Lack of Accuracy of the GRACE score to Predict Coronary Anatomy in Acute Coronary Syndromes

Introduction Coronary anatomy is one of the strongest risk predictors in Acute Coronary Syndromes (ACS), which justifies early coronary angiography. Diagnostic scores for predicting outcomes are usually superior to clinical judgment. Despite being validated for prognosis, the GRACE score has been used to discriminate patients with high or low probability of anatomical severity. Objective To test the hypothesis that the GRACE score actually predicts anatomical severity. Methods The study was carried out by assessing consecutive patients with ACS who underwent invasive angiography. Severe anatomical disease was defined as obstructive involvement (≥ 70% in diameter) in (1) left main coronary artery or (2) double or triple vessel disease involving proximal left anterior descending artery or (3) subocclusion. The GRACE score was evaluated under numerical and dichotomous tests. Results A total of 733 patients were evaluated, aged 63 ± 14 years, 61% male and GRACE score of 119 ± 37. Obstructive coronary disease was observed in 81% of the patients, classified as one, two or three vessel disease, or left main coronary artery involvement in 28%, 23%, 26% and 4%, respectively. The area under the ROC curve of the GRACE score was 0.65 (95% CI = 0.61 - 0.69) for predicting severe disease. The cutoff point below which the first GRACE tertile is defined (109) was used to dichotomize low-risk (N = 318) and medium-high-risk (N = 415) samples. This standard definition of intermediate-high risk by the GRACE score (> 109) revealed sensitivity of 67% in detecting severe anatomy (95% CI = 61% - 72%) and specificity of 50% (95% CI = 46% - 55%), resulting in positive likelihood ratio of 1.3 (95% CI = 1.2 - 1.5) and negative likelihood ratio of 0.66 (95% CI = 0.55 - 0.80). There was a weak correlation between GRACE and anatomical scores such as SYNTAX (r = 0.36, P < 0.001) and Gensini (r = 0.36, P < 0.001). Conclusion Despite statistical association with extent of anatomical coronary disease, the GRACE Score is not accurate to predict severity of disease before coronary angiography.