Low-Risk ACS: The HEART trial and how we got there
Author: Jason Brown, Capt, USAF, MD (EM Resident Physician, University of Maryland) // Editor: Alex Koyfman, MD
In the first decade of the 21st century, a collection of risk-stratification tools were developed in an effort to better identify patients at the highest risk for a major acute coronary event (MACE). The first two were the Thrombolysis In Myocardial Infarction (TIMI) and Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin (eptifibatide) Therapy (PURSUIT). These were followed by the Global Registry of Acute Coronary Events (GRACE) and Fast Revascularisation in InStability in Coronary disease (FRISC). These scoring systems were developed via multivariable logistic regression of preexisting data sets derived from patients that have already ruled in for ACS; meaning, these were the most highly associated risk factors for people with disease.
These four scoring systems were invaluable to cardiologists. They gave good, reproducible data that helped determine how to treat patients with known ACS. However, they did little to change how emergency physicians practice. Whether or not to admit a case of ACS was never the question in these studies. TIMI, PURSUIT, GRACE, and FRISC were all very useful in stratifying patients with ACS into treatment groups based on their likelihood of mortality at variable intervals.
Further complicating the issue is the fact that even very low scores in these risk-stratification tools did not correspond to negligible rates of MACE. For instance, a publication by Pollack et al in 2006 showed a MACE rate of 2.1% with a TIMI of 0 and a 5% MACE rate for a TIMI of 1 for patients presenting to the ED with chest pain. Considering that you get 1 point for taking an aspirin in the last 7 days, these data are disconcerting for emergency physicians.
To the HEART of the matter…
The HEART score was one of the first prospective studies for the evaluation of chest pain patients in an emergency department setting using clinical gestalt and expert opinion to drive decision-making. The five components are History, ECG, Age, Risk factors, and Troponin; scored 0-2 per parameter with scores ranging from 0-10. Their initial investigation showed a 2.5% rate of MACE at 30 days with those patients scoring 0-3. These patient characteristics are very similar to the history and exam elements defined in the American Heart Association’s (AHA) 2010 position paper on the evaluation of chest pain in the emergency department wherein a low-risk patient was considered one with a <2.5% risk of MACE at 30 days.
In 2008, Six, Backus, and Kelder published an article wherein they applied the HEART score to an undifferentiated cohort of patients presenting to the ED with chest pain. They found a low rate of MACE in patients scoring 0-3 (2.5%) and postulated that this group of patients were suitable for early discharge from the ED. This was retrospectively validated in 2010 and showed MACE incidence of ~1% in those scoring 0-3. This was externally and prospectively validated in 2013 with MACE incidence 1.7% in those scoring 0-3.
The HEART score provides emergency physicians with solid, reproducible evidence that there is a cohort of patients presenting to the ED with chest pain who are suitable for early discharge.
Hopefully, the next iteration of the AHA guidelines will include HEART and recognize the utility in early discharge.
References // Further Reading:
1. Antman EM, Cohen M, Bernink PJ, et al. The TIMI risk score for unstable angina/non-ST elevation MI: A method for prognostication and therapeutic decision making. JAMA. 2000;284(7):835-42.
2. Boersma E, Pieper KS, Steyerberg EW, et al. Predictors of outcome in patients with acute coronary syndromes without persistent ST-segment elevation. Results from an international trial of 9461 patients. The PURSUIT Investigators. Circulation. 2000;101(22):2557-67.
3. Fox KA, Dabbous OH, Goldberg RJ, et al. Prediction of risk of death and myocardial infarction in the six months after presentation with acute coronary syndrome: prospective multinational observational study (GRACE). BMJ. 2006;333(7578):1091.
4. Lagerqvist B, Diderholm E, Lindahl B, et al. FRISC score for selection of patients for an early invasive treatment strategy in unstable coronary artery disease. Heart. 2005;91(8):1047-52.
5. Pollack CV, Sites FD, Shofer FS, Sease KL, Hollander JE. Application of the TIMI risk score for unstable angina and non-ST elevation acute coronary syndrome to an unselected emergency department chest pain population. Acad Emerg Med. 2006;13(1):13-8.
6. Amsterdam EA, Kirk JD, Bluemke DA, et al. Testing of low-risk patients presenting to the emergency department with chest pain: a scientific statement from the American Heart Association. Circulation. 2010;122(17):1756-76.
7. Six AJ, Backus BE, Kelder JC. Chest pain in the emergency room: value of the HEART score. Neth Heart J. 2008;16(6):191-6.
8. Backus BE, Six AJ, Kelder JC, et al. Chest pain in the emergency room: a multicenter validation of the HEART Score. Crit Pathw Cardiol. 2010;9(3):164-9.
9. Backus BE, Six AJ, Kelder JC, et al. A prospective validation of the HEART score for chest pain patients at the emergency department. Int J Cardiol. 2013;168(3):2153-8.