Optimizing Therapeutic Hypothermia Depths in Acute Type A Aortic Dissection Repair.

Introduction: Existing evidence regarding the impact of hypothermic circulatory arrest (HCA) depth in acute type A aortic dissection (ATAAD) repair lacks robustness concerning blood loss and mortality. We aimed to assess whether using mild and moderate HCA (MMHCA) versus deep and profound HCA (DPHCA) in ATAAD repair is associated with reduced bleeding risk, lower in-hospital mortality, and improved long-term survival.

Methods: This retrospective cohort study spanned from 2003 to 2023. ATAAD repair patients were identified from hospital records, with exclusion criteria applied to those who died before surgery, those with symptoms lasting longer than 14 d, and those who operated on without HCA. Patients in the DPHCA group underwent surgery with HCA (T ≤ 20°C), while those in the MMHCA group had temperatures ranging from 34°C to 20.1°C.

Results: Out of 549 eligible ATAAD patients, the MMHCA group exhibited a reduced rate of chest re-exploration for bleeding (39% versus 14%, P < 0.005), decreased blood loss after surgery (1637 mL versus 1045 mL, P < 0.005), and lower volumes for red blood cell transfusions (1375 mL versus 903 mL, P < 0.005) compared with the DPHCA group. Additionally, the MMHCA group had lower crude and age- and sex-adjusted in-hospital mortality rates, with a mortality rate ratio of 0.65 (P = 0.003). Cox regression analysis revealed a 25% reduction in long-term mortality for the MMHCA group compared with the DPHCA group (hazard ratio = 0.75; P = 0.045).

Conclusions: ATAAD repair using MMHCA and antegrade cerebral perfusion is associated with lower blood loss and improved immediate and long-term survival.