P5636Lipid core burden index is associated with microcirculatory dysfunction even in stable angina pectoris; Insights from intracoronary electrocardiography

Abstract

Abstract Background Combined near-infrared spectroscopy (NIRS) and intravascular ultrasonography (NIRS-IVSU) is an imaging modality for precise detection of lipid core burden. Distal embolization has been reported to be a mechanism of microcirculatory dysfunction (MD) caused by percutaneous coronary intervention (PCI). High lipid core burden index at the 4-mm maximal segment (max-LCBI(4)) has been associated with the cardiovascular event. A max-LCBI(4) of >500 was related to perioperative myocardial infarction even in patients with stable angina pectoris. Unlike 12-lead electrocardiography, intracoronary electrocardiography can detect slight ischemia during PCI, maybe indicating distal embolization. However, whether PCI for culprit plaques with a low max-LCBI(4) can cause MD is unclear. Thus, this study aimed to investigate whether plaques with low max-LCBI(4) influence MD, using intracoronary electrocardiography. Methods Forty consecutive patients who underwent PCI for stable angina pectoris due to stenosis of the proximal segment of the left anterior descending artery were enrolled. NIRS-IVUS was performed in all the patients before predilatation to evaluate for the culprit lesion. Total LCBI and max-LCBI(4) within the culprit lesion were measured. On gray-scale IVUS, vessel area, lumen area, plaque volume, and percent (%) plaque volume were measured. Intracoronary electrography was performed at stent implantation to measure the time from the initiation of S-T segment elevation from the isoelectric baseline to the return of S-T segment to the isoelectric baseline after the deflation of the stent balloon, which was defined as the severity of the MD. The patients were divided into 2 groups according to median max-LCBI(4) (high [n=20] and low LCBI groups [n=20]). Results The mean age was 72±6 years. Of the patients, 80% were male. The mean overall max-LCBI(4) was 140±100. Max-LCBI(4) was significantly higher in the high-LCBI(4) group than in the low-LCBI(4) group. No significant differences in age, body mass index, American College of Cardiology and American Heart Association classification, and low-density lipoprotein level were found between the groups, as well as in the gray-scale IVUS parameters such as %plaque volume. The mean time from the initiation of the initiation of S-T segment elevation from the isoelectric baseline to the return of S-T segment to the isoelectric baseline was significantly longer in the high LCBI group than in the low LCBI group (33 vs 12 sec, P=0.01) despite no change in the S-T segment on 12-lead electrography. The S-T segment elevation occurred only during stent balloon inflation and returned to the isoelectric baseline immediately after stent balloon deflation at a max-LCBI(4) of 0. The no-reflow and slow flow phenomena were not observed. Conclusion Even low max-LCBI(4) on NIRS-IVUS was associated with MD during PCI in patients with stable angina pectoris.