Results
In total, 186 patients had a CACS with corresponding CTCA performed. Of these, 94 had a CACS of zero. However, three patients had significant motion artefacts on the CTCA that made interpretation difficult and were, hence, excluded from the study. The distribution of the patients with CACS with corresponding CTCA is shown in figure 2.
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Figure 2.
The distribution of the patients with coronary angiography calcium scoring (CACS) with corresponding computed tomography coronary angiography (CTCA)
This study compares the value of a zero calcium score with findings of significant luminal narrowing on CTCA. The 91 patients included in this study had baseline characteristics as shown in Table 2.
The degrees of stenoses as determined by CTCA are summarised in figure 3.
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Figure 3.
The degrees of stenoses as determined by computed tomography coronary angiography (CTCA)
The single case of severe stenosis was reported in a 45-year-old woman with no pre-existing medical conditions who was referred to the cardiology clinic with atypical chest pain. Due to her low-risk profile, she was referred on for CACS and CTCA. Although there was an absence of calcification, the CTCA suggested a severe left main stem lesion. She proceeded to have formal invasive coronary angiography, which showed angiographically normal coronary circulation. The CTCA pictures were retrospectively reviewed, and the apparent stenosis was deemed to be a result of motion artefact.
The single severe stenosis case picked up by the CTCA would amount to a negative predictive value of 99% (95% confidence interval [CI] 94–100%) for significant stenosis in low-risk patients with a calcium score of zero. Unfortunately, sensitivity and specificity cannot be calculated from this data set as only the test negative patients, i.e. CACS zero, have been reported in this study.