Impact of Extremely Hot Days on Emergency Department Visits for Cardiovascular Disease among Older Adults in New York State.

Prior studies have reported the impact of ambient heat exposure on heat-related illnesses and mortality in summer, but few have assessed its effect on cardiovascular diseases (CVD) morbidity, and the association difference by demographics and season. This study examined how extremely hot days affected CVD-related emergency department (ED) visits among older adults from 2005-2013 in New York State. A time-stratified case-crossover design was used to assess the heat-CVD association in summer and transitional months (April-May and September-October). Daily mean temperature >95th percentile of regional monthly mean temperature was defined as an extremely hot day. Extremely hot days were found to be significantly associated with increased risk of CVD-related ED visits at lag day 5 (OR: 1.02, 95% CI: 1.01-1.04) and lag day 6 (OR: 1.01, 95% CI: 1.00-1.03) among older adults in summer after controlling for PM concentration, relative humidity, and barometric pressure. Specifically, there was a 7% increased risk of ischemic heart disease on the day of extreme heat, and increased risks of hypertension (4%) and cardiac dysrhythmias (6%) occurred on lag days 5 and 6, respectively. We also observed large geographic variations in the heat-CVD associations.