Coronary artery disease is a heart disease where the coronary arteries supplying the heart muscles with blood have impaired flow, presenting with chest pain, ischemia, myocardial infarction, and sudden cardiac death. It is diagnosed clinically, with ECG, or with stress testing. It is treated with medications and stenting/ bypass.

Pathophysiology

• Caused by coronary artery atherosclerosis or coronary artery spasm

Coronary Atherosclerosis

• Occurs at areas of high turbulence such as bifurcations
• Gowing plaque causes lumen narrowing -> insufficient blood flow for perfusion
  • Results in angina pectoris
• Plaque rupture: causes acute thrombus that interrupts blood flow, causing acute myocardial ischemia (acute coronary syndrome)
  • Location of ischemia will create different presentations

Coronary Artery Spasm

• Transiently increased vascular tone
• Temporarily narrowed lumen and reduced blood flow
• Can be due to either exaggerated response to vasoconstricting stimuli or local hypercontractility
  • Vasoconstriction can be due to drugs (cocaine, nicotine)

Contextual Factors

• Factors leading to atherosclerosis
  • Poor cholesterol levels (high LDL, high lipoprotein a, low HDL)
  • Diabetes mellitus
  • Smoking
  • Obesity
  • Physical inactivity
• Genetic disposition

Clinical Manifestation

General

• Weakness
• Lightheadedness

Cardiac

• Angina: chest pain or discomfort

Pulmonary

• Shortness of breath

Abdominal

• Nausea

Musculoskeletal

• Arm/ shoulder pain or discomfort

Complications

• Heart failure
• Sudden cardiac death

Diagnosis

• ECG: can show acute coronary syndromes with ST elevation or depression
• Echocardiogram: can reveal ischemia
• Stress testing: used to cause angina, a sign of inadequate perfusion

Visualising Plaques

• Coronary artery calcium scan: can quantitatively measure amount of plaque formation
• Cardiac catheterisation and angiogram: can show areas of poor perfusion where contrast does not travel

Rule Out

• Chest x-ray: for ruling out other causes of cheset pain and shortness of breath

Treatment

Lifestyle Modifications

• Smoking cessation
• Weight loss
• Healthy diet (low cholesterol, low sodium)
• Regular exercise
• Comorbidity control (hypertension, diabetes)

Medications

Acute Thrombosis

• Fibrinolytic drugs, such as TPA

Angina

• Nitrate: dilates coronary arteries and decreases venous return
  • Decreases cardiac work to reduce angina symptoms

Long-Term

• Antiplatelet drugs: prevents clot formation
  • Atheromatous plaque stability
  • Improves endothelial function
• Statin: lowers LDL to prevent further plaque formation
• Beta-blocker: reduces angina symptoms
  • Reduces heart rate and contractility -> decreasd oxygen demand
  • Can be combined with calcium channel blockerse for added effect
• ACEi/ ARB: reduces mortality when LV dysfunction is present

Percutaneous Coronary Intervention (PCI)

• Indicated with acute coronary syndrome or stable disease with angina despite medical treatment

Steps

1. Ballon angioplasty to open the occluded vessel
2. Drug-eluting stent placed to keep vessel open
   • Antiproliferative drug prevents re-stenosis
3. Cardiac rehabilitation is recommended

Complications

• In-stent thrombosis can occur due to thrombogenicity of stent material
• Often occurs within first 48 hours
  • Risk greatly reduces after endothelialisation over the stent
  • Drug-eluting stents increases endothelialisation time, increasing risk of thrombosis
• Risk can be reduced with antiplatelet therapy adherence

Post-Stent Medication Regimen

• Encouraged to start anticoagulation prior to procedure

• Statin started after stent placement if not already used to prevent future plaque formation

Coronary Artery Bypass Grafting (CABG)

• Graft vessel is harvested and used to bypass the clotted segment of the affected coronary arteries

• Often done on cardiopulmonary bypass
  • Risk of cognitive dysfunction or behavioural changes
• Second bypass much higher risk than the first