Risk score for arch reconstruction under circulatory arrest with hypothermia: The ARCH score

Objective: Currently, there is no risk scores built to predict risk in thoracic aortic surgery. This study aims to develop and internally validate a risk prediction score for patients who require arch reconstruction with hypothermic circulatory arrest.
Methods: From 2002 to 2018, data for 2270 patients who underwent aortic arch surgery in 12 institutions in Canada were retrospectively collected. The outcomes modeled included in-hospital mortality and a modified Society of Thoracic Surgeons-defined composite for mortality or major morbidity. Multivariable logistic regression using least absolute shrinkage and selection operator selection method and mixed-effect regression model was used to select the predictors. Internal calibration of the final models is presented with an observed-versus-predicted plot.
Results: There were 182 in-hospital deaths (8.0%), and the incidence of Society of Thoracic Surgeons-defined composite for mortality or major morbidity was 27.9%. Variables that increased risk of mortality are age, chronic obstructive pulmonary disease, atrial fibrillation, peripheral vascular disease, New York Heart Association class >= III symptoms, acute aortic dissection or rupture, use of elephant trunk, concomitant surgery, and increased cardiopulmonary bypass time, with median c-statistics of 0.85 on internal validation. The c-statistics was 0.77 for the model predicting Society of Thoracic Surgeons-defined composite. Internal assessment shows good overall calibration for both models. Conclusions: We developed and internally validated a risk score for patients undergoing arch surgery requiring hypothermic circulatory arrest using a multicenter database. Once externally validated, the ARCH (Arch Reconstruction under Circulatory arrest with Hypothermia) score would allow for better patient risk-stratification and aid in the decision-making process for surgeons and patient prior to surgery.