In looking for the optimal risk-stratifying system for chest pain patients, we analyzed the HEART score. The first study on the HEART score was done Backus et al, proving that the HEART score is an easy, quick, and reliable predictor of outcomes in chest pain patients.10 The HEART score had good discriminatory power, too. The C statistic for the HEART score for ACS occurrence shows a value of 0.83. This signifies a good-to-excellent ability to stratify all-cause chest pain patients in the ED for their risk of MACE. The application of the HEART score to our patient population demonstrated that the majority of the patients belonged to the low-risk category, as reported in the first cohort study that applied the HEART score.8 The relationship between the HEART score category and occurrence of MACE within 6 weeks showed a curve with 3 different patterns, corresponding to the 3 risk categories defined in the literature.11,12 The risk stratification of chest pain patients using the 3 categories (0-3, 4-6, 7-10) identified MACE with an incidence similar to the multicenter study of Backus et al,10,11 but with a greater risk of MACE in the high-risk category (Figure).
Thus, our study confirmed the utility of the HEART score categories to predict the 6-week incidence of MACE. The sensitivity, specificity, and positive and negative predictive values for the established cut-off scores of 4 and 7 are shown in Table 8. The patients in the low-risk category, corresponding to a score < 4, had a very high negative predictive value, thus identifying a small-risk population. The patients in the high-risk category (score ≥ 7) showed a high positive predictive value, allowing the identification of a high-risk population, even in patients with more atypical presentations. Therefore, the HEART score may help clinicians to make accurate management choices by being a strong predictor of both event-free survival and potentially life-threatening cardiac events.11,12
Our study tested the efficacy of the HEART score pathway in helping clinicians make smart diagnostic and therapeutic choices. It confirmed that the HEART score was accurate in predicting the short-term incidence of MACE, thus stratifying patients according to their risk severity. In our study, 67 of 141 patients (47.52%) had low-risk HEART scores, and we found the 6-week incidence of MACE to be 1.49%. We omitted the diagnostic and treatment evaluation for patients in the low-risk category and moved onto discharge. Overall, 66 of 67 patients (98.51%) in the low-risk category had an uneventful recovery following discharge. Only 2 of 67 these patients (2.99%) of patients had health care utilization following discharge. Therefore, extrapolation based on results demonstrates reduced health care utilization. Previous studies have shown similar results.9,12,14,16 For instance, in a prospective study conducted in the Netherlands, low-risk patients representing 36.4% of the total were found to have a low MACE rate (1.7%).9 These low-risk patients were categorized as appropriate and safe for ED discharge without additional cardiac evaluation or inpatient admission.9 Another retrospective study in Portugal,12 and one in Chennai, India,15 found the 6-week incidence of MACE to be 2.00% and 2.22%, respectively. The results of the first HEART Pathway Randomized Control Trial14 showed that the HEART score pathway reduces health care utilization (cardiac testing, hospitalization, and hospital length of stay). The study also showed that these gains occurred without any of the patients that were identified for early discharge, suffering from MACE at 30 days, or secondary increase in cardiac-related hospitalizations. Similar results were obtained by a randomized trial conducted in North Carolina17 that also demonstrated a reduction in objective cardiac testing, a doubling of the rate of early discharge from the ED, and a reduced length of stay by half a day. Another study using a modified HEART score also demonstrated that when low-risk patients are evaluated with cardiac testing, the likelihood for false positives is high.16 Hoffman et al also reported that patients randomized to coronary computed tomographic angiography (CCTA) received > 2.5 times more radiation exposure.16 Thus, low-risk patients may be safely discharged without the need for stress testing or CCTA.
In our study, 30 out of 141 patients (21.28%) had high-risk HEART scores (7-10), and we found the 6-week incidence of MACE to be 90%. Based on the pathway leading to inpatient admission and intensive treatment, 23 of 30 patients (76.67%) patients in our study underwent coronary angiography and further therapeutic treatment. In the high-risk category, 28 of 30 patients (93.33%) patients had an uneventful recovery following discharge. Previous studies have shown similar results. A retrospective study in Portugal showed that 76.9% of the high-risk patients had a 6-week incidence of MACE.12 In a study in the Netherlands,9 72.7% of high-risk patients had a 6-week incidence of MACE. Therefore, a HEART score of ≥ 7 in patients implies early aggressive treatment, including invasive strategies, when necessary, without noninvasive treatment preceding it.8
In terms of intermediate risk, in our study 44 of 141 patients (31.21%) patients had an intermediate-risk HEART score (4-6), and we found the 6-week incidence of MACE to be 18.18%. Based on the pathway, they were kept in the observation ward on admission. In our study, 7 of 44 patients (15.91%) underwent coronary angiography and further treatment; 42 of 44 patients (95.55%) had an uneventful recovery following discharge. In a prospective study in the Netherlands, 46.1% of patients with an intermediate score had a 6-week MACE incidence of 16.6%.10 Similarly, in another retrospective study in Portugal, the incidence of 6-week MACE in intermediate-risk patients (36.7%) was found to be 15.6%.12 Therefore, in patients with a HEART score of 4-6 points, immediate discharge is not an option, as this figure indicates a risk of 18.18% for an adverse outcome. These patients should be admitted for clinical observation, treated as an ACS awaiting final diagnosis, and subjected to noninvasive investigations, such as repeated troponin. Using the HEART score as guidance in the treatment of chest pain patients will benefit patients on both sides of the spectrum.11,12