Background Coronary stent implantation is an important method for the treatment of acute myocardial infarction. However, in-stent restenosis (ISR) and nontarget lesions (NTLs) may occur in patients after stent implantation, then causing myocardial ischemia. At present, the commonly used noninvasive technique for detecting ISR is computed tomography angiography (CCTA). However, this technique is susceptible to metal artifacts. Computed tomographic myocardial perfusion imaging (CTP) technique can non-invasively diagnose myocardial ischemia and is not affected by metal artifacts, which has important guiding significance for the clinical diagnosis and treatment of ISR and NTLs.
Objective To evaluate the diagnostic value of dynamic CTP technique in patients with ISR or NTLs after coronary stent implantation, with invasive coronary angiography (ICA) combined with fractional flow reserve (FFR) using as the criteria.
Methods A total of 113 patients (mean age of 64.56 ± 8.46 years) with angina pectoris after coronary stent implantation in Chinese PLA General Hospital from October 2019 to December 2021 were prospectively included, including 93 males (82.3%) and 20 females (17.7%). All patients were examined by dynamic load dynamic CTP combined with CCTA, and ICA and FFR were measured within one week. CTP and CCTA data were independently analyzed by two physicians, and myocardial blood flow (MBF) and CCTA diameter stenosis rate (DS) were calculated. ICA stenosis ≥ 90% or FFR ≤ 0.80 were considered functionally significant. The differences of MBF between ischemic and non-ischemic myocardium were compared, the subject operating characteristic curve was drawn and the area under the curve (AUC) was calculated. The cut-off value of MBF was calculated by the most approximate index, and the diagnostic efficacy of DS ≥ 50%, MBF and the combination of DS and MBF were calculated at patient level and vascular level, respectively.
Results A total of 62 patients (54.9%) with 96 coronary arteries (30.4%) were found to have ISR or NTLs by ICA or FFR examination. No matter at patient level or vascular level, the AUC of DS ≥ 50% combined with MBF in the diagnosis of myocardial ischemia was significantly better than that of DS ≥ 50% alone (0.80 vs 0.60, P < 0.001; 0.85 vs 0.68, P < 0.001). On the vessel-based analysis in vessels without stent implantation, the AUC of DS ≥ 50% combined with MBF was higher than that of DS ≥ 50% and MBF (0.90 vs 0.79, P < 0.001; 0.90 vs 0.87, P = 0.040). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 0.89, 0.74, 0.46, 0.96 and 0.77, respectively.
Conclusion Compared with ICA and FFR, dynamic CTP significantly improves the diagnostic efficacy of CCTA alone in patients with suspected ISR or NTLs after coronary stent implantation.
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