Did you know you could end up with a heart attack or stroke when you get the flu?

Most of us associate influenza, also known as the flu, with respiratory complications such as pneumonia.

Recent studies have cautioned that influenza increases the risk of heart attack by more than 10 times in the first 7 days after contracting the flu. ¹

This is especially so if you are 65 and over, regardless of whether you have a history of heart disease or are living with chronic illnesses such as heart disease, diabetes, lung disease and kidney disease. ²

As cautioned by Professor Datuk Dr Zulkifli Ismail, Technical Committee Chairman of the Immunise4Life Programme, it’s time to rethink the flu.

He added, “It is not just a fever, runny nose, cough and body aches, it could seriously harm your heart.”

In industrialised countries, most deaths associated with flu occur among older persons aged 65 years and above. ³

It is important to highlight that influenza can present as a relatively mild respiratory illness or even atypically without a fever and with a cough, fatigue and confusion in older persons only to set off a sequence of catastrophic events. ⁴

The best way to protect against flu and its potentially serious complications is by getting the annual flu vaccine. ⁵

HOW INFLUENZA STRESSES YOUR HEART 

An infection springs our immune system into action.

While our immune system protects us from infectious diseases such as the flu, the inflammation that occurs as part of the immune response can also damage our own tissues and organs when a strong response is stimulated.⁶

One example is the effect of COVID-19 that triggers the hyperactivation of the immune system and the uncontrolled release of cytokines which are small molecules that aid cell-to-cell communication in immune responses and stimulate the movement of cells towards sites of infection.

The uncontrolled release of cytokines termed “cytokine storm” is used to describe a variety of events that may ultimately result in multi-organ failure and death.⁷

Studies suggest that the same inflammatory response to infection can trigger a cardiovascular event when you get influenza infection.⁸

How exactly does this happen?

As explained by the President of the National Heart Association Malaysia (NHAM) and consultant cardiologist Dr Alan Fong, it is believed that your body’s immune response coupled with the direct effects of flu on the inner lining of blood vessels or atherosclerotic plaques during an influenza virus infection could lead to plaque rupture, occlusion of arteries and subsequently causing a heart attack or stroke.

He added, “Furthermore, there are other factors that play a role such as physiological stress, increased heart rate or changes in metabolic factors such as the utilisation of glucose, fatty acid and protein in response to infection.”

ARE YOU AT RISK?

A pre-pandemic study found that influenza virus infection more likely triggers a heart attack compared to other respiratory infections.⁹

Another study found that flu increases the risk of heart attack and stroke in adults aged 40 years and above even though they had no prior history of these diseases.¹⁰

In older persons, there are changes that occur in the immune system that leads to a decline in the ability of the body to fight off infections such as the flu; this is known as immunosenescence. This was explained by Professor Dr Tan Maw Pin who chairs the Flu & Older Persons Sub-Committee of the Malaysian Influenza Working Group (MIWG).

She added, “In addition to this, aging contributes to chronic, non-infectious, low-grade inflammation, known as inflammaging which plays a key role in the cause and progression of chronic conditions such as cardiovascular diseases.”

“Aging also promotes the development and progression of atherosclerosis which is the most common cause of acute coronary syndrome, a term used for situations where the blood supplied to the heart is suddenly blocked.”

She concluded, “Hence, when an older person gets the flu, all these factors put them at higher risk of developing a heart attack and stroke.”

OLDER PERSONS WITH CARDIOVASCULAR RISK FACTORS

Here in Malaysia, we are a rapidly aging nation and although people are living longer, they are not necessarily living healthier lives.¹¹

According to the National Health & Morbidity Survey 2018 findings for older persons aged 60 years and above, 5 in 10 self-reported hypertension, 28% for diabetes mellitus and 42% for hypercholesterolemia.¹²

Hypertension, high cholesterol levels, diabetes and obesity are risk factors for cardiovascular disease.¹³

According to consultant endocrinologist Dr Azraai Nasruddin, a representative from the Malaysian Endocrine & Metabolic Society (MEMS), diabetics are at a higher risk of developing prolonged illness, hospitalisation and even death caused by flu even though their diabetes is well-managed.

He added, “Since there is an increased susceptibility to both infections such as the flu and cardiovascular diseases in diabetics, they are at greater risk of suffering acute cardiovascular events caused by flu.”

OLDER PERSONS WITH ESTABLISHED CARDIOVASCULAR DISEASE¹⁴

Serious viral illness such as the flu can exacerbate underlying cardiovascular diseases such as coronary artery disease and heart failure.

This exacerbation contributes to a heart attack through the increased metabolic demand brought upon by fever, increased heart rate, and low oxygen levels in your blood.

FLU VACCINATION CAN PROTECT YOUR HEART

Aside from the recommendation from the World Health Organisation (WHO), the Centers for Disease Control and Prevention and the Advisory Committee on Immunization Practices have recommended influenza vaccination for everyone 6 months and older, including those with high-risk conditions, such as heart disease, for decades.¹⁵

The Inter-American Society of Cardiology and the World Heart Federation have also pointed out the strong correlation between influenza and cardiovascular events and believe that flu vaccination is a safe and proven strategy to reduce cardiovascular events.¹⁶

Studies have found that the flu vaccination was associated with a 34% lower risk of major adverse cardiovascular events, and patients with recent acute coronary syndrome had a 45% lower risk.¹⁷

There was also an 18% reduced risk of death reported in patients with heart failure.¹⁸

In type 2 diabetics, studies have shown that the flu vaccination reduces the risk of heart failure by 22%, stroke by 30%, heart attack by 19% and pneumonia by 15%.¹⁹

Flu vaccination does not require behaviour change or a daily intervention, yet it prevents cardiovascular events as well as as other evidence-based approaches such as statin therapy, antihypertensive therapy, and smoking cessation.²⁰

AGE HEALTHILY WITHOUT THE FLU 

As a population ages rapidly, new challenges arise for both individuals and the societies.

We see an increasing prevalence of multimorbidity, disability and frailty which reemphasises the need for healthy aging so that people can live longer and better lives.

Alongside proper nutrition and exercise, immunisation is one of the pillars to promote and maintain healthy aging.²²

The recent pandemic has highlighted the need for infection prevention for vaccine preventable diseases such as influenza especially in older persons with multiple chronic conditions and disabilities.

The best way to protect yourself from severe flu infection is by getting the annual flu shot.⁵

While some people who get a flu vaccine may still get sick with influenza, flu vaccination has been shown in several studies to reduce severity of illness.⁵

Besides vaccination, the spread of flu can be reduced by practicing COVID-19 SOPs such as wearing a mask, proper handwashing, avoiding contact with people who are sick, covering your coughs and sneezes and disinfecting contaminated surfaces.²³

In Malaysia, flu can occur year-round.²⁴

It is advisable to make flu vaccination an annual priority in older persons especially those with underlying chronic diseases.

The flu vaccination is available at most private clinics in Malaysia. Click here to find a clinic near you.