Coronary artery disease (CAD) diagnosis and risk stratification are enhanced by various non-invasive procedures, among these are calcium score CT scan (CAC) and myocardial perfusion imaging (MPI) for anatomic and functional assessment, respectively. Although the usefulness of each is proven, at present there conflicting studies on their correlation, with some studies showing these two as independent predictors of CAD. This study aimed to determine the correlation of MPI and CAC as CAD predictors.
Methods: Among 370 suspected CAD patients who had MPI and CAC from 2005-2070, only 32 patients fulfilled the selection criteria and were included in this study. These patients had no known CAD and coronary intervention and underwent MPI and CAC within a six-month period interval. An MPI score of 0 was given to normal results, a score of 7 in the presence of ischemia, and a score of 2 in the presence of infarcts. The CAC result was positive if more than 400 and negative if less than or equal to 400. Their clinical profile was correlated with the results.
Results: Spearman's correlation of rank coefficient analysis showed a significant correlation of MPI and CAC scores (r = 0.4677, which is greater than the critical values 0.306 and 0.432 at a equal to 0.05 and 0.07, respectively). Chi squared testing (at a = 0.05) revealed a significant effect of the following risk factors present in the subjects on their MPI and CAC scores: hypertension (X2c = 78.75 and 78.25), dyslipidemia (X2c = 30.75 and
33.25), diabetes (X2c = 25 and 77.75), obesity (X2c = 25 and 78.25), cerebrovascular disease (X2c = 43.75 and 43.725), smoking history (X2c = 75.88 and 75.75) and alcohol intake (X2c = 45 and 44.75). These were above the chi squared cutoff value of 7.82.
Conclusion: There is a significant correlation between MPI and CAC scores, such that as the CAC score value increases, the MPI score increases, corresponding to an abnormal MPI result. In addition, hypertension and dyslipidemia, diabetes, cerebrovascular disease, smoking and alcohol intake are the risk factors, which showed significant effect on both MPI and CAC scores.