Clinical PaperEarly coronary angiography and induced hypothermia are associated with survival and functional recovery after out-of-hospital cardiac arrest☆
Introduction
Out-of-hospital cardiac arrest (OHCA) is the third leading cause of death in North America, afflicting an estimated 382,000 persons in the US per year,1 with a case-mortality rate of 94.7%.2 Reversal of cardiac arrest requires rapid restoration of cardiac activity using defibrillation, reperfusion, mechanical or pharmacological support. Differences between communities and emergency medical services (EMS) response systems contribute to differences in survival after OHCA between regions.2, 3
In-hospital interventions after OHCA4, 5, 6, 7 may prevent secondary injury and ameliorate ischemia-reperfusion injury to multiple organs, especially the heart and brain.8 Induced hypothermia,9, 10 coronary artery reperfusion,11, 12, 13 hemodynamic optimization,7, 14 ventilator management15 and neurological prognostication16 all can influence outcomes. However, the use of these interventions is variable. While there are a number of European studies about the prevalence of hypothermia implementation,17, 18, 19 in North America neither the prevalence of these intervention nor the relationship of these interventions with patient outcomes have been measured.
This study was a planned secondary analysis of a randomized controlled trial to examine the relationship between in-hospital interventions and outcomes after OHCA in a large North American network. The parent trial tested the influence of two EMS interventions, which were found to have no effect on outcome.20, 21 The primary hypothesis of this study was that early coronary angiography or reperfusion and induced hypothermia are associated with survival and favorable functional status after OHCA.
Section snippets
Study design and setting
Between June 2007 and October 2009, 10 US and Canadian clinical sites in the Resuscitation Outcomes Consortium (ROC) enrolled consecutive OHCA patients treated by 150 EMS agencies in a multicenter, randomized controlled trial (ROC-PRIMED; clinicaltrials.gov NCT00394706). This trial tested the effect on functional recovery and on survival to hospital discharge of performing cardiopulmonary resuscitation (CPR) for a brief (∼30 s) interval or for 3 min prior to rhythm analysis and defibrillation
Results
Of 16,875 subjects treated by EMS, 3981 (23.6% of all subjects) arrived at a hospital and had pulses lasting for >60 min (Fig. 1). A total of 1317 subjects (33.1% of hospitalized; 7.8% of total) survived to hospital discharge, and 1006 (25.3% of hospitalized; 6.0% of total) had favorable functional status at hospital discharge (Table 1).
Subjects were treated in 151 hospitals with a median of 262 (IQR 172, 419) beds of which 72 (47.7%) had residency programs, and 21 (14.0%) were level 1 trauma
Discussion
This study confirms that use of induced hypothermia and a strategy of early coronary angiography and reperfusion are associated with survival and favorable functional outcomes after OHCA. These are the largest prospective data from a North American cohort to date to provide estimates of the rate early coronary angiography (19.2%) and induced hypothermia (39.3%) for OHCA patients. These procedures are used more often in hospitals that treat higher numbers of OHCA subjects, and the number of
Limitations
This observational study cannot establish causal connections between hospital interventions, survival and functional outcome. Survival bias may contribute to apparent beneficial effects of coronary reperfusion or hypothermia, because patients who are very unstable and die soon after cardiac arrest are less likely to receive further interventions. Clinician assessment of prognosis through unmeasured variables may have influenced the selection of patients for treatment.
Conclusions
Early coronary angiography and induced hypothermia are associated with improved outcomes after OHCA. Hospitals that treat a higher numbers of OHCA subjects are more likely to attempt early coronary reperfusion and to induce hypothermia, and these hospitals have higher rates of favorable outcome.
Conflict of interest statement
There are no reported conflicts of interest directly related to this work. The ROC is supported by a series of cooperative agreements to nine regional clinical centers and one Data Coordinating Center (5U01 HL077863 – University of Washington Data Coordinating Center, HL077866 – Medical College of Wisconsin, HL077867 – University of Washington, HL077871 – University of Pittsburgh, HL077872 – St. Michael's Hospital, HL077873 – Oregon Health and Science University, HL077881 – University of
Acknowledgements
A preliminary version of these data was presented as a Poster and Abstract at the American Heart Association Scientific Sessions (Resuscitation Science Symposium Meeting) on November 3, 2012. Circulation 2012: 126: A154.
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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2013.12.028.