Coronary stenosis describes the constriction or occlusion of the coronary arteries, essential for myocardial perfusion. This pathological condition predominantly arises from the progressive accumulation of atherosclerotic plaques, impeding arterial blood flow. The resultant ischemia manifests clinically as angina pectoris, dyspnea, and other symptomatic presentations of coronary artery disease (CAD). In the absence of timely and effective intervention, these stenosis may culminate in critical outcomes, including myocardial infarction or sudden cardiac death.
The development of coronary stenosis involves various factors, including lipid accumulation. Lipids play a crucial role in atherosclerosis, leading to the formation of plaques within the coronary arteries. Studies have shown that dyslipidemia, particularly high levels of LDL cholesterol and triglycerides, is associated with an increased risk of coronary artery disease (CAD)[
1,
2]. Furthermore, the presence and severity of coronary artery stenosis can be predicted by assessing metabolic and lipidomic profiles, providing insights into the pathogenesis of CAD [
3]. Non-invasive imaging techniques like CT coronary angiography can help identify subclinical atherosclerosis and high-risk plaque features, aiding in risk stratification and treatment targets for patients with asymptomatic CAD[
4]. Additionally, cardiac mechanical parameters, such as vessel myocardium strain and strain rate, have been correlated with the severity of coronary artery stenosis, offering a potential diagnostic tool for CAD[
5].
Current Management of Coronary Stenosis
The management of coronary stenosis has evolved significantly, incorporating a blend of advanced interventional techniques and foundational lifestyle modifications. Among the cornerstone treatments for coronary stenosis, diet, exercise, and smoking cessation play pivotal roles in conservative management, aiming to reduce cardiovascular risks and improve patient outcomes. Smoking cessation is highlighted as a critical intervention, associated with a reduction in cardiovascular events by up to 50%, underscoring its importance in the therapeutic arsenal against coronary heart disease (CHD) [
6]. Similarly, physical endurance training, as part of a comprehensive rehabilitation program, has been shown to reduce cardiac mortality in CHD patients by approximately 30%, presenting a compelling case for its inclusion as an alternative to interventional measures in selected patients [
7]. Dietary modifications further contribute to the risk reduction strategy, emphasising the role of an appropriate diet in preventing cardiovascular events [
8]. These lifestyle interventions are complemented by medical treatments including acetylsalicylic acid, statins, ACE-blockers, and beta-blockers, which have become the standard in medical therapy for CHD [
9]. Despite the advancements in percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), which have significantly improved the management of coronary artery disease (CAD), the importance of conservative treatment remains undiminished [
10]. The integration of lifestyle modifications with medical and invasive treatments reflects a holistic approach to managing coronary stenosis. This approach is supported by advancements in diagnostic and therapeutic procedures, including the use of intravascular imaging to guide interventions [
11], and the development of novel pharmacological options for refractory angina [
12,
13]. Moreover, the selection of treatment strategies, whether invasive or conservative, is informed by a thorough assessment of the patient’s condition, including the use of coronary computed tomography angiography (CCTA) for planning and guiding coronary interventions [
13]. Diet, exercise, and smoking cessation are integral to the current treatment paradigms for coronary stenosis, serving as foundational elements that complement the advanced therapeutic options available today. These lifestyle interventions are essential for risk reduction and are pivotal in the comprehensive management of patients with coronary artery disease [
14].
The management of coronary stenosis involves a multifaceted approach, incorporating antiplatelets, beta-blockers, statins, and ACE inhibitors as cornerstone therapies. Antiplatelet agents, particularly the more potent P2Y12-inhibitors like prasugrel and ticagrelor, play a critical role in acute coronary syndrome (ACS) treatment by preventing thrombotic events, although there remains a need for balancing antithrombotic efficacy against bleeding risk[
15]. Beta-blockers, on the other hand, are not only pivotal in managing arrhythmias and treating angina pectoris and heart failure but also in controlling hypertension, a major risk factor in the cardiovascular continuum. Their combination with ACE inhibitors is especially beneficial due to their complementary actions on the sympathetic nervous system and renin-angiotensin-aldosterone system, offering improved cardiovascular outcomes[
16]. Statins are another essential component in this regimen, known for their role in reducing plasma levels of myeloperoxidase (MPO) in patients with coronary artery disease (CAD), indicating their influence on inflammatory markers associated with atherosclerosis[
17]. ACE inhibitors have shown promise in providing cardiovascular protection and reducing ischemic events and complications in cardiac surgery patients, highlighting their importance beyond blood pressure control[
18]. Recent studies have also compared the efficacy of angiotensin receptor blockers (ARBs) with ACE inhibitors, each combined with statin therapy, suggesting substantial reductions in cardiovascular events and mortality in patients with newly diagnosed coronary heart disease, although these findings are subject to debate due to potential biases in study design[
19]. For patients with stable angina, a combination of anti-ischemic agents including beta-blockers, nitrates, and calcium channel blockers, alongside metabolic agents and vasodilator therapies, are recommended to prevent myocardial infarction and improve quality of life[
20]. In acute settings, such as ACS, the combination of antiplatelet agents and anticoagulants is crucial for preventing coronary events[
13]. Furthermore, in the context of acute myocardial infarction (AMI) treated with revascularization, the combined use of beta-blockers and ACEI/ARB has been associated with the lowest incidence of all-cause mortality and heart failure hospitalisation, underscoring the synergistic benefits of these medications[
21]. In summary, the current therapeutic strategy for managing coronary stenosis emphasises a comprehensive approach involving antiplatelets, beta-blockers, statins, and ACE inhibitors, each playing a unique role in mitigating the risk of cardiovascular events and improving patient outcomes[
22,
23].
