Coronary Heart Disease

Coronary heart disease (CHD), also called coronary artery disease (CAD) or ischaemic heart disease, is the most common heart condition in Singapore and the leading cause of death and disability in the country. It is responsible for approximately 20% of all deaths in Singapore, with over 3,000 Singaporeans dying from heart attack and related conditions each year.

CHD develops when the coronary arteries, the blood vessels that supply oxygen and nutrients directly to the heart muscle, become narrowed or blocked by the progressive accumulation of fatty, cholesterol-rich plaques within the arterial walls. This process, called atherosclerosis, begins early in life and advances silently over decades. By the time symptoms appear, the disease is often already significant.

CHD in Singapore: Why it Demands Attention

Singapore's CHD burden reflects a combination of population risk factors that make it a particularly significant health priority:

• Leading cause of death: CHD and related acute coronary events account for a greater proportion of deaths in Singapore than any other single condition.
• Elevated South Asian risk: Indian Singaporeans face significantly higher CHD risk than other ethnic groups, developing the disease at younger ages and at lower traditional risk factor thresholds. An Indian Singaporean man with borderline cholesterol and mildly elevated blood pressure carries a meaningfully higher absolute risk than a Chinese or Malay Singaporean man with the same profile.
• Diabetes is prevalent: Approximately 1 in 9 Singapore adults has type 2 diabetes, which is an independent and powerful cardiovascular risk factor. Diabetes accelerates atherosclerosis and doubles the risk of CHD.
• Hypertension and dyslipidaemia are common and frequently undertreated. Many patients are on medication but have not reached evidence-based treatment targets
• Sedentary lifestyle and diet: Urbanisation, processed food consumption, and sedentary work environments have progressively eroded the population's metabolic health over recent decades.

How CHD Presents: The Clinical Spectrum

Coronary heart disease is not a single clinical entity -- it encompasses a spectrum of presentations from completely asymptomatic disease detected on imaging to acute life-threatening cardiac arrest. Understanding where a patient sits on this spectrum determines the urgency and nature of treatment.

• Stable angina: Chest pain or pressure that predictably occurs during exercise or stress and improves with rest or nitrate medication. It happens because a fixed narrowing in the coronary arteries limits blood flow when the heart needs more oxygen. Treatment includes lifestyle changes, medications, and statins, with procedures to improve blood flow considered if symptoms are not controlled.
• Unstable angina: Chest pain that occurs at rest, during sleep, or with little activity, and may become more frequent or severe. It is usually caused by a plaque that is unstable and may form a blood clot, reducing blood flow to the heart. It is a medical emergency requiring urgent hospital assessment and treatment.
• NSTEMI (Non-ST-elevation MI): A heart attack caused by a partial blockage of a coronary artery, leading to heart muscle damage. Troponin levels are raised, but the ECG does not show ST elevation. Treatment usually includes antiplatelet medication, anticoagulants, and early coronary angiography, with angioplasty/stenting when needed.
• STEMI (ST-elevation MI): A serious heart attack caused by a complete blockage of a coronary artery. The ECG shows ST elevation, indicating significant heart muscle damage. It is a medical emergency, and treatment aims to restore blood flow as quickly as possible, usually with emergency angioplasty (PCI).
• Silent Myocardial Ischaemia: Reduced blood flow to the heart that occurs without chest pain or other obvious symptoms. It is more common in people with diabetes, as nerve damage can reduce the ability to feel pain. Although there are no symptoms, it can still increase the risk of a heart attack.
• Sudden Cardiac Death: A sudden cardiac arrest caused by a dangerous abnormal heart rhythm, often due to reduced blood flow or a heart attack. It can happen without warning, sometimes being the first sign of coronary heart disease. Identifying and treating people at high risk can help prevent a potentially fatal first event.

Symptoms of Coronary Heart Disease

Symptoms of CHD reflect the underlying mechanism -- reduced blood flow to the heart muscle (ischaemia) during periods of increased demand (exertion, stress, cold exposure).

Classic symptoms requiring medical assessment

• Chest pain, pressure, tightness, or heaviness: Typically in the centre of the chest; may radiate to the left arm, jaw, neck, back, or right arm. The classical description is 'an elephant sitting on my chest'. Often provoked by exertion and relieved by rest in stable disease.
• Breathlessness on exertion: Beyond what would be expected for the level of activity; may be the primary symptom particularly in women and in people with diabetes
• Pain, numbness, or tingling in the left arm, jaw, neck, or upper back: In combination with exertion or stress, these are angina equivalents
• Palpitations: A sensation of rapid, pounding, or irregular heartbeat; may indicate arrhythmia triggered by ischaemia

Symptoms in women, people with diabetes, and older adults

CHD symptoms in women, people with diabetes, and the elderly often differ from the textbook presentation. These populations more frequently experience:

• Unexplained and persistent fatigue: Disproportionate tiredness that develops over weeks
• Nausea, indigestion, or upper abdominal discomfort: Frequently misattributed to gastrointestinal causes
• Shortness of breath as the primary or only symptom: Without accompanying chest pain
• Lightheadedness or near-fainting during exertion
• Silent ischaemia: No symptoms at all; disease is detected only on cardiac testing

Risk Factors for Coronary Heart Disease

There are several risk factors of Coronary Heart Disease. Some factors that may increase your risk include:

