Heart Failure (HFrEF & HFpEF) Diagnosis, Staging & 4-Pillar GDMT

Heart Failure (HFrEF & HFpEF) Diagnosis, Staging & 4-Pillar GDMT

Classification, Pathophysiology, and Neurohormonal Activation

Heart failure (HF) is classified by Left Ventricular Ejection Fraction (LVEF) on echocardiography:

• Heart Failure with Reduced Ejection Fraction (HFrEF): LVEF <=40%. Impaired contractility (systolic dysfunction) primarily caused by ischemic heart disease or dilated cardiomyopathy.
• Heart Failure with Mildly Reduced Ejection Fraction (HFmrEF): LVEF 41% to 49%. Managed similarly to HFrEF.
• Heart Failure with Preserved Ejection Fraction (HFpEF): LVEF >=50%. Impaired relaxation and diastolic stiffness (diastolic dysfunction) associated with aging, hypertension, obesity, metabolic syndrome, and AFib.

Progression of HFrEF is driven by chronic neurohormonal activation:

1. RAAS Activation: Reduced renal perfusion stimulates renin release, raising angiotensin II and aldosterone. This causes arterial vasoconstriction, sodium/water retention, myocardial fibrosis, and LV remodeling.
2. Sympathetic Overdrive: Elevated norepinephrine causes tachycardia, increased oxygen demand, cardiotoxicity, and beta-1 receptor downregulation.
3. Natriuretic Peptide Breakdown: Endogenous counter-regulatory mechanisms (ANP and BNP) are overwhelmed by sustained neurohormonal stress.

Diagnostic Workup: Clinical Signs, Biomarkers, and Imaging

Diagnosis synthesizes clinical history, exam findings, biomarkers, and imaging.

Framingham Criteria: Requires 2 major criteria OR 1 major + 2 minor criteria:

• Major Criteria: Paroxysmal nocturnal dyspnea, orthopnea, jugular venous distension (JVD >4 cm), rales, cardiomegaly, acute pulmonary edema, S3 gallop, hepatojugular reflux, weight loss >4.5 kg in 5 days on diuretics.
• Minor Criteria: Ankle edema, nocturnal cough, exertional dyspnea, hepatomegaly, pleural effusion, tachycardia (HR >120 bpm).

Biomarkers: B-type Natriuretic Peptide (BNP >100 pg/mL) or NT-proBNP (>300 pg/mL) supports acute heart failure. Normal levels rule out HF.

• Clinical Pearls: Obesity lowers natriuretic peptide levels. Aging and CKD elevate levels. Patients taking an ARNI (sacubitril/valsartan) display elevated plasma BNP because sacubitril inhibits neprilysin (which degrades BNP). Therefore, NT-proBNP MUST be measured instead of BNP to evaluate patients on an ARNI.

Echocardiography: Transthoracic Echocardiography (TTE) is mandatory to quantify LVEF, chamber size, wall motion, and diastolic filling pressures (E/e' ratio).

ACC/AHA Staging System vs. NYHA Functional Classification

• Stage A: At risk without structural heart disease (HTN, DM).

• Stage B: Structural heart disease without HF symptoms (low EF, prior MI).

• Stage C: Structural heart disease with prior or current HF symptoms.

• Stage D: Refractory HF requiring advanced interventions.

• NYHA Class I: No limitation of physical activity.

• NYHA Class II: Slight limitation; comfortable at rest, ordinary activity causes symptoms.

• NYHA Class III: Marked limitation; comfortable at rest, less than ordinary activity causes symptoms.

• NYHA Class IV: Symptoms present at rest; unable to carry on any physical activity.

Recognizing that NYHA functional class fluctuates based on symptom control and treatment response whereas ACC/AHA staging only progresses forward is essential for clinical tracking.

The 4-Pillar Guideline-Directed Medical Therapy (GDMT) for HFrEF

All HFrEF patients (LVEF <=40%) should receive 4-Pillar GDMT:

Management of HFpEF (LVEF >=50%)

SGLT2 inhibitors (Dapagliflozin 10 mg or Empagliflozin 10 mg) are a Class I recommendation for HFpEF (EMPEROR-Preserved, DELIVER), significantly reducing HF hospitalizations and CV death. Additional options in HFpEF include MRAs (spironolactone), ARNI (sacubitril/valsartan), and loop diuretics for fluid overload, combined with strict blood pressure control (<130/80 mmHg).

Symptom Control and Device Therapy

• Loop Diuretics (Furosemide, Bumetanide, Torsemide): Control congestion and restore euvolemia. Diuretics improve symptoms but do NOT reduce overall mortality.
• Device Therapy: Implantable Cardioverter-Defibrillator (ICD) is recommended for primary prevention of sudden cardiac death if LVEF <=35% despite >=3 months of optimal GDMT. Cardiac Resynchronization Therapy (CRT) is indicated for LVEF <=35%, LBBB, and QRS >=150 ms.

Geriatric Considerations & Digoxin Toxicity

Digoxin Clinical Rules: Digoxin may be added for symptomatic control in persistent NYHA Class III-IV HFrEF or AFib rate control. Digoxin does NOT reduce mortality. Therapeutic concentration window is narrow (0.5 to 0.9 ng/mL).

• Digoxin Toxicity Symptoms: Anorexia, nausea, vomiting, confusion, and visual disturbances (xanthopsia—yellow-green halos around lights). Cardiac manifestations include sinus bradycardia and AV block.
• Toxicity Triggers: Hypokalemia (potassium competes with digoxin for Na+/K+-ATPase binding; low potassium enhances digoxin binding and toxicity), hypomagnesemia, and renal decline.

Patient Education: Educate on daily morning weight checks after voiding. Patients must report weight gain of >2 to 3 lbs in 24 hours or >5 lbs in 1 week, indicating fluid retention requiring loop diuretic adjustment. Restrict sodium to <2,000 mg/day.