Aortic Stenosis & NSTEMI: Symptoms, Diagnosis, and Treatment

Posted on May 19, 2024 in Medicine & Health

Aortic Stenosis (AS)

Definition

Narrowing of the aortic valve, obstructing blood flow from the left ventricle (LV) to the ascending aorta during systole.

Etiology

CongenitalAcquired
  • Bicuspid
  • Unicuspid
  • Quadricuspid
  • Calcification (65+ years)
  • Rheumatic (40-60 years)
  • Disturbances of Ca2+ metabolism
  • Rheumatoid arthritis
  • Renal disease
  • Fabry disease

Pathophysiology

  1. Increased LV systolic & diastolic pressure → Prolonged ejection time
  2. LV pressure overload → LV concentric hypertrophy
  3. Increased myocardial O2 consumption → Decreased relative myocardial perfusion
  4. LV myocardial ischemia → LV myocardial fibrosis
  5. Increased LV filling pressure → Increased pulmonary venous pressure → Pulmonary blood congestion

NSTEMI

Definition

Subendocardial myocardial infarction, involving only part of the ventricle wall and characterized by superficial ischemia.

Clinical Features

  • Angina lasting > 20 minutes
  • Deep, substernal pain
  • Aching pressure
  • Pain radiating to back/jaw
  • No relief with nitroglycerin
  • Pain may start at night (e.g., 4 AM) with increasing severity

Diagnosis

Physical ExamECGBiomarkers
  • Hypertension or hypotension
  • Increased or decreased heart rate
  • Gallop rhythm
  • Systolic murmur
  • Pulmonary edema
  • Obtain within 10 minutes of admission
  • ST changes
  • Left bundle branch block (LBBB)
  • Myoglobin, total CK, CK-MB, troponin T & I
  • Elevated 5x the normal → Immediate invasive management
X-rayEchocardiography
  • Pulmonary edema
  • Heart dilation
  • Regional wall motion defect
  • Assess LV function

Other Diagnostic Tools

  • Perfusion scintigraphy (Thallium 201)
  • Interventional studies:
    • Coronary artery angioscopy
    • Intracoronary echocardiography
  • Stress test
  • 24-hour ECG

Risk Assessment

GRACE ScoreTIMI Score
  • Age
  • Blood pressure, heart rate
  • Elevated cardiac biomarkers
  • Elevated serum creatinine
  • Killip class at presentation
  • Cardiac arrest on admission
  • ST changes
  • Age 65+ years
  • > 3 CAD risk factors
  • Known CAD
  • Aspirin use within 7 days
  • Severe angina (> 2 episodes/24 hours)
  • ST changes
  • Positive cardiac markers

Treatment

Strategies

  • Decrease myocardial O2 demand (nitrates, β-blockers, ACE-I)
  • Reocclusion prophylaxis (antiplatelets, anticoagulants)
  • Atherplaque stabilization (statins)
First Aid: MONA RulePharmacological Treatment SequenceNew Antiplatelet Drugs
  • Morphine 3-5 mg IV
  • Oxygen 4-8 L/min
  • Nitrates IV
  • Aspirin 150-300 mg
  1. β-blockers (metoprolol 25, 50, 100 mg)
  2. ACE-I (ramipril 2.5, 5, 10 mg)
  3. Nitrates (ISMN 10, 20, 40, 60 mg)
  4. Statins (atorvastatin 10, 20, 40, 80 mg)
  5. Antiplatelet (aspirin 75-150 mg, clopidogrel 75 mg)
  • Ticagrelor 90 mg 2x/day
  • Prasugrel 10 mg daily
  • Clopidogrel 75 mg daily

Invasive Coronary Angiography Indications

Very High Risk (PCI < 2 hours)High Risk (PCI < 24 hours)Moderate Risk (PCI < 72 hours)
  • Hemodynamically unstable
  • Life-threatening arrhythmias
  • Mechanical complications
  • Rise or fall in troponin
  • Dynamic ST changes
  • Diabetes mellitus
  • Renal insufficiency
  • LVEF < 40%

