Cardiovascular Disorders

Heart Failure

Clinical Overview and Exam Mastery Guide focused on HF classification, HFrEF mortality-reducing therapy, acute decompensation, and high-yield exam traps.

HFrEF
EF at or below 40 percent
Core Framework
4 foundational pillars
Symptom Agent
Loop diuretics
Exam Focus
Mortality vs symptom drugs

Hemodynamic Snapshot

Cardiac output down RAAS activation fluid retention

Simple visual map: reduced output drives neurohormonal activation and congestion.

1. What Is Heart Failure?

Heart failure is a clinical syndrome where the heart cannot pump sufficient blood to meet the body's metabolic needs. It results from structural or functional impairment of ventricular filling or ejection.

2. Classification

By Ejection Fraction Definition Exam Note
HFrEF EF at or below 40 percent Most mortality therapy questions focus here
HFmrEF EF 41 to 49 percent Intermediate EF phenotype
HFpEF EF at or above 50 percent Different evidence profile vs HFrEF

NYHA Functional Classes

  • Class I: no symptoms
  • Class II: symptoms with moderate exertion
  • Class III: symptoms with minimal exertion
  • Class IV: symptoms at rest

ACC/AHA Stages

  • Stage A: at risk
  • Stage B: structural disease, no symptoms
  • Stage C: structural disease plus symptoms
  • Stage D: advanced refractory heart failure

3. Pathophysiology

Step 1: Reduced cardiac output
Step 2: RAAS and sympathetic activation
Step 3: Ventricular remodeling
Step 4: Sodium and water retention

Neurohormonal Cycle Diagram

Reduced output Low forward flow RAAS activation Vasoconstriction / aldosterone SNS activation Tachycardia / stress response Remodeling Progressive dysfunction Congestion Na/H2O retention
Modern heart failure therapy targets neurohormonal overactivation.

4. Clinical Presentation

Dyspnea Orthopnea PND Peripheral edema Fatigue Weight gain

Diagnostic Support

  • Elevated BNP or NT-proBNP
  • Clinical congestion and volume status findings

Key Confirmatory Test

  • Echocardiogram confirms ejection fraction phenotype
  • Used to separate HFrEF vs HFpEF pattern

5. Guideline-Directed Medical Therapy (HFrEF)

All symptomatic HFrEF patients should receive four foundational therapies to reduce mortality and hospitalizations.

1) ARNI or ACEI/ARB

ARNI preferred when appropriate.

2) Evidence-Based Beta Blocker

Carvedilol, metoprolol succinate, bisoprolol.

3) MRA

Spironolactone or eplerenone.

4) SGLT2 Inhibitor

Dapagliflozin or empagliflozin.

4-Pillar GDMT Diagram (HFrEF)

HFrEF EF at or below 40% ARNI/ACEI/ARB Beta blocker MRA SGLT2 inhibitor Outcomes Lower mortality and HF hospitalizations

A. ARNI (Sacubitril/Valsartan)

MOA

  • Sacubitril inhibits neprilysin
  • Valsartan blocks angiotensin II receptor
  • Net: less RAAS drive, more natriuretic signaling

Benefits and Risks

  • Reduces mortality and hospitalization
  • Hypotension, hyperkalemia, renal impairment
  • Contra: ACEI overlap (36-hour washout), pregnancy, angioedema history

B. ACE Inhibitors

Examples: lisinopril, enalapril.

  • MOA: reduce angiotensin II and aldosterone activity
  • Benefits: mortality reduction and slower progression
  • Side effects: dry cough, hyperkalemia, renal dysfunction, angioedema
  • Contraindications: pregnancy, bilateral renal artery stenosis, prior angioedema

C. ARBs

Examples: losartan, valsartan.

  • MOA: block AT1 receptor and reduce vasoconstriction
  • Benefit: mortality reduction, no ACEI cough
  • Risks: hyperkalemia and renal dysfunction
  • Contraindications: pregnancy, bilateral renal artery stenosis

D. Evidence-Based Beta Blockers

  • Only carvedilol, metoprolol succinate, bisoprolol reduce mortality
  • MOA: reduce sympathetic stress and reverse remodeling over time
  • Side effects: bradycardia, hypotension, fatigue
  • Do not initiate during acute decompensated instability

E. Mineralocorticoid Receptor Antagonists (MRA)

Spironolactone, eplerenone.

  • Reduce sodium retention and fibrosis/remodeling
  • Benefits: lower mortality and hospitalization
  • Risks: hyperkalemia, renal dysfunction, gynecomastia (spironolactone)
  • Avoid with potassium above 5.0 mEq/L or severe renal impairment

F. SGLT2 Inhibitors

Dapagliflozin, empagliflozin.

  • Promote glucosuria and natriuresis
  • Benefits: lower HF hospitalization and mortality, even without diabetes
  • Risks: genital infections, volume depletion, rare euglycemic DKA
  • Contra: type 1 diabetes and severe renal impairment by agent
HFrEF Flow: Confirm EF at or below 40 percent
Start: ARNI (or ACEI/ARB)
Add: evidence-based beta blocker, MRA, SGLT2 inhibitor
Then: use diuretics for congestion and monitor potassium/renal function

6. Additional Therapies

Hydralazine + Isosorbide Dinitrate

  • Hydralazine: arterial vasodilation
  • ISDN: venous vasodilation
  • Reduces preload and afterload
  • Mortality benefit, especially in Black patients
  • Side effects: headache, hypotension, reflex tachycardia

Ivabradine

  • MOA: inhibits If current in SA node
  • Lowers heart rate without reducing blood pressure
  • Side effects: bradycardia, visual disturbances
  • Contraindications: AFib, severe bradycardia

7. Symptom Control

Loop Diuretics

Examples: furosemide, bumetanide.

  • MOA: block Na-K-2Cl transporter in loop of Henle
  • Improve congestion symptoms through diuresis

High-Yield Caveat

  • Improves symptoms and volume control
  • Does not reduce mortality by itself
  • Watch for hypokalemia, dehydration, hypotension

8. Acute Decompensated Heart Failure

Initial: IV loop diuretics and oxygen support
If low output: consider inotropes (dobutamine, milrinone)
If hypertensive: consider vasodilator support
Avoid aggressive beta blocker initiation during acute unstable decompensation.

Guideline References

AHA/ACC/HFSA Guideline for Heart Failure

https://www.ahajournals.org/doi/10.1161/CIR.0000000000001063

ACC Guideline Hub

https://www.acc.org/guidelines/hubs/heart-failure

9. Common Exam Traps

Digoxin improves symptoms but does not reduce mortality.
Non-DHP calcium channel blockers are contraindicated in HFrEF.
Only carvedilol, metoprolol succinate, and bisoprolol reduce mortality.
Diuretics improve symptoms, not survival.
ACE inhibitor plus ARB combination is not routinely recommended.

10. Quick Revision Summary

Must Remember

  • EF at or below 40 percent defines HFrEF
  • Four-pillar therapy is the treatment core
  • Differentiate mortality-reducing drugs from symptom-only drugs

Monitoring Focus

  • Track potassium and renal function
  • Avoid non-DHP CCB in HFrEF
  • Reassess congestion, blood pressure, and heart rate regularly

Practice Questions Placeholder

  • Topic: Heart Failure
  • Subtopics: HFrEF, HFpEF, GDMT, acute decompensation, monitoring