New study finds severely cold days increase the risk of cardiovascular deaths

Be careful where you spend your days during the winter season, especially if you have existing heart problems. Believe it or not, there is an additional nine people dying for every one thousand deaths from cardiovascular disease due to extremely cold weather. Having an extremely cold temperature increases the risk of death among people with cardiovascular disease.

With the consistent changing of climate, we may experience different degrees of coldness or hotness anywhere in the world, which is quite unusual for a particular time of the year. Now, what does climate change have to do with our heart health? 

Extreme cold days increase cardiovascular deaths

A new study published in the American Heart Association’s journal Circulation revealed that people with cardiovascular disease, most especially heart failure, increase their risk of death whenever they experience extreme temperatures. 

Whether extremely hot or cold temperatures, it can be linked with a greater risk of cardiovascular mortality, according to an analysis of data from different countries around the world. However, the trend was less concerning on days of extreme heat, which can be accounted for an additional two deaths.

Among the types of cardiovascular disease, the most number of additional deaths come from people with heart failure. The research found that exactly thirteen deaths were recorded during extremely cold days, while close to three whenever the weather was extremely hot. 

Aside from heart failure, some other heart conditions that put patients at risk in extremely cold weather are arrhythmia and ischemic heart disease, and who suffered from strokes. In fact, even those with an irregular heartbeat are recommended to take precautions as they can be at risk as well. 

With the previous context of the United Kingdom experiencing a deadly 40C temperature in the north during the summertime, the new study has ultimately helped in understanding the relationship between climate change and health [1]. 

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Common risk factors of cardiovascular disease worldwide

About 16 percent of the total deaths around the world are caused by heart problems, as reported by the World Health Organization (WHO). Cardiovascular disease has been one of the biggest causes of death worldwide since the year 2000. By 2019, the number has even increased by more than two million to 8.9 million deaths worldwide. 

An unhealthy diet, lack of physical activity, excessive use of alcohol beverages and tobacco use are the ultimate behavioural risk factors for acquiring cardiovascular disease. The effects of the mentioned behavioural risk factors may occur in individuals by some health indications, including high blood pressure, raised blood glucose and blood lipids and overweight and obesity. The identified intermediate risk factors can be checked in primary care facilities and determine an increased risk of heart attack, heart failure, stroke and other heart complications.

In addition to that, there are also numerous underlying determinants of heart problems. These can include the major forces driving social, economic and cultural change, such as globalisation, urbanisation and population aging. Other determinants of cardiovascular disease include poverty, stress and hereditary factors – and now, experts could potentially include climate change. 

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There are ways to reduce your risk of having cardiovascular disease, such as stopping tobacco use, decreasing salt in your diet, consuming more fruit and vegetables, regular physical activity and avoiding the harmful use of alcohol. Moreover, drug treatment for hypertension, diabetes and high blood lipids is needed to lower cardiovascular risk. Such treatments can prevent heart attacks and strokes among people with these heart-related conditions [2].

More about the new study and its findings

Carried out by the Multi-Country Multi-City Collaborative Research Network, this new research is intensively conducted and peer-reviewed by many scholars in the field. The researchers have collected and analysed data from 32 million cardiovascular deaths that occurred between the years 1979 and 2019 in hundreds of cities in 27 different countries around the world.

They categorised the data of deaths in occurrence between the hottest and coldest 2.5 percent of days for each city and compared them to each other, and with consideration of the days which had “optimal temperature” – referring to the temperature that has the lowest rates of deaths. 

From this method, they found that one in every 100 cardiovascular deaths may be because of the extreme temperature days. More particularly, extremely hot days can cause an additional 2.2 deaths in every 1,000 cardiovascular deaths, while the numbers of deaths are higher on extremely cold days, which can be accounted for 9.1 additional deaths.

Furthermore, the temperature effects were more significant when looking at heart failure deaths. Additional deaths from heart failure in extreme temperatures showed the greatest number among any other types of heart disease. There are about 2.6 additional deaths on hot days while 12.8 on cold ones. 

The thing is that the exact reason is still unknown. However, the closest explanation that health experts can tell us is about the progressive nature of heart failure as a disease, as the patients are susceptible to temperature effects. They also added that this is an important finding considering that one out of four patients suffering from heart failure is readmitted to the hospital within thirty days after discharge. Plus, only twenty percent of patients with heart failure survive ten years after diagnosis [3].

Climate change as a risk factor for heart diseases 

As mentioned above, the researchers specifically highlighted that climate change could be an added risk factor in cardiovascular disease deaths because of its association with extreme temperatures. With climate change’s substantial swings to extreme hot and cold temperatures, this unstable switching could affect heart health. 

Experts are yet to investigate the burden of extreme temperatures further. This study has started the study in discovering what climate change might hold for heart problem risks. With the continuous climate change and unprecedented pace of warming, research studies must also include this on the front line. 

On the other hand, one expert stated that there is no such thing as so-called “extreme temperatures,” and heat and cold are context-specific and location-specific. One example is a 104 Fahrenheit day in Kuwait is a typical summer day; meanwhile, a 104 Fahrenheit day in London resulted in “widespread, incalculable damage” [4].

The climate change and human health

The new study opens the discussion about the relativity of environmental exposures to human health. In the 1960s, there was a decline in heart disease deaths as cardiologists identified the culprits, which were tobacco use, physical inactivity, Type 2 diabetes and high blood pressure. However, the current challenge is understanding the degree of impacts of climate change on health, as stated by a research fellow at the Harvard T.H. Chan School of Public Health. 

Another health professional from Stanford University emphasised that this new study goes beyond medicine as it contributes to the ongoing societal discussions on climate and human health as well. This is a good start in digging deeper into defining the relationships between these two, considering that the world is facing consistent climate changes. 

The researchers further concluded that more studies are needed to come up with strategies for mitigating the impact of extreme temperatures in the context of climate change. Moreover, they recommend targeted warning systems and provide advice for people who are vulnerable to cardiovascular disease to take extra precautions whenever necessary to prevent added deaths during the period of extreme weather, especially in cold temperatures. 

Health experts also urged the science and medicine field to be on top of emerging environmental exposures, more particularly, the professional cardiology organisations to commission guidelines and scientific statements about the intersection of extreme temperatures and cardiovascular health. By doing this, they can provide appropriate directions to healthcare professionals and determine the gaps in clinical data for future priorities for research.

Taking care of your heart health 

The American Heart Association (AHA) warns the public that temperatures higher than 26 degrees Celsius can compromise the heart, putting vulnerable people at high risk. The officials added that precautions are essentially important for elderly people, people with high blood pressure, who have obesity or a history of either heart disease or stroke. 

This is due to heat causing your heart to work even harder by moving blood from your major organs to underneath the skin, meaning your heart pumps more blood which puts it under more stress. On hot days, you must stay hydrated, avoid doing outdoor activities in the hottest parts of the day, wear sunblock, and dress in lightweight and light-coloured clothes.

During the winter season or cold days, your blood vessels contract and coronary arteries constrict; this is because your heart tries to keep the blood further inside, aiming to maintain warmth for the vital organs. With this process, your blood pressure may increase, putting you at a high risk of heart attack and stroke. 

You must wear layers of clothes to keep warm and remember to bundle up, such as wearing gloves, a hat or a scarf that covers your mouth. Do your exercise indoors as much as possible and keep your body hydrated. Get yourself vaccinated against winter viruses, such as the flu. You may also want to avoid added calories from cold drinks [5].

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Photograph: Jelena Stanojkovic/Shutterstock

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