Dr Rachel Bastiaenen, PhD, St George's University of London, St George's Hospital London, UK

Chest pain is the most common presenting complaint in the emergency department for adult males. Triple-rule-out computed tomographic (TRO CT) angiography has been proposed as a cost-effective technique to evaluate the coronary arteries, aorta, pulmonary arteries and adjacent intrathoracic structures in patients with acute chest pain. The principle aim of the test is to evaluate for coronary disease, aortic dissection and pulmonary embolism (PE) within a single scan. CT coronary angiography has high negative predictive value (approaching 100%) for coronary disease in populations with low to intermediate pre-test probability and TRO CT has the potential to either define an alternative diagnosis or, if negative, to allow early discharge saving resources spent on costly inpatient stays. Proponents of TRO CT believe that it can safely eliminate the need for further diagnostic testing in over 75% of patients (1).

Recent data published by Burris et al. compared the diagnostic yield of TRO CT versus CT coronary angiography (CTA) alone in 12,834 patients with acute chest pain presentations enrolled in the Advanced Cardiovascular Imaging Consortium (ACIC) registry. Diagnostic yields were similar overall (TRO 17.4% vs CTA 18.3%; p=0.37). In the emergency department TRO was associated with higher yields of aortic dissection (TRO 1.8% vs CTA 0.9%; p=0.005) and PE (TRO 1.0% vs CTA 0.1%; p<0.001). However this came at the expense of increased non-diagnostic image quality (9.4% of TRO scans), radiation and contrast doses associated with TRO. The authors felt that although TRO was feasible it could not be recommended for all patients with chest pain and may be best suited to those with clinical scenarios that suggest a higher risk of PE or aortic dissection (2).

Another potential problem associated with TRO is the logistics associated with providing a complex ECG gated cardiovascular CT scan via an out-of-hours service. At present there is no guidance regarding use of the TRO CT. It seems likely that large-scale prospective evaluation of the technique and cost effectiveness calculations will be required. And careful patient selection will be vital.

  1. Halpern EJ. Triple-rule-out CT angiography for evaluation of acute chest pain and possible acute coronary syndrome. Radiology 2009;252(2):332-45.
  2. Buris AC, Boura JA, Raff GL et al. Triple rule out versus coronary CT angiography in patients with acute chest pain: Results from the ACIC consortium. JACC Cardiovasc Imaging 2015;8(7):817-25.
Cardio Debate Expert Comments

Joint Expert Comment by Dr Alastair J Moss & Prof David E Newby

Missing the diagnosis of a potentially fatal myocardial infarction, aortic dissection or pulmonary embolus is a major clinical problem, and is often at the forefront of an emergency physician’s mind. Is a single non-invasive imaging test the answer?

The registry data published by Burris et al. highlights the diagnostic differences between CT coronary angiography and triple rule-out computed tomographic angiography (TRO-CTA): namely, that wider thoracic coverage and better contrast opacification of the pulmonary vasculature increase the diagnostic yield for pulmonary emboli (1). However, only a minority of pulmonary emboli are associated with substernal chest pain (<15%) (2) and using TRO-CTA indiscriminately in this group is unlikely to impact on downstream management. If TRO-CTA were used unselectively in acute chest pain presentations, we estimate that 200 patients would undergo unnecessary scanning to detect a single patient with pulmonary embolism.

CT coronary angiography can positively change the management in a quarter of patients with suspected angina (3). Whether similar benefits can be achieved in acute chest pain presentations is currently unknown and this is the subject of the ongoing RAPID-CTCA trial (NCT02284191). If TRO-CTA is to have a role, then appropriate patient selection is imperative to ensure that the right patient gets the right test.

References

  1. Burris AC 2nd, Boura JA, Raff GL, Chinnaiyan KM. Triple Rule Out versus Coronary CT angiography in patients with acute chest pain: results from the ACIC consortium. JACC Cardiovasc Imaging 2015;8(7):817-25.
  2. Pollack CV, Schreiber D, Goldhaber SZ, Slattery D, Fanikos J, O’Neil BJ, Thompson JR, Hiestand B, Briese BA, Pendleton RC, Miller CD, Kline JA. Clinical characteristics, management, and outcomes of patients diagnosed with acute pulmonary embolism in the emergency department: initial report of EMPEROR (Multi- center Emergency Medicine Pulmonary Embolism in the Real World Registry). J Am Coll Cardiol 2011;57(6):700 – 706.
  3. 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. Lancet 2015;285(9985):2383-91.

Joint Expert Comment by Prof David E NewbyDr Alastair J Moss

Missing the diagnosis of a potentially fatal myocardial infarction, aortic dissection or pulmonary embolus is a major clinical problem, and is often at the forefront of an emergency physician’s mind. Is a single non-invasive imaging test the answer?

The registry data published by Burris et al. highlights the diagnostic differences between CT coronary angiography and triple rule-out computed tomographic angiography (TRO-CTA): namely, that wider thoracic coverage and better contrast opacification of the pulmonary vasculature increase the diagnostic yield for pulmonary emboli (1). However, only a minority of pulmonary emboli are associated with substernal chest pain (<15%) (2) and using TRO-CTA indiscriminately in this group is unlikely to impact on downstream management. If TRO-CTA were used unselectively in acute chest pain presentations, we estimate that 200 patients would undergo unnecessary scanning to detect a single patient with pulmonary embolism.

CT coronary angiography can positively change the management in a quarter of patients with suspected angina (3). Whether similar benefits can be achieved in acute chest pain presentations is currently unknown and this is the subject of the ongoing RAPID-CTCA trial (NCT02284191). If TRO-CTA is to have a role, then appropriate patient selection is imperative to ensure that the right patient gets the right test.

References

  1. Burris AC 2nd, Boura JA, Raff GL, Chinnaiyan KM. Triple Rule Out versus Coronary CT angiography in patients with acute chest pain: results from the ACIC consortium. JACC Cardiovasc Imaging 2015;8(7):817-25.
  2. Pollack CV, Schreiber D, Goldhaber SZ, Slattery D, Fanikos J, O’Neil BJ, Thompson JR, Hiestand B, Briese BA, Pendleton RC, Miller CD, Kline JA. Clinical characteristics, management, and outcomes of patients diagnosed with acute pulmonary embolism in the emergency department: initial report of EMPEROR (Multi- center Emergency Medicine Pulmonary Embolism in the Real World Registry). J Am Coll Cardiol 2011;57(6):700 – 706.
  3. 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. Lancet 2015;285(9985):2383-91.