(A-144) The Effect of Heat on The Heart Failure Exacerbation Caused by Alpha-blockers

Background: Elderly individuals are especially at risk during extreme heat events due to their thermoregulatory response is often impaired. Previous studies have indicated that the use of α-blockers is associated with an increased the risk of heart failure hospitalization. Alpha blockers are frequently prescribed to older adults for the treatment of benign prostatic hyperplasia, therefore it is worth exploring whether ambient heat increases the risk of heart failure exacerbation in those using alpha blockers.

Objectives: To assess the association between ambient heat and heart failure hospitalization among individuals using alpha blockers.

Methods: We identified cases of heart failure exacerbation in adults over 65 years old using α-blockers in Taiwan. We used 5 alpha reductase inhibitor and muscarinic receptor antagonists as negative control. We employed a time-stratified, bidirectional case-crossover study design. The study period included summer months May – September from 2016 through 2019. We then estimated odds of heart failure exacerbation by heat index (HI) percentile categories using conditional logistic regression with a time-stratified case-crossover design.

Results: There were 29,346 cases of heart failure exacerbation among alpha blocker users and 10,049 cases in the negative control group. The incidence rates were 14.2 per 1,000 person-year and 11.8 per 1,000 person-year respectively. Odds ratios of heart failure exacerbation in alpha blocker users for HI >99th, 95–98th, 85–94th, and 75–84th percentiles compared with the 25–74th percentile was 1.17 (95% CI, 1.06–1.3), 1.01 (0.96–1.08), 1.07 (95% CI, 1.02–1.13), 1.07 (95% CI, 1.01–1.12), 0.78 (95% CI, 0.64–0.95) respectively. In all HI categories, the odds ratios for negative controls do not show statistical significance.

Conclusions: High ambient temperature was associated with increased heart failure exacerbation risk in alpha blocker users.