Introduction

Chronic coronary syndromes are also known as stable coronary artery disease (CAD), stable ischemic heart disease (SIHD), chronic stable angina or stable angina pectoris. This is a clinical syndrome resulting from structural and/or functional changes related to chronic diseases of the coronary arteries and/or microcirculation leading to transient, reversible myocardial demand versus blood supply mismatch culminating in hypoperfusion (ischemia) usually but not always precipitated by exertion, emotion or other stress and presenting as angina or constricting discomfort in the chest, neck, jaw, shoulder, back or arms, dyspnea or may be asymptomatic. This is stable for long periods of time but most often progressive and may destabilize at any time with acute coronary syndrome (ACS) development. Angina is stable when it is not a new symptom and when there is no deterioration in frequency, duration or severity of episodes; chest discomfort is predictable and reproducible at a particular level of exertion and relieved with rest or Nitroglycerin.

Epidemiology

Chronic coronary syndromes are the leading cause of death worldwide. The global prevalence of ischemic heart disease (IHD) in 2020 is 138/100,000 in males and 90/100,000 in females. The prevalence in 2020 ranges from 1,556 to <3,345/100,000 in Southeast Asia. Furthermore, the prevalence of chronic coronary syndrome or stable angina increases with age.

Etiology

Chronic coronary syndromes can be attributed to myocardial ischemia of which atherosclerotic coronary artery disease is the most common cause. Obstructive coronary artery disease has ≥50% stenosis while non-obstructive coronary artery disease has <50% stenosis. Patients (mostly women) may also present with ischemic manifestations without epicardial coronary artery narrowing or obstruction (ie microvascular angina).

Non-atherosclerotic cardiac causes of chronic ischemic heart disease include coronary artery abnormalities (eg congenital abnormalities of the coronary arteries, coronary artery dissection, coronary arteritis in association with systemic vasculitides, coronary spasm, and radiation-induced coronary disease) and myocardial bridging.

Pathophysiology

Chronic coronary syndromes are due to inadequate blood supply to the myocardium as a result of obstruction of the epicardial coronary arteries, usually resulting from atherosclerosis. Pathogenetic mechanism includes an imbalance in the myocardial oxygen supply (ie reduced blood flow and oxygen delivery to the myocardium) and demand (ie increased workload and myocardial oxygen requirements). Other mechanisms include mural thrombosis, microvascular dysfunction, vasoconstriction at the site of a dynamic stenosis, and non-coronary or non-vascular processes (eg myocardial energy derangements, blood rheology abnormalities, or extravascular microcirculatory compression).

Risk Factors

Assess for Ischemic Heart Disease Risk Factors

Chronic Coronary Syndromes_Disease Background

The presence of ischemic heart disease risk factors should be assessed. Examples are smoking, dyslipidemia (eg familial hypercholesterolemia), diabetes mellitus (DM), hypertension, obesity, metabolic syndrome, chronic kidney disease (CKD), physical inactivity, old age, and a family history of premature cardiovascular disease (CVD). A history of cerebrovascular disease, peripheral artery disease (PAD), myocardial infarction (MI) or coronary revascularization also increases the likelihood of ischemic heart disease. Patients with more frequent or severe angina are more prone to developing the primary event compared to those without angina.

Classification

Classification of Angina Severity

Classifying the severity of angina helps determine the functional impairment, response to therapy and prognosis of the patient. Examples are the Canadian Cardiovascular Society Classification, Duke Specific Activity Index, and Seattle Angina Questionnaire. The Canadian Cardiovascular Society Classes I and II categorize patients as mild or stable while classes III and IV categorize patients as severe or unstable.

Canadian Cardiovascular Society Angina Classification
Class	Level of Symptoms
Class I	Ordinary activity does not cause angina Angina due to strenuous, rapid or prolonged exertion only
Class II	Moderate exertion causes angina Slight limitation of ordinary activity when done rapidly, after meals, walking uphill, under emotional stress, in cold or windy weather or during the first few hours after waking up Angina when walking >2 blocks on the same level and climbing >1 flight of stairs at a normal pace under normal conditions
Class III	Marked limitation of ordinary physical activity Angina when walking 1 or 2 blocks on the same level or climbing 1 flight of stairs at a normal pace under normal conditions
Class IV	Unable to carry out any physical activity without discomfort or angina may be present at rest
Reference: Vrints C, Andreotti F, Koskinas KC, et al. 2024 ESC guidelines for the management of chronic coronary syndromes. Eur Heart J. 2024 Aug 30:ehae177.

Categories of Chronic Coronary Syndromes

Based on the different presentations of patients as categorized by the 2023 American Heart Association (AHA)/American College of Cardiology (ACC)/American College of Clinical Pharmacy (ACCP)/American Society for Preventive Cardiology (ASPC)/National Lipid Association (NLA)/Preventive Cardiovascular Nurses Association (PCNA) guideline:

Patients discharged after hospitalization for an acute coronary syndrome event or after coronary revascularization procedure and after stabilization of all cardiovascular events
Patients with left ventricular systolic dysfunction and known or suspected coronary artery disease or with established cardiomyopathy considered to be of ischemic origin
Patients with stable angina symptoms (or ischemic equivalents such as dyspnea or arm pain with exertion) managed medically with or without positive imaging test results
Patients with angina symptoms and evidence of coronary vasospasm or microvascular angina
Patients diagnosed with chronic coronary syndromes based only on screening study results (eg stress test, coronary computed tomography angiography [CCTA]) and is treated as such by physician

Based on the different presentations of patients with suspected or established chronic coronary syndromes by the 2024 European Society of Cardiology (ESC):

Category 1: Symptomatic patients with reproducible stress-induced angina or ischemia with epicardial obstructive coronary artery disease
Category 2: Patients with angina or ischemia due to epicardial vasomotor abnormalities or functional/structural microvascular changes without epicardial obstructive CAD (angina with non-obstructive coronary arteries [ANOCA]/ischemia with non-obstructive coronary arteries [INOCA])
Category 3: Non-acute patients post-ACS or after a revascularization
Category 4: Non-acute patients with left ventricular dysfunction or heart failure of ischemic or cardiometabolic origin
Category 5: Asymptomatic patients in whom epicardial coronary artery disease is detected at screening, an imaging test for refining cardiovascular risk assessment or as an incidental finding for another indication

The presence of these scenarios may increase or decrease patient’s risk for future cardiovascular events. Insufficiently controlled cardiovascular risk factors, ineffective lifestyle modifications and/or medical therapy, or unsuccessful revascularization may increase the risk for cardiovascular events. An appropriate secondary prevention and successful revascularization have been shown to reduce risk for major cardiovascular events.

Chronic Coronary Syndromes Disease Background