Detrimental Effect of Coronary Flow Redistribution after PCI: An Angiographic Fluid Dynamic and Machine Learning Study
Loc T Vu, MD, Tan Tao U School of Medicine, Long An, Viet Nam
Loc T Vu, MD1, Tra T Ngo, MD2, Ben Beula2, Hien DN Duong1, Thach N. Nguyen, M.D., FSCAI2, Minh BA Thai1, Dang H Nguyen1, Duc T Truong1, Linh P Pham1, Hoa PT Bui1, Ngan Thy Chu3, Minh HN Le3 and Loc NP Nguyen Phuoc4, (1)Tan Tao U School of Medicine, Long An, Viet Nam, (2)Cardiovascular Research, Methodist Hospital, Merrillville, IN, (3)University of Medicine and Pharmacy, HCM, Viet Nam, (4)Tan Tao University, Tan Duc E. City, Long An, Vietnam
Keywords: Coronary and Imaging & Physiology
Background
Based on fluid dynamics, in the left coronary system, the blood was distributed accordingly to the left anterior descending and circumflex artery. After percutaneous coronary intervention (PCI), the blood flow increased at the PCI artery. Did the new redistribution of flow cause any detrimental effect to the non PCI artery?
Methods
Coronary angiographies before and after PCI were included. In the new method of dynamic angiographic protocol, the contrast was injected until the index arteries were completely opacified. As the injection of contrast stopped, the blood in white color moved in and displaced the contrast in black. The movement of the blood in white above a black background could be reviewed frame by frame (15 frames per second) searching for (1) size of the segment proximal to the stent, (2) length of arterial phase of the PCI and (3) non-PCI arteries. At the same time, an AI program was trained to measure the size and the length of the arterial phase by Machine learning, supervised and unsupervised Deep Learning and Convoluted Neural Networks.
Results
Fifty patients undergoing PCI were included. In 15/50 cases (30%) the proximal segment of the PCI artery had vasoconstriction if the stented area was larger than the proximal segment. These vasoconstrictions disappeared after nitroglycerin was given intracoronary. If there was no overdilation of the stented segment, there was no proximal vaso-constriction. The arterial phase in the PCI artery was shorter because the flow was brisk after elimination of the lesion (45/50 of cases or 90%). However the arterial phase in the non PCI artery increased by 4 images or 0.26 second. This means that the flow to the non-PCI artery was lower because more blood was diverted to the PCI artery. In 3 cases, the ramus intermedius branch developed severe occlusion after 6 months while they were patent during the index PCI.
Conclusions
In the left coronary system, stenting of PCI artery (1) diverted the blood from the non-PCI artery, (2) caused vasoconstriction in the proximal segment of the PCI artery and (3) later obstruction due to inadequate blood flow at the non-PCI artery. This short and long term detrimental effect needs to be taken in account when discussing the benefits of PCI.