Ischaemic Heart Disease

Ischaemic Heart Disease (IHD), also known as Coronary Artery Disease (CAD) or Coronary Heart Disease (CHD), is a condition characterised by reduced blood flow to the heart muscle due to narrowing or blockage of the coronary arteries. This restriction of blood supply leads to a deficiency of oxygen and nutrients (ischaemia) in the myocardium, impairing its ability to function effectively. It remains one of the leading causes of morbidity and mortality worldwide, contributing substantially to global cardiovascular disease burden.

Background and Definition

Ischaemic Heart Disease arises primarily from atherosclerosis, a pathological process in which fatty deposits, cholesterol, calcium, and other substances accumulate within the arterial wall to form plaques. Over time, these plaques cause narrowing (stenosis) or complete occlusion of coronary arteries, thereby restricting myocardial perfusion.
The disease encompasses a spectrum of clinical manifestations, including:

• Stable angina pectoris, characterised by chest pain during exertion or stress.
• Unstable angina, involving unpredictable or worsening chest pain.
• Myocardial infarction (heart attack), resulting from complete blockage and myocardial tissue death.
• Silent ischaemia, where reduced perfusion occurs without noticeable symptoms.

Epidemiology

Ischaemic Heart Disease is a global health concern, accounting for millions of deaths annually. It is the leading cause of death in both developed and many developing countries. Risk increases with age and is higher among men, though postmenopausal women also experience rising prevalence.
Key epidemiological trends include:

• Higher incidence in populations with sedentary lifestyles, poor dietary habits, and obesity.
• Decreasing mortality in some developed countries due to improved prevention, early diagnosis, and advanced treatment.
• Rising prevalence in low- and middle-income countries due to urbanisation, smoking, and increased life expectancy.

Aetiology and Risk Factors

The aetiology of Ischaemic Heart Disease is multifactorial, with both modifiable and non-modifiable risk factors contributing to its development.
Modifiable Risk Factors:

• Atherosclerosis (primary underlying cause)
• Hypertension (high blood pressure)
• Dyslipidaemia – elevated low-density lipoprotein (LDL) cholesterol and reduced high-density lipoprotein (HDL) cholesterol
• Smoking – promotes endothelial injury and oxidative stress
• Diabetes mellitus – accelerates vascular damage
• Obesity – particularly central obesity, increasing metabolic and vascular strain
• Physical inactivity – reduces cardiovascular efficiency
• Unhealthy diet – high in saturated fats, refined carbohydrates, and salt
• Excessive alcohol consumption and psychological stress

Non-Modifiable Risk Factors:

• Age (risk increases with advancing age)
• Sex (males at higher risk before menopause)
• Family history of premature cardiovascular disease
• Genetic predisposition

Pathophysiology

The underlying process in Ischaemic Heart Disease is atherosclerosis of the coronary arteries. The development follows several stages:

1. Endothelial dysfunction – Damage to the inner lining of the coronary arteries due to mechanical stress, toxins, or high cholesterol.
2. Fatty streak formation – Accumulation of lipids and inflammatory cells beneath the endothelium.
3. Plaque progression – Growth of fibrofatty lesions that narrow the arterial lumen.
4. Plaque rupture or erosion – Triggers platelet aggregation and thrombus (clot) formation, which can acutely obstruct blood flow.

The resultant myocardial ischaemia leads to decreased oxygen delivery. When oxygen demand exceeds supply, it produces symptoms such as chest pain or, in severe cases, necrosis of cardiac tissue (myocardial infarction). Chronic or repeated ischaemia may lead to heart failure due to weakening of the myocardium.

Clinical Manifestations

The presentation of Ischaemic Heart Disease varies depending on the extent and duration of ischaemia.
Typical symptoms include:

• Chest pain or pressure (angina pectoris), often described as a squeezing or constricting sensation behind the sternum.
• Radiation of pain to the left arm, neck, jaw, or back.
• Shortness of breath, especially on exertion.
• Sweating, nausea, and dizziness.
• Palpitations or irregular heartbeat.

In stable angina, pain occurs predictably with physical activity and is relieved by rest or nitroglycerin. Unstable angina indicates a worsening condition with unpredictable pain, even at rest, often preceding a heart attack. Myocardial infarction produces more severe, prolonged pain unrelieved by rest, associated with tissue necrosis.

Diagnosis

Diagnosis relies on clinical evaluation, electrocardiographic changes, imaging, and biochemical markers.
Common diagnostic methods include:

• Electrocardiogram (ECG): Detects ischaemic changes such as ST-segment depression, elevation, or T-wave inversion.
• Cardiac biomarkers (e.g., troponins): Indicate myocardial injury or infarction.
• Echocardiography: Evaluates wall motion abnormalities and cardiac function.
• Coronary angiography: Provides direct visualisation of coronary artery blockages.
• Stress testing: Assesses myocardial response to physical or pharmacological stress.
• CT Coronary Angiography: Non-invasive method to detect coronary calcifications and stenosis.

Management and Treatment

The management of Ischaemic Heart Disease involves both lifestyle modification and medical or surgical intervention.
Lifestyle Modifications:

• Smoking cessation
• Regular physical activity
• Weight reduction
• Dietary control (low saturated fat, high fibre)
• Limiting alcohol intake and managing stress

Pharmacological Therapy:

• Antiplatelet agents (e.g., aspirin, clopidogrel) to prevent thrombosis
• Beta-blockers to reduce heart rate and oxygen demand
• Nitrates to relieve angina by dilating coronary vessels
• Calcium channel blockers for vasodilation and symptom control
• Statins to lower LDL cholesterol and stabilise plaques
• ACE inhibitors or ARBs to improve cardiac function and reduce afterload

Revascularisation Procedures:

• Percutaneous Coronary Intervention (PCI): Balloon angioplasty with or without stent placement to reopen narrowed arteries.
• Coronary Artery Bypass Grafting (CABG): Surgical rerouting of blood flow around blocked arteries using grafts.

Prompt recognition and treatment of acute myocardial infarction, including reperfusion therapy, are vital for reducing mortality and preventing complications.

Complications

Untreated or advanced Ischaemic Heart Disease can lead to serious complications such as:

• Myocardial infarction (heart attack)
• Cardiac arrhythmias (including ventricular fibrillation or sudden cardiac death)
• Heart failure due to chronic ischaemic damage
• Cardiogenic shock in severe cases
• Chronic stable angina with reduced quality of life

Prevention

Prevention of IHD focuses on risk factor modification and early intervention:

• Controlling blood pressure, blood glucose, and cholesterol levels.
• Promoting a heart-healthy diet rich in fruits, vegetables, and whole grains.
• Encouraging regular physical exercise and maintaining a healthy body weight.
• Avoiding tobacco and moderating alcohol consumption.
• Regular screening and monitoring in high-risk individuals.

Prognosis

Prognosis depends on the severity of coronary artery involvement, timeliness of treatment, and control of risk factors. With effective lifestyle changes and medical management, many patients can live productive lives. Early intervention and adherence to secondary prevention measures substantially reduce recurrence and mortality.

Significance

Ischaemic Heart Disease represents one of the most extensively studied and clinically significant cardiovascular conditions. It provides insight into the interplay of lifestyle, metabolic health, and vascular biology. Efforts to reduce global IHD burden continue to focus on prevention, early detection, and equitable access to care, as the disease remains a major contributor to global disability and premature death.