Association of low body temperature and poor outcomes in patients admitted with worsening heart failure: A substudy of the efficacy of vasopressin antagonism in heart failure outcome study with tolvaptan (EVEREST) trial

Aims Risk stratification in patients admitted with worsening heart failure (HF) is essential for tailoring therapy and counselling. Risk models are available but rarely used, in part because many require laboratory and imaging results that are not routinely available. Body temperature is associated with prognosis in other illnesses, andwe hypothesized that low body temperature would be associated with worse outcomes in patients admitted with worsening HF. Methods and results The Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study with Tolvaptan (EVEREST) trial was an eventdriven, randomized, double-blind, placebo-controlled study of tolvaptan in 4133 patients hospitalized for worsening HF with an EF<40%. Co-primary endpointswere all-cause mortality and cardiovascular (CV) death or HF rehospitalization. Body temperature was measured orally at randomization and entered in analyses both as a continuous variable and categorized into three groups (<36°C, 36-36.5°C, and>36.5°C) using Coxregression models. The composite ofCVdeath or HF rehospitalization occurred in 1544 patients within 1 year. For every 1°C decrease in body temperature, the risk of adverse outcomes increased by16%[hazard raio (HR) 1.16,95%confidence interval (CI) 1.04-1.28], after adjustment for age, gender, race, systolic blood pressure, EF, blood urea nitrogen, and serum sodium. In fully adjusted analysis, the risk of adverse outcomes in the lowest body temperature group (<36°C) was 51% higher than that of the index group (>36.5°C) (HR 1.35, 95% CI 1.15-1.58). Conclusions Low body temperature is an independent marker of poor cardiovascular outcomes in patients admitted with worsening HF and reduced EF.