Cardiovascular · Year 1 · from Cardiovascular

Case 1: Heart Failure with Reduced Ejection Fraction (HFrEF) - Post-MI Cardiomyopathy

Patient Presentation

Demographics: 67-year-old male

Chief Complaint: Progressive shortness of breath and leg swelling for 6 weeks

History of Present Illness: A 67-year-old male with history of anterior STEMI 18 months ago (treated with primary PCI to LAD) presents with progressive dyspnea on exertion over the past 6 weeks. He previously could walk 2 blocks without difficulty but now becomes short of breath after walking 50 feet. He reports orthopnea, requiring 3 pillows to sleep, and describes episodes of waking up gasping for air at night (PND). He has noticed bilateral leg swelling and a 10-pound weight gain over the past month. He admits to dietary indiscretion with high salt intake and occasionally forgetting his medications.

Physical Examination:

  • Vital Signs: BP 102/68 mmHg, HR 92 bpm, RR 22/min, SpO2 92% on room air
  • General: Fatigued appearance, mild respiratory distress
  • Cardiovascular:
  • JVP elevated to 12 cm H2O
  • PMI displaced laterally and inferiorly to 6th intercostal space, anterior axillary line
  • S3 gallop present
  • Soft holosystolic murmur at apex (functional MR)
  • Lungs: Bilateral basilar crackles to mid-lung fields
  • Abdomen: Hepatomegaly, positive hepatojugular reflux
  • Extremities: 2+ pitting edema to knees bilaterally

Workup

  • BNP: 1,840 pg/mL (elevated, normal <100)
  • Labs:
  • Na 132, K 4.8, Cr 1.6, BUN 38
  • Troponin negative
  • ECG: Sinus rhythm, Q waves V1-V4 (prior anterior MI), low voltage
  • Chest X-ray:
  • Cardiomegaly (CTR >0.5)
  • Bilateral pleural effusions
  • Cephalization of pulmonary vessels
  • Kerley B lines
  • Echocardiogram:
  • LV ejection fraction 25%
  • Anterior and apical akinesis (scar from prior MI)
  • LV end-diastolic dimension 6.8 cm (dilated)
  • Moderate functional mitral regurgitation
  • Elevated E/e' ratio suggesting elevated filling pressures

Diagnosis

Acute decompensated heart failure with reduced ejection fraction (HFrEF) - NYHA Class III Etiology: Ischemic cardiomyopathy (post-anterior MI)

Heart Failure Correlation:

Pathophysiology of Systolic Dysfunction:

  1. Primary Insult - Myocardial Infarction:
  • LAD occlusion caused anterior wall and apical infarction
  • Irreversible myocyte death and scar formation
  • Loss of contractile tissue
  1. Ventricular Remodeling:
  • Eccentric hypertrophy: sarcomeres added in series
  • Chamber dilation to maintain stroke volume (Frank-Starling)
  • Spherical shape change from normal ellipse
  • Increased wall stress (Law of LaPlace: T = P x r / 2h)
  1. Neurohormonal Activation:
  • Reduced cardiac output triggers compensatory mechanisms:
  • Sympathetic activation: Increases HR and contractility acutely
  • RAAS activation: Causes vasoconstriction and fluid retention
  • ADH release: Water retention, hyponatremia
  • Initially compensatory, becomes maladaptive chronically:
  • Myocyte toxicity from catecholamines
  • Fibrosis from angiotensin II and aldosterone
  • Progressive remodeling and dysfunction
  1. Functional Mitral Regurgitation:
  • LV dilation stretches mitral annulus
  • Papillary muscle displacement prevents leaflet coaptation
  • MR creates additional volume overload - vicious cycle

Why Symptoms Develop:

Elevated Filling Pressures (Congestion):

  • Dilated, non-compliant LV requires higher filling pressures
  • Transmitted backward to LA, pulmonary veins
  • Pulmonary congestion causes dyspnea, orthopnea, PND
  • Systemic congestion causes JVD, edema, hepatomegaly

Reduced Cardiac Output:

  • Damaged ventricle cannot meet metabolic demands
  • Fatigue, exercise intolerance
  • Prerenal azotemia (elevated Cr/BUN)
  • Hyponatremia from water retention exceeding sodium

Treatment

Acute Management:

  1. Diuresis:
  • IV furosemide 40-80 mg bolus
  • Goal: 1-2 L negative fluid balance daily
  • Monitor electrolytes, creatinine
  1. Oxygen supplementation
  2. Sodium and fluid restriction

Guideline-Directed Medical Therapy (GDMT):

  1. ACE Inhibitor/ARNI:
  • Sacubitril/valsartan (ARNI) preferred over ACE-I
  • Blocks RAAS, prevents remodeling
  • Mortality reduction proven
  1. Beta-Blocker:
  • Carvedilol, metoprolol succinate, or bisoprolol
  • Start low, titrate slowly after euvolemia achieved
  • Blocks maladaptive sympathetic activation
  • Mortality reduction and reverse remodeling
  1. Mineralocorticoid Receptor Antagonist:
  • Spironolactone or eplerenone
  • Blocks aldosterone-mediated fibrosis and sodium retention
  • Mortality reduction in HFrEF
  1. SGLT2 Inhibitor:
  • Dapagliflozin or empagliflozin
  • Cardiovascular benefit regardless of diabetes status
  • Reduces HF hospitalizations and mortality

Device Therapy:

  • ICD: Primary prevention (EF 35% despite 3 months GDMT)
  • CRT: If LBBB with QRS >150 ms and persistent symptoms

Clinical Image

Image Description: Chest radiograph demonstrating cardiomegaly with an enlarged cardiac silhouette. The cardiothoracic ratio exceeds 50%, indicating significant cardiac enlargement consistent with heart failure. Additional findings may include pulmonary vascular congestion.

Source: Wikimedia Commons - Cardiomegaly License: Public Domain URL: https://commons.wikimedia.org/wiki/File:Cardiomegally.PNG

All cases for this lecture as Markdown