Objectives To study the clinical impact of a very high coronary artery calcium score (CAC >1000) in patients with no known coronary artery disease (CAD) and normal single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). The secondary aim was to evaluate whether triple vessel disease would support the notion of balanced ischaemia as an underlying mechanism of false negative SPECT MPI in patients with very high CAC.
Background No data exist on the clinical value of high CAC in patients with normal SPECT MPI.
Methods 50 patients with suspected CAD and normal stress/rest SPECT MPI and CAC >1000 prospectively underwent invasive coronary angiography as the standard of reference. Coronary lesions with ≥50% luminal diameter narrowing on invasive coronary angiography were considered to represent significant stenosis.
Results The median total CAC was 1975 (range 1018–8046). In 37/50 (74%) patients, coronary angiography revealed one-vessel disease (1-VD) (n=15), 2-VD (n=10) or 3-VD (n=12). Twenty-six revascularisations (percutaneous coronary intervention/coronary artery bypass grafting) were performed in seven (6/1), seven (6/1) and 12 (7/5) patients with 1-VD, 2-VD and 3-VD, respectively.
Conclusions In patients with normal SPECT MPI, a CAC >1000 confers a high diagnostic added value for detecting CAD. This is not solely based on unmasking balanced ischaemia due to epicardial 3-VD, as it occurred predominantly in patients with 1-VD and 2-VD.
- Coronary artery disease
- coronary calcium score
- balanced ischaemia
- normal SPECT/MPI
- CT scanning
- nuclear cardiology
- radionuclide imaging
- coronary artery disease (CAD)
- myocardial perfusion
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JRG and APP contributed equally to this work.
Funding This study was supported by a grant from the Swiss National Science Foundation (SNSF) and by the ZHIP (Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland).
Competing interests None.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the local ethics committee of the University Hospital Zurich.
Provenance and peer review Not commissioned; externally peer reviewed.