Modifiable Risk Factors

• High LDL (bad) cholesterol and low HDL (good) cholesterol: The most directly atherogenic risk factor
• Hypertension (high blood pressure): Damages the arterial wall endothelium, initiating plaque formation
• Smoking: The most potent preventable cardiovascular risk factor; doubles to quadruples the risk of CHD
• Type 2 diabetes and insulin resistance: Accelerates atherosclerosis and impairs vascular endothelial function
• Obesity: Particularly central (abdominal) adiposity; raises blood pressure, triglycerides, and promotes insulin resistance
• Physical inactivity: Independent cardiovascular risk factor beyond its effects on weight
• Chronic psychological stress and sleep disorders, including obstructive sleep apnoea
• Excessive alcohol consumption
• Unhealthy diet high in saturated fat, trans fat, and refined carbohydrates

Non-Modifiable Risk Factors

• Age: Your risk increases progressively from 45 in men and from 55 in women
• Male sex: Men develop CHD approximately 10 years earlier than women on average
• Premature family history: A first-degree male relative with CHD before 55, or female relative before 65, significantly increases individual risk
• Ethnicity: South Asian (Indian, Pakistani, Sri Lankan, Bangladeshi) individuals have a significantly higher risk of CHD at younger ages and lower risk factor thresholds; CHD is approximately 3 times more common in Indian men in Singapore than in Chinese men
• Postmenopausal status in women: Loss of oestrogen's protective vascular effects
• Personal history of prior heart attack or stroke

How Coronary Heart Disease is Diagnosed?

The diagnostic pathway depends on whether the presentation is acute (suspected heart attack -- managed as a medical emergency) or elective (assessment of chest pain, breathlessness, or risk stratification in an asymptomatic high-risk individual). The tests below apply primarily to the elective setting.

• Resting ECG (Electrocardiogram):Records the electrical activity of the heart. Identifies acute MI (ST elevation or depression), old infarcts (Q waves), arrhythmias, left ventricular hypertrophy, and conduction abnormalities. A normal resting ECG does not exclude significant CHD -- approximately 50% of patients with severe CHD have a normal resting ECG.
• Exercise Stress Test (Treadmill Test):ECG monitoring during progressive treadmill exercise. Identifies ST changes indicative of exercise-induced ischaemia, exercise capacity, heart rate response, arrhythmias, and blood pressure response. Positive test suggests significant coronary disease requiring further investigation. Limited sensitivity in certain populations -- particularly women.
• Echocardiogram (Cardiac Ultrasound): Real-time ultrasound imaging of cardiac structure and function. Assesses ejection fraction (pumping function), wall motion abnormalities (indicating areas of ischaemia or old infarction), valve disease, and pericardial effusion. Stress echocardiography (echo during pharmacological or exercise stress) improves sensitivity for detecting ischaemia.
• Coronary Calcium Score (CT Calcium Scoring): Non-invasive CT scan that detects and quantifies calcium deposits within the coronary arteries -- a direct marker of subclinical atherosclerosis. The calcium score (Agatston score) predicts future cardiovascular events better than any single traditional risk factor. A score of zero in a low-to-intermediate risk patient has excellent negative predictive value. Ideal screening test for asymptomatic high-risk individuals.
• CT Coronary Angiography (CTCA): Having a weekly alcohol intake above the recommended limits have been associated with an increased risk of CHD. Also avoid binge drinking as it increases your risk of a heart attack.
• Nuclear Myocardial Perfusion Imaging (MPI): It is important to keep your blood pressure, cholesterol and blood sugar levels under control with a healthy diet, exercising regularly, and taking your medication if necessary.
• Coronary Angiography (Invasive): Catheter-based X-ray imaging with intravenous contrast directly within the coronary arteries. The gold standard for coronary anatomy visualisation -- most detailed, most accurate, and allows simultaneous measurement of fractional flow reserve (FFR) to assess the haemodynamic significance of stenoses. Allows immediate PCI treatment in the same procedure if appropriate.
• Blood Tests: Full lipid panel (LDL, HDL, triglycerides, total cholesterol), fasting glucose and HbA1c (diabetes), renal and liver function (before prescribing statins and other medications), troponin (cardiac muscle damage -- elevated in heart attack), BNP/NT-proBNP (heart failure marker), full blood count, and thyroid function.
• Cardiac MRI: High-resolution MRI of the heart providing detailed assessment of myocardial viability (live vs scar tissue), ejection fraction, wall motion, and late gadolinium enhancement patterns. Particularly valuable for assessing the extent of damage after a heart attack, for evaluating myocarditis, and when echocardiography is insufficient.

Living with Coronary Heart Disease

A diagnosis of CHD -- even after a heart attack -- is not the end of an active life. With appropriate treatment, risk factor management, and lifestyle modification, many patients with CHD live full and active lives for decades after their diagnosis. The following principles guide long-term management:

• Take all prescribed medications reliably: The evidence-based combination of antiplatelet, statin, beta-blocker, and ACE inhibitor has been shown to reduce mortality significantly; stopping medications is a common cause of avoidable cardiac events
• Know your numbers: Your LDL target, blood pressure target (below 130/80 mmHg), HbA1c target (below 7% in diabetic CHD patients), and body weight target. 
• Attend all follow-up appointments: CHD is a dynamic condition; risk factor control needs regular review and medication adjustment
• Recognise recurrence symptoms: Know what angina feels like, know the symptoms of a heart attack, and know to call 995 immediately rather than waiting
• Engage in cardiac rehabilitation: Do not skip it; the evidence for benefit is as strong as for any medication
• Manage stress: Chronic psychological stress directly increases cardiovascular event rates through cortisol-mediated vascular effects and platelet activation
• Do not smoke: There is no safe level of smoking in established CHD