lifestyle/health/catastrophic-thinking-fear-amygdala.html

2. When should a treadmill test be done, and why it should not be done for everyone.

Article by Dr Rajeev Jayadevan

https://www.onmanorama.com/lifestyle/health/2018/03/17/heart-disease-treadmill-when-test-health.html

3. How anyone can become a life saver: a common man’s guide to CPR, includes training videos. Article by Dr Rajeev Jayadevan

https://www.onmanorama.com/lifestyle/health/6-step-first-aid-guide-to-save-life.html

4. The truth about cooking oils: the good, the bad and the ugly. Article by Dr Rajeev Jayadevan

5. Getting to know the cholesterol family. Article by Dr Rajeev Jayadevan

6. How to calculate individual coronary risk

https://tools.acc.org/ascvd-risk-estimator-plus/#!/calculate/estimate/

7. Burden of disease in India by national commission on macroeconomics and health

https://www.who.int/macrohealth/action/NCMH_Burden%20of%20disease_(29%20Sep%202005).pdf#page=215

8. All-Cause Mortality and Cardiovascular Mortality in Kerala State of India: Results From a 5-Year Follow-up of 161 942 Rural Community Dwelling Adults - C. R. Soman, V. R. Kutty, S. Safraj, K. Vijayakumar, K. Rajamohanan, K. Ajayan, 2011

9. Premature Atherosclerotic Cardiovascular Disease: Trends in Incidence, Risk Factors, and Sex‐Related Differences, 2000 to 2016 | Journal of the American Heart Association

10. Risk factors for early MI in South Asians, the INTERHEART study

https://jamanetwork.com/journals/jama/fullarticle/20515911. Increased risk of heart events following COVID-19

12. Kerala population structure

https://statisticstimes.com/demographics/india/kerala-population.php

13. Death and birth registration in India

https://www.thehindu.com/news/national/births-and-deaths-registration-still-low-in-india/article4630425.ece

14. Causes of death vary by state. This could partly be the result of variation in the certification process.

https://timesofindia.indiatimes.com/india/ischemic-heart-disease-is-the-top-killer-across-most-indian-states/articleshow/61651295.cms

15. Acute coronary syndromes

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.117.029870

16. US Preventive services Task force recommends against routine cardiac screening among low risk adults

https://www.uspreventiveservicestaskforce.org/home/getfilebytoken/cAs__BR8J4rgcZ4vQgfaTx#:~:text=The%20US%20Preventive%20Services%20Task,10%25)%20for%20CHD%20events.

17. Maternal mortality rate in India

https://www.pib.gov.in/PressReleasePage.aspx?PRID=1697441

18. Road Accident injury rate, Kerala

https://timesofindia.indiatimes.com/city/kochi/kerala-tops-in-near-fatal-accidents/articleshow/72090166.cms

19. Grievous injury rate Kerala Page 64, Government of India MORTH data

https://morth.nic.in/sites/default/files/Road_Accidednt.pdf20. The dark side of pregnancy, a condition that carries a death risk of 1:885, article by Dr Rajeev Jayadevan

https://www.onmanorama.com/lifestyle/health/2018/01/30/health-risks-of-pregnancy-complication-doctors-advise.html