Letter by Guo et al Regarding Article, "Endovascular Versus External Targeted Temperature Management for Patients With Out-of-Hospital Cardiac Arrest: A Randomized, Controlled Study".

To the Editor: We read with great interest the recent article by Deye et al concerning “Endovascular Versus External Targeted Temperature Management for Patients With Out-of-Hospital Cardiac Arrest.” Their excellent study on this important subject deserves applause. However, we have some concerns about the strength of their conclusion that endovascular cooling was not significantly superior to basic external cooling in terms of a favorable outcome. We think that endovascular cooling has more advantages than surface cooling. Time to target temperature (33°C) was significantly shorter and target hypothermia was more strictly maintained in the endovascular than in the surface group. In addition, it is capable of a more controlled rewarming period. Recent studies have demonstrated that early application of therapeutic hypothermia, rapid achievement of target cooling temperature, and optimal rewarming strategy are recognized as the key factors for improving survival and neurological outcomes. Therefore, from the theoretical aspect, endovascular cooling could improve survival and neurological outcomes in comparison with surface cooling. Furthermore, although no significant difference in neurological outcomes and hospital mortality was observed between the surface and endovascular cooling methods, only 28% of patients in the endovascular cooling group survived after major neurological damage. Given that so few survived, we think that the superiority of endovascular cooling might be not fully demonstrated. Therefore, we propose that the effect of this cooling method on neurological outcome and hospital mortality after cardiac arrest be studied in larger numbers of patients.