Targeted Temperature Management After In-Hospital Cardiac Arrest: An Ancillary Analysis of Targeted Temperature Management for Cardiac Arrest With Nonshockable Rhythm Trial Data

Abstract

Background: Targeted temperature management (TTM) currently is the only treatment with demonstrated efficacy in attenuating the harmful effects on the brain of ischemia-reperfusion injury after cardiac arrest. However, whether TTM is beneficial in the subset of patients with in-hospital cardiac arrest (IHCA) remains unclear.

Research question: Is TTM at 33 °C associated with better neurological outcomes after IHCA in a nonshockable rhythm compared with targeted normothermia (TN; 37 °C)?

Study design and methods: We performed a post hoc analysis of data from the published Targeted Temperature Management for Cardiac Arrest with Nonshockable Rhythm randomized controlled trial in 584 patients. We included the 159 patients with IHCA; 73 were randomized to 33 °C treatment and 86 were randomized to 37 °C treatment. The primary outcome was survival with a good neurologic outcome (cerebral performance category [CPC] score of 1 or 2) on day 90. Mixed multivariate adjusted logistic regression analysis was performed to determine whether survival with CPC score of 1 or 2 on day 90 was associated with type of temperature management after adjustment on baseline characteristics not balanced by randomization.

Results: Compared with TN for 48 h, hypothermia at 33 °C for 24 h was associated with a higher percentage of patients who were alive with good neurologic outcomes on day 90 (16.4% vs 5.8%; P = .03). Day 90 mortality was not significantly different between the two groups (68.5% vs 76.7%; P = .24). By mixed multivariate analysis adjusted by Cardiac Arrest Hospital Prognosis score and circulatory shock status, hypothermia was associated significantly with good day 90 neurologic outcomes (OR, 2.40 [95% CI, 1.17-13.03]; P = .03).

Interpretation: Hypothermia at 33 °C was associated with better day 90 neurologic outcomes after IHCA in a nonshockable rhythm compared with TN. However, the limited sample size resulted in wide CIs. Further studies of patients after cardiac arrest resulting from any cause, including IHCA, are needed.

Keywords: in-hospital cardiac arrest; moderate therapeutic hypothermia; neurological outcome; nonshockable rhythm.