Fact check: It's true, climate change increases risk of heart failure deaths

A new study published by Harvard School of Public Health has shown that extreme temperatures, caused by climate change, are linked with heart disease deaths.

This is contrary to a claim by a social media user who claimed that heart failure due to climate change is a joke and is an attempt to control people.

The study, which was published on December 12, 2022 in the journal circulation showed that temperature extremes increased the risk of death among people with cardiovascular diseases, and that one in every 100 cardiovascular deaths may be due to extremely hot or cold days which have been blamed on climate change.

When conducting the study, researchers analysed data from 1979 to 2019, from more than 32 million cardiovascular deaths in 567 cities, in 27 countries.

They also compared heart related deaths that took place on the hottest and coldest days, with those deaths that happened on days that had optimal temperatures.

They established that for every 1,000 heart related deaths, there were more than two excess deaths on extremely hot days, and more than nine excess deaths on extremely cold days.

They also found that, among the types of heart diseases, most additional deaths occurred among people with heart failure.

Another study titled Climate change and cardiovascular disease: implications for global health stated that in 2019, approximately 18.6 million people died from cardiovascular disease worldwide.

It also states that direct exposure to extreme weather events, ambient temperatures, heat waves, cold spells and pollutants can exacerbate disease in individuals with underlying cardiovascular conditions and contribute to the development of disease in those without known cardiovascular conditions.

“The indirect effects of climate change on cardiovascular health involve multiple complex exposure pathways including access to healthy food and clean water, transportation, housing, electricity, communication systems, medical assistance and other social determinants of health, all of which are essential for the maintenance of cardiovascular health,” says the study.

Anthropogenic climate change has resulted in extreme temperatures, altered meteorology and extreme weather events. Climate change can affect cardiovascular health both directly and indirectly.

Direct pathways occur through exposure to extreme temperatures and poor air quality, which promote systemic inflammation, indirect pathways include exposure to the byproducts of climate change such as damaged health infrastructure, wildfires and secondary pollutants,” said the study.

“Temperature extremes might have an influence on the risk of developing diabetes and might be associated with poor glycaemic control in patients with underlying diabetes.
 

Globally the relative risk of all-cause death amid cardiovascular death increases sharply if the mean daily temperature goes above or below the optimum temperature,” adds the study.

Another study titled Impact of global warming on weight of patients with heart failure during the 2019 heatwave in France involved researchers in France collecting and analysing data from people with heart disease using an electronic chronic disease management system.

The data had been collected between June 2019 to September 2019 to assess the effect of two heat waves that had occurred during that period.

The study, led by Dr Francois Roubille, president-elect of the Heart Failure group from the French Society of Cardiology (FSC) also sought to establish the association between people’s weight, the ambient temperature on the same day, and the temperature two days prior to the weight measurement.

They found a strong association between temperature and weight, with weight dropping as the temperature rose.

“When healthy people drink more fluids during hot weather, the body regulates their urine output. This does not work in the same way for people with heart failure because they take diuretics. Above all, they receive drugs that could lead to side effects under extreme temperature, for instance, diuretics,” said Dr Roubille.

The study also noted that the weight of people with heart failure changed because of the heatwave, an observation that researchers thought indicated a worsening of the patients’ conditions.

The Centers for Disease Control (CDC) states in their Heat Exposure and Cardiovascular Health Report that extreme heat events are a leading cause of weather-related injury and death in the United States, and under a changing climate, are predicted to increase in both frequency and intensity.

“Prolonged heat exposure from extreme heat events places an increased strain on the heart and may lead to heat-related illness if the cardiovascular system fails to properly thermo-regulate internal body temperature. Every individual is susceptible to heat-related illness, however, those with reduced cardiovascular function and pre-existing cardiovascular diseases are at a greater risk for morbidity and mortality during extreme heat events,” says CDC.

“In a hot environment, the autonomic nervous system causes widening of the blood vessels in the skin to allow for greater heat transfer from the body to its surroundings. A portion of blood from abdominal organs, and in severe cases all organ systems, is redirected to the skin to accommodate the dissipation of internal heat,” narrates the report.

“Maintaining a steady blood pressure during such significant vasodilation requires an increased cardiac output which is achieved through an elevation in heart rate and myocardial contractility. Usually the cardiovascular systems of the young and healthy can adapt to such demands with respect to heat. However, in the elderly and those with pre-existing cardiovascular conditions such as coronary heart disease and heart failure, the heart is not as proficient at meeting the increased demand required to rid the body of the excess heat. Individuals that belong to these populations are more susceptible to adverse health outcomes from extreme heat exposure,” adds the report.

To survive a heat wave, health care providers may recommend that people constantly hydrate, seek air-conditioned buildings, wear light-colored clothing and wide brimmed hats, and participate less in outdoor activities than extreme heat events. In the workplace, a way to address heat stress is to reduce the physical workload per individual and encourage more frequent and longer breaks to allow the workers to dissipate their excess internal heat.

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This fact check was produced by Nation with support from Code for Africa’s Pesa Check, International Fact Checking Network, and African Fact Checking Alliance Network.