Tissue characteristics of culprit lesion and myocardial tissue-level perfusion in non-ST-segment elevation acute coronary syndromes: The EARLY-MYO-ACS study.

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. EARLY-MYO-ACS 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 iMap intravascular ultrasound (IVUS) in NSTE-ACS patients. METHODS: A total of 408 patients with coronary artery disease (246 NSTE-ACS and 162 stable angina pectoris) undergoing coronary angiography, grayscale-IVUS and iMap-IVUS were enrolled. Tissue characteristics of culprit lesion were analyzed by the iMap-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 were significantly greater in NSTE-ACS than that in stable angina pectoris (20.8 ±â€¯7.9% vs. 15.9 ±â€¯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 ±â€¯7.3% vs. 19.6 ±â€¯7.4%, P < 0.001). Moreover, patients with impaired myocardial tissue-level perfusion (TMPG 0-2) had greater necrotic percentages within the culprit lesion than those with normal TMPG (25.0 ±â€¯8.1% vs. 18.4 ±â€¯6.7%, P < 0.001). Multivariate analysis revealed that iMap-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 was 20.09% 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-PCI iMap-IVUS could predict post-PCI impaired myocardial tissue-level perfusion in NSTE-ACS patients (Trial Registration: ChiCTR-OCH-13003046).