Impact of plaque burden and composition on coronary slow flow in ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention: intravascular ultrasound and virtual histology analysis.

Aim: Coronary slow flow (SF) is an important complication of percutaneous coronary intervention (PCI) associated with poor prognosis. The aim was to assess grey-scale intravascular ultrasound (IVUS) and virtual histology (VH-IVUS) characteristics of culprit lesion in ST-elevation myocardial infarction (STEMI).

Methods: A total of 295 consecutive patients with STEMI underwent coronary angiogram and IVUS. Following PCI, patients divided into two groups; SF (thrombolysis in myocardial infarction [TIMI] flow  ≤ 2,  = 74) and normal flow (NF) (TIMI flow >2,  = 221). Coronary plaque burden and its composition in relation to SF were evaluated.

Results: On grey-scale IVUS, the plaque area (12.3 mm 11.5 mm,  = .01), plaque volume (110.7 mm 99.8 mm,  < .001), lesion external elastic membrane (EEM) cross-sectional area (14.9 mm 14.0 mm,  = .011) and remodelling index (1.3 1.2,  = .043) were significantly higher in SF group. On VH-IVUS, absolute fibrous volume (48.1 mm 41.5 mm,  ≤ .001), fibrofatty volume (23.8 mm . 18.6 mm,  = .015), necrotic core volume (8.3 mm 5.5 mm,  < .001), dense calcium volume (1.2 mm 0.6 mm,  = .003) and thin cap fibroatheroma either single (30.1% 16.1%,  < .001) or multiple (9.6% 1.8%,  < .001) were higher in SF arm. In multivariable analysis, absolute necrotic core volume (odds ratio  =  1.159; 95% CI 1.030-1.305,  = .015) was the only independent predictor of SF.

Conclusions: Higher necrotic core volume as detected by VH-IVUS may be a potential risk factor for the development of coronary SF phenomenon in patients with STEMI after PCI.