EuroSCORE II

EuroSCORE II (European System for Cardiac Operative Risk Evaluation) is the most widely used risk prediction model for operative mortality in adult cardiac surgery worldwide. This second-generation model, published by Nashef and colleagues in 2012, replaced the original EuroSCORE (1999) and the logistic EuroSCORE with an updated model derived from contemporary cardiac surgical practice. It provides individualized risk estimates that are essential for informed consent, clinical decision-making, quality benchmarking, and research in cardiac surgery.

EuroSCORE II was derived from a multinational database of 22,381 consecutive adult cardiac surgery patients operated on during a 12-week period in 2010 across 154 hospitals in 43 countries. The model incorporates 18 patient and procedure-related risk factors in a logistic regression framework. Patient factors include age, sex, renal function, extracardiac arteriopathy, poor mobility, previous cardiac surgery, chronic lung disease, active endocarditis, critical preoperative state, diabetes on insulin, NYHA functional class, left ventricular function, recent myocardial infarction, and pulmonary hypertension. Procedure factors include surgical urgency, weight of the procedure, and surgery on the thoracic aorta.

The model addresses several limitations of its predecessor. The original EuroSCORE was derived from 1995 data and increasingly overestimated mortality as cardiac surgical outcomes improved over time. EuroSCORE II uses contemporary data, improved statistical methodology, and a more nuanced coding of variables. For example, renal function is now classified using creatinine clearance categories rather than a simple creatinine cutoff, and pulmonary hypertension and NYHA class are treated as graded rather than binary variables.

Left ventricular function is one of the most important predictors in the model. The ejection fraction categories range from good (above 50%) to very poor (20% or below), with each step representing a significant increase in operative mortality risk. Severely impaired LV function limits the heart's ability to tolerate cardiopulmonary bypass, aortic cross-clamping, and the hemodynamic challenges of the immediate postoperative period. Combined with NYHA class, LV function provides a comprehensive assessment of cardiac functional status.

Surgical urgency dramatically affects predicted mortality. Elective cases carry the lowest risk, while salvage procedures (ongoing CPR or mechanical circulatory support en route to the operating room) carry the highest. Emergency and urgent cases have intermediate but substantially elevated risk. The weight of the intervention also matters significantly: isolated CABG carries the lowest procedural risk, while combined procedures (e.g., CABG plus valve replacement plus aortic surgery) carry progressively higher mortality risk due to longer operative times, more extensive surgical trauma, and greater hemodynamic manipulation.

EuroSCORE II serves multiple clinical functions beyond individual risk prediction. It enables quality benchmarking by comparing observed mortality rates against expected (EuroSCORE II-predicted) rates, producing observed-to-expected ratios that identify programs performing better or worse than predicted. It facilitates heart team discussions about the optimal treatment strategy (surgical vs. percutaneous vs. medical) by quantifying surgical risk. In clinical trials, it provides baseline risk stratification for comparing treatment groups. Its widespread adoption makes it an indispensable tool in modern cardiac surgery practice, though its predictions should always be interpreted within the broader clinical context of each individual patient.