Impact of Hyperemic State on Angio-IMR Performance

Study Overview and Procedural Protocol

This is a prospective, multi-center, diagnostic accuracy study employing a self-controlled design. All participants will undergo coronary angiography and physiological assessment according to standard clinical indications. During the procedure, specific angiographic images will be systematically captured for the target vessel at three distinct physiological time points:

Resting State: Baseline coronary angiography without any hyperemic agents. Sub-hyperemic State: Following the intracoronary administration of nitroglycerin.

Maximal Hyperemic State: During continuous intracoronary infusion of adenosine to achieve maximal microvascular vasodilation.

Immediately following image acquisition, the reference standard measurement-Wire-IMR-will be performed using a pressure-sensor-equipped guidewire under maximal hyperemia.

Core Laboratory Imaging Analysis and Blinding

All angiographic data will be de-identified and transferred to a centralized, independent Cardiovascular Imaging Core Laboratory at Zhongshan Hospital, Fudan University. The analysis will be conducted as follows:

Software Platforms: Five different commercially available Angio-IMR software platforms (anonymized as A, B, C, D, and E) will be used to calculate microvascular resistance.

Independent Analysis: Five dedicated analysts, each specialized in one specific software platform, will perform the calculations. Each analyst will be blinded to the patients' clinical information, the Wire-IMR gold standard results, and the results from the other four software platforms.

Standardization: A primary researcher, not involved in the software measurements, will pre-define the target vessel segments and measurement frames to ensure consistency across all five software platforms.

Statistical Considerations and Data Management The study aims to determine if the coronary hyperemic state significantly alters the fluid dynamics modeling utilized by Angio-IMR algorithms. AUC will be calculated for each software at each of the three states. A head-to-head comparison of AUCs will be performed using DeLong's test. To maintain data integrity, results from the core laboratory and the clinical centers will remain strictly separated until the final database lock.

Inclusion criteria

• Stable angina or suspected coronary heart disease.
• Scheduled for coronary angiography and physiological assessment.
• Target vessel with stenosis < 50% or 50%-90% with fractional flow reserve (FFR) > 0.80.
• Provided informed consent.

Exclusion criteria

• Hemodynamic instability (acute myocardial infarction, cardiogenic shock, severe arrhythmia).
• Contraindications to angiography (e.g., end-stage renal disease).
• Contraindications to adenosine (e.g., severe asthma, high-degree atrial-ventricular block).
• Life expectancy < 1 year or pregnancy.
• Target vessel unsuitable for wire operation (left main lesion, severe tortuosity) or stenosis > 90%.