Does Extreme Temperature Influence Heart Disease Mortality

Severe temperatures increase the likelihood of heart failure mortality. It suggests the need for mitigating methods in an era of climate change.

Highlights:

Heart disease mortality rates are highest during extreme climatic conditions
Cold weather enhanced the likelihood of heart failure mortality by 37% and 12% due to extreme heat
It implies that climate change is a growing public health concern and emphasizes the importance of investigating it as a possible cause of health disparities

According to a new study published in the American Heart Association’s journal Circulation, excessively hot or cold temperatures increase a heart disease patient’s chance of death. The global research of more than 32 million cardiovascular deaths over 40 years measured more mortality on days when temperatures were at their greatest or lowest compared to more moderate climate days.

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‘People with heart failure are the most vulnerable to extreme cold and extreme heat days, with a 12% increased risk of death on extreme heat days and 37% on cold days.’

Impact of Climate Change on Heart Health

“It underscores the urgent need to develop measures that will help our society mitigate the impact of climate change on cardiovascular disease,” said study co-author Haitham Khraishah, M.D., a cardiovascular disease fellow at the University of Maryland School of Medicine (UMSOM) and University of Maryland Medical Center (UMMC).

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Heart Failure Mortality Rate Influenced by Weather

People with heart failure were the most likely to be negatively influenced by extreme cold and extreme heat days, with a 12% higher chance of dying on extreme heat days compared to optimal temperature days in a specific city. Cold temperatures elevated the chance of heart failure mortality by 37%.

The findings were based on an examination of health data from more than 32 million cardiovascular deaths that occurred between 1979 and 2019 in 567 cities across 27 nations and five continents. The definition of extreme weather varied by city. It was defined as the top or bottom 1% of the ‘minimum mortality temperature’, which is the temperature with the lowest death rate.

The researchers discovered that for every 1,000 cardiovascular deaths:

Hot days (over 86° F in Baltimore) were responsible for an additional 2.2 deaths

Extreme cold days (below 20° F in Baltimore) accounted for 9.1 extra deaths

People with heart failure had the highest number of extra deaths among all categories of cardiac disorders (2.6 additional deaths on extremely hot days and 12.8 on extremely cold days)

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Why Does Temperature Change Affect Heart Failure Patients

“While we do not know the reason why temperature effects were more pronounced with heart failure patients it could be due to the progressive nature of heart failure as a disease,” said Dr. Khraishah. “One out of four people with heart failure are readmitted to the hospital within 30 days of discharge, and only 20% of patients with heart failure survive 10 years after diagnosis.”

Climate change has been observed to induce weather extremes on both ends of the spectrum with hotter summers and colder winters. A 2021 study published in the journal Science discovered that Arctic warming created a chain reaction of events that disrupted the polar vortex, resulting in times of extreme cold in the Northern hemisphere.

Barrak Alahmad, M.D., Ph.D., research fellow at the Harvard T.H. Chan School of Public Health at Harvard University in Boston and a faculty member at the College of Public Health at Kuwait University in Kuwait City was the corresponding author of the study. Dr. Khraishah and Dr. Alahmad worked for four years with colleagues from more than 35 universities worldwide to create the heart disease mortality database for this study.

“This study provides an indisputable link between extreme temperatures and heart disease mortality from one of the largest multinational datasets ever assembled,” said Mark T. Gladwin, M.D., Dean, UMSOM, Vice President for Medical Affairs, University of Maryland, Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor. “The data can be more deeply mined to learn more about the role of health disparities and genetic predispositions that make some populations more vulnerable to climate change.”

According to Dr. Khraishah, such questions will be addressed in future research.

Some of the study’s drawbacks include a lack of data from South Asia, the Middle East, and Africa. Due to the absence of data, it is possible that excessive heat had a greater influence than was first recorded.

The researchers included humidity and air pollution, which could have contributed to an increase in mortality in areas with severe temperatures. They also considered the delayed effect of temperature on human health (lag effect) as well as the climate zone.

“This landmark paper is a call to view climate change as a growing public health concern and highlights the need to investigate it as a potential cause of health disparities,” said Stephen N. Davis, MBBS, Chair of the Department of Medicine at UMSOM and Physician-in-Chief at UMMC.

Source-Medindia

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