European Journal of Cardiovascular Medicine

Acute coronary syndrome (ACS) continues to represent a significant global health burden and remains one of the foremost causes of morbidity and mortality worldwide. Among its clinical manifestations, ST-elevation myocardial infarction (STEMI) constitutes the most critical and life-threatening presentation, often associated with extensive myocardial damage and adverse short- and long-term outcomes. Early and accurate risk stratification at the time of presentation is essential to guide therapeutic strategies, estimate prognosis, and ensure efficient utilization of healthcare resources.

The Global Registry of Acute Coronary Events (GRACE) risk score is one of the most widely validated clinical tools for predicting both in-hospital and post-discharge mortality among ACS patients, including those with STEMI. The GRACE model integrates eight readily obtainable clinical and laboratory parameters—namely age, systolic blood pressure, heart rate, Killip class, serum creatinine, cardiac arrest at presentation, ST-segment deviation, and elevated cardiac biomarkers—to generate a robust and reliable estimate of mortality risk.¹

Complementing the GRACE model, the Synergy Between PCI with Taxus and Cardiac Surgery (SYNTAX) score provides an angiographic assessment of coronary artery disease (CAD) complexity. Derived from detailed coronary angiographic findings, the SYNTAX score quantifies lesion characteristics, including number, location, and severity, thereby offering an anatomical perspective on disease burden. Elevated SYNTAX scores have consistently been linked with poorer outcomes, particularly in patients undergoing percutaneous coronary intervention (PCI), and are frequently used to guide revascularization strategies between PCI and coronary artery bypass grafting (CABG).¹

In recent years, several investigators have explored the relationship between these two risk assessment systems to determine whether clinical severity as captured by GRACE correlates with anatomical complexity as reflected by SYNTAX. Studies conducted in various populations, including those from India, have reported a significant positive correlation between GRACE and SYNTAX scores, suggesting that both indices may concurrently predict adverse outcomes in STEMI.² Similarly, multicenter analyses have demonstrated that while the GRACE score is fundamentally a clinical prognostic tool, it also exhibits meaningful association with angiographic lesion severity determined by SYNTAX.³ Collectively, these observations indicate that an integrated assessment combining clinical and angiographic parameters could enhance risk prediction in STEMI patients—particularly valuable in resource-constrained settings where timely access to invasive evaluation may be limited.

Despite these insights, data from Indian populations remain limited. Most available studies have been single-center in nature and have included heterogeneous ACS cohorts, limiting their generalizability. In this context, the present study was designed to specifically evaluate the correlation between GRACE and SYNTAX scores in patients presenting with STEMI at a tertiary care hospital and to assess their comparative utility in predicting in-hospital outcomes.

Study Design and Setting:

This was a prospective, observational, analytical study conducted at the Department of Medicine, Dr. Vithalrao Vikhe Patil Foundation’s Medical College and Hospital, Ahmednagar, Maharashtra, India. The study was carried out over a 9-month period (March–November 2024) after obtaining approval from the Institutional Ethics Committee.

Study Population:

A total of 50 patients were taken out of which 7 were excluded. 43 patients with acute ST-elevation myocardial infarction (STEMI) were taken for study.

Inclusion Criteria

• Adults ≥18 years diagnosed with STEMI

Exclusion Criteria

• Prior myocardial infarction within 6 weeks
• Incomplete angiographic or clinical data
• Contraindication of thrombolysis
• Cases of permanent or temporary pacemaker insertion
• Refusal to provide consent

Ethical Considerations:

Informed written consent was obtained from all participants. Confidentiality of patient data was strictly maintained.

Data Collection:

At admission, demographic and clinical details were recorded, including systolic blood pressure, heart rate, Killip class, and laboratory parameters (serum creatinine, cardiac enzymes). GRACE scores parameters(age, heart rate, systolic blood pressure, creatinine, Killip class, cardiac arrest, ST-segment deviation, elevated cardiac enzymes) were calculated using the standardized online calculator.⁴

Angiographic Assessment:

All patients underwent coronary angiography during hospitalization. The SYNTAX score was calculated by cardiologist using the SYNTAX score calculator (www.syntaxscore.org).

Outcome Measures:

Patients were monitored for in-hospital adverse events, including mortality, recurrent ischemia, arrhythmias, and cardiogenic shock. The primary outcome was in-hospital mortality. Secondary outcomes included major adverse cardiovascular events (MACE).

