Coronary Artery Disease (CAD)

Coronary artery disease (CAD) is a disease of heart vessels that causes atherosclerosis and its manifestations. Atherosclerosis is defined as the thickening of vessel walls due to the deposition of fat and cholesterol inside it. Thickening causes the lumen of these vessels to narrow, obstructing blood flow and hence oxygen flow. Depending upon the extent of narrowing, various manifestations such as angina, unstable angina, myocardial infarction, etc., can be caused.

Coronary artery disease begins in childhood and gradually progresses when the clinical manifestations become apparent in middle or old age. Atherosclerosis is a Greek word that means “focal accumulation of fat.” According to one hypothesis, atherosclerosis begins in response to endothelial injury. The injured vessel is more susceptible to deposition of fats and thrombus formation.

Types 

CAD manifests itself as:

• Asymptomatic state
• Stable angina
• Unstable angina
• Acute myocardial infarction
• Chronic ischemic cardiomyopathy
• Congestive heart failure
• Sudden cardiac arrest

Atherosclerosis occurs worldwide, with greater incidence in developed countries in Europe and US. The prevalence is less in Mediterranean regions as they use more monounsaturated fatty acids in their diet.
The exact number of cases of CAD is difficult to measure because the condition is usually asymptomatic and starts in childhood, progressing to middle age, where the most advanced lesions begin to form.
Factors that increase the risk of CAD are:

• Male gender
• Middle to old age
• High levels of cholesterol in the body
• Smoking
• Alcohol intake
• Chronic inflammatory conditions
• Diabetes
• Hypertension
• Family history
• Depression
• Obesity
• Autoimmune disorders
• Infectious agents

Signs and symptoms of coronary artery disease include:

• Chest pressure or chest pain
• Jaw pain
• Shortness of breath
• Weakness
• Fatigue
• Dizziness
• Palpitations
• Leg swelling
• Increased body weight
• Sweating
• Syncope
• Heavy breathing
• Heart murmurs upon examination
• High or low blood pressure
• Pulmonary edema 

Following labs are used to diagnose CAD:

• Complete blood count (CBC)
• Lipid profile
• ECG
• Blood glucose levels (HbA1c)
• Liver function tests
• Renal function tests
• Cardiac troponin
• Thyroid function tests
• CRP
• Imaging studies that include echocardiography, nuclear imaging, MRI, and coronary angiography

Differential diagnoses of CAD include:

• Angina pectoris
• Unstable angina
• Acute pericarditis
• Dilated cardiomyopathy
• Coronary artery vasospasm
• Hypertension
• Kawasaki disease
• Myocarditis
• Nicotine addiction
• Pulmonary embolism 

The mainstay of treatment against CAD is to prevent the process of atherosclerosis by eliminating the causative factors and preventing any clinical manifestations such as angina or MI from developing. Clinical manifestations of CAD vary, ranging from angina, MI to ischemic cardiac myopathy. These are managed accordingly. Interventional treatment procedures for them include:

• Coronary artery bypass graft (CABG)
• Percutaneous intervention (PCI)
• Percutaneous transluminal coronary angioplasty (PTCA)

CAD is almost always caused by atherosclerosis, and the most common cause of atherosclerosis is a high level of blood cholesterol. Statins are used to treat high levels of cholesterol in the body.

Dietary modifications are also advised, including limiting the intake of bad cholesterols and increasing fiber intake in the diet. Insulin resistance is also known to cause high body cholesterol levels, as seen in diabetes type 2. Good glycemic control with treatment compliance and limited sugar intake is aimed for diabetic patients to prevent hypercholesteremia in these patients.

ACE inhibitors are used for blood pressure control and prophylaxis as their use has been linked with a decrease in remodeling of heart muscle after acute coronary syndrome.

Antiplatelets cause blood thinning and are also used to prevent thrombus formation inside coronary vessels.

Following medications are used to manage CAD:

• Nitrates
• Beta-blockers
• Calcium channel blockers
• ACE inhibitors
• Antiplatelet agents
• Aspirin

The prognosis of CAD depends upon the extent of the disease and systemic involvement. The factors that influence prognosis include compliance with the medical therapy, earlier detection, and prophylaxis with lifestyle modifications, presence of comorbid conditions, presence of arrhythmias, revascularization potential, and plaque stability.
People with angina and unstable angina that comply with medication and exercise proper care have a good prognosis. People with myocardial infarction (MI) or congestive heart failure (CHF) who develop complications have higher mortality.

• The most important prevention strategy against CAD is adopting a healthy lifestyle so avoidable causes such as obesity and hypercholesteremia can be controlled.
• Lifestyle modifications include an optimum diet with a low cholesterol level and a high level of fiber in the diet. Bad cholesterols such as animal oils and fats should be avoided.
• People with a family history of cardiac diseases and hypercholesteremia should undergo screening for risk factors early and adopt lifestyle changes instantly to avoid manifestations of CAD such as MI.
• With proper treatment and healthy lifestyle choices, comorbidities such as hypertension and diabetes should be kept in check and under control
• Pregnant women are at increased risk of developing complications such as miscarriages, stillbirth, etc., with CAD. They should be managed for the disease during pregnancy accordingly.
• People with autoimmune diseases should seek care and treatment as they are prone to coronary artery disease.
• Smoking and alcohol intake should be avoided as they are associated with an increased risk of thrombus formation and obstruction of vessels.
• Reduce daily stress by seeking help for stress management.