Ischemic Heart Disease (IHD)

• Ischemic Heart Disease (IHD) is a condition also known as coronary artery disease (CAD) or coronary heart disease (CHD).
• IHD refers to a lack of oxygen ("ischemia") and decreased or absent blood flow to the myocardium, resulting from coronary artery narrowing or obstruction.
• Angina is a clinical syndrome with pain or discomfort, primarily in the chest, but potentially emanating from the jaw, shoulder, back, or arm, and is typically the result of ischemia or IHD.
• IHD can manifest as silent ischemia without clinical symptoms, chronic stable exertional angina pectoris (SA), or coronary artery vasospasm (variant or Prinzmetal angina) unrelated to atherosclerosis.

ACS (Acute Coronary Syndromes)

• Unstable angina (USA).
• Non-ST-segment elevation myocardial infarction (NSTEMI).
• ST-segment elevation myocardial infarction (STEMI).

Statistics (CHD)

• The average age to have a first heart attack is 65.8 years for men and 70.4 years for women.
• 15.5 million Americans have CHD.
• CHD is the single largest killer of American men and women, accounting for one in every six deaths in the U.S. (2010).
• Approximately 40% of individuals experiencing a coronary event die from it.
• CHD causes > 50% of all cardiovascular events in men and women under 75 years of age.
• Angina is the initial manifestation of IHD in over 50% of patients.
• The lifetime risk of developing CHD after age 40 is 49% for men and 32% for women.
• After menopause, CHD rates in women increase to 2 to 3 times that of premenopausal women of the same age.

Anatomy

• Large epicardial coronary arteries constrict and relax, serving mainly as conductance vessels (R1).
• Intramyocardial arterioles exhibit striking changes, known as resistance vessels (R2).
• These arterioles branch into a dense capillary network supplying basal blood flow, and they dilate to maintain coronary blood flow.

Myocardial Oxygen Supply and Demand

• Coronary blood flow, oxygen extraction, and oxygen availability determine myocardial oxygen supply.
• Heart rate, contractility, and intramyocardial wall tension determine myocardial oxygen demand.
• In IHD, increased demand in the face of a fixed oxygen supply leads to ischemia.
• Alterations in MVO₂ are critically important in producing ischemia, so interventions are intended to alleviate ischemia.

Pathophysiology of IHD

• In chronic stable angina, atherosclerotic plaques cause coronary artery narrowing, reducing coronary blood flow.
• Plaques obstruct blood flow in the epicardial vessels (R1), which decreases lumen size and increases resistance.
• Epicardial arteries narrowed critically (≥ 70%) cause arterioles (R2) to dilate, maintaining flow to avert ischemia at rest (autoregulation).
• Atherosclerosis in ≥1 of the main coronary arteries or their branches causes IHD.

Stenosis

• Left main.
• Left anterior descending (LAD).
• Left circumflex.
• Right coronary arteries (RCA).

Symptom Analysis for Stable Angina

• Angina quality includes squeezing, grip-like, pressure-like, suffocating, or heavy chest sensations, aching, vise-like, crushing, burning, tightness, or deep discomfort.
• Angina is almost never sharp or stabbing and usually does not change with position or respiration.
• The location of angina is usually substernal that radiates to the neck, jaw, epigastrium, or arms.
• Pain above the mandible, below the epigastrium, or over the left lateral chest wall is rarely anginal.
• Other symptoms include nausea, diaphoresis, shortness of breath (SOB), and anxiety.
• Stable angina discomfort lasts 2 to 20 minutes; discomfort or dull ache lasting for hours is rarely angina.
• Precipitating factors for stable angina include exercise, walking, gardening, cold weather, postprandial state, emotional stress, and sexual activity.
• Stable angina is relieved by rest or sublingual nitroglycerin (SL NTG) within 30 seconds to several minutes.

Risk Factors (IHD)

• Being male and over 45 years old or female and over 55 years of age, or post-menopausal.
• Family history of premature IHD (male < 55 years, female < 65 years).
• Hypertension (BP > 140/90 mmHg or on antihypertensive therapy).
• Smoking.
• Hyperlipidemia.
• HDL < 40 mg/dL (> 60 mg/dL subtracts one risk factor).
• Diabetes.
• Obesity (BMI >30 kg/m²).
• Sedentary lifestyle.
• PMH of CVD.
• Peripheral vascular disease (PVD).

