The Coronary "CAT" Scan is Out of the Bag Now!

Case Presentation

• 57 year old woman with past history of type 2 diabetes mellitus, hypertension, and hyperlipidemia presenting with acute onset chest pain

• This is the first time she has ever experienced chest pain. Its described as constant pressure in character, 8/10 in intensity, and non-radiating,

• No lightheadedness, nausea, vomiting, dyspnea, or diaphoresis.

• Pain is not reproducible on exam. Heart is regular rate and rhythm no murmurs rubs or gallop. Lung clear to auscultation bilaterally. No lower extremity edema.

• Troponin: <0.04 x3, no changes on serial electrocardiographs (ECG).

• She takes 81 mg aspirin daily. Was given aspirin 324 mg daily and sublingual nitroglycerin with improvement of chest pain.

She is at intermediate risk of acute coronary syndrome (ACS) with a thrombolysis in myocardial infraction (TIMI) score of 2 and HEART score of 5. ST elevation myocardial infarction (STEMI) has been ruled out, but her presentation is concerning for non-ST elevation acute coronary syndrome (NSTE-ACS). She undergoes coronary computed tomography angiography (CCTA) and only mild stenosis is visualized.

Clinical Question

How sensitive is CCTA for ruling out ACS in low to intermediate risk patients, and can a patient be discharged directly from the emergency department with a negative CCTA?

Summary of Evidence

1. CCTA is very sensitive test with a very high negative predictive value that if negative can eliminate the possibility of clinically significant coronary artery stenosis and short-term risk of major adverse cardiac events (MACE).

2. A prospective, multicenter study of 230 subjects with known CAD who underwent both coronary angiography and CCTA showed that CCTA has a sensitivity of 94%, and specificity of 83% when compared to invasive angiography for detection of >50% stenosis. Positive predictive value (PPV) and negative predictive value (NPV) were 48%, and 99% respectively. (1)

3. Another similar prospective multicenter study of 360 patients showed sensitivity of 99% and specificity of 64%. PPV and NPV were 86%, and 97%. (2)

4. A meta-analysis of 9 studies with a total of 1559 patients with low to intermediate risk chest pain found that CCTA had a 99.3% negative predictive value for excluding MACE within 30 days. (3)

5. CCTA has similar clinical outcomes as other testing modalities but leads to more interventions.

6. In a meta-analysis of 4 randomized controlled trials of 3226 subjects at low to intermediate risk of ACS, there was no difference in rates of MACE between patients who underwent CCTA compared to “usual care.” (4)

7. A meta-analysis of 10 studies with 6285 subjects found that there was no difference in mortality or MACE between CCTA and “standard of care” testing but patients who underwent CCTA had more invasive coronary angiographies and revascularizations performed.

Recommendations

1. A negative CCTA excludes ACS in patients at low to intermediate risk and they can be safely discharged directly from the ED. (1-3)

2. CCTA may be associated with increased use of angiography and revascularization, without associated clinical benefit. This is related to the low specificity of the test, and means that a positive CCTA should be interpreted with caution.

References

1. Budoff, Matthew J., et al. "Diagnostic performance of 64-multidetector row coronary computed tomographic angiography for evaluation of coronary artery stenosis in individuals without known coronary artery disease: results from the prospective multicenter ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography) trial." Journal of the American College of Cardiology 52.21 (2008): 1724-1732.

2. Meijboom, W. Bob, et al. "Diagnostic accuracy of 64-slice computed tomography coronary angiography: a prospective, multicenter, multivendor study." Journal of the American College of Cardiology 52.25 (2008): 2135-2144.

3. Takakuwa, Kevin M., et al. "A meta-analysis of 64-section coronary CT angiography findings for predicting 30-day major adverse cardiac events in patients presenting with symptoms suggestive of acute coronary syndrome." Academic radiology 18.12 (2011): 1522-1528.

4. Hulten, Edward, et al. "Outcomes after coronary computed tomography angiography in the emergency department: a systematic review and meta-analysis of randomized, controlled trials." Journal of the American College of Cardiology 61.8 (2013): 880-892.

5. Gongora CA, Bavishi C, Uretsky S, et al. Acute chest pain evaluation using coronary computed tomography angiography compared with standard of care: a meta-analysis of randomised clinical trials. Heart 104.3 (2018): 215-221.