Tissue Characteristics Of Culprit Lesion And Myocardial Tissue-level Perfusion In NSTE-ACS Patients: Novel Findings From The Imap-acs-ii Study Using 40-mhz Radiofrequency Intravascular Ultrasound Imaging System

Objective: The impact of tissue characteristics of culprit lesion on myocardial tissue-level perfusion in non-ST-segment elevation acute coronary syndrome(NSTE-ACS)remains unclear.IMAP-ACS-II study was a prospective observational study to investigate the relationship between pre-percutaneous coronary intervention(PCI)culprit plaque characteristics and post-PCI myocardial tissue-level perfusion with i Map intravascular ultrasound(IVUS)in NSTE-ACS patients.Methods: A total of 408 patients with coronary artery disease(246NSTE-ACS and 162 stable angina pectoris)undergoing coronary angiography,grayscale-IVUS and i Map-IVUS were enrolled in the IMAP-ACS-II study.Tissue characteristics of culprit lesion was analyzed by the i Map-IVUS system as fibrotic,lipidic,necrotic,or calcified tissue.Epicardial coronary perfusion was assessed by TIMI flow grade(TFG),and myocardial tissue-level perfusion was assessed by both TIMI myocardial perfusion grade(TMPG)and TIMI myocardial perfusion frame count(TMPFC).Results: The percentages of necrotic volume within the culprit lesion was significantly greater in NSTE-ACS than that in stable angina pectoris(20.8±7.9% vs.15.9±7.2%,P<0.001).Patients with impaired epicardial coronary perfusion(TFG 0-2)had higher necrotic percentage within the culprit lesion than those with normal TFG(27.9±7.3% vs.19.6±7.4%,P<0.001).Moreover,patients with impaired myocardial tissue-level perfusion(TMPFC > 90)had greater necrotic percentages within the culprit lesion than those with normal TMPFC(25.0±8.1% vs.18.4±6.7%,P<0.001).Multivariate analysis revealed that i Map-derived necrotic volume percentage was independently associated with reduced post-PCI TMPG(OR 2.39 [95% CI 1.60 to 3.57],P=0.009)and impaired post-PCI TMPFC(OR 2.89 [95% CI 1.62 to 5.16],P = 0.008).The ROC curve showed that the optimal threshold of necrotic volume percentage was20.09% and 21.03% to predict impaired TMPG and TMPFC,respectively.Conclusion: Increased necrotic fraction of the culprit lesion is independently associated with impaired myocardial tissue-level perfusion in NSTE-ACS patients.Thus,plaque composition assessed by pre-PCIi Map-IVUS could predict post-PCI impaired myocardial tissue-level perfusion in NSTE-ACS patients...