Stress myocardial CT perfusion evaluation of myocardial blood flow (MBF) mean value, and correlation of MBF defect and main risk factors

Background Stress Myocardial CT perfusion has emerged as a noninvasive modality for simultaneous anatomical and functional assessment of coronary artery disease, in a single scan session [1,2,3,4,5]. This study investigates the relationship between MBF defects and main cardiovascular risk factors in a cohort of 140 patients, providing reproducible thresholds that may distinguish normal from abnormal perfusion. Methods A total of 140 patients (mean age 67.9±11.1 years; 75% men) were studied by stress myocardial CT perfusion (regadenoson). MBF stress response was classified as normal (MBF=0) or impaired (MBF=1). Patients were categorized based on MBF response, risk factors and Ischeic Heart Disease (IHD) status for statistical analysis. Chi-squared analysis, Pearson correlation coefficient (r) and Odds Ratio were used for statistical analysis. Results Clinical characteristic are shown in Tab.1. Distribution of perfusion findings are represented in Graphic 1. The mean MBF across all AHA segments was 159.92 ml/100ml/min (n = 2208 segments).When stratified by perfusion status, segments with a perfusion defect showed a significantly lower mean MBF of 90.46 ml/100ml/min (n = 359), compared to 171.32 ml/100ml/min (n = 1849) in segments without perfusion defects, with a significant difference (p < 0.01) [Graphic 2.]. These results support the use of MBF values around 90.46 ml/100ml/min as a potential cut-off for identifying abnormal perfusion, and values around 170 ml/100ml/min as representative of normal perfusion.When stratifying patients based on the presence of ischemic heart disease (IHD), the distribution of MBF responses revealed notable differences [Graphic 3], with a moderate positive correlation between MBF impairment and the presence of IHD (Pearson correlation coefficient r = 0.29; chi-squared test χ² = 8.81, p = 0.003), suggesting that reduced MBF may be more associated with the presence of previous IHD , and distribution of MBF status is not independent of IHD status. Furthermore, patients with an MBF defect were found to have a fourfold increased risk of having IHD [Odds Ratio (OR) 4.00, 95% confidence interval of 1.57 to 10.2], suggesting that MBF impairment is a strong noninvasive marker of myocardial ischemia.Furthermore, the data suggest that CT perfusion has a diagnostic relevance in enhancing the likelihood of detecting ischemia in patients with established IHD. Regarding tha main clinical risk factors, only Peripheral Artery Disease (PAD) showed a statistically significant correlation with MBF defect (r = 0.194, p = 0.044) [Tab 2., Graphic 4]. Conclusions MBF impairment detected by CT stress perfusion is significantly associated with previous known IHD and PAD.According to our data, stress cardiac CT perfusion evaluation of MBF appears to be more effective in patients with pre-existing IHD and in those with PAD, representing population subgroups at higher risk for inducible ischemia.Image 1. Graphics Image 2. Tables