Use of the Thrombolysis in Myocardial Infarction Risk Index for Elderly Patients With ST-Segment Elevation Myocardial Infarction

Background: Thrombolysis in Myocardial Infarction (TIMI) Risk Index (TRI) is a simple risk assessment tool for patients with ST-segment elevation myocardial infarction (STEMI). However, its applicability to elderly patients with STEMI undergoing percutaneous coronary intervention (PCI) is uncertain. Methods: This was a retrospective analysis of elderly (≥60 years) patients who underwent PCI for STEMI from January 2010 to April 2016. TRI was calculated on admission using the following formula: heart rate × (age/10)²/systolic blood pressure. Discrimination and calibration of TRI for in-hospital events and 1 year mortality were analyzed. Results: Totally 1,054 patients were divided into three groups according to the tertiles of the TRI: <27 (n = 348), 27-36 (n = 360) and >36 (n = 346). The incidence of acute kidney injury (AKI; 7.8 vs. 8.6 vs. 24.0%, p < 0.001), AHF (3.5 vs. 6.6 vs. 16.2%, p < 0.001), in-hospital death (0.6 vs. 3.3 vs. 11.6%, p < 0.001) and MACEs (5.2 vs. 5.8 vs. 15.9%, p < 0.001) was significantly higher in the third tertile. TRI showed good discrimination for in-hospital death [area under the curve (AUC) = 0.804, p < 0.001; Hosmer-Lemeshow p = 0.302], which was superior to its prediction for AKI (AUC = 0.678, p < 0.001; Hosmer-Lemeshow p = 0.121), and in-hospital MACEs (AUC = 0.669, p < 0.001; Hosmer-Lemeshow p = 0.077). Receiver-operation characteristics curve showed that TRI > 42.0 had a sensitivity of 64.8% and specificity of 82.2% for predicting in-hospital death. Kaplan-Meier analysis showed that patients with TRI > 42.0 had higher 1 year mortality (Log-rank = 79.2, p < 0.001). Conclusion: TRI is suitable for risk stratification in elderly patients with STEMI undergoing PCI, and is thus of continuing value for an aging population.