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BACKGROUND: Coronary artery calcification score (CACS) is well validated prognostic tool in coronary artery disease (CAD). The data on the prevalence of myocardial ischemia on Myocardial Perfusion Single Photon Emission Computed Tomography (MPS) in symptomatic patients with zero CACS and low to intermediate risk probability is lacking and controversial.
PURPOSE: The aim of our study was to evaluate the capability of zero CACS to exclude myocardial ischemia on MPS.
METHODS: A total 157 patients (mean age 53 +/- 10 years; 88 (56%) female patients,69 (44%) male patients who were suspected to have CAD and having low to intermediate pretest likelihood for CAD underwent CACS on dedicated CT scanners, CACS was reported as zero in all patients, subsequently all patients underwent MPS. Patients with abnormal MPS underwent additional imaging with CCTA.
RESULTS: All patients had zero CACS, 122 (78%) had normal MPS, and 35 (22%) had abnormal MPS, abnormal MPS includes fixed defect 22 (13%), equivocal 10 (6%), and reversible defect 4 (3%). All patients with abnormal MPS had further imaging with CTCA, CTCA was normal in 30 (85%) patients, one patient had coronary artery stenosis more than 50%, one patient had coronary artery stenosis less than 50%, one patient had anomalous origin coronary artery, and 2 patients had myocardial bridging. Patients with abnormal MPS and normal coronary artery had dilated Cardiomyopathy 14 (40%), asymmetrical septal hypotrophy, 1 (3%), and mitral valve disease 3 (9%).
CONCLUSION: Zero CACS in stable patients with low or intermediate risk indicate very low likelihood of obstructive CAD, less than 1%. Patients with Zero CACS and normal MPS most likely will not benefited from further testing; however, patients with abnormal MPS will need further imaging with CCTA. CCTA is helpful in this group of patients for evaluation of coronary artery and cardiac morphology.