Plaque composition analysis by iMap-intravascular ultrasound predicts peri-procedural myocardial injury in patients undergoing percutaneous coronary intervention

Abstract

Purpose: Percutaneous Coronary Intervention (PCI) is often complicated by peri-Procedural Myocardial Injury (PMI) as manifested by cardiac troponin elevation, which is associated with increased cardiac events. However, the method of prediction for PMI has not been established. The purpose of the present study was to investigate whether plaque composition analysis by iMap-Intravascular Ultrasound (iMap-IVUS), a novel radiofrequency intracoronary imaging system, can predict the PMI assessed by high-sensitive cardiac troponin T (hs-TnT). Methods: Forty-five culprit plaques in patients with stable angina pectoris, whose hs-TnT levels before PCI were normal, were imaged using iMap-IVUS before PCI. Volumetric iMap-IVUS analysis was performed across the entire lesion segment, and cross-sectional area analysis was performed at the minimum lumen site. The iMap-IVUS analysis classified tissue characteristics into 4 major components including fibrotic, lipidic, necrotic, and calcified. Those were reported in absolute amounts and as a percentage of plaque area or volume. The hs-TnT was measured before and within 24 hours after PCI, and their differences were expressed as Δhs-TnT. The PMI was defined as hs-TnT elevation after PCI of >5× upper limit level. Results: Of the 45 patients, the PMI was observed in 13 patients (29%) after PCI. The absolute and percent necrotic areas (6.9±3.7 vs. 4.1±2.7 mm2, p=0.007, and 51±12 vs. 34±15%, p=0.001) and the absolute and percent necrotic volumes (50.5±31.2 vs. 28.6±21.3 mm3, p=0.015, and 43±13 vs. 27±11%, p=0.001, respectively) were significantly greater, and the percent fibrotic areas and volumes (36±12 vs. 53±17%, p=0.002, and 45±13 vs. 61±13%, p=0.002, respectively) were significantly smaller in patients with PMI compared with those without PMI. The Δhs-TnT correlated positively with absolute and percent necrotic area and volume, lesion length, remodeling index, stent length, and negatively with absolute and percent fibrotic area and volume. Multivariate logistic regression analysis showed that percent necrotic volume was the only independent predictor of the PMI (odds raio, 1.11; 95% CI, 1.03–1.20; p=0.005). The area under the receiver-operator characteristic curve for percent necrotic volume predicting the PMI was 0.81. The optimal cut-off value of percent necrotic volume for predicting the PMI was 40% (sensitivity 73%, specificity 79%). Conclusions: Plaque composition analysis by iMap-IVUS shows that the PMI often occurs in lesions with large necrotic volumes.