Heart Failure with Preserved Ejection Fraction

Detailed Overview

HFpEF accounts for approximately half of all heart failure cases and is increasingly recognized as a systemic, proinflammatory, multiorgan syndrome rather than an isolated cardiac disease. It is strongly driven by comorbidities like aging, obesity, hypertension, and metabolic syndrome. The clinical significance of HFpEF is profound due to its soaring prevalence, high morbidity, and historical lack of disease-modifying therapies, though recent trials with SGLT2 inhibitors have marked a breakthrough. The stiffened ventricle requires elevated atrial pressures to fill, leading to backward congestion into the pulmonary and systemic veins.

Epidemiology & Demographics

Prevalence is rising due to an aging population and obesity epidemic. Accounts for >50% of heart failure hospitalizations. Predominantly affects older adults (often >70 years) and has a higher prevalence in females compared to HFrEF.

Etiological Mechanism

The etiology is typically multifactorial, driven by chronic comorbidities that induce systemic microvascular inflammation. Primary drivers are long-standing hypertension (causing LV hypertrophy), obesity, diabetes mellitus, and aging. Infiltrative cardiomyopathies (like Cardiac Amyloidosis) are a distinct, critical etiology within the HFpEF spectrum.

Primary Causes

Chronic hypertension, metabolic syndrome/obesity, normal aging (senile cardiac stiffening), Transthyretin Cardiac Amyloidosis (ATTR), Hypertrophic Cardiomyopathy.

• Obesity and Metabolic Syndrome: Epicardial adipose tissue secretes proinflammatory adipokines, causing coronary microvascular dysfunction and myocardial fibrosis.
• Hypertension: Increases cardiac afterload, forcing the left ventricle to thicken (concentric hypertrophy), reducing chamber compliance.

Systemic comorbidities trigger a systemic proinflammatory state, leading to coronary microvascular endothelial inflammation. This reduces nitric oxide (NO) bioavailability, decreasing protein kinase G (PKG) activity in cardiomyocytes. Low PKG causes hypophosphorylation of titin (the giant myocardial spring protein), making the cardiomyocytes excessively stiff. Concurrently, inflammation drives fibroblasts to deposit excess interstitial collagen. The resulting stiff, non-compliant Left Ventricle requires abnormally high Left Atrial (LA) pressures to achieve adequate diastolic filling. This elevated pressure transmits backward, causing pulmonary venous congestion (dyspnea) and right heart failure/systemic congestion (edema), while the inability to augment cardiac output during exercise causes severe fatigue.

Characteristic Clinical Presentation

• Exertional Dyspnea: Shortness of breath out of proportion to physical activity, often the dominant symptom.
• Severe Fatigue: Due to the heart's inability to increase stroke volume and cardiac output during exertion.
• Peripheral Edema: Swelling in the ankles and legs due to right-sided fluid backup.

Physical Examination Signs

• S4 Gallop: An extra heart sound in late diastole caused by the forceful atrial contraction against a stiff, non-compliant ventricle.
• Elevated Jugular Venous Pressure (JVP) with a prominent 'a' wave.
• Pulmonary crackles/rales at the lung bases due to pulmonary edema.

• Atrial Fibrillation: Chronic left atrial stretch and remodeling lead to AFib in over 50% of patients, which acutely worsens diastolic filling and can trigger flash pulmonary edema.
• Group 2 Pulmonary Hypertension: Chronic backward transmission of left-sided filling pressures leads to pulmonary vascular remodeling.

Diagnostic Criteria & Guidelines

1. Symptoms/signs of heart failure. 2. LVEF ≥ 50%. 3. Objective evidence of structural heart disease (LV hypertrophy or Left Atrial enlargement) AND/OR diastolic dysfunction (E/e' ratio > 15 on echo). 4. Elevated NT-proBNP (>125 pg/mL, though often lower in obesity). Gold standard is invasive right heart catheterization showing PCWP ≥ 15 mmHg at rest or ≥ 25 mmHg with exercise.

Differential Diagnosis

• Coronary Artery Disease (Ischemia)
• Chronic Obstructive Pulmonary Disease (COPD)
• Constrictive Pericarditis

Laboratory Tests & Biomarkers

• NT-proBNP: Elevated, but often lower than in HFrEF. Obese patients may have falsely normal levels (e.g., < 100 pg/mL) due to increased clearance by adipose tissue.

Imaging Modalities & Findings

• Echocardiogram:

• H2FPEF Score
  A clinical score using Heavy (BMI), Hypertensive, Atrial Fibrillation, Pulmonary hypertension, Elder (>60), and Filling pressures to estimate probability of HFpEF.

Second-Line & Adjunctive Therapy

Mineralocorticoid Receptor Antagonists (Spironolactone 25 mg daily) can decrease hospitalizations, particularly in patients with LVEF on the lower end of normal (50-60%). Strict management of blood pressure and arrhythmias (e.g., rate/rhythm control for AFib) is crucial.

Surgical & Procedural Management

Bariatric surgery for morbidly obese HFpEF phenotypes. Interatrial shunt devices are currently under clinical investigation to decompress the left atrium.

Recommended Lifestyle Changes

• Aggressive weight loss via caloric restriction; exercise training is highly beneficial for improving functional capacity.
• Sodium restriction to prevent volume overload.

Patient Counseling & Advice

Counsel that while their 'heart squeeze' is normal, their heart is 'stiff.' Emphasize that weight loss and exercise are as important as medications. Managing their other conditions (blood pressure, diabetes) is the key to treating the heart.

Follow-Up & Monitoring Schedule

Regular clinical assessment of volume status (JVP, edema, orthopnea). Monitor renal function and potassium, especially if using Spironolactone or SGLT2i. Echocardiogram to monitor for worsening structural changes.

Preventive Strategies

Preventing the metabolic syndrome: maintaining a normal BMI, regular aerobic exercise, and aggressive control of hypertension and diabetes.

Morbidity is high with frequent readmissions. 5-year mortality approaches 50%, similar to HFrEF, though deaths in HFpEF are more often non-cardiovascular (driven by age and comorbidities). SGLT2 inhibitors are improving this trajectory.