Impact of plaque components on no-reflow phenomenon after stent deployment in patients with acute coronary syndrome: a virtual histology-intravascular ultrasound analysis

Abstract

Aims: We used virtual histology-intravascular ultrasound (VH-IVUS) to evaluate the relation between coronary plaque characteristics and no-reflow in acute coronary syndrome (ACS) patients.

Methods and results: A total of 190 consecutive ACS patients were imaged using VH-IVUS and analysed retrospectively. Angiographic no-reflow was defined as TIMI flow grade 0, 1, and 2 after stenting. Virtual histology-intravascular ultrasound classified the colour-coded tissue into four major components: fibrotic, fibro-fatty, dense calcium, and necrotic core (NC). Thin-cap fibroatheroma (TCFA) was defined as focal, NC-rich (≥10% of the cross-sectional area) plaques being in contact with the lumen in a plaque burden≥40%. Of the 190 patients studied at pre-stenting, no-reflow was observed in 24 patients (12.6%) at post-stenting. The absolute and %NC areas at the minimum lumen sites (1.6±1.2 vs. 0.9±0.8 mm2, P<0.001, and 24.5±14.3 vs. 16.1±10.6%, P=0.001, respectively) and the absolute and %NC volumes (30±24 vs. 16±17 mm3, P=0.001, and 22±11 vs. 14±8%, P<0.001, respectively) were significantly greater, and the presence of at least one TCFA and multiple TCFAs within culprit lesions (71 vs. 36%, P=0.001, and 38 vs. 15%, P=0.005, respectively) was significantly more common in the no-reflow group compared with the normal-reflow group. In the multivariable analysis, %NC volume was the only independent predictor of no-reflow (odds ratio=1.126; 95% CI 1.045-1.214, P=0.002).

Conclusion: In ACS patients, post-stenting no-reflow is associated with plaque components defined by VH-IVUS analysis with larger NC and more TCFAs.

Figure 1

The absolute (A) and relative (B) plaque components at the minimum lumen site. Virtual histology-intravascular ultrasound analysis classified the colour-coded tissue into four major components: green [fibrotic (FT)]; yellow-green [fibro-fatty (FF)]; white [dense calcium (DC); and red [necrotic core (NC)]. At the minimum lumen site, the absolute and relative necrotic core areas and the absolute dense calcium area were significantly greater in the no-reflow group than in the normal-reflow group; conversely the relative fibro-fatty area was significantly smaller in the no-reflow group than in the normal-reflow group.

Figure 2

The absolute (A) and relative (B) plaque components at the largest necrotic core site. Virtual histology-intravascular ultrasound analysis classified the colour-coded tissue into four major components: green [fibrotic (FT)]; yellow-green [fibro-fatty (FF)]; white [dense calcium (DC); and red [necrotic core (NC)]. At the largest necrotic core site, the absolute and relative necrotic core areas and absolute dense calcium area were significantly greater in the no-reflow group than in the normal-reflow group; conversely relative fibrotic and fibro-fatty areas were significantly smaller in the no-reflow group than in the normal-reflow group.

Figure 3

The volumetric absolute (A) and relative (B) plaque components. Virtual histology-intravascular ultrasound analysis classified the colour-coded tissue into four major components: green [fibrotic (FT)]; yellow-green [fibro-fatty (FF)]; white [dense calcium (DC); and red [necrotic core (NC)]. The absolute and relative necrotic core and dense calcium volumes were significantly greater in the no-reflow group than in the normal-reflow group; conversely relative fibrotic and fibro-fatty volumes were significantly smaller in the no-reflow group than in the normal-reflow group.

Figure 4

The relative plaque components at the proximal (A) and distal (B) reference sites. Virtual histology-intravascular ultrasound analysis classified the colour-coded tissue into four major components: green [fibrotic (FT)]; yellow-green [fibro-fatty (FF)]; white [dense calcium (DC); and red [necrotic core (NC)]. At the proximal reference sites, the relative necrotic core and fibrotic areas were significantly greater in the no-reflow group than in the normal-reflow group; conversely relative fibro-fatty area was significantly smaller in the no-reflow group than in the normal-reflow group. At the distal reference sites, the relative necrotic core and dense calcium areas were significantly greater in the no-reflow group than in the normal-reflow group.

Figure 5

The incidence of thin-cap fibroatheromas. Virtual histology-intravascular ultrasound-detected thin-cap fibroatheroma was defined as a necrotic core ≥10% of plaque area in at least three consecutive frames without overlying fibrous tissue in the presence of ≥40% plaque burden. The presence of at least one thin-cap fibroatheroma and multiple thin-cap fibroatheromas within culprit lesions was more common in the no-reflow group than in the normal-reflow group.