Near-Infrared Spectroscopy Patterns as Indicator of Perioperative Stroke in Acute Type A Aortic Dissection

Neurologic complications remain a major cause of morbidity in patients undergoing surgical repair of acute type A aortic dissection (ATAAD). Near-infrared spectroscopy (NIRS) is used for continuous, noninvasive monitoring of cerebral oxygenation during cardiopulmonary bypass; however, its utility in predicting perioperative stroke remains inadequately defined. A retrospective cohort study was conducted in 175 patients who underwent ATAAD repair between 2015 and 2023. Patients were stratified by the occurrence of perioperative stroke (n = 47, 26.9%). Intraoperative NIRS data, including cerebral regional oxygen saturation (crSO₂) values at key procedural timepoints and signal variability with band power and crest factor, were analyzed in conjunction with demographic, anatomic, and postoperative variables. Patients with stroke exhibited significantly lower minimum NIRS values during deep hypothermic circulatory arrest (DHCA) (left: 46.7 (15.7-69.4) vs. 52.2 (22.0-81.6); right: 47.0 (23.3-78.5) vs. 56.3 (20.2-85.0); p = 0.03 and p < 0.01). Within the stroke group, NIRS signal variability was significantly greater (crest factor and standard deviation; p < 0.05) and showed blunted recovery post-DHCA. crSO₂ values below 50% were more frequent in the stroke group (p = 0.04). Right common carotid artery dissection was more prevalent in the stroke group (40% vs. 23%, p = 0.04). ICU length of stay was significantly increased in patients with stroke. Cerebral desaturation and NIRS signal instability during DHCA are significantly associated with perioperative stroke in ATAAD repair. These findings support the prognostic value of intraoperative cerebral oximetry in detecting critical ischemic thresholds and identifying at-risk perfusion patterns.