Heart Failure Lecture Notes by Jerome Rao

Introduction

  • Speaker: Jerome Rao, heart failure cardiologist at the Victorian Heart Hospital

  • Purpose of the lecture: Discuss heart failure, covering key aspects such as etiology, epidemiology, clinical features, investigations, management, and pharmacology.

  • Structure: Information presented on slides serves as a reference for students' future study.

1. Etiology of Heart Failure

Overview

  • Heart failure has a broad range of causes.

  • Variations in causes from very common to less common.

  • Ischemic cardiomyopathy: most prevalent cause that must be excluded for most patients.

Non-Ischemic Cardiomyopathies

1. Genetic or Familial Cardiomyopathies

  • Includes inherited forms leading to systolic dysfunction.

2. Toxins

  • Alcohol: sustained excessive use leads to cardiomyopathy (not binge drinking).

  • Cocaine and methamphetamines: significant contributors, particularly meth-related cardiomyopathy affecting 5-10% of users.

  • Cancer therapies: modern treatments like checkpoint inhibitors linked to increased cardiomyopathy cases.

3. Rhythm-Related Problems

  • Tachycardia can weaken the heart muscle over time.

  • Conditions such as atrial fibrillation, pacemakers can also contribute.

4. Inflammatory Causes

  • Infectious causes (e.g., myocarditis) and non-infectious autoimmune conditions are significant contributors (overarching category).

5. Metabolic Causes

  • Thyroid dysfunction: both hyperthyroidism and hypothyroidism can lead to reduced heart function.

6. Infiltrative Cardiomyopathies

  • Conditions involving abnormal substance deposition in cardiac muscle, such as:

    • Amyloidosis: protein deposition.

    • Sarcoidosis: granulomatous tissue deposition.

    • Hemochromatosis: iron deposition.

7. Physiological Stress Cardiomyopathy

  • Resulting from conditions like rapid breathing (tachypnea), septic states, or during pregnancy (peripartum cardiomyopathy).

2. Epidemiology in Australia

Prevalence

  • Approximately 100,000 Australians over 18 diagnosed with heart failure; about 0.5% of the population.

  • Prevalence increases significantly in older age groups (5-10% for individuals over 65).

  • Associated statistics:

    • 180,000 hospitalizations annually.

    • Approximately 5,000 deaths per year.

    • Historically, one of the leading causes of death in Australia.

Demographics

  • Disease disproportionately affects males and individuals from lower socioeconomic backgrounds.

  • Higher prevalence in indigenous population and people residing in regional/remote areas.

3. Clinical Features

Symptoms Related to Fluid Overload

  • Common manifestations due to fluid retention include:

    • Breathlessness (Dyspnea): Can be exertional or at rest.

    • Orthopnea: Difficulty breathing while lying down.

    • Peripheral Edema: Swelling in the ankles or legs.

    • Ascites: Abdominal swelling indicative of fluid accumulation.

Fatigue

  • Normal fatigue due to reduced exercise tolerance must be evaluated against the patient's baseline functioning (e.g., changes over months).

Risk Factors and History

  • Essential history to assess risk factors includes:

    • Diabetes, hypertension, alcohol use, drug use.

    • History of ischemic heart disease, thyroid disease, and cancer.

  • Symptoms indicating ischemia include exertional chest pain and atypical presentations (e.g., epigastric pain).

  • Assess for arrhythmias, palpitations, and syncope.

NYHA Classification of Heart Failure

  • Classification system for heart failure symptoms:

    • Class I: No symptoms and no exercise limitation.

    • Class II: Mild symptoms with slight limitation of physical activity.

    • Class III: Moderate symptoms with noticeable limitation of physical activity; comfortable at rest.

    • Class IV: Severe symptoms at rest; unable to carry out physical activity without discomfort.

4. Investigations and Evaluation

Standard Diagnostic Tests

  • ECG (Electrocardiogram): Assesses heart rhythm and QRS complex width; significant if wide QRS > 150ms.

  • Chest X-ray: Useful for assessing heart size (cardiomegaly) and checking for lung fluid.

  • Echocardiogram: Key echocardiographic parameters include:

    • Left ventricular (LV) ejection fraction.

    • Right ventricular (RV) ejection fraction.

    • Regional wall motion abnormalities (RWMA).

  • Laboratory Tests: Regular tests include:

    • B-type natriuretic peptide (BNP).

    • Thyroid function tests.

    • Iron studies, and cardiac troponin levels.

  • Cardiac MRI: Provides detailed imaging of cardiac muscle, useful for diagnostics.

  • Coronary Assessment: Essential to rule out ischemic causes; options include CT scans or invasive coronary angiography.

5. Management of Heart Failure

Diuretics

  • Primary focuses on symptom relief.

  • Five main types of diuretics, with loop diuretics (e.g., furosemide) being the most common.

  • Diuretics primarily facilitate sodium and potassium excretion, beneficial for managing fluid overload but offer no mortality benefit.

Pharmacological Therapies (Four Pillars)

1. Beta Blockers

  • Function: Counteract effects of sympathetic nervous system activation in heart failure.

  • Benefits: Reduced heart rate and improved overall mortality, especially in those with an ejection fraction < 40%.

  • Common agents: Include metoprolol, carvedilol.

2. ACE Inhibitors & ARBs

  • Medications: e.g., sacubitril/valsartan (Entresto).

  • Action: Reduces negative vascular effects by inhibiting the renin-angiotensin-aldosterone system.

  • Benefit: Significant reduction in mortality and hospitalization rates.

3. Mineralocorticoid Receptor Antagonists (MRAs)

  • Includes spironolactone and eplerenone.

  • Action: Block aldosterone, enhancing potassium retention and countering fluid reabsorption facilitators.

  • Evidence: Studies show mortality reduction in heart failure populations.

4. SGLT2 Inhibitors

  • Medications: e.g., empagliflozin and dapagliflozin.

  • Initially developed for diabetes treatment, but found effective in heart failure by promoting diuresis and lowering extracellular fluid volume.

  • Key studies reported significant declines in hospitalization and mortality rates.

Combination Therapy

  • Significant improvements in overall outcomes when combining these therapies:

    • Overall mortality risk drops dramatically with all four medications combined.

    • Supports a number needed to treat (NNT) of 4, indicating extremely high efficacy.

Advanced Therapies

  • Device Implantation: For patients with persistent symptoms despite optimal drug therapy:

    • Cardiac Resynchronization Therapy (CRT): Targets patients with significant electrical dysynchrony.

    • Revascularization: Evidence supporting surgical interventions but lesser evidence for stenting.

    • Mitral Valve Interventions: Addressing mitral regurgitation can be beneficial.

    • Wireless Implantable Monitors: Emerging technology to monitor fluid status in patients remotely.

Conclusion

Key Takeaways

  1. Heart failure is prevalent and should be routinely considered in clinical practice.

  2. Ischemic cardiomyopathy remains a common cause that needs exclusion.

  3. Effective pharmacologic therapy available; diuretics are not sufficient alone—important to initiate and optimize multi-drug regimens.