Cardiac Ischemia

IncidenceNumbers (% or LR)
1. Patients presenting to emergency room with chest pain before consideration of risk factors 1% [1]
2. Patients in primary care with chest pain 0.11% [2]
Risk Factor
1. Prior abnormal stress test LR 3.1 [3]
2. Established vascular disease (e.g. CAD, PAD) LR 2.2
3. DiabetesLR 1.4
4. Male genderLR 1.3
5. Age <45, 45-65, >65 LR 1, 1.8, 3.1 [1]
Symptoms/Syndrome
1. Typical chest pain (pressure type pain, worse w/ activity or stress, better w/ rest or nitroglycerin LR 1.9
2. Associated sweatingLR 1.3
3. Associated shortness of breathLR 1.2
4. ECG with any new T wave inversion, ST depression, Q waves LR 3.6
5. Pleuritic or reproducible CP (decrease) LR 0.3
6. No other clinical symptoms or syndrome LR 0.8
TestClinical sensitivityClinical specificity
1. HS troponin99% 86%
2. Exercise stress ECG61% 74%
3. Exercise stress Echo77% 84%
4. Exercise Stress Spect88% 80%
5. CCTA95% 80%
Other
Explanation for + test without disease:
For stress testing - patient with non-ischemic cardiomyopathy
Explanation for - test without disease:
For stress testing - patient with left circumflex coronary artery disease

Discussion

Incidence and risk factors:

Incidence was determined based on studies of patients presenting to emergency rooms, focusing on overall risk of ischemia before adding in factors with an estimate of 1%.[1,3]. Studies of chest pain in primary care identified much lower incidence of 0.11% annually.[2] This is consistent with other estimates.[4]

Risk factors were identified primarily from a systematic review in JAMA Rational Clinical Examination series by Fanaroff et al in 2015.[5] the most salient risk factors for teaching were selected by authors for inclusion given limited space. Age was considered an important risk factor not addressed by likelihood ratio cutoffs. We evaluated the representation of risk by age from the HEART score.[1] The HEART score divides age into <45 years, 45-65, >65 years and assigns 0, 1 or 2 points by group. Points in HEART represent a low score (0-3 points) risk of major adverse cardiac event (MACE) of 0.9-1.7% or a moderate score (4-6 points) risk of MACE 12-16.6%. This equates to a LR of +1.8 for each point, or a +LR of 1.8 for age 45-65 and a +LR of 3.1 for age >65.

Symptoms/Syndromes:

Symptoms and syndromes were also taken from the systematic review in JAMA Rational Clinical Examination series by Fanaroff et al. in 2015.[5] Authors identified symptoms that were most salient from an educational perspective.

Test sensitivity & specificity

Identification of sensitivity and specificity for high sensitivity troponin came primarily from a cohort study of patients in the UK and US.[6] In this study, sensitivity was set at 99% and clinical specificity was identified to be 86%.

The most recent guideline identified that evaluated sensitivity and specificity of common tests was Fihn et al.[7] This has clear summaries of the sensitivity and specificity of multiple cardiology tests.

From this review [7] we identified the following test characteristics:

  • Exercise ECG: sensitivity 61%, specificity 74%
  • Exercise stress echo: sensitivity 77%, specificity 84%
  • Exercise stress spect: sensitivity 88%, specificity 80%
  • CCTA sensitivity 95%, specificity 80%. The sensitivity is the midpoint of what is quoted. The specificity is at the lower range. The reason is that some patients will have artifact from a variety of reasons – primarily blooming artifact (calcium), which leads to overestimation of actual plaque. Some experts believed 80% itself may be an overestimate.

References

  1. Poldervaart JM, Reitsma JB, Backus BE, et al. Effect of Using the HEART Score in Patients With Chest Pain in the Emergency Department. Ann Intern Med. 2017;166(10):689-697. doi:10.7326/M16-1600

  2. Ruigómez A, Rodríguez LAG, Wallander M-A, Johansson S, Jones R. Chest pain in general practice: incidence, comorbidity and mortality. Family Practice. 2006;23(2):167-174. doi:10.1093/fampra/cmi124

  3. Fanaroff AC, Rymer JA, Goldstein SA, Simel DL, Newby LK. Does This Patient With Chest Pain Have Acute Coronary Syndrome?: The Rational Clinical Examination Systematic Review. JAMA. 2015;314(18):1955-1965. doi:10.1001/jama.2015.12735

  4. Genders TSS, Steyerberg EW, Hunink MGM, et al. Prediction model to estimate presence of coronary artery disease: retrospective pooled analysis of existing cohorts. BMJ. 2012;344:e3485. doi:10.1136/bmj.e3485

  5. Fanaroff AC, Rymer JA, Goldstein SA, Simel DL, Newby LK. Does This Patient With Chest Pain Have Acute Coronary Syndrome?: The Rational Clinical Examination Systematic Review. JAMA. 2015;314(18):1955-1965. doi:10.1001/jama.2015.12735

  6. Shah ASV, Sandoval Y, Noaman A, et al. Patient selection for high sensitivity cardiac troponin testing and diagnosis of myocardial infarction: prospective cohort study. BMJ. 2017;359:j4788. doi:10.1136/bmj.j4788

  7. Fihn SD, Gardin JM, Abrams J, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2012;60(24):e44-e164. doi:10.1016/j.jacc.2012.07.013

 Authors: Daniel Morgan, Deborah Korenstein, Sanket Dhruva