Heart deaths caused by extreme heat in the US expected to TRIPLE in coming decades, study warns

Extreme heat brought on by climate change could see cardiovascular deaths triple within 50 years, warns a new study.

In a scenario where only minimal efforts to reduce emissions were made, heat-influenced cardiovascular deaths – including by stroke and heart attack – could increase by as much as 233 percent over the next 13 to 47 years, scientists predict.

Currently, one person dies every 33 seconds in the United States from cardiovascular disease, which describes diseases to the heart or blood vessels. 

The research team behind the study, published in the American Heart Association journal Circulation, warned deaths will be more prevalent among elderly and black populations.

The study’s lead author, Dr Sameed Khatana, an assistant professor of medicine at the University of Pennsylvania and a staff cardiologist at the Philadelphia Veterans Affairs Medical Center, said his research demonstrated the growing role the climate will play in our lives as the climate crisis continues

Researchers predicting cardiovascular death rates brought on by elevated temperatures warn they could more than double across the United States.

The researchers advise that more aggressive policies to reduce greenhouse gas emissions could reduce the number of deaths from extreme heat.

Between 2008 and 2019, extreme heat in the US was associated with 1,651 excess cardiovascular deaths each summer.

How much – and how quickly – greenhouse gas emissions rise in the coming decades will have a profound effect on extreme heat and peoples’ health.

The study, from researchers at the University of Pennsylvania, previously examined county-by-county data in the US to demonstrate the link between a greater number of extreme heat days and an increase in cardiovascular deaths between 2008 and 2017.

This previous data formed a benchmark for the analysis in the new study, which used models for future greenhouse gas emissions as well as the future socioeconomic and demographic makeup of the US population to predict the possible impact between 2036 and 2065.

They estimated the excess number of cardiovascular deaths associated with extreme heat by comparing the predicted number of deaths for each county if no extreme heat occurred with the number of excess deaths if the projected number of heat days occurred.

The analysis revealed that even if currently proposed reductions in emissions were fully implemented and adhered to, excess cardiovascular deaths due to extreme heat would be 162 percent higher by the middle of the century compared to the 2008-2019 baseline.

Even worse, if greenhouse gas emissions were not strictly implemented, excess cardiovascular deaths due to extreme heat would be projected to increase by 233 percent in the coming decades.

Depending on how aggressively green policies are implemented, adults aged 65 and older are projected to have a 2.9 to 3.5 times greater increase in cardiovascular death due to extreme heat, compared with those aged between 20 and 64.

Non-Hispanic black adults would also be projected to have a 3.8 to 4.6 times greater increase in cardiovascular death due to extreme heat when compared with non-Hispanic white adults, depending on how strictly green policies are implemented and adhered to.

Projected increases in deaths due to extreme heat were not significantly different among adults in other racial or ethnic groups or between genders.

The study’s lead author, Dr Sameed Khatana, an assistant professor of medicine at the University of Pennsylvania and a staff cardiologist at the Philadelphia Veterans Affairs Medical Center, said his research demonstrated the growing role the climate will play in our lives as the climate crisis continues.

‘Climate change and its many manifestations will play an increasingly important role on the health of communities around the world in the coming decades,’ Dr Khatana explained.

‘Climate change is also a health equity issue as it will impact certain individuals and populations to a disproportionate degree and may exacerbate preexisting health disparities in the US.

‘The magnitude of the percent increase was surprising.

‘This increase accounts for not only the known association between cardiovascular deaths and extreme heat but is also impacted by the population getting older and the proportionate increases in the number of people from other races and/or ethnicities in the US.’

Dr Khatana continued: ‘Previous studies have suggested black residents may have less access to air conditioning; less tree cover; and a higher degree of the ‘urban heat island effect’ — built-up areas having a greater increase in temperature than surrounding less-developed areas.

‘Living conditions may also have a role in terms of social isolation, which is experienced by some older adults and has previously been linked with a higher probability of death from extreme heat.’

The study’s projections also raise questions over whether infrastructure interventions, such as increasing tree cover in certain neighborhoods, could reduce the number of people affected by extreme heat in the US – though some European studies suggest this prove true.

As a baseline, the researchers used county-by-county records from 2008-2019 for deaths during summer months with a primary cause of any cardiovascular condition (including heart attack and stroke), and related data such as the age, sex, race and ethnicity of each person who died and the number of extreme heat days (days with a maximum heat index of 90°f – 32.22°C – or higher) during the month of the death.

The heat index considers both heat and humidity because that reflects how the human body experiences high temperatures, with high humidity interfering with the body’s ability to release heat by sweating.