Aims: Residual SYNTAX score (rSS) is known to be associated with cardiac events. We sought to investigate the association between rSS and greyscale and virtual histology (VH)-intravascular ultrasound (IVUS) plaque morphology, and the association between rSS and non-culprit-related major adverse cardiac events (MACE) using data from the PROSPECT study.
Methods and results: A total of 697 patients with acute coronary syndromes were enrolled in the PROSPECT study. Three-vessel greyscale and VH-IVUS were performed. Among them, 688 patients with paired baseline SS or SYNTAX score and rSS were identified and divided into three groups – rSS=0 (n=184), 0 <rSS ≤8 (n=364), and rSS >8 (n=140). MACE was defined as the composite of cardiac death, cardiac arrest, myocardial infarction, or rehospitalisation for unstable or progressive angina. There was a significant difference in the three-year non-culprit-related MACE rates among the three groups (5.7% versus 11.9% versus 19.7%, lowest to highest rSS; p=0.004) mainly due to rehospitalisation for unstable or progressive angina. On multivariable analysis, patients with ≥1 lesion with plaque burden ≥70% or ≥1 lesion with a minimum lumen area ≤4 mm2 and total dense calcium volume per patient were significantly correlated with rSS. Insulin-treated diabetes mellitus, rSS, and patients with ≥1 lesion with plaque burden ≥70% were independent predictors of non-culprit-related MACE.
Conclusions: Plaque morphology based on greyscale IVUS and VH-IVUS was significantly correlated with rSS, and rSS and plaque burden ≥70% independently predicted non-culprit-related MACE.