The Value Of CT Flow Reserve Fraction In Evaluating Myocardial Bridge Related Ischemia In Left Anterior Descending Branch

Objective To investigate the diagnostic value of CT flow reserve fraction(FFR_CT)in evaluating associated myocardial ischemia induced by left anterior descending branch myocardial bridge（MB）and the risk factors of FFR_CTvalue at the narrowest part of the left anterior descending branch coronary artery（MCA）in the presence of calcified plaque.Methods A total of 124 patients diagnosed as MB in the middle part of the left anterior descending branch or middle left anterior descending artery（MB）with calcified plaques at the proximal end of MCA by coronary artery CT angiography were selected,60 patients with MB alone,and 64 patients with MB combined with calcified plaques at the proximal end of MCA,all MB are greater than 2mm thick.The Kappa consistency test was used to compare the consistency between the criteria for diagnosing myocardial ischemia with the FFR_CT≤0.8 at the narrowest part of MCA segment and the clinical criteria for myocardial ischemia.124 patients were divided into simple MB group or MB with calcified plaque group according to whether MB was complicated with calcified plaque,and the clinical data between the groups were compared.64 patients with MB and calcified plaque were divided into abnormal FFR_CTgroup(FFR_CT≤0.8)and normal FFR_CTgroup(FFR_CT>0.8)with FFRCT value equal to 0.8 at the narrowest part of MCA segment as the boundary point,the dates between the two groups were compared.Logistic regression was used to analyze the risk factors of abnormal FFRCT values at the narrowest part of the MCA segment in MB with calcified plaques near the MCA.Results The Kappa consistency test between the criteria for diagnosing myocardial ischemia and the criteria for clinically diagnosing myocardial ischemia was better（Kappa value=0.773,P<0.001）when FFR_CTat the narrowest part of MCA segment was less than or equal to≤0.8.MB combined with calcified plaque near MCA was more likely to have myocardial ischemia symptoms than pure MB（the ratio of myocardial ischemia symptoms between the two groups was 43.75%vs.20.00%,P=0.005）.When MB was combined with calcified plaque near MCA.Logistic regression analysis showed that the degree of coronary artery stenosis at the calcified plaque,the calcification integral of calcified plaque,and the degree of MCA constriction stenosis were the risk factors causing the abnormal FFR_CTvalue at the narrowest MCA segment,with OR values were 3.428,1.022,1.171,respectively,and the P values were 0.040,0.027,0.012 respectively.Conclusions The occurrence of myocardial ischemia can be better judged by monitoring the FFR_CTat the narrowest part of the MCA segment of the left anterior descending artery.When the middle segment of the left anterior descending branch MB with calcified plaque at the proximal end of the MCA,the degree of coronary artery stenosis at the calcified plaque,the calcification integral of the calcified plaque,and the degree of MCA constriction stenosis are risk factors for causing abnormal FFR_CTvalue at the narrowest part of the MCA segment.