The current interventional treatments for coronary stenosis include percutaneous coronary intervention (PCI) with angioplasty and stent placement, and coronary artery bypass grafting (CABG). Both treatments have evolved significantly, offering distinct advantages based on patient-specific factors, such as the complexity of coronary artery disease (CAD) and patient comorbidities. PCI, particularly with the use of drug-eluting stents (DES), has become a widely accepted treatment for coronary stenosis, including in-stent restenosis (ISR) and severe stenosis of the left main coronary artery (LMCA). Modern DES reduces the incidence of ISR and is recommended for repeated PCI in cases of ISR. The advancements in stent technology and procedural techniques have contributed to PCI’s favourable outcomes in patients with LMCA disease, showing non-inferiority to CABG in terms of mortality and major adverse cardiac events in patients with low-to-intermediate anatomical complexities[
24,
25]. However, the presence of severe coronary calcium can increase the complexity of PCI, necessitating advanced plaque-modification devices and techniques, such as rotational atherectomy and lithoplasty, to prepare the lesion adequately for stent placement[
6,
26]. CABG, on the other hand, remains the standard of care for patients with unprotected left-main disease (ULMD) and multivessel disease (MVD), particularly in those with high anatomical complexity or specific lesion characteristics, such as proximal left anterior descending (pLAD) artery stenosis. CABG is associated with more durable revascularization and lower rates of repeat revascularization compared to PCI. However, it is also associated with a longer recovery period and, in some cases, higher rates of early stroke[
8,
27]. The choice between PCI and CABG is influenced by several factors, including the patient’s clinical presentation, the anatomical complexity of CAD, and the presence of comorbid conditions. Recent guidelines and clinical trials, including the ISCHEMIA study, have provided insights into the optimal management strategies for patients with chronic coronary syndromes (CCS), emphasising the role of modern conservative therapy alongside interventional treatments[
7]. Moreover, the treatment of CAD in special populations, such as cancer patients, has highlighted the importance of individualised care plans, taking into consideration the unique risks and benefits of each treatment modality[
10]. In conclusion, the choice between angioplasty with stent placement and CABG for the treatment of coronary stenosis is complex and must be tailored to the individual patient’s needs, based on a thorough assessment of the clinical and anatomical factors, as well as the patient’s preferences and expected outcomes[
28].
Regenerative medicine, particularly through the use of stem cell therapies, has shown significant promise in addressing long-standing diseases, including those affecting the heart. The novel CRISPR-Cas9 gene editing technology has enabled precise and efficient gene manipulation, facilitating the development of cell-based therapies for incurable diseases[
29]. Stem cell therapy, especially using mesenchymal stem cells (MSCs), has emerged as a breakthrough in treating cardiovascular diseases by promoting the regeneration of infarcted myocardium, which conventional treatments fail to achieve[
30]. The success of cell-based therapies in treating ischemic heart disease hinges on the type of stem cells used, their delivery method, and the underlying disease[
31]. The potential of stem cells in cardiology lies in their ability to regenerate myocardial tissue, offering a permanent solution beyond temporary measures like stents and medications[
32]. However, the transition from somatic, non pluripotent stem or progenitor cells to induced pluripotent stem cells (iPSCs) has marked a significant advancement, moving closer to clinical trials[
33]. Despite the marginal results of clinical trials to date, the integration of stem cell therapy with conventional therapies holds the potential to address the health problems of advanced cardiovascular patients[
34]. The lack of guideline-based indications for stem cell-based therapy remains a challenge, highlighting the need for further research to establish appropriate criteria[
35]. Efforts to improve the efficacy of somatic cardiac cell therapy include selecting specific cellular subpopulations and enhancing delivery methods[
36]. The field of regenerative cardiology is rapidly evolving, with adult stem cells and iPSCs playing crucial roles in developing cell-based strategies for heart disease treatment[
37]. Collaboration between biotechnology and tissue engineering has led to novel therapeutic strategies, including stem cells and nanotechnology, showing promising effects in managing CAD[
38]. Together, these advancements in regenerative medicine and stem cell therapy offer hope for more effective treatments for coronary stenosis, potentially revolutionising the approach to cardiovascular disease management.
Current treatments for coronary stenosis face various challenges and limitations. Severe coronary artery calcification poses a significant obstacle to successful percutaneous coronary intervention, affecting acute and long-term outcomes [
39]. In-stent restenosis remains a concern, with a failure rate of 10-15% leading to repeat procedures in about 40% of patients within a year [
40]. Additionally, the prevalence of coronary artery calcification in patients with advanced age, chronic kidney disease, and diabetes complicates lesion preparation before stent deployment, often resulting in suboptimal outcomes [
41]. Despite advancements like drug-eluting stents reducing in-stent restenosis rates, challenges persist due to aggressive neointimal proliferation and neoatherosclerosis, making DES-ISR treatment complex [
42]. Treatment with all-trans-retinoic acid (atRA) has shown promising results in reversing coronary artery stenosis. Research conducted on a mouse model of Kawasaki disease demonstrated that atRA significantly suppressed coronary artery inflammation and reduced the incidence of stenosis by suppressing smooth muscle cell migration [
43]. Additionally, a study on drug-coated balloons (DCB) for in-stent restenosis found that a new coating formulation (Agent) was non-inferior to standard DCB in reducing late lumen loss, indicating a potential treatment option for coronary stenosis [
44]. Furthermore, cardiovascular medications like angiotensin converting enzyme inhibitors (ACEIs), aldosterone receptor antagonists (ARBs), statins, and calcium channel blockers (CCBs) have been associated with improved coronary flow reserve[
45]. However, to the authors’ knowledge, there is not yet any non-invasive treatment that can reverse coronary stenosis.