The European System for Cardiac Operation Risk Evaluation (EuroSCORE) is widely used for predicting in-hospital mortality after cardiac surgery. A new score (EuroSCORE II) has been recently developed to update the previously released versions. This study was undertaken to validate EuroSCORE II, to compare its performance with the original EuroSCOREs and to evaluate the effects of the removal of those factors that were included in the score even if they were statistically non-significant. Data on 12 325 consecutive patients who underwent major cardiac surgery in a 6-year period were retrieved from three prospective institutional databases. Discriminatory power was assessed using the c-index and comparison among the scores' performances was performed with Delong, bootstrap, and Venkatraman methods. Calibration was evaluated with calibration curves and associated statistics. The in-hospital mortality rate was 2.2%. The discriminatory power was high and similar in all algorithms (area under the curve 0.82, 95% CI: 0.79–0.84 for additive EuroSCORE; 0.82, 95% CI: 0.79–0.84 for logistic EuroSCORE; 0.82, 95% CI: 0.80–0.85 for EuroSCORE II). The EuroSCORE II had a fair calibration till 30%-predicted values and over-predicted beyond. The removal of non-significant factors from EuroSCORE II did not affect performance, being both the calibration and discrimination comparable. This validation study demonstrated that EuroSCORE II is a good predictor of perioperative mortality. It showed an optimal calibration until 30%-predicted mortality. Nonetheless, it does not seem to significantly improve the performance of older versions in the higher tertiles of risk. Moreover, it could be simplified, as the removal from the algorithm of non-significant factors does not alter its performance.

The number of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) worldwide is increasing dramatically [1], and reports from China, Iran, Italy and other areas hit hard by SARS-CoV-2 are chilling. The metropolitan area of Milan and its surrounding region of the Lombardy are one of the worst affected in Italy, and Europe at the moment. As of 29 March 2020, there have been 97 689 cases with 10 779 fatalities due to COronaVIrus Disease 2019 (COVID-19) in whole of Italy; of these, 41 007 (6360 fatalities) have occurred in Lombardy region [2]. In order to slow down viral transmission, local authorities and the Italian government have imposed strong containment measures by quarantining initial COVID-19 clusters and followed by a complete nationwide lock-down. The exponential increase in COVID-19-positive patients and the dramatically increasing need for intensive care unit (ICU) surge capacity for the management of critically ill patients has led the emergency task force of the Lombardy region to reallocate ICU resources [3]. In addition, elective surgery has been cancelled and beds dedicated to cardiac, neurosurgery and partially coronary care units reassigned to COVID-19-patients. For this reason, 16 of the 20 cardiac surgical units in the Lombardy region have discontinued their activities, with the remaining 4 units forming ‘the hub’ for the 16 other closed units (spokes). In this hub-and-spoke system, all urgent and emergency cases are sent to these 4 units, including those that cannot be delayed for more than 60 days. Moreover, beds for critically ill patients are also obtained from the reconversion of operation and recovery rooms (A. Parolari, personal communication).