Cardiac output, heart rate and stroke volume during targeted temperature management after out-of-hospital cardiac arrest: Association with mortality and cause of death

AIM: Myocardial dysfunction and low cardiac index are common after out-of-hospital cardiac arrest (OHCA) as part of the post-cardiac arrest syndrome. This study investigates the association of cardiac index during targeted temperature management (TTM) with mortality.

METHODS: In the TTM-trial, which randomly allocated patients to TTM of 33 °C or 36 °C for 24 h, we prospectively and consecutively monitored 151 patients with protocolized measurements from pulmonary artery catheters (PAC) as a single site substudy. Cardiac index, heart rate and stroke volume were measured at 3 time-points during the 24 h TTM period and averaged. Uni- and multivariate Cox regression was used to assess association with mortality.

RESULTS: Of 151 patients, 50 (33%) were deceased after 180 days. Cardiac index during TTM was not significantly associated with mortality in univariate (HR: 0.84 [0.54-1.31], p = 0.59) or multivariate analyses (HRadjusted: 1.03 [0.57-1.83], p = 0.93). Cardiac index during TTM was also not significantly associated with non-neurological death (HRadjusted: 1.25 [0.43-3.59], p = 0.68). Higher heart rate (p = 0.03) and lower stroke volume (p = 0.04) were associated with increased mortality in univariate, but not multivariate analyses. No hemodynamic variables were associated with cerebral death, however, increasing lactate during TTM (HRadjusted: 2.15 [1.19-3.85], p = 0.01) and lower mean arterial pressure during TTM (HRadjusted: 0.89 [0.81-0.97], p = 0.008) were independently associated with non-neurological death.

CONCLUSION: Cardiac index during TTM after resuscitation from OHCA is not associated with mortality. Future studies should investigate whether certain subgroups of patients could benefit from targeting higher goals for cardiac index.