What is Ischemic Heart Disease (IHD)?

Ischemic Heart Disease (IHD)

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, which can occur through several mechanisms:

• Primary mechanism: Atherosclerotic narrowing of coronary arteries
• Secondary mechanisms:
  • Functional alterations in coronary circulation
  • Supply-demand mismatch
  • Coronary vasospasm

This oxygen supply-demand mismatch leads to myocardial ischemia, which if prolonged, can result in myocardial injury or infarction 1, 2.

Clinical Syndromes

IHD encompasses a spectrum of clinical presentations:

1. Chronic Coronary Syndrome (Stable IHD)

• Characterized by stable angina pectoris
• Predictable chest discomfort with exertion or stress
• Pain typically relieved by rest or nitroglycerin within minutes 1

2. Acute Coronary Syndrome

• Unstable angina
• Non-ST-elevation myocardial infarction (NSTEMI)
• ST-elevation myocardial infarction (STEMI) 1, 3

Epidemiology

IHD is a major public health issue with significant impact on mortality and morbidity:

• Affects approximately 1 in 3 adults in the United States
• Includes more than 13 million with coronary artery disease and more than 9 million with angina pectoris
• Prevalence increases with age: approximately 23% of men and 15% of women aged 60-79 years have IHD
• Responsible for nearly 380,000 deaths in the United States annually
• Economic burden is enormous: $156 billion in direct and indirect costs 4, 1

Risk Factors

Key risk factors for IHD development 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

Sex-Specific Considerations

Important sex-related differences exist in IHD:

• Age-standardized incidence and prevalence are lower in females than males
• Pathophysiology, clinical manifestations, treatment responses differ between sexes
• Women often present with atypical symptoms (sharp chest pain, nausea, vomiting, midepigastric discomfort)
• Prevalence and impact of risk factors may differ between males and females 4, 1

Diagnostic Approach

The diagnostic approach to suspected IHD includes:

1. Clinical evaluation
2. Resting ECG - helps establish diagnosis and assess risk
3. Functional or anatomic imaging - recommended as initial test in symptomatic patients where obstructive disease cannot be excluded by clinical assessment alone

Cardiac stress testing is indicated in most symptomatic patients suspected of having IHD to establish diagnosis and identify high-risk patients who might benefit from intervention 4, 1.

Treatment Considerations

Treatment approaches include:

• Lifestyle modifications to address risk factors
• Pharmacological therapy:
  • Statins like atorvastatin to reduce cardiovascular events (MI, stroke, revascularization) 5
  • Antiplatelet agents
  • Beta-blockers (particularly beneficial in patients with history of angina or MI) 6
  • Other antihypertensives when indicated
• Revascularization when appropriate based on symptoms and risk assessment
• Emerging approaches such as therapeutic angiogenesis for severe disease 7

Risk Stratification

Risk assessment is essential, particularly for patients with unstable symptoms:

• Those at high or moderate risk require prompt transfer to an emergency department or coronary care unit
• Coronary angiography is recommended for risk assessment in patients with clinical characteristics and noninvasive test results indicating high likelihood of severe IHD
• Coronary angiography should not be used in patients who are not candidates for revascularization or in those with low-risk features 4

Clinical Pitfalls to Avoid

• Underdiagnosis in women due to atypical presentations
• Overreliance on typical symptoms in elderly patients who may present atypically
• Inappropriate use of coronary angiography in low-risk patients or those who are not candidates for revascularization
• Failure to consider functional causes of ischemia beyond obstructive coronary disease
• Inadequate risk factor modification which is essential for long-term management