Canadian Cardiovascular Society (CCS) Classification

• Class I: Normal physical activity does not cause angina and occurs with strenuous, extended, or recreational activity.
• Class II: Angina limits ordinary activity, such as walking or climbing stairs quickly, uphill walking, walking after meals, cold weather, stress, waking, and walking more than two blocks or climbing more than one flight of stairs at a normal pace.
• Class III: Angina limits physical activity and occurs walking one to two blocks or climbing one flight of stairs at a normal pace.
• Class IV: Angina may be present at rest, so physical activity cannot be carried out without discomfort.

Diagnosis and Evaluation

• Physical examination by health professional.

Lab Tests/Data

• CBC (hemoglobin, platelets).
• Fasting glucose.
• Fasting lipid panel.
• Cardiac isoenzymes.
• PT/aPTT.
• 12-lead electrocardiogram (ECG) should be done in all patients with angina-like symptoms, within 10 minutes of presentation.
• Treadmill/bicycle ECG stress test.
• Stress echocardiography.
• Stress myocardial perfusion imaging.
• Angiography or catheterization.

Management of Chronic Stable Angina

• Short-term goals include stabilizing chest pain/discomfort and reducing or preventing anginal symptoms, preventing ischemia and subsequent infarction, and improving exercise tolerance and quality of life.
• Long-term goals include altering or modifying the underlying process of ischemia, risk factor modification and optimizing medical management, preventing primary or secondary CV events (MI, HF), stabilizing the pattern of chest pain, and decreasing overall CV mortality and morbidity.

ACC/AHA Guideline Recommendations for CV Risk

Smoking

• Complete cessation and no exposure to environmental tobacco smoke reduces coronary events by 15-25% within 2 years.

Blood Pressure Control

• Systolic/Diastolic blood pressure must be less than 140/90 mm Hg.

Lipid Management

• Initiate statin therapy in individuals with clinical ASCVD.

Lifestyle

• Physical activity (30-60 min, at least 5 days/wk) with moderate-intensity aerobic activity and increased daily activities, which decreases anginal symptoms, improves functional capacity and endothelial function.
• Daily exercise is as effective as revascularization at one-year, resulting in fewer CV events and improved exercise tolerance.
• Body mass index should be maintained between (18.5-24.9 kg/m squares).
• Men should have a waist circumference of less than 40 in and for women, less than 35 in.
• Manage diabetes to avoid a 10 fold increase in CVD; maintain HbA1c < 7%.
• Get an annual influenza vaccination due to elevated risk of cardiovascular disease.

Pharmacotherapy

• Nitroglycerin to relieve acute symptoms.
• Pharmacotherapy to prevent recurrent ischemic symptoms (antianginal) with beta-blockers, calcium channel blockers, and long-acting nitrates.
• Pharmacotherapy can prevent acute coronary syndromes and death (vasoprotective agents) through primary and secondary prevention using antiplatelet agents, statins, ACE inhibitors, ARBs, and risk factor control/influenza vaccine.
• Hormone replacement therapy, antioxidants, folic acid, and herbal supplements have no beneficial effects.

Angina Treatment Mnemonic

• A: Aspirin, anti-anginals.
• B: Beta-blockers and blood pressure control.
• C: Cholesterol control and cigarette cessation.
• D: Diet and diabetes management.
• E: Education and exercise.

Oral Antiplatelet Agents

• Aspirin reduces death and nonfatal MI in primary and secondary prevention.
  • Acute Attack: 325 mg chew and swallow.
  • Maintenance: 75-162 mg daily in all patients with stable ischemic heart disease (SIHD). ESC recommends 75 mg daily. Increased doses can increase bleeding. GI bleeding, GI intolerance, and allergy are all adverse effects.
• Observed doubling of peptic ulcer bleeding when the ASA dose was increased from 75 to 160 mg.
• Clopidogrel is the only P2Y12 inhibitor indicated for patients with stable IHD that has better tolerability and fewer hematological side effects than ticlopidine. More clinical trials are done with clopidogrel in stable population and none with prasugrel/ticagrelor. Clopidogrel is better than ASA in CAPRIE. Combination with ASA in high-risk patients increases risk of major bleeding. Aspirin is usually prescribed between the range of 75-162 mg daily in combination with chronic CAD (SIHD), irrespective of symptoms, unless contraindicated. Clopidogrel (75 mg daily), is administered when ASA is contraindicated or as therapy after ASA failure in high-risk patients.
• Prasugrel/ticagrelor can also be given as an alternative to Clopidogrel.