After data collection, the collected data were filtered, coded, and analyzed using the statistical software SPSS 22.0 to calculate descriptive statistical features such as frequency and percentage (%). The model's accuracy was assessed using the Hosmer-Lemeshow test, with p-value >.05 indicating a well-fitted model. The DeLong test was used to compare the area under the ROC curve for each pair of scores, and the results were statistically significant at p < .05.

Females represent the majority of the study population with 73.5%. Non ST-segment elevation myocardial infarction was the most prevalent clinical presentation, representing 69.1%, while unstable angina had the lowest prevalence at 14.7%. The most common internal medicine treatment approach was conservative management, representing 69.1% (Table 1). The highest rates of in-hospital and 6-month mortality were observed in the group treated with internal medicine and presenting with non ST-segment elevation myocardial infarction (Fig. 1). The majority of in-hospital and 6-month mortality occurred in the high-risk groups according to the scoring systems, with statistically significant differences (p < .05) (Appendix B).

Fig. 1.

Mortality rates according to clinical presentations and treatment approaches in acute coronary syndrome.

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The GRACE score showed a good prognostic value for in-hospital mortality (AUC = 0.805, p = .002) and a quite good prognostic value for 6-month mortality (AUC = 0.786, p = .001) in patients with acute coronary syndrome (Appendix B). The TIMI risk score had a poor prognostic value for both in-hospital mortality (AUC = 0.682, p = .068) and 6-month mortality (AUC = 0.692, p = .024) (Appendix B). The HEART risk score showed a quite good prognostic value for in-hospital mortality (AUC = 0.738, p = .017) and a good prognostic value for 6-month mortality (AUC = 0.825, p < .001) (Fig. 2) and (Table 2).

Fig. 2.

Area under the ROC curve of the HEART score for in-hospital mortality prediction in patients with acute coronary syndrome (E) and 6-month mortality (F).

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The Hosmer-Lemeshow test shows that the GRACE score and TIMI score achieved goodness-of-fit for the ACS population, and the HEART score achieved goodness-of-fit for the in-hospital ACS population but not for the 6-month follow-up ACS population (Table 3). The prognostic values of in-hospital mortality for acute coronary syndrome patients were not statistically different between the 2 different scoring systems. The prognostic values of 6-month mortality for acute coronary syndrome patients were not statistically different between the 2 different scoring systems (Table 4).

In our study population, 73.5% are female, which differs from some other studies3,4 conducted in the Vietnamese population. However, our findings align with studies indicating that gender differences become less significant as age increases.12,13 It's noteworthy that with advancing age, the risk of acute coronary syndrome and related complications tends to increase.14,15 The majority of patients in our study (69.9%) were managed with internal medicine without PCI, similar to the findings in Tan Van Nguyen's study.3 Additionally, our study reported in-hospital and 6-month mortality rates of 14.7% and 22.1%, respectively, which were higher than those reported by foreign authors, such as Keith Fox, with a rate of 19.8%.16,17

The GRACE score demonstrated a strong ability to differentiate between risk categories for in-hospital and 6-month mortality in patients with non-ST-elevation acute coronary syndrome, consistent with findings from other studies.17-19 In our study, the average HEART score was 7 points, with the high-risk group comprising 55.9% of patients. This finding was similar to the study conducted by Six et al, where the HEART score was 6.51 ± 1.84.20 Our study showed that the in-hospital mortality rate in the high-risk group was significantly higher than in the moderate-risk group (11.8% vs. 2.9% with p = .05). Similarly, the 6-month mortality rate was also higher in the high-risk group compared to the moderate-risk group (19.1% vs. 2.9% with p = .024). Therefore, the HEART score demonstrated a good ability to differentiate between risk categories in predicting both in-hospital and 6-month mortality, which aligns with the study by authors AJ Six, BE Backus, and JC Kelder.20

Regarding in-hospital mortality, the GRACE score exhibited the best prognostic value, while the TIMI score had the lowest prognostic value. The area under the ROC curve for the GRACE, TIMI, and HEART scores was AUC = 0.805, AUC = 0.682, and AUC = 0.738, respectively. However, these differences were not statistically significant when comparing each pair using the DeLong test. Our study results differ from those of authors where the AUC for GRACE, TIMI, and HEART scores were AUC = 0.73, AUC = 0.80, and AUC = 0.86, respectively.21,22 Kao et al.'s study on a group of diabetic patients with non-ST-elevation acute coronary syndrome in Taiwan also showed that the TIMI score had a better predictive ability for major cardiovascular events within 1 year after discharge compared to GRACE (AUC under the ROC curve = 0.74 vs. 0.72). The authors explained that the inferior prognostic performance of GRACE was due to the relatively low number of patients in Killip classes III/IV.23

For 6-month mortality, the HEART score had the highest prognostic value with an AUC under the ROC curve of 0.825, followed by the GRACE score with an AUC of 0.786, and the TIMI score had the lowest prognostic value with an AUC of 0.692. However, these differences were not statistically significant when comparing each pair using the DeLong test. A study by Hang Zhu in a female patient group showed that the GRACE score had a higher prognostic value than TIMI (AUC = 0.81 vs. AUC = 0.68), and the difference was statistically significant.2

We believe that the HEART score has strengths in including various cardiovascular risk factors, such as hypercholesterolemia, hypertension, diabetes, smoking, family history of early coronary artery disease, obesity, and history of coronary artery disease, contributing to its superior prognostic value compared to other scores. Moreover, relying on a minimum number of variables, including clinical history, electrocardiogram, age, cardiovascular risk factors, and cardiac enzymes, makes the HEART score simple and convenient. However, the Hosmer-Lemeshow test results indicated that the HEART score is not suitable for predicting 6-month mortality. Thus, we hope to see further studies in the future to evaluate the role of this score in predicting mortality in acute coronary syndrome patients, particularly at the 6-month mark.