Radial wall strain for residual risk stratification after percutaneous coronary intervention.

BACKGROUND: Percutaneous coronary intervention effectively treats flow-limiting stenoses; however, untreated non-target vessels with vulnerable plaques remain a major contributor to future adverse cardiovascular events. Plaque strain is a promising marker of plaque vulnerability but traditionally requires complex modelling and expensive intracoronary imaging. We developed a novel artificial intelligence algorithm for subpixel-level lumen delineation, enabling real-time automated assessment of radial wall strain (RWS) from routine angiography. AIMS: This post hoc study sought to determine the prognostic value of RWS for predicting future cardiac events in non-target vessels over 5 years, using the high-quality TARGET All Comers randomised trial. METHODS: This blinded analysis included all 1,551 enrolled patients. Angiographic image quality was independently assessed prior to blinded computation of RWS. A prespecified cutoff value of maximal RWS (RWSmax) ≥13% was used to define increased plaque vulnerability. The primary endpoint was a non-target vessel-oriented composite endpoint (NT-VOCE), a composite of cardiac death, non-target vessel myocardial infarction and non-target vessel revascularisation over 5 years, as prospectively adjudicated in the parent trial. Following blinded RWS analysis, the results were integrated into the trial database, and the outcomes were unblinded and linked to corresponding vessel-level outcomes. RESULTS: RWS was successfully evaluated in 1,384 non-target vessels from 802 patients. Baseline RWSmax independently predicted the NT-VOCE, with an adjusted hazard ratio (HR) of 4.82 (95% confidence interval [CI]: 3.14-7.40; p<0.0001) and an adjusted area under the curve (AUC) of 0.73 (95% CI: 0.69-0.78; p<0.0001). Predictive accuracy was highest for non-target vessel revascularisation (adjusted AUC 0.92, 95% CI: 0.88-0.95; p<0.0001). In the subgroup with high-quality angiographic images, RWS demonstrated even greater predictive performance for the NT-VOCE (adjusted HR 6.89, 95% CI: 3.15-15.07; p<0.0001). CONCLUSIONS: In this retrospective post hoc analysis, RWS was independently associated with long-term adverse events in deferred non-target vessels, with its prognostic value most evident for subsequent non-target vessel revascularisation. Elevated baseline RWSmax was strongly associated with the NT-VOCE, with the highest predictive accuracy in vessels with high-quality angiographic imaging. Ongoing and planned prospective, randomised trials are evaluating the role of RWS-guided risk stratification.