This study aimed to evaluate the correlation of Heart Risk score with Syntax score thereby evaluating the ability of Heart Risk Score to predict the existence and severity of coronary artery disease in an Iranian population who were admitted to ED with CP. As far as we know, this is the first time that a study has been done to directly correlate Heart Risk Score with Syntax score. Our study showed that the early diagnosis of patients with complex coronary artery disease is possible by using Heart Risk Score at ED. High Heart Risk Score indicates severe CAD substantiated by a significant positive correlation with Syntax score (p < 0.001, R = 0.493). Syntax score is an approved scoring system that considers number of lesions, functional importance, and complexity of lesions. This score classifies patients into low (≤ 22), medium (23–32), and high risk (≥ 33) (15). Syntax score is a suitable indicator for early and long-term clinical outcomes (13, 15, 16). Also, it helps cardiologist to choose the appropriate revascularization modality (17). However, its use is restricted because it is an angiography-based scoring system.
In the present population, coronary angiography was performed in 6 patients who had Heart Risk Score of ≤ 3. All these patients had normal or nearly normal coronary arteries with respect to atherosclerotic plaque formation (syntax of < 15). We showed that a Heart Risk Score of ≥ 6 identifies coronary artery disease patients with syntax score ≥ 22 with sensitivity, specificity, and negative predictive value of 52%, 74.7%, and 82.3%, respectively. Of all the patients with normal angiography results only one of them had a Heart Risk Score more than 7 which shows that Heart Risk Score can differentiate patients with extensive coronary artery disease from those without extensive coronary artery involvement. There is consistency between our study and prior findings on implementing urgent and detailed interventions in patients with Heart Risk Score of ≥ 7 (7–12). These findings reinforces the need for a valid and reliable tool like Heart Risk Score to reduce unnecessary angiography and consequently increased burden.
Heart Risk Score was initially developed to identify patients who benefited from early discharging. Low Heart Risk Score indicates low-risk patients and is useful for decreasing the duration of hospitalization and relevant costs (1, 18, 19). Heart Risk Score was reported to be a good to excellent indicator for determining risk of MACE in patients with CP at ED (1). In a retrospective study on 29196 patients who were referred to ED because of CP, a Heart Risk Score of 5 was considered for early discharging. They reported that the probability of repeated cardiovascular events in those with a Heart Risk Score of < 5 was only 1.1% (20). Defining an accurate cut-off value is useful in postponing administration of clopidogrel and ticagrelor, ADP-receptor inhibitors, for patients who may undergo CABG after primary examinations.
In a prospective study on 2440 patients with CP in ED, Heart Risk Score of nearly one third of patients was 0–3 with a risk of 1.7% for MACE showing the feasibility of quick discharge without any serious concerns about upcoming adverse events. Also, this strategy saves incurred unnecessary costs. Those with Heart Risk Score of 7–10 constituted 17.5% of the population with 50.1% risk of MACE who were referred for quick coronary intervention (1). Risk of MACE in a population of low-risk (Heart Risk Score of ≤ 3) CP patients was reported to be 0.6% (21, 22). This shows the substantial potential of Heart Risk Score as a reliable tool in reducing cardiac testing.
In some studies, the association of other risk score systems like GRACE and TIMI were evaluated with regard to Syntax score (23–25). TIMI and GRACE are among scoring systems that were developed for risk stratification of ACS patients in CCU (1). Sometime clinicians use these scoring systems for CP patients in ED which includes an undifferentiated population, despite the fact that they are not tailored for this purpose (26–29). Heart Risk Score is superior to TIMI and GRACE in predicting risk of cardiovascular events for all-cause CP patients in ED. It helps care providers to choose appropriate treatment. Screening of 1748 patients presenting with CP at ED revealed that the ability of Heart Risk Score to identify low-risk individuals as well as prediction of MACE was higher than GRACE and TIMI (11). Also, GRACE score calculation needs a computer which limits its use. In contrary, Heart Risk Score, which could be calculated from admission data typically within 1 h, is specifically designed for patients with CP in ED.
The strongest scoring system should identify maximum number of true low- risk patients along with low-risk patients who are at risk of developing MACE. Available clinical data and computer-independent calculation of Heart Risk Score make it a valuable tool for early evaluation of patients with CP admitted to ED with respect to prognosis, clinical outcome, and applying therapeutic choice (1). Our Study further added evidence for the utility of this score by incorporating Syntax score and showing the correlation of Heart Risk Score with Syntax score.
Limitations Of Study
The main limitation is the low number of patients with low Heart Risk Score who underwent coronary angiography. Another study with longer duration to include more of such patients could be especially useful. Also despite the fact that Heart Risk Score increased with Syntax score but the Heart Risk Score of patients with 3VD involvement was lower than patients with 2VD, but because of the low number of cases we could not analyze the reason for this unexpected finding.