Therapeutic hypothermia and coronary angiography are mandatory after out-of-hospital cardiac arrest: Yes
Coronary artery disease among out-of-hospital cardiac arrest patients with no obvious extra-cardiac cause 
ST elevation or LBBB
Significant CAD (%)
Angiographic ACS (%)
Spaulding et al. 
Anyfantakis et al. 
Dumas et al. 
Sideris et al. 
Hypoxic–ischaemic brain injury is the cause of death in approximately two-thirds of the patients who die after admission to an intensive care unit (ICU) following OHCA . Although much of this brain injury occurs during the period of cardiac arrest (no flow) and during cardiopulmonary resuscitation (low flow), the damage may continue to evolve for hours to days after circulation and oxygenation have been restored . There is evidence that a period of mild hypothermia started after return of spontaneous circulation (ROSC) can reduce the severity of neurological injury after cardiac arrest. One randomised trial  and a pseudorandomised trial  demonstrated improved neurological outcome among comatose survivors of ventricular fibrillation out-of-hospital cardiac arrest (VF OHCA) who were cooled to 32–34 °C for 12–24 h compared with those who were not cooled. On the basis of these results and data from animal studies , in 2003 the International Liaison Committee on Resuscitation (ILCOR) recommended the use of therapeutic hypothermia (TH) for patients remaining comatose after VF OHCA . At that time, there were few data on the use of TH in comatose patients following cardiac arrest from other rhythms or after in-hospital cardiac arrest (IHCA), but the ILCOR advisory statement indicated that TH might also be beneficial under such circumstances. Since then, several observational studies with historical or concurrent control groups have shown benefit after cooling in comatose survivors after OHCA from non-shockable rhythms , although such studies carry risk of bias, and some observational studies have shown no benefit for TH after cardiac arrest from non-shockable rhythms . Contrary to the prevailing opinion several years ago, mild hypothermia may also be beneficial in the presence of cardiogenic shock: in a case series of 14 such patients, cooling improved cardiac index, stroke volume and mean arterial blood pressure .
In the recent targeted temperature management (TTM) trial unconscious survivors of all-rhythm OHCA were assigned randomly to TTM at either 33 or 36 °C; there was no difference in all-cause mortality or neurological function at 180 days . The message from this study is not that we should abandon temperature control; patients in both arms of the trial had their temperature controlled and, most importantly, fever, which is associated with poor neurological outcome after cardiac arrest , was prevented. Even after return to normothermia after a period of TH, continued temperature control is important. In a recent study of 270 patients resuscitated and treated with TH following all-rhythm OHCA, post-hypothermia fever of 38.5 °C or higher was associated with increased 30-day mortality even after controlling for potential confounders . The results of the TTM trial have left us with some uncertainty about the optimal target temperature but some form of temperature control after cardiac arrest remains important.
In the study of treated OHCAs in this issue, application of TTM was associated with improved survival, although after risk adjustment this association was lost . Given the prospective randomised data showing benefit for TTM after OHCA from shockable rhythms and the observational data showing benefit for TTM after OHCA from non-shockable rhythms, in our opinion TTM should be included as part of the post-resuscitation care of all comatose OHCA patients admitted to an ICU. Observational studies indicate that, after risk adjustment, optimal long-term outcomes after OHCA are achieved with a combination of TTM and PCI . Thus, in our opinion, all comatose survivors of OHCA without an obvious non-cardiac cause should undergo both PCI and TTM.
Conflicts of interest
JPN is Editor-in-Chief of Resuscitation. AC declares no conflicts of interest.