Absent coronary artery calcium excludes inducible myocardial ischemia on computed tomography/positron emission tomography

Abstract

We set out to determine whether a coronary artery calcium (CAC) score of zero on computed tomography (CT) would predict a normal myocardial perfusion positron emission tomography (PET) in a population mostly at intermediate pretest likelihood of coronary artery disease (CAD). We enrolled 206 outpatients (36% men, mean age 60 ± 13 years) referred for Rb-82 myocardial perfusion PET/CT for suspected CAD. CAC scoring was performed by the Agatston method. The PET images were scored on a 5-point scale using a 17-segment left ventricular model. A summed stress score ≥ 2 was considered abnormal. Multivariable logistic regression analysis was used to test the independent predictive value of a CAC score of zero to exclude inducible myocardial ischemia. Ninety-nine of 206 patients (48%) had a CAC score of zero and of these only 1 had inducible ischemia on PET. This yielded a negative predictive value of 99% (95% CI 95%-100%). CAC score of zero was the strongest independent predictor of a normal myocardial perfusion PET (OR = 0.05; 95% CI = 0.006-0.38; p = 0.004). In a population of predominately intermediate likelihood of CAD, a CAC score of zero excludes inducible ischemia on myocardial perfusion PET.