Long-Term Management

  • Lifestyle changes
  • Initiate high-intensity statin therapy
  • Antihypertensive therapy
  • Dual antiplatelet therapy
  • ACE-I in LV dysfunction, hypertension, diabetes
  • β-blockers if LVEF < 40%

Angina Pectoris (AP)

Angina & Ischemia

  1. Myocardial O2 demand > oxygen supply
  2. Cellular acidosis & lactate release
  3. ST depression on ECG

Note: ST depression in the absence of angina is called silent ischemia.

Important: Angina = Ischemia

Blood Supply to the Myocardium

  • Coronary artery stenosis → Stable angina if > 70% lumen obliteration
  • Coronary artery spasm (endothelial dysfunction)
  • Hypercoagulation states
  • Anemia
  • Increased or decreased heart rate
  • Myocardial hypertrophy

Myocardial O2 Demand

  • Physical/emotional exertion
  • Tachycardia
  • Myocardial hypertrophy

Risk Factors

Modifiable (1st Line)UnmodifiableNormal Lipid Profile
  • Dyslipidemia
  • Hyperfibrinogenemia
  • Smoking
  • Arterial hypertension
  • Diabetes mellitus
  • Familial predisposition
  • Increased age
  • Male sex
  • Total cholesterol: < 5.0 mmol/L
  • LDL cholesterol: < 3.0 mmol/L
  • HDL cholesterol: > 1.0 mmol/L
  • Triglycerides: < 2.0 mmol/L

Clinical Features

  • Pain sensation: pressure, squeezing, burning, or numbness
  • Triggers: physical/emotional stress, cold
  • Location: substernal or parasternal area, epigastric
  • Radiation: neck, shoulder, arm (mostly left)
  • Duration: 0.5-15 minutes
  • Relief: 1.5-3 minutes after sublingual nitroglycerin
  • Levine’s sign: patient demonstrates pain with clenched fist over chest
  • Dyspnea, nausea, anxiety, cold sweating

Classification

Angina ClassDescription
Class IAngina only with strenuous exertion, prolonged exertion, or strenuous exercise. No symptoms with mild to moderate exertion.
Class IIAngina with high but usual daily physical activity. Moderate exertion elicits symptoms.
Class IIIAngina with moderate physical activity (e.g., walking 100 meters). Mild exertion elicits symptoms.
Class IVAngina with light physical activity or even at rest. Minimal exertion or rest elicits symptoms.

Diagnosis

Clinical FeaturesECGEchocardiographyPerfusion Scintigraphy (Thallium 201)
  • Pallor
  • Increased heart rate
  • Increased blood pressure
  • Gallop rhythm
  • Paradoxical S2
  • Paradoxical movement
  • May be normal (50% of patients) at rest
  • Needs continuous recording
  • ST depression or elevation, T wave inversion, R wave decrease
  • Assess cardiac muscle
  • Size of cavities
  • Systolic & diastolic function of LV
  • Total segmental function of LV
  • Interventional studies:
    • Coronary artery angioscopy
    • Intracoronary echocardiography
  • Stress test
  • 24-hour ECG

Treatment

Goals

  • Alleviate/prevent anginal pain
  • Increase quality of life
  • Fast diagnosis of MI and prevent ischemic death
Increase Oxygen SupplyDecrease Oxygen DemandLifestyle Changes
  • Nitrates
  • ACE-I
  • Revascularization procedures:
    • Percutaneous coronary intervention
    • Coronary bypass operation
  • Nitrates
  • β-blockers
  • Calcium channel blockers (CCB)
  • Ivabradin
  • Ranolazine
  • Improve nutrition
  • Decrease body weight
  • Increase physical activity
  • Decrease blood pressure
  • Modify modifiable risk factors