Ischemic Heart Disease (IHD): Definition and Overview
Ischemic heart disease (IHD) is a condition characterized by inadequate supply of oxygen and metabolic substrate to the myocardium due to coronary artery disease or functional alterations in coronary circulation, leading to myocardial ischemia. 1
Pathophysiology
IHD results from an imbalance between myocardial oxygen supply and demand. This mismatch can occur through several mechanisms:
- Atherosclerotic coronary artery disease: The most common cause, involving plaque buildup in coronary arteries
- Functional alterations in coronary circulation: Including microvascular dysfunction and coronary vasospasm
- Supply-demand mismatch: Can occur even without obstructive coronary disease 1, 2
Clinical Presentations
IHD encompasses a spectrum of clinical syndromes:
Chronic Coronary Syndrome (Stable IHD):
- Characterized by stable angina pectoris
- Predictable chest discomfort with exertion or stress
- Relieved by rest or nitroglycerin within minutes 1
Acute Coronary Syndrome:
- Unstable angina
- Non-ST-elevation myocardial infarction (NSTEMI)
- ST-elevation myocardial infarction (STEMI) 1
Clinical Characteristics of Angina
Typical Angina (All Three Features)
- Substernal chest discomfort with characteristic quality and duration
- Provoked by exertion or emotional stress
- Relieved by rest or nitroglycerin 1
Atypical Angina
- Meets two of the above characteristics 1
Noncardiac Chest Pain
- Meets one or none of the typical anginal characteristics 1
Epidemiology
IHD is a major public health problem:
- Affects approximately 1 in 3 adults in the United States
- Includes 17 million with coronary heart disease and nearly 10 million with angina pectoris
- Among persons 60-79 years of age, approximately 25% of men and 16% of women have coronary heart disease
- Leading cause of death in both men and women 1
Risk Factors
Key risk factors for IHD include:
- Smoking
- Hyperlipidemia
- Diabetes mellitus
- Hypertension
- Family history of premature coronary artery disease
- Obesity or metabolic syndrome
- Physical inactivity
- History of cerebrovascular or peripheral artery disease 1
Diagnostic Approach
The diagnostic approach to suspected IHD includes:
Clinical evaluation:
- Detailed history of chest pain characteristics
- Assessment of cardiovascular risk factors
- Physical examination (often normal in stable IHD)
Resting ECG: May show evidence of prior MI, ST-T wave changes, or conduction abnormalities
Functional or anatomic imaging: Recommended as initial test in symptomatic patients where obstructive disease cannot be excluded by clinical assessment 1, 2
Clinical Pitfalls and Caveats
Atypical presentations: Women and elderly patients often present with atypical symptoms such as sharp chest pain, nausea, vomiting, or midepigastric discomfort 1
Risk stratification: Patients with unstable angina must be risk-stratified, as those at high or moderate risk require prompt transfer to an emergency department or coronary care unit 1
Coexisting conditions: May precipitate or exacerbate angina by increasing myocardial oxygen demand (hyperthermia, hyperthyroidism, cocaine abuse) or decreasing oxygen supply (anemia, hypoxemia) 1
Sex differences: The pre-test probability of coronary heart disease is higher in men, whereas the pre-test probability of vasomotor disorders is higher in women 3
IHD represents a dynamic process that can be modified through lifestyle changes, pharmacological therapies, and revascularization, potentially resulting in disease stabilization or regression 2.