Statistical Analysis:

Data were analyzed using SPSS version 22.0 (SPSS Inc., Chicago, IL, USA). Continuous variables were expressed as mean ± SD, and categorical variables as frequencies and percentages. Correlation between GRACE and SYNTAX scores was assessed using Pearson’s correlation coefficient. ROC curve analysis was performed to compare their predictive accuracy for in-hospital mortality. A p-value <0.05 was considered statistically significant.

Out of 50 patients, a total of 43 patients with STEMI were included in the study. The mean age was 65.9 ± 11.4 years (range 36–83), with a male predominance (58.1%). Most patients (88.4%) were aged >50 years. The mean heart rate was 87.4 ± 14.9 bpm, mean systolic blood pressure 125.5 ± 29.9 mmHg, and mean serum creatinine 1.0 ± 0.4 mg/dL. The mean GRACE score was 138.9 ± 33.5, and the mean SYNTAX score was 15.7 ± 4.0 (Table 1).

Table 1: Demographic and clinical profile of the Study Cohort

GRACE- Global Registry of Adverse Cardiac Events, SYNTAX-Synergy between Percutaneous Coronary Intervention

Killip class distribution showed that 46.5% were in Class I, 25.6% in Class II, 16.3% in Class III, and 11.6% in Class IV. Cardiac arrest at admission was observed in 7% of patients. The left anterior descending artery was the most frequently involved culprit vessel (27.9%), followed by combined RCA + LCX involvement (14%) and multivessel patterns (Figure 1).

Figure 1: Percentage of Vessels involved among the study cohort

Stratification analysis demonstrated that all patients in the low (≤108) and intermediate (109–140) GRACE categories had SYNTAX scores <23. Among the high-risk GRACE group (>140), 10% had SYNTAX ≥23, although this association was not statistically significant (p = 0.29) (Table 2).

Table 2: Stratification of the study population based on GRACE Score and SYNTAX Score

In contrast, Killip Class IV was strongly associated with complex CAD, with 40% of patients having SYNTAX ≥23 (p = 0.001), whereas all patients in Killip Classes I–III had SYNTAX <23 (Table 3).

Table 3: Stratification of the study population based on Killip Class and SYNTAX Score

Patients with SYNTAX ≥23 had significantly lower systolic blood pressure compared with those with SYNTAX <23 (65.0 ± 21.2 mmHg vs. 128.4 ± 27.1 mmHg, p = 0.002), while heart rate and creatinine showed no significant differences (Figure 2).

Figure 2: Mean clinical parameters distributed according to SYNTAX Score

Correlation analysis revealed a very strong positive association between GRACE and SYNTAX scores (r = 0.988, p = 0.001), indicating that higher clinical risk was closely linked to greater angiographic complexity (Figure 3).

Figure 3: Correlation between and GRACE Score and SYNTAX Score

The principal finding of this prospective observational study is the identification of an exceptionally strong and statistically significant positive correlation between the GRACE and SYNTAX scores among patients presenting with ST-elevation myocardial infarction (STEMI) (r = 0.988, p = 0.001). This observation suggests that in STEMI, the clinical risk as estimated by GRACE closely parallels the angiographic complexity of coronary artery disease (CAD) as reflected by the SYNTAX score. Furthermore, advanced Killip class and hypotension were significantly associated with higher SYNTAX scores, highlighting the intricate relationship between clinical instability and the anatomical severity of coronary lesions.

Previous research exploring the relationship between clinical and angiographic risk models in acute coronary syndromes (ACS) has yielded heterogeneous results. Hammami et al. documented only a weak but statistically significant association (r = 0.23, p < 0.001) in a cohort comprising patients with unstable angina and NSTEMI, and their study failed to establish reliable predictive capacity for severe CAD (SYNTAX ≥ 33). Similarly, Rahmani et al. found a weak positive correlation (r = 0.34, p < 0.001) between GRACE and SYNTAX scores in a comparable ACS population. By contrast, Namazi et al. (2024) observed a stronger relationship (r = 0.867, p < 0.001) in an Iranian ACS cohort that included STEMI, NSTEMI, and unstable angina patients. Bekler et al. also included STEMI cases and reported a moderate correlation (r = 0.427, p < 0.001), while Sofidis et al. described a weak-to-moderate association (r = 0.32, p < 0.001). Collectively, these findings suggest that although the two risk assessment models generally trend in a similar direction, the strength of association varies considerably according to population characteristics, inclusion criteria, and methodological differences.

