Australian researchers examined the association between daily average temperature and "years of life lost" due to cardiovascular disease.
Years of life lost measured premature death by estimating years of life lost according to average life expectancy.
"The findings are important because of how the body responds to temperate extremes, the growing obesity trend and Earth's climate changes," said Cunrui Huang, the study's lead researcher and scholar at the School of Public Health and Institute of Health and Biomedical Innovation at Queensland University of Technology (QUT) in Brisbane.
"With increasing rates of obesity and related conditions, including diabetes, more people will be vulnerable to extreme temperatures and that could increase the future disease burden of extreme temperatures," Huang said in a statement.
Researchers collected data on daily temperatures in Brisbane between 1996 and 2004 and compared them to documented cardiovascular-related deaths for the same period.
Brisbane has hot, humid summers and mild, dry winters. The average daily mean temperature was 68.9 degrees Fahrenheit (20.5 degrees Celsius), with the coldest 1 percent of days (53 F /11.7 C) characterised as cold spells and the hottest 1 percent (84.5 F/ 29.2 C ) heat waves.
Per 1 million people, 72 years of life were lost per day due to CVD, researchers said.
Risk of premature CVD death rose more when extreme heat was sustained for two or more days, researchers found.
"This might be because people become exhausted due to the sustained strain on their cardiovascular systems without relief, or health systems become overstretched and ambulances take longer to reach emergency cases," Adrian G Barnett, co-author of the study, said.
The study was published in the journal Circulation: Cardiovascular Quality and Outcomes.
