Combined single-photon emission computed tomography-myocardial perfusion imaging with coronary calcium score for assessing coronary disease

Purpose: Coronary artery disease (CAD) underestimation represents a major pitfall of single-photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI). Coronary artery calcium score (CACS) has emerged as a sensitive tool for the assessment of suspect CAD; however, the integration of SPECT-MPI with CACS has been seldom evaluated, so far, and was therefore the aim of the present study. Methods: Patients undergoing SPECT-MPI with CACS and subsequent coronary angiography were included. ROC curves were used to identify the CACS values best predictive for CAD. In SPECT-MPI negative patients, the formula: defined the optimal CACS cut-points. The Systematic Coronary Risk Evaluation 2 was applied for 10-year cardiovascular risk estimation. Significant CAD was defined for an epicardial coronary stenosis >70 or 50% for the left main. Results: Among 124 patients, 61 (49.19%) displayed positive SPECT-MPI, whereas 69 (56%) had significant CAD at angiography. Sensitivity, specificity, and positive predictive value (PPV) for SPECT-MPI were, respectively, 74, 82, and 84%. Considering 63 SPECT-MPI negative cases, the index values for CACS at the optimal cutoff value of 1949 were: sensitivity 28%, specificity 89%, and PPV 50%, allowing to further detect five (8%) of the patients with significant CAD. The increased discriminative power of the combined SPECT-MPI with CACS was not conditioned by the pretest cardiovascular risk. Conclusion: Among patients with suspect CAD undergoing SPECT-MPI, the addition of CACS in negative cases allows to detect a consistent further 8% of patients with significant CAD, thus limiting the risk of disease underestimation and offering potential prognostic benefits.