Among vessels with preserved coronary flow, angiography-derived radial wall strain (RWS) analysis has the potential to further discriminate vessels at risk of 1-year adverse events, according to a post hoc analysis of the FAVOR III China study. Shengxian Tu, PhD, of Shanghai Jiao Tong University, Bo Xu, MBBS, of Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, and Fuwai Hospital, Chinese Academy of Medical Sciences, Shenzhen, all in China, and colleagues reported these findings in a manuscript published Monday online and in the Feb. 28 issue of the Journal of the American College of Cardiology. The authors aimed to evaluate the incremental value of angiography-derived RWS in risk stratification of non–flow-limiting mild coronary narrowing. Identification of vulnerable plaque by intracoronary imaging adds incremental information to physiological assessment, with the potential of preventing further adverse events. The simultaneous application of invasive functional and morphological assessments is restricted by equipment availability, financial considerations, as well as prolonged procedural duration. Recently, a simplified method was developed, in which RWS is derived by delineating relative changes of lumen diameter within a cardiac cycle from coronary angiograms, which can be immediately available after quantitative flow ratio (QFR) analysis. The maximum RWS (RWSmax) in interrogated lesions was found to correlate positively with optical coherence tomography–derived lipid burden and lipid-to-cap ratio, and to correlate negatively with fibrous cap thickness. In the present study, the researchers performed a post hoc analysis of the FAVOR III China study population to determine the predictive value of RWS on untreated non–flow-limiting vessel–related adverse events at 1-year follow-up in order to determine the incremental value of angiography-based strain analysis beyond physiological assessment, particularly in lesions with deferred revascularization. The vessel oriented composite endpoint (VOCE) was defined as the composite of vessel-related cardiac death, vessel-related nonprocedural myocardial infarction and ischemia-driven target vessel revascularization). During 1-year follow-up, VOCE occurred in 46 of 824 vessels, with a cumulative incidence of 5.6%. RWSmax was predictive of 1-year VOCE with an area under the curve of 0.68 (95% confidence interval [CI]: 0.58-0.77; P < 0.001). The incidence of VOCE was 14.3% in vessels with RWSmax >12% vs 2.9% in those with RWSmax ≤12%. In the multivariable Cox regression model, RWSmax >12% was a strong independent predictor of 1-year VOCE in deferred non–flow-limiting vessels (adjusted hazard ratio [HR]: 4.44; 95% CI: 2.43-8.14; P < 0.001). The risk of deferred revascularization based on combined normal RWSmax and Murray–law-based quantitative flow ratio (µQFR) was significantly reduced compared with µQFR alone (adjusted HR: 0.52; 95% CI: 0.30-0.90; P = 0.019). The relevance of RWS for prediction of vessel-related events has an underlying rationale and biological plausibility. Theoretically, RWS represents the comprehensive effects of external forces, mainly in circumferential direction, on plaque and coronary wall with heterogenous componential and structural properties. High-strain pattern identified by intravascular ultrasound elastography and palpography is associated with plaque vulnerability and stenosis severity and is positively correlated with clinical presentation of acute coronary syndrome and high serum C-reactive protein levels. Moreover, mechanical deformation of coronary plaques may induce fibrous cap fatigue and contribute to plaque rupture directly. The present analysis provides the first evidence of the incremental prognostic value of RWS in nonischemic vessels. This raises the opportunity for combining physiological guidance and strain analysis for strategy guidance during percutaneous coronary intervention, both indexes being obtained in the same setting solely from the widely available coronary angiogram. An editorial comment was written by Francesco Prati, MD, and Flavio Giuseppe Biccirè, MD, both of the Centro per la Lotta Contro L’Infarto–CLI Foundation, Rome. According to this editorial, the study by Tu, Xu and colleagues should be seen as a valuable contribution in the relentless search for identifying high-risk plaques, and the authors should be congratulated for having adopted a simple technical solution investigating both the angiography-derived hemodynamic relevance (QFR) and the strain pattern (RWS), without the use of intravascular catheters. Regarding the future, the possibility to improve patient prognosis by preventively stenting non–flow-limiting coronary lesions with high-risk plaque features remains unknown and will be addressed by ongoing randomized controlled trials such as INTERCLIMA and COMBINE-INTERVENE, the editorialists wrote. Two different approaches will possibly compete in the future: a first simply based on angiography and enriched with postprocessing solutions versus a second, more complex one that requires imaging catheters to study plaque components. Studies are needed to understand which will prevail. The study was supported by the National Natural Science Foundation of China, the Science Foundation Ireland Research Professorship Award, the Top Hospital and Specialty Excellence of Fujian Province, and the National Clinical Research Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences. Sources: Tu S, Xu B, Chen L, et al. Short-Term Risk Stratification of Non–Flow-Limiting Coronary Stenosis by Angiographically Derived Radial Wall Strain. J Am Coll Cardiol 2023;81:756–767. Prati F, Biccirè FG. Radial Wall Strain and Plato’s Cave: Are Shadows Enough to Get the Truth? J Am Coll Cardiol 2023;81:768–770. Image Credit: Pitchy – stock.adobe.com