Intravascular ultrasound–guided percutaneous coronary intervention in acute coronary syndrome stratified by the TVF-ACS risk score: the IVUS-ACS trial

Abstract Aims The IVUS-ACS trial demonstrated that intravascular ultrasound (IVUS) guidance reduces target-vessel failure (TVF) in patients with acute coronary syndromes (ACSs) undergoing percutaneous coronary intervention (PCI). Whether this benefit applies to all ACS patients across the spectrum of risk is unknown. We sought to develop a new risk score for 1-year TVF after PCI in ACS and determine whether IVUS guidance compared with angiography guidance improves outcomes in both high- and low-risk patients. Methods and results From the angiography-guided group of the IVUS-ACS trial (n = 1743), the TVF-ACS risk score was developed using the least absolute shrinkage and selection operator method in a derivation group (n = 1288), and its robustness was assessed in an internal validation group (n = 455). External validation was then performed separately in the IVUS-XPL and ULTIMATE trials. Outcomes in high- and low-risk patients randomized to IVUS guidance vs. angiography guidance were then examined. Ten readily available clinical, laboratory, and angiographic variables were selected for inclusion in the TVF-ACS risk score. A cut-off value of 15.64 discriminated angiography-guided PCI patients at high-risk vs. low risk [area under the curve (AUC) 0.715, 95% confidence interval (CI) 0.653–0.777]. The AUC was similar in the validation group [0.709 (95% CI 0.630–0.788)]. High-risk patients exhibited a higher 1-year rate of TVF compared with low-risk patients [19.8 vs. 5.7%, hazard ratio (HR) 3.81, 95% CI 2.06–7.02, P = 0.00002]. Among 3486 randomized patients, IVUS guidance compared with angiography guidance reduced 1-year TVF in high-risk patients (6.9 vs. 17.6%; HR 0.38, 95% CI 0.24–0.59) with a lesser effect in low-risk patients (3.2 vs. 4.3%; HR 0.75, 95% CI 0.51–1.11; Pinteraction = 0.02). External validation in the IVUS-XPL and ULTIMATE trials confirmed these benefits but with consistent effects in high- and low-risk patients (Pinteractions = 0.49 and 0.92, respectively). Conclusion The TVF-ACS risk score reliably stratifies ACS patients undergoing PCI into high- and low-risk groups. The benefits of IVUS guidance during PCI are most pronounced in high-risk ACS patients, although all ACS patients are likely to benefit.