Scientists have long known that temperature changes affect the incidence of heart attacks. However, most of the research done to date has been conducted in temperate climates, where temperatures vary widely.
Now a team of researchers has investigated how the narrow temperature ranges of a tropical climate affect the incidence of a specific type of myocardial infarction (the medical term for a heart attack) in Singapore. The researchers say their findings, published in the journal Science of the total environmentmay have implications for health policies for populations in cosmopolitan cities in the tropics.
“Using 10 years of nationally collected data, we found strong evidence that a 1°C drop in ambient temperature increased the risk of any type of acute myocardial infarction in the population by 12 percent,” said co-senior author Professor Marcus Ong, director. from the Health Services & Systems Research Program and the Duke-NUS Medical School’s Pre-hospital & Emergency Research Center (PERC).
“In addition, people aged 65 and older appeared about 20 percent more vulnerable to colder temperatures compared to younger people,” added Prof. Ong, who is also a senior consultant in the emergency medicine department at Singapore General Hospital (SGH).
The study, which was conducted in collaboration with Singapore’s National Environment Agency (NEA), analyzed daily patient records from the Singapore Myocardial Infarction Registry. The researchers were specifically looking for people who had a non-ST segment elevation myocardial infarction (NSTEMI). This is a type of acute heart attack that occurs when a blood vessel that supplies the heart becomes partially blocked. When doctors examine the patient’s electrocardiogram (ECG) results, they don’t find the easily recognizable ST elevation indicative of another type of heart attack, STEMI, which occurs when the coronary artery is completely blocked. Since the 1980s, the incidence of NSTEMI has increased while that of STEMI has decreased.
The researchers were able to collect 60,643 reports of NSTEMI between 2009 and 2018. They then statistically analyzed how the onset of NSTEMI in these patients correlated with local meteorological data obtained from weather stations across Singapore, including average temperature and rainfall.
Cooler ambient temperatures were independently associated with an increased risk of NSTEMI up to 10 days after a temperature drop. There were no sex differences regarding the effects of warmer or colder temperatures on NSTEMI risk. Also, changes in rainfall were not associated with an increased risk.
“Our study found that even in a relatively warm part of the world, cooler ambient temperatures increased the risk of heart attacks,” says Dr. Andrew Ho, one of the study’s first authors, who is an Assistant Professor at PERC and an Associate Consultant in SGH’s Department of Emergency Medicine. “This improves our understanding that deviations from the temperature to which one is accustomed can lead to harmful physical stress. Consistent with our previous studies showing that the elderly were more susceptible to environmental stressors, including air pollution, we found some evidence that this group of individuals walked. a greater risk of heart attacks at lower temperatures.”
“There are several individual-level risk factors for cardiovascular disease, but none are as commonly experienced as weather patterns,” said Dr. Joel Aik, an environmental epidemiologist and co-senior author of the NEA study, who is also an adjunct is an assistant professor. with PERC. “Daily weather variations may lead to cardiovascular disease in at-risk individuals, with particular implications for Singapore’s aging population. In the context of climate change, these findings highlight a risk factor that poses a significant risk to public health.”
Further studies over a longer period of time are needed to confirm the results. The team also recommends research that helps identify the biological pathways involved in increased vulnerability of the elderly to cold-related NSTEMI in the tropics.
Materials supplied by Duke-NUS Medical School. Note: Content is editable for style and length.