Heat waves increase heart risk

Extreme temperatures -- heat waves or cold spells -- may increase the risk of premature cardiovascular disease death, Australian researchers say. Lead author Cunrui Huang of the School of Public Health and Institute of Health and Biomedical Innovation at Queensland University of Technology in Brisbane examined the association between daily average temperature and "years of life lost" due to cardiovascular disease. Exposure to extreme temperatures can trigger changes in blood pressure, blood thickness, cholesterol and heart rate, Huang explained. "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. Huang and colleagues collected data on daily temperatures in Brisbane from 1996 to 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 with the coldest 1 percent of days -- 53 degrees -- characterized as cold spells and the hottest 1 percent -- 84.5 degrees -- heat waves, Huang said. The study, published in the journal Circulation: Cardiovascular Quality and Outcomes, found the risk of premature cardiovascular disease death rose more when extreme heat was sustained for two or more days.