Abstract
BackgroundImaging stress tests are not ideally accurate to predict anatomically obstructive CAD, leading to a non-trivial rate of unnecessary iCA. This may depend on the threshold used to indicate iCA, and maybe CTA or, one step earlier, CT calcium score could spare most unnecessary iCA in only mildly positive cSE. We assessed the diagnostic accuracy of contrast stress-echocardiography (cSE) in comparison with invasive coronary angiography (iCA), and CT angiography (CTA) only in case of equivocal tests, to find hints helping reduce falsely positive cSE in the suspicion of coronary artery disease (CAD).MethodsPatients who were indicated cSE for suspected CAD between 2012 and 2016, who also underwent iCA were selected and diagnostic results compared. A second group, specifically with equivocal cSE who underwent CTA was also analyzed.Results137 subjects with equivocal cSE and CTA and 314 with cSE (any result) and iCA were selected. In the CTA-equivocal cSE group, an Agatston score < 105 and a coronary flow reserve (CFR-LAD) <1.7 had very high negative predictive value (99%, 92% respectively) to exclude obstructive CAD. The Agatston score was the most significant incremental predictor of CAD beyond clinical variables (chi square 31 to 47, p < 0.001). In the iCA group a more-than-mild reversible wall motion abnormality (WMA) demonstrated high positive predictive value for CAD (89%), while CFR-LAD appeared less useful. More-than-mild reversible WMA was the most significant predictor of CAD beyond clinical variables (chi square 37.5 to 56, p < 0.001).ConclusionsOur data suggest iCA should be indicated only for more-than-mild reversible WMA at cSE, due to the very high positive predictive value for CAD of this finding, while mildly positive tests should be shifted to non-invasive CT, with CTA performed only for coronary calcium Agatston score > 100, since lower scores demonstrated very high negative predictive value for CAD, not justifying proceeding to CTA and even less to iCA.
Highlights
Imaging stress tests are not ideally accurate to predict anatomically obstructive coronary artery disease (CAD), leading to a non-trivial rate of unnecessary invasive coronary angiography (iCA)
Out of overall 3275 contrast stress-echocardiography (cSE) performed between 2012 and 2016, we found 137 subjects satisfying the definition for equivocal cSE who underwent CT angiography (CTA) after cSE and within 90 days, who had no history of prior myocardial infarction or revascularization, and 314 who underwent iCA within 90 days after cSE
The only cSE imaging variable significantly differing between the 2 groups was CFR-LAD, which was lower in the CAD group, while the Computed tomography (CT)-derived coronary calcium, measured as the Agatston score, was significantly higher in the CAD group
Summary
Imaging stress tests are not ideally accurate to predict anatomically obstructive CAD, leading to a non-trivial rate of unnecessary iCA. This may depend on the threshold used to indicate iCA, and maybe CTA or, one step earlier, CT calcium score could spare most unnecessary iCA in only mildly positive cSE. We assessed the diagnostic accuracy of contrast stress-echocardiography (cSE) in comparison with invasive coronary angiography (iCA), and CT angiography (CTA) only in case of equivocal tests, to find hints helping reduce falsely positive cSE in the suspicion of coronary artery disease (CAD). Diagnostic tests are usually forced into a binary classification, positive or negative, and imaging functional tests for suspected CAD make no exception This simplistic classification does not fit for all patients. Our lab’s routine practice to assess multiple variables and indicate iCA on the basis of WM, and on myocardial perfusion, CFR-LAD data or clinical suspicion, makes WM accuracy data only partially affected by referral bias
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