External validation of the GRACE risk score 2.0 in the contemporary all-comers GLOBAL LEADERS trial

Objectives: This study aimed to assess the predictive ability of the Global Registry of Acute Coronary Events (GRACE) risk score 2.0 in contemporary acute coronary syndrome (ACS) patients, and its relation to antiplatelet strategies.

Background: The predictive value of the GRACE risk score in the contemporary ACS cohort and the appropriate antiplatelet regimen according to the risk remain unclear.

Methods: This is a subgroup analysis of the all-comers, randomized GLOBAL LEADERS trial, comparing ticagrelor monotherapy versus conventional dual-antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI). The GRACE risk score 2.0 with 1-year mortality prediction was implemented. The randomized antiplatelet effect was assessed in predefined three GRACE risk-groups; low-risk (GRACE <109), moderate-risk (GRACE 109-140), and high-risk (GRACE >140).

Results: The GRACE risk score was available in 6,594 out of 7,487 ACS patients among whom 1,743, 2,823, and 2,028 patients were classified as low-risk, moderate-risk, and high-risk, respectively. At 1 year, all-cause mortality occurred in 120 patients (1.8%). The discrimination ability of the GRACE model was moderate (C-statistic = 0.742), whereas 1-year mortality risk was overestimated (mean predicted mortality rate: 3.9%; the Hosmer-Lemeshow chi-square: 21.47; p = 0.006). There were no significant interactions between the GRACE risk strata and effects of the ticagrelor monotherapy on ischemic or bleeding outcomes at 1 year compared to the reference strategy.

Conclusion: The GRACE risk score 2.0 is valuable in discriminating high risk ACS patients, however, the recalibration of the score is recommended for better risk stratification. There is no significant differences in efficacy and safety of ticagrelor monotherapy across the three GRACE risk strata.