What is a Low-Risk Patient?

“Low-risk patients” are defined as those who are hemodynamically stable, free of arrhythmias and ischemic electrocardiographic changes, and have negative sequential cardiac biomarkers.

Some lower-risk NSTEMI and Unstable Angina (UA) patients may be discharged if follow-up can be arranged.  Discussing these patient cases with your consultant service is recommended.

Options

• Discharge home
• Discharge home with further testing
• Serial testing
• Consult CCU

*If your pre-test probably is very low, or very high, you likely do not need further testing.

See: Risk stratifying low-risk chest pain in the ED.

Further Testing

Further testing to find Coronary Artery Disease (stable) or Acute Coronary Syndrome (NSTEMI/UA)

1. Exercise Treadmill Test
2. ’MIBI’ Test (Nuclear Stress Test) = myocardial perfusion imaging (MPI)
3. Cardiac CT (CTCA)
4. Stress Echocardiography

Guidelines (Stable)

1. American College of Cardiology/AHA 2013: ‘Appropriate’ or ‘may be appropriate’ in stable chest pain patients
2. Canadian Cardiovascular Society 2014: ‘We suggest that patients with an interpretable rest ECG who are able to exercise should have an exercise ECG test (ideally free of anti-ischemic drugs) (Conditional Recommendation, Low-Quality Evidence)’.
3. NICE Update 2016: Exercise ECG should no longer be used to diagnose or exclude stable angina in ‘new chest pain patients’.

Guidelines (NSTEMI/Unstable Angina)

1. American College of Cardiology/AHA 2014: ‘It is reasonable for patients with possible ACS who have normal serial ECGs and cardiac troponins to have a treadmill ECG’ (Level of Evidence: A).
2. Canadian Cardiovascular Society 2014: ? Intermediate-risk → observe → no high-risk features on observation → stress test/perfusion scan.
3. NICE 2010: Recommend further research on ischemia testing.

Evidence / Benefit / Harm

1. Sensitivity: 61-68%
2. Specificity: 70-77%
3. Genders et. Al: 2012 Retrospective pooled analysis of individual patient data: ‘the diagnostic value of exercise electrocardiography is limited’
4. High false positive leading to further downstream testing

Conclusions

1. It’s easy to order
2. It’s familiar
3. Can be difficult to perform for patients, but easy for facilities
4. Best performed on low and intermediate-risk patients who can exercise and have normal ECGs
5. But is it time for a paradigm shift IF you have access to other modalities

Guidelines

1. American College of Cardiology 2013: ‘appropriate’ or ‘rarely appropriate’.
2. Canadian Cardiovascular Society 2014:

• We suggest that the initial test in patients able to exercise, with a rest ECG that precludes ST segment interpretation, should exercise MPI or exercise echocardiography (Conditional Recommendation, Moderate-Quality Evidence).
• We suggest that the initial test in patients without LBBB or paced rhythm who cannot exercise be vasodilator stress MPI or dobutamine echocardiography (Conditional Recommendation, Moderate Quality Evidence).
• We recommend that the initial test in patients with LBBB or ventricular paced rhythm should be either vasodilator stress MPI or CCTA (Strong Recommendation, High-Quality Evidence).

Guidelines (NSTEMI/Unstable Angina)

1. American College of Cardiology/AHA 2014: It is reasonable for patients with possible ACS who have normal serial ECGs and cardiac troponins to have stress or rest MPI (Level of Evidence: B).
2. Canadian Cardiovascular Society 2014:  intermediate risk  observe  no high-risk features on observation  stress test/perfusion scan.
3. NICE 2010: recommend further research on ischemia testing.

Evidence / Benefit / Harm

1. High sensitivity and negative predictive value
2. Acute MPI: may decrease hospitalization, likely low yield
3. Radiation Exposure

Conclusions

1. Gives information on location/extent of ischemia
2. It’s not easy to order (outside of urban centers)
3. It’s not easy to perform (4 hours!)
4. Best performed on: intermediate to high-risk patients who cannot exercise and/or have an abnormal baseline ECG

Guidelines

1. American College of Cardiology: ‘rarely appropriate’, ‘may be appropriate’, ‘appropriate’.

2. Canadian Cardiovascular Society 2014:

• We recommend that the initial test in patients with LBBB or ventricular paced rhythm should be either vasodilator stress MPI or CCTA (Strong Recommendation, High-Quality Evidence).
• We suggest that CCTA not be used in patients who are believed likely to warrant invasive angiography on the basis of high-risk symptom pattern, high pretest probability of CAD, severe risk factors, or important reasons to minimize exposure to radiation or contrast material (Conditional Recommendation, Low-Quality Evidence).
• NICE Update 2016: CTCA for all stable patients requiring further workup (includes atypical and typical angina along with low-risk clinical assessment but ECG changes.

Guidelines (NSTEMI / Unstable Angina)

1. American College of Cardiology/AHA 2014: In patients with possible ACS and a normal ECG, normal troponins and no history of CAD, it is reasonable for patients with possible ACS to initially perform CTCA (Level of Evidence: A).
2. NICE 2010: recommend further research on ischemia testing.

