Accuracy and Clinical Outcomes of Computed Tomography Coronary Angiography in the Presence of a High Coronary Calcium Score

BackgroundA high coronary calcium burden may adversely affect image quality of CT coronary angiography (CTCA). The ability to rule out clinically significant disease in this setting is uncertain.MethodsWe examined CTCA findings in patients with a calcium score of >600. Utilising a search of death notices, structured patient interview and medical records, downstream investigations, cardiovascular events, revascularisation and mortality were recorded.ResultsSixty patients with a calcium score >600 had CTCA performed on the same day. Coronary disease findings were: mild 28%, moderate 33%, severe 32% and non-diagnostic 7%. During a median 1.75-year follow-up, 31 (53%) of patients underwent further assessment for coronary disease, eight patients (13%) underwent revascularisation and there were two non-cardiovascular and one cardiovascular deaths. No patient with mild or moderate disease at CTCA had subsequently demonstrated ischaemia, was deemed to require PCI or suffered cardiac mortality. The negative predictive value of CTCA for subsequent PCI and all-cause mortality was 97% (100% for cardiac mortality only). The positive predictive value of CTCA for revascularisation or CV death was 42%.ConclusionIn patients with an elevated coronary calcium score, a negative CTCA implies an excellent short-term outcome and appears to exclude clinically significant coronary disease.