Same Procedure, Different Temperatures: Neurological and Survival Outcomes in Frozen Elephant Trunk Repair Under Mild vs. Moderate Hypothermia

All articles of this category (opens in new window) Background: Aortic arch repair carries substantial risks of mortality and neurological injury. While deep hypothermic circulatory arrest (DHCA) alone is no longer sufficient, selective antegrade cerebral perfusion (SACP) combined with moderate-to-mild systemic hypothermia is standard in many European centers. However, optimal temperature management during frozen elephant trunk (FET) procedures remains debated. The aim of this study was to evaluate stroke and mortality outcomes in FET patients treated with moderate or mild hypothermic circulatory arrest (HCA). Methods: This retrospective, dual-center study included 234 patients undergoing elective or urgent total aortic arch replacement with FET from January 2015 to March 2025. All surgeries used hypothermic circulatory arrest (HCA) with SACP. Patients were stratified by systemic temperature during HCA: mild hypothermia (>30°C; n = 62) and moderate hypothermia ( 18 years and complete arch replacement via FET under moderate or mild hypothermia. Postoperative neurological events, 30-day, and 1-year mortality were analyzed. Results: The mean age of the total cohort was 61.1 ± 11.2 years, with 64.1% male patients. Urgent cases accounted for 40.2%, and 28.6% were redo surgeries. Axillary cannulation was used in over 90%. Bilateral ACP was more frequent in the moderate hypothermia group (30°C: 22.6%; p < 0.001). Mild hypothermia patients had shorter cardiopulmonary bypass (126.5 vs. 211.1 minutes; p < 0.001) and cross-clamp times (74.1 vs. 124.1 minutes; p < 0.001). Stroke rates were similar (>30°C: 9.5% vs. 30°C: 1.6% vs. 0.999). Stroke tended to be higher with HCA > 50 minutes (12.8% vs. 5.3%; p = 0.126). Thirty-day (9.7% vs. 10.5%; p = 0.861) and 1-year mortality (11.3% vs. 13.4%; p = 0.674) showed no significant differences between the groups. Conclusion: Aortic arch repair in the FET technique with mild hypothermia and SACP provides neurological and survival outcomes comparable to moderate hypothermia. ACP minimizes the need for deep hypothermia. Systemic mild hypothermia, depending on the duration of circulatory arrest, can be recommended in elective and emergent aortic arch repair. No advantage of bilateral over unilateral ACP was observed. Prospective randomized trials are necessary to confirm the findings of this retrospective study. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany