Deep hypothermic circulatory arrest (DHCA) is essential for pulmonary thromboendarterectomy (PTE). The optimal safe duration of DHCA remains controversial. This study evaluates the association between total DHCA duration and postoperative neurologic events and major adverse cardiac events (MACEs) following PTE.

All PTE patients at a single institution from October 2017 to March 2025 were retrospectively analyzed and categorized into “standard” and “extended” cohorts. Extended DHCA was defined as total time >1 standard deviation above the median (60 min). DHCA was performed at 20°C and limited to 20-min intervals with 10 min of reperfusion. Outcomes assessed included 30-d neurologic events and MACE. Independent associations were evaluated using inverse probability weighting with Firth bias reduction methods.

Extended DHCA patients exhibited higher residual pulmonary vascular resistance (4.0 versus 3.0 Wood Units, P = 0.032) but both groups were equally likely to achieve a 50% reduction from baseline (extended 44.8% versus standard 62%, P = 0.097). On inverse probability weighting analysis, DHCA duration was not independently associated with neurologic events (odds ratio [OR] 0.88, 95% confidence interval [CI] 0.01-8.04, P = 0.877). Peripheral arterial disease was independently associated with neurologic events (OR 22.3, 95% CI 7.46-4730, P < 0.001) along with extracorporeal membrane oxygenation use (preoperative and intraoperative) (OR 82.7). Extended DHCA time was independently associated with MACE (OR 6.46, 95% CI 0.90-228, P = 0.010), along with preoperative pulmonary vascular resistance (OR 1.18, 95% CI 1.00-1.84, P = 0.027).

Extended DHCA was not independently associated with neurological events after PTE but was independently associated with MACE. Balancing total circulatory arrest duration with complete bilateral endarterectomy is paramount for successful PTE surgery.