Preoperative Hematocrit Is Not Associated With Stroke After Surgery for Acute Type A Aortic Dissection.

Objective: To determine the impact of hematocrit on adverse neurologic events after acute type A aortic dissection (ATAAD) repair under deep hypothermic circulatory arrest.

Design: Retrospective study of consecutive aortic surgeries from 2010 to 2021.

Setting: Single institution.

Participants: Patients undergoing open ATAAD repairs, excluding those with preoperative cerebral malperfusion syndrome (defined as neurologic deficit with radiographic evidence of cerebral branch vessel malperfusion).

Interventions: Patients were split into three groups: normal, low, and high hematocrit.

Measurements & main results: A total of 527 patients were included, of which 355 (67.3%) had normal hematocrit, 143 (27.1%) had low hematocrit, and 29 (5.5%) had high hematocrit. Overall, 20 (3.8%) patients had a postoperative stroke, which was comparable across groups (p = 0.59). Patients with normal hematocrit had lower in-hospital mortality (p = 0.02) and lower transfusion rates (p < 0.001), while re-exploration for bleeding was similar across groups (p = 0.68). After multivariable adjustment, there was no association between hematocrit and postoperative stroke (odds ratio [OR]: 1.00, 95% confidence interval [CI]: 0.99, 1.00, p = 0.79). Compared with normal hematocrit, there was no association between low hematocrit (OR: 1.59, 95% CI: 0.77, 3.28, p = 0.21) or high hematocrit (OR: 2.48, 95% CI: 0.74, 8.29, p = 0.14) and in-hospital mortality.

Conclusions: Preoperative hematocrit was not associated with stroke or mortality after ATAAD repair. The rheologic effect of hematocrit on cerebral perfusion under deep hypothermia may be minimal.