Coronary heart disease

Coronary heart disease (CHD) is the abbreviation for coronary atherosclerotic heart disease, also known as ischemic heart disease, which typically refers to the heart disease manifested as myocardial ischemia, hypoxia or necrosisstenosis or obstruction due to coronary artery atherosclerosis. 

Risks

According to the statistics of WHO, cardiovascular disease (CVD) is the leading cause of deaths worldwide; the number of patients died of CVD accounted for about 31% of all deaths globally, of whom about 8.8 million died of CHD. More than 3/4 of CVD cases were in low- and middle-income countries; over 16 million patients died of non-contagious diseases before the age of 70, 82% of which were from low- and middle-income countries, and 37% of which were caused by CVD.

According to a report issued by China Insights Consultancy, the number of patients with CHD in China reached 17 million in 2020, which was expected to reach 28.8 million in 2030. According to statistics, about 80% of sudden cardiac death was caused by CHD and its complications. Therefore, CHD is also known as the "No.1 killer of human beings".

Treatment

In addition to changing daily habits, drug therapy and coronary revascularization are also conventional treatment for CHD. Coronary revascularization includes percutaneous coronary intervention (PCI) and surgical coronary artery bypass grafting. PCI is a minimally invasive procedure, in which the operator uses a small incision in the patient's wrist or the base of the thigh to deliver a device through an arterial vessel into a diseased coronary vessel in the heart, and the blood flow can be restored by balloon dilatation, stent implantation or other operations.

PCI has developed rapidly since the 1970s. With the continuous emergence of new devices and technologies, the continuous optimization of drug therapy and the long-term experience accumulation by physicians, the incidence of perioperative complications of PCI has been reduced significantly, also with the long-term prognosis of patients improved greatly. At present, PCI has become the optimal treatment for patients with CHD, and the number of operations completed has reached one million. However, the number of patients with CHD in China continues to increase with the increasing aging population, thus the number of PCI operation continues to climb accordingly.

Currently, coronary angiography is still the major imaging tool to diagnose coronary artery disease, figuring out the range, distribution and severity of the lesion, and providing guidance for coronary intervention. However, the severity and morphology of coronary artery lesions cannot be accurately evaluated with coronary angiography, thus making it difficult to formulate accurate treatment strategies or optimize PCI during the procedure. The application of intravascular imaging technology can make up for the above shortcomings and refresh the PCI treatment model.

Precise PCI with OCT guidance

Optical coherence tomography (OCT) is an intravascular imaging technology emerging in recent years, which rapidly generates coronary artery cross-sectional images by collecting and analyzing the near-infrared light signals reflected from different tissues. Compared with ultrasound, near-infrared light is featured with shorter wavelength and higher frequency. Therefore, OCT can acquire longitudinal image sequences with higher resolution in a faster and safer manner, and realize microstructure imaging of blood vessel walls comparing with IVUS.

OCT is an intravascular imaging technology with the highest resolution at present. It has an axial resolution up to 10 μm, making it possible to visualize the fine structures of the blood vessel clearly. OCT is also called as "optical biopsy" in the medical field due to the high consistency between its imaging results and the results of pathological biopsy. Thus it can be used to guide and optimize the PCI process, providing more accurate diagnosis and supporting the individualized treatment.

OCT examination before stenting can provide qualitative and quantitative analysis of coronary artery anatomical structure, lesion category information and distribution so as to accurately assess target vessel diameter, stenosis degree and lesion range, understand basic composition, characteristics and morphology of plaques, guide the selection of appropriate stent diameter and length, and determine the optimal landing point. OCT has unique advantages in terms of diagnosis, especially for unstable plaques and thrombosis, which is conducive to formulating more accurate PCI strategies. OCT examination after stent implantation can assist in determining the necessity of post-balloon dilatation, selection of post-dilatation balloon diameter, evaluating the performance of stent implantation, and reducing complications caused by stent implantation. 

In addition to more accurate guidance and optimization of PCI, OCT also has unique value for some complex lesions. For example, OCT can accurately identify the pathogenesis as plaque rupture or plaque erosion in patients with acute coronary syndrome (ACS), avoiding unnecessary stent placement. Furthermore, OCT can make a more accurate quantitative score for calcified lesions and guide the selection of effective pre-treatment options. With the help of 3D reconstruction feature, OCT can accurately manipulate the guidewire to penetrate through the mesh of the stent and enter the side branch of the bifurcation lesions. OCT can also be used to evaluate the long-term effects of bioabsorbable stents and other novel medical devices with eluting drugs, and has become an important evaluation tool in the premarket clinical studies the emerging medical devices. During the follow-up of stent efficacy, OCT can be applied to assess the degree of neointimal tissue coverage of the stent struts and thrombosis adhesion, which is conducive to guiding the operators to formulate individual antiplatelet treatment for different patients and decide the proper discontinuation time. Meanwhile, OCT can also be used to identify the causes of stent failure, so as to provide a basis for formulating the remedial strategies.