Heart rate before ICU discharge: a simple and readily available predictor of short- and long-term mortality from critical illness.

purposeA heart rate >90 bpm serves as one of four characteristics defining the systemic inflammatory response syndrome and is used in scoring systems to predict in-hospital mortality of intensive care unit (ICU) patients. Despite its central role in critical illness, specific data regarding the relationship between heart rate and outcome are rare.

methodsIn this post hoc analysis of a prospectively collected database, we analyzed the value of heart rate averaged from four predefined time points during the last 24 h before ICU discharge as a predictor of post-ICU in-hospital and post-hospital mortality in medical ICU patients. Furthermore, the relationship between heart rate and inflammation, as well as the influence of rate control medications on the association between heart rate and outcome were identified.

resultsAmong the 702 ICU patients discharged from the ICU, 7.1 % died before hospital discharge. At 4 years of follow-up, post-hospital mortality was 14.4 %. Multivariate Cox proportional hazards models revealed heart rate before ICU discharge (HR 5.95; 95 % CI 1.24-28.63; p = 0.03) as an independent predictor of post-ICU in-hospital mortality. Both heart rate (HR 2.56; 95 % CI, 1.05-6.34; p = 0.04) and the C-reactive protein serum concentration before ICU discharge (HR, 1.26; 95 % CI, 1.09-1.46; p = 0.002) were independently associated with post-hospital mortality. Heart rate control therapy reduced the risk of post-ICU in-hospital (HR 0.38; 95 % CI, 0.18-0.81; p = 0.01) and post-hospital (HR, 0.47; 95 % CI, 0.22-1.00; p = 0.05) mortality.

conclusionHeart rate evaluated 24 h before ICU discharge was independently associated with post-ICU in-hospital and post-hospital mortality. Pharmacological interventions to control heart rate may beneficially influence post-ICU mortality.