Optimal circulatory arrest temperature for aortic hemiarch replacement with antegrade brain perfusion

This study sought to identify the optimal temperature for moderate hypothermic circulatory arrest in patients undergoing elective hemiarch replacement with antegrade brain perfusion.

The Society of Thoracic Surgeons adult cardiac surgery database was queried for elective hemiarch replacements using antegrade brain perfusion for aneurysmal disease (2014-2019). Generalized estimating equations and restricted cubic splines were used to determine the risk-adjusted relationships between temperature as a continuous variable and outcomes.

Elective hemiarch replacement with antegrade brain perfusion occurred in 3898 patients at 374 centers with a median nadir temperature of 24.9°C (first quartile, third quartile = 22.0°C, 27.5°C) and median circulatory arrest time of 19 minutes (first quartile, third quartile = 14.0 minutes, 27.0 minutes). After adjustment for comorbidities, circulatory arrest time, and individual surgeon, patients cooled between 25 and 28°C had an early survival advantage compared with 24°C, whereas those cooled between 21 and 23°C had higher risks of mortality compared with 24°C. A nadir temperature of 27°C was associated with the lowest risk-adjusted odds of mortality (odds ratio, 0.62; 95% confidence interval, 0.42-0.91). A nadir temperature of 21°C had the highest risk of mortality (odds ratio, 1.4; 95% confidence interval, 1.13-1.73). Risk of experiencing a major morbidity was elevated in patients cooled between 21 and 23°C, with the highest risk occurring in patients cooled to 21°C (odds ratio, 1.12; 95% confidence interval, 1.01-1.24).

For patients with aneurysmal disease undergoing elective hemiarch with antegrade brain perfusion, circulatory arrest with a nadir temperature of 27°C confers the greatest early survival benefit and smallest risk of postoperative morbidity.