Our study distinguishes itself in two key aspects. Firstly, it focuses exclusively on STEMI patients a relatively homogeneous population characterized by higher hemodynamic compromise and more extensive coronary occlusion. Secondly, our results demonstrate an extraordinarily strong correlation (r = 0.988), substantially exceeding that reported in earlier studies. This suggests that in the setting of STEMI, clinical deterioration reflected by the GRACE parameters—such as hypotension, tachycardia, and elevated Killip class—mirrors the underlying anatomical burden of disease with remarkable precision.

The observed correlation may be attributable to the uniformity of our patient cohort. In contrast to NSTEMI and unstable angina populations, where the GRACE score can be influenced by chronic comorbidities (e.g., renal dysfunction, diabetes, or prior cardiac events) unrelated to acute lesion complexity, STEMI patients typically exhibit large thrombus burden, multivessel involvement, and marked hemodynamic instability. This alignment between clinical and anatomical severity likely explains the higher correlation observed. Supporting this hypothesis, 40% of patients in Killip class IV in our study demonstrated high SYNTAX scores (>23), indicating that more severe left ventricular dysfunction is often accompanied by complex coronary anatomy.

Another important contextual factor is the mode of treatment. In our study, the majority of patients were managed with thrombolytic therapy using streptokinase due to the absence of primary PCI facilities. In such settings, where mechanical reperfusion is unavailable, clinical deterioration is more directly linked to the extent of coronary obstruction and lesion complexity. Conversely, in studies conducted in PCI-capable centers, prompt revascularization may attenuate the clinical consequences of anatomical disease, thereby weakening the correlation between GRACE and SYNTAX scores.

These findings carry several important clinical and public health implications.
First, they highlight the potential utility of the GRACE score as a rapid, non-invasive surrogate marker for estimating CAD complexity before angiography. In resource-limited or rural healthcare settings lacking immediate PCI access, GRACE scoring at admission could help identify high-risk patients who may benefit from early transfer to tertiary centers with revascularization capabilities.

Second, our results underscore the complementary nature of the two scoring systems. The GRACE score remains a validated tool for short- and long-term mortality prediction in ACS, while the SYNTAX score provides anatomical detail crucial for guiding revascularization decisions between PCI and CABG. Evidence from prior studies indicates that integrating these models into a combined SYNTAX–GRACE algorithm enhances prognostic accuracy beyond either score alone. Our findings reinforce the value of such integrative approaches, particularly in STEMI populations where timely and precise risk stratification is essential for optimal outcomes.

Third, these observations may inform future updates in clinical practice guidelines. Current recommendations prioritize early invasive strategies in NSTEMI patients with high GRACE scores. Although STEMI management already emphasizes urgent reperfusion, our data suggest that patients with high GRACE scores may also possess more complex coronary anatomy, potentially requiring CABG or multivessel PCI. This emphasizes the need for early multidisciplinary “heart team” evaluation in high-GRACE STEMI cases to determine the most appropriate revascularization strategy.

The strengths of our study include its prospective design, exclusive focus on a homogeneous STEMI cohort, and the simultaneous evaluation of both clinical and angiographic parameters within the same hospitalization period. Nevertheless, certain limitations must be acknowledged. The relatively small sample size (n = 43) limits statistical power and external generalizability. Being a single-center study conducted in a non-PCI-capable rural hospital, the findings may not directly translate to urban or tertiary care settings with advanced interventional facilities. Moreover, follow-up was confined to in-hospital outcomes, and long-term prognostic implications were not assessed. Additionally, the SYNTAX scoring was performed by cardiologists involved in patient management, introducing a potential element of observer bias.

Future research should aim to validate these findings in larger, multicentric STEMI cohorts representing diverse healthcare environments. Extending follow-up duration to evaluate mortality and major adverse cardiovascular events would help clarify the prognostic implications of the observed relationship. Incorporating additional risk determinants—such as diabetes mellitus, metabolic syndrome, or inflammatory markers—could further refine predictive accuracy. Furthermore, studies assessing combined GRACE–SYNTAX algorithms specifically within Indian populations are warranted to develop contextually relevant, evidence-based risk stratification models that integrate both clinical and angiographic perspectives.

Our study demonstrates a strong and statistically significant correlation between GRACE and SYNTAX scores in STEMI patients, indicating that clinical deterioration parallels increasing anatomical complexity. Higher SYNTAX scores were associated with elevated Killip class and hypotension, highlighting the close relationship between hemodynamic instability and the extent of coronary lesions. The combined use of GRACE and SYNTAX scores can enhance early risk assessment and guide clinical decision-making, particularly in resource-limited settings where immediate angiography may not be available. Future large-scale, multicentric studies incorporating long-term follow-up and revascularization outcomes are warranted to further validate and expand these findings.

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