Unstable Angina in the Era of Cardiac Troponin Assays with Improved Sensitivity-A Clinical Dilemma

Am J Med. 2017 Dec;130(12):1423-1430.e5. doi: 10.1016/j.amjmed.2017.05.037. Epub 2017 Jun 21.


Background: There is an expectation that with the adoption of more sensitive cardiac troponin (cTn) assays, unstable angina would become a rarity. However, recent data from the SWEDEHEART registry demonstrated that 15% of patients admitted with non-ST-elevation acute coronary syndrome still were regarded as having unstable angina. We aimed to further investigate the clinical characteristics and outcome of these patients.

Methods: This was a retrospective, registry-based analysis (SWEDEHEART) including 3204 unstable patients, 18,194 non-ST-elevation myocardial infarction (NSTEMI) patients, and 977 controls without acute cardiovascular disease. All patients had available data on peak cTnT levels (more sensitive assay) and 1-year outcome.

Results: The annual proportions of patients with unstable angina (2009-2013) among those with non-ST-elevation acute coronary syndrome ranged from 9.4% to 15.3%. Only 1239 unstable angina patients (39.7%) had a peak cTnT level ≤14 ng/L. Patients with unstable angina tended to be younger than those with NSTEMI but had higher prevalence of most cardiovascular risk factors and more advanced coronary artery disease. Compared with controls, the adjusted hazard ratios (95% confidence interval) regarding major cardiovascular events were 2.97 (1.30-6.78) and 5.44 (2.54-11.65) in unstable angina patients with peak cTnT ≤14 ng/L and >14 ng/L, respectively.

Conclusion: The diagnosis of unstable angina is still commonly used, even in the era of more sensitive cTn assays. Minor cTnT elevation is common, which makes unstable angina difficult to distinguish from NSTEMI. Patients with unstable angina have a nonneglectable cardiovascular risk. We suggest that the clinical management of patients presenting with unstable symptoms should depend on their estimated cardiovascular risk rather than on strictly applied diagnostic criteria.

Keywords: Acute coronary syndrome; Cardiac troponin; Risk prediction; Unstable angina.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Angina, Unstable / blood*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Non-ST Elevated Myocardial Infarction / blood*
  • Retrospective Studies
  • Risk Factors
  • Sensitivity and Specificity
  • Troponin / blood*


  • Troponin