Fully Automated Quantitative Coronary Angiography Versus Optical Coherent Tomography Guidance for Coronary Stent Implantation (FLASH): Multicenter, Randomized Controlled Non-Interiority Trial

1. AI-QCA-assisted DES implantation

After coronary angiography, AI-QCA software will be used to determine the lesion length and the reference vessel diameter in real time to determine the appropriate stent size for implantation. The procedure is performed as follows:

1. Select the optimal projection angle providing the best view of the lesion.
2. Provide sufficient nitroglycerin for vasodilation. If the lesion is severely stenotic, perform balloon angioplasty, followed by nitroglycerin supply.
3. Perform AI-QCA to measure the length of the lesion and the inside diameter of the proximal and distal reference vessels.
4. Determine the stent length and size according to the AI-QCA measurements. Select a stent that is 20% larger than the distal reference vessel diameter and that can provide coverage for both the proximal and distal reference vessels.
5. Perform high-pressure balloon dilation after stent implantation, with the final balloon size being 20% larger than the distal and proximal reference vessel diameters.
6. Perform a final coronary angiogram if no procedural complications are observed on the angiogram and stent expansion is confirmed.
7. Perform a final OCT to measure the stent area (mm2), the primary efficacy endpoint.
8. If significant suboptimal stent results, such as severe underexpansion, extensive strut malapposition, or major stent edge dissection, occur, additional procedures to correct them are permitted to ensure patient safety, although they are generally discouraged. (The primary endpoint will be assessed by OCT run before such correction.)
9. OCT guided DES implantation

After coronary angiography, OCT is performed to determine the appropriate stent size for implantation. After the stent procedure, OCT is performed again to check for an area that is smaller than the area of distal reference vessel and for sufficient dilatation. If necessary, high-pressure balloon dilation is performed to minimize residual stenosis. The procedure is performed as follows:

1. Select the optimal projection angle providing the best view of the lesion.
2. Provide sufficient nitroglycerin for vasodilation. If the lesion is severely stenotic, perform balloon angioplasty, followed by nitroglycerin supply.
3. Perform OCT to obtain pre-procedural images of the vessel. If there is a stenosis and OCT images cannot be obtained, perform OCT after adequate balloon angioplasty.
4. Determine the length and size of the stent to be implanted according to the OCT images. Select the stent size in consideration of the mean lumen diameter and mean external elastic lamina (EEL) diameter of the distal reference vessel. If the EEL is not observed, use a stent that is 0.25 mm larger than the mean lumen diameter. Select the length by measuring the length of the proximal and distal reference vessel segments on the OCT.
5. Perform high-pressure balloon dilation after stent implantation. Select the final balloon size by considering the inside diameters of the distal and proximal reference vessels and EEL diameter.
6. Perform OCT. If no procedure-related complications are observed and there is no underexpansion or malapposition of the stent, perform a final coronary angiogram. If procedure-related complications or underexpansion or malapposition of the stent is observed, correct it, and then perform a final OCT to measure the stent area (mm2), the primary efficacy endpoint.