Evidence / Benefit / Harm

1. Sensitivity: 94-100%
2. Specificity: 89-91%
3. Obesity, high coronary calcium burden, cardiac arrhythmias and tachycardia can adversely affect image interpretation⁴
4. Increased downstream testing and healthcare costs
5. Radiation and contrast material
6. Not of use for patients with prior revascularization

Evidence / Benefit / Harm ER Patients

1. Grunau et. al 2016: For ED patients with chest pain who underwent brief observation, CCTA and EST had similar 30-day angiography rates, but CCTA patients underwent significantly fewer overall cardiac investigations.
2. Foy et. al 2015: ‘Patients with chest pain evaluated in the ED who do not have an MI are at very low risk of experiencing an MI during short- and longer-term follow-up in a cohort of privately insured patients. This low risk does not appear to be affected by the initial testing strategy. Deferral of early non-invasive testing appears to be reasonable’.

Conclusions

1. Anatomical test
2. Quick to perform and order, but only at certain centers
3. Patients need to safely rate controlled at HR 60
4. ? Increased downstream testing on patients w/ non-obstructive lesions
5. ? Consider first line in low to intermediate-risk patients with suspected CAD

Many testing modalities exist for the evaluation of chest pain; CCTA may be emerging as the go-to first-line test, specifically in low to intermediate-risk populations without known CAD.

1. Krishnan S, Venn R, Blumenthal DM, et al. Utilization of stress testing for low-risk patients with chest discomfort in the emergency department. J Nucl Cardiol. 2019;26(5):1642-1646. doi:10.1007/s12350-017-1172-9

   
   

2. Wolk MJ, Bailey SR, Doherty JU, et al. ACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease… J Am Coll Cardiol. 2014;63(4):380-406. doi:10.1016/j.jacc.2013.11.009

   
   

3. Mancini et al. Canadian Cardiovascular Society Guidelines for the Diagnosis and Management of Stable Ischemic Heart Disease. Can J Cardiol. 2014; 30: 837-840. 

   
   

4. Timmis A, Roobottom CA. National Institute for Health and Care Excellence updates the stable chest pain guideline with radical changes to the diagnostic paradigm. Heart 2017;103:982–986. doi:10.1136/heartjnl-2015-308341

   
   

5. Genders Tessa S S, et al. Prediction model to estimate presence of coronary artery disease: retrospective pooled analysis of existing cohorts BMJ 2012; 344 :e3485.

   
   

6. Park S, Sanchez D. The limited utility of cardiac stress testing in low-intermediate risk young adults presenting with chest pain. Circulation.

   
   

7. 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):1756-1776. 

   
   

8. SCOT-HEART investigators. CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial [published correction appears in Lancet. 2015 Jun 13;385(9985):2354]. Lancet. 2015;385(9985):2383-2391. 

   
   

9. Douglas PS, Hoffmann U, Lee KL, et al. PROspective Multicenter Imaging Study for Evaluation of chest pain: rationale and design of the PROMISE trial. Am Heart J. 2014;167(6):796-803.e1. 

   
   

10. SCOT-HEART Investigators, Newby DE, Adamson PD, et al. Coronary CT Angiography and 5-Year Risk of Myocardial Infarction. N Engl J Med. 2018;379(10):924-933. 

    
    

11. Hoffmann U, et al. Coronary CT angiography versus standard evaluation in acute chest pain. N Engl J Med. 2012 Jul 26;367(4):299-308. 

    
    

12. Amsterdam EA, et al. 2014 AHA/ACC Guideline for the Management of Patients with Non-ST-Elevation Acute Coronary Syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2014 Dec 23;64(24):e139-e228. 

    
    

13. Fitchett DH, et al. Assessment and management of acute coronary syndromes (ACS): a Canadian perspective on current guideline-recommended treatment–part 1: non-ST-segment elevation ACS. Can J Cardiol. 2011 Nov-Dec;27 Suppl A:S387-401. 

    
    

14. National Clinical Guideline Centre (UK). Unstable Angina and NSTEMI: The Early Management of Unstable Angina and Non-ST-Segment-Elevation Myocardial Infarction. London: Royal College of Physicians (UK); 2010. PMID: 21977549.

    
    

15. Udelson JE, et al. Myocardial perfusion imaging for evaluation and triage of patients with suspected acute cardiac ischemia: a randomized controlled trial. JAMA. 2002 Dec 4;288(21):2693-700. 

    
    

16. Cremer PC, et al. Myocardial perfusion imaging in emergency department patients with negative cardiac biomarkers: yield for detecting ischemia, short-term events, and impact of downstream revascularization on mortality. Circ Cardiovasc Imaging. 2014 Nov;7(6):912-9. 

    
    

17. Grunau B, et al. Comparison of Rates of Coronary Angiography and Combined Testing Procedures in Patients Seen in the Emergency Room With Chest Pain (But No Objective Acute Coronary Syndrome Findings) Having Coronary Computed Tomography Versus Exercise Stress Testing. Am J Cardiol. 2016 Jul 15;118(2):155-61. 

    
    

18. Foy AJ, et al. Comparative effectiveness of diagnostic testing strategies in emergency department patients with chest pain: an analysis of downstream testing, interventions, and outcomes. JAMA Intern Med. 2015 Mar;175(3):428-36.