Original Title: CT Angiography for the Prediction of Hemodynamic Significance in Intermediate and Severe Lesions. Head-to-Head Comparison with Quantitative Coronary Angiography Using Fractional Flow Reserve as the Reference Standard.

Reference: Matthew J. Budoff et al. J Am Coll Cardiol Img. 2016;9(5):559-564.

The aim of this study was to compare the diagnostic accuracy of non-invasive CT angiography and conventional quantitative coronary angiography to detect significant coronary stenoses against fractional flow reserve (FFR) as gold standard.

CT angiography is a non-invasive alternative to detect and rule out heart disease; however, it tends to overestimate lesions.

FFR was used as gold standard given its capacity to improve outcomes in guiding revascularization procedures.

A total 252 patients from 5 countries underwent CT and coronary angiography in 407 lesions.

Severity of lesions, according to CT and quantitative angiography, was classified between 0% and 29%, 30% and 49%, 50% and 69% and between 70% and 100%. All lesions ≥50% were automatically regarded as obstructive.

Functional significance of lesions was classified according to FFR 0.8 cutoff value, as usual.

According to FFR, out of the 407 lesions, 151 (37%) were functionally significant.

CT angiography

Diagnostic accuracy – 69%

Sensitivity – 79%

Specificity – 63%

Positive predictive value – 55%

Negative predictive value 83%

Quantitative angiography

Diagnostic accuracy – 71%

Sensitivity – 74%

Specificity – 70%

Positive predictive value – 59%

Negative predictive value 82%

The area under the curve to identify capacity to detect lesions that cause ischemia was similar, with 0.75 for CT angiography and 0.77 for quantitative coronary angiography (p = 0.6).

There were no differences when considering left anterior descending artery (0.71 vs. 0.73; p=0.6), left circumflex artery (0.78 vs. 0.85; p=0.4) and right coronary artery (0.80 vs. 0.83; p=0.6).

Conclusion

CT and conventional angiography have similar diagnostic capacity to detect lesion-specific ischemia.

Editorial Comment

CT angiography is a less invasive and safer diagnostic tool, and in some countries, less expensive than conventional angiography. On the other hand, it has the disadvantage of additional radiation and contrast doses, which cannot be solved with ad-hoc PCI, and may render it less useful in cases when the risk of heart disease is high.