Very long-term prognostic value of SYNTAX score, intravascular ultrasound and near-infrared spectroscopy in patients with coronary artery disease: 12-year follow-up

Introduction The Synergy Between PCI With Taxus and Cardiac Surgery (SYNTAX) score is an angiographic tool to grade the severity and complexity of coronary artery disease (CAD). Intravascular ultrasound virtual histology (IVUS-VH), and near-infrared spectroscopy (NIRS), can be used to assess coronary plaque characteristics. The value of these three instruments for mortality prediction beyond five years has not yet been established in patients with low to intermediate complex CAD. Objective This study aims to investigate the very long-term predictive value of the SYNTAX score, plaque characteristics derived by IVUS-VH and NIRS, for all-cause mortality in patients with low to intermediate complex CAD. Methods We examined 581 patients with an indication for coronary angiography due to chronic (CCS) or acute coronary syndrome (ACS), enrolled between 2008-2011. Upfront and when applicable, flow-limiting lesions in a culprit vessel were treated with percutaneous coronary intervention (PCI). The SYNTAX score was calculated pre-PCI for the entire coronary system. IVUS-VH (in all) and NIRS (in 195 patients) was obtained in a non-culprit segment of at least 40 mm. In these segments, several IVUS-VH-derived compositional plaque features were assessed and the NIRS-derived lipid core burden index (LCBI) was measured. The Kaplan-Meier method, and Cox regression models were used to assess the association between the SYNTAX score, imaging-derived plaque characteristics, and all-cause mortality during very long-term follow-up. We adjusted for potential confounders, including age, sex, clinical risk factors, medical history, angiography indication, PCI performed and statin use. Results Mean (standard deviation) age was 62 (11) years, 76% were men, and 55% had an ACS as index event. A PCI of a culprit-vessel was performed in 89% and 90% were on statin therapy at discharge. During median follow-up of 12.8 years (IQR: 10.1-13.4), 177 patients died. Median (25th-75th percentile) SYNTAX-score was 9.0 (4.0 – 15.0), less than 1% had a high SYNTAX score (≥ 33). A doubling in SYNTAX score was associated with a 25% increased mortality risk (adjusted hazard ratio [aHR] 1.25, 95% confidence interval [CI] 1.05-1.48;p=0.012). Dense calcified plaque was associated with a 21% higher mortality risk per doubling in percentage (aHR: 1.21, 95% CI 1.02-1.42; p=0.026), and fibrous plaque associated with a 46% lower mortality risk per doubling in percentage (aHR 0.54, 95% CI 0.34-0.87; p=0.011) (Table, Figure). These findings remained consistent after adjusting for the SYNTAX score. NIRS-derived LCBI was not associated with very long-term mortality. Conclusion Angiography based SYNTAX-score, and IVUS-VH-derived percentage segmental fibrous and dense calcified plaque, independently predict 12-year mortality risk in patients with low to intermediate complex CAD.12-year all-cause mortality risk