The Effect of Severe Coronary Calcification on Diagnostic Performance of Computed Tomography-Derived Fractional Flow Reserve Analyses in People with Coronary Artery Disease

Abstract

Background: Negative CCTA can effectively exclude significant CAD, eliminating the need for further noninvasive or invasive testing. However, in the presence of severe CAD, the accuracy declines, thus necessitating additional testing. The aim of our study was to evaluate the diagnostic performance of noninvasive cFFR derived from CCTA, compared to ICA in detecting hemodynamically significant stenoses in participants with high CAC scores (>400).

Methods: This study included 37 participants suspected of having CAD who underwent CCTA and ICA. CAC was calculated and cFFR analyses were performed using an on-site machine learning-based algorithm. Diagnostic accuracy parameters of CCTA and cFFR were calculated on a per-vessel level.

Results: The median total CAC score was 870, with an IQR of 642-1370. Regarding CCTA, sensitivity and specificity for RCA were 60% and 67% with an AUC of 0.639; a LAD of 87% and 50% with an AUC of 0.688; an LCX of 33% and 90% with an AUC of 0.617, respectively. Regarding cFFR, sensitivity and specificity for RCA were 60% and 61% with an AUC of 0.606; a LAD of 75% and 54% with an AUC of 0.647; an LCX of 50% and 77% with an AUC of 0.647. No significant differences between AUCs of coronary CTA and cFFR for each vessel were found.

Conclusions: Our results showed poor diagnostic accuracy of CCTA and cFFR in determining significant ischemia-related lesions in participants with high CAC scores when compared to ICA. Based on our results and study limitations we cannot exclude cFFR as a method for determining significant stenoses in people with high CAC. A key issue is accurate and detailed lumen segmentation based on good-quality CCTA images.

Keywords: computed tomography; coronary angiography; fractional flow reserve; sensitivity and specificity.

Figure 1

Flowchart of selected participants.

Figure 2

ROC curves of CCTA and cFFR for each coronary artery. RCA—right coronary artery, LAD—left anterior descending artery, LCX—left circumflex artery, AUC—area under the curve, CCTA—coronary computed tomography angiography, cFFR—one dimensional (1D) FFR analysis.

Figure 3

An 80-year-old male with a CAC score of 868.5, exhibiting prominent calcifications in the LAD artery ((A)—arrow), underwent CCTA. The CCTA revealed severe stenosis in the mid-segment of the LAD artery ((B)—arrow, (C)—arrow). A cFFR test confirmed a significant stenosis in the same segment ((D)—arrow), with a cFFR value of less than 0.7. Consequently, ICA was performed, which confirmed 80% stenosis in the LAD ((E)—arrow). This was followed by percutaneous coronary intervention (PCI) with stenting and the final angiography exam showed complete revascularization ((F)—arrow). CAC—coronary artery calcium, LAD—left anterior descending, CCTA—coronary computed tomographic angiography, cFFR—computed fractional flow reserve, ICA—invasive coronary angiography, PCI—percutaneous coronary intervention.

Figure 4

A 63-year-old male with a history of arterial hypertension and nonspecific arrhythmia underwent CCTA. The CAC score was 1406.7. Extensive calcified and mixed plaques were found in the RCA, with severe stenosis of up to 85% and in the RCA ((A)—arrow), and moderate stenosis of 65% in the LCX ((B)—arrow). A cFFR confirmed the significance of both lesions, with cFFR values of less than 0.7 in the RCA and 0.76 in the LCX ((C)—arrows). ICA revealed long 80–99% stenoses in the middle segment of the RCA ((D)—arrow) and a 90% stenosis in the proximal LCX ((E)—arrow). Immediate PCI of the RCA was performed with complete revascularization ((F)—arrow) which was complicated by anaphylactic shock. A few days later, after premedication, PCI of the LCX was performed with stent implantation and complete revascularization ((G)—arrow). CCTA—coronary computed tomographic angiography, CAC—coronary artery calcium, RCA—right coronary artery, LCX—left circumflex artery, cFFR—computed fractional flow reserve, ICA—invasive coronary angiography, PCI—percutaneous coronary intervention.

Figure 5

A 54-year-old male underwent CCTA for suspected ischemic heart disease. The CAC score was 417. Calcified plaques were found in both the RCA ((A)—arrows) and LAD ((B)—arrows) causing moderate stenoses (50–52% in the LAD and 63% in the proximal RCA). Image (C) shows a VRT reconstruction image of coronary arteries with multiple small plaques on LAD. A cFFR test showed no significant stenoses (D) which was subsequently confirmed on ICA (E). CCTA—coronary computed tomographic angiography, CAC—coronary artery calcium, RCA—right coronary artery, LAD—left anterior descending artery, VRT—volume rendering technique, cFFR—computed fractional flow reserve, ICA—invasive coronary angiography.