Accuracy of the GRACE Score for mortality prediction in myocardial infarction with nonobstructive coronary arteries (MINOCA)

Introduction Myocardial infarction with nonobstructive coronary arteries (MINOCA) patients account for 3.5 to 15% of all myocardial infarctions. The GRACE risk score is a well-validated tool for estimating short- and long-term risk in acute coronary syndrome, but the accuracy of the risk score for prognostic stratification in patients with MINOCA remains uncertain. Purpose We aimed to investigate whether the GRACE risk score can predict mortality in a real-world cohort of patients presenting with MINOCA. Methods We retrospectively analyzed patients admitted with MINOCA in a single center. Patients who were diagnosed with myocarditis and Takotsubo syndrome were excluded from the analysis. The GRACE risk score on admission was calculated. Patients were divided into a low-intermediate risk group (≤ 140 points, 71.5%) and a high-risk group (>140 points, 28.5%) according to their GRACE risk scores. Receiver operating characteristic (ROC) analysis was used to quantify the accuracy of the GRACE risk score to estimate both in-hospital and one-year mortality in MINOCA patients. Results Of a total of 3721 myocardial infarction patients, MINOCA was identified in 11.6% (n=430). 313 patients had complete data for the calculation of the GRACE on admission and were included in the analysis. Mean age was 65±12 years, and 49% (n=154) of patients were male. Mean GRACE score was 125±31 points. Patients in the high-risk group were older (74±9 vs. 61±11 years, p<0.001), had a higher incidence of in-hospital mortality (0.4% vs. 5.6%, p=0.008), and had a higher rate of one-year mortality (2.7% vs. 19.5%, p<0.001), compared with the low-intermediate risk group. There were no differences regarding sex and cardiovascular risk factors between the groups. In-hospital mortality was 1.9% and one-year mortality was 7.3%. ROC curve analysis showed that the GRACE risk score has a high value in predicting in-hospital mortality (AUC ROC 0.892; 95% CI 0.798–0.986; p=0.001), and one-year mortality (AUC ROC 0.826; 95% CI 0.739–0.0.914; p<0.001) in MINOCA patients. (Figure 1). The overall c-statistics were similar compared with estimates obtained from patients with myocardial infarction and significant coronary artery disease: in-hospital mortality (AUC ROC 0.0.849; 95% CI, 0.807–0.891; p<0.001); and one-year mortality (AUC ROC 0.776; 95% CI, 0.747–0.806; p<0.001). Conclusions In conclusion, the GRACE risk score provides potentially valuable prognostic information on in-hospital and one-year mortality when applied to MINOCA patients.