Heart Failure: Pathophysiology and Management
Heart failure is a complex clinical syndrome characterized by the heart's inability to pump blood effectively enough to meet the body's metabolic demands, typically due to impaired ventricular filling or ejection, requiring a comprehensive approach to diagnosis and management based on the latest guidelines. 1
Pathophysiology of Heart Failure
- Heart failure results from injury to the myocardium from various causes including ischemic heart disease, hypertension, and diabetes 2
- Less common etiologies include cardiomyopathies, valvular disease, myocarditis, infections, systemic toxins, and cardiotoxic drugs 2
- The pathophysiological process involves myocyte loss, segmental scarring, interstitial fibrosis, myocardial slippage, and myocyte hypertrophy, leading to progressive cardiac enlargement and dysfunction 3
- Compensatory mechanisms initially maintain cardiac output but eventually contribute to disease progression:
- Frank-Starling mechanism (increased preload)
- Ventricular remodeling (increased volume and wall thickness)
- Neurohormonal activation (to maintain tissue perfusion) 2
Classification and Diagnosis
- Heart failure is classified based on ejection fraction:
- Heart failure with reduced ejection fraction (HFrEF, EF ≤40%)
- Heart failure with mildly reduced ejection fraction
- Heart failure with preserved ejection fraction (HFpEF, EF ≥50%) 4
- Severity is assessed using the New York Heart Association (NYHA) functional classification 4
- Diagnostic approach includes:
- Plasma natriuretic peptides (BNP, NT-proBNP) - particularly useful as a 'rule out' test due to high negative predictive value 5
- Echocardiography - essential for confirming diagnosis and determining type of heart failure 4
- Holter monitoring - not valuable for diagnosis but useful for detecting arrhythmias that may cause or exacerbate symptoms 5
Management of Heart Failure with Reduced Ejection Fraction (HFrEF)
First-Line Pharmacological Therapy
- ACE inhibitors are recommended as first-line therapy in patients with reduced LV systolic function 5
- β-blockers (bisoprolol, metoprolol succinate, carvedilol, and nebivolol) should be initiated in all patients with HFrEF regardless of symptom severity 5
- Both ACE inhibitors and β-blockers reduce morbidity and increase survival in patients with left ventricular systolic dysfunction 5
- Either ACE inhibitors or β-blockers can be started first, as high-quality evidence shows similar outcomes with either approach 5
Additional Pharmacological Therapy
- Diuretics are essential for symptomatic treatment when fluid overload is present (pulmonary congestion or peripheral edema) 5
- Diuretics should always be administered in combination with ACE inhibitors when possible 5
- For patients intolerant to ACE inhibitors, angiotensin receptor blockers (ARBs) are an alternative 5
- For patients intolerant to both ACE inhibitors and ARBs, combination therapy with hydralazine and nitrates is recommended 5
- Mineralocorticoid receptor antagonists (aldosterone antagonists) provide additional benefits for patients with persistent symptoms 6
- Sodium-glucose cotransporter-2 (SGLT2) inhibitors have demonstrated reductions in morbidity, mortality, and hospitalizations 1
Device Therapy
- Implantable cardioverter defibrillators (ICDs) improve survival in appropriate patients 6
- Cardiac resynchronization therapy (CRT) reduces mortality and morbidity in patients with persistently severe symptoms and a wide QRS on the electrocardiogram 6
- Left ventricular assist devices may be indicated in some patients with end-stage heart failure 6
Management of Heart Failure with Preserved Ejection Fraction (HFpEF)
- There is insufficient evidence to recommend specific therapies for HFpEF, other than:
- Treatment of comorbid conditions
- Diuretic therapy to manage fluid retention 5
- Rehabilitation should be offered to patients with HFpEF, as symptoms and prognosis are similar to those of left ventricular systolic dysfunction 5
- Management of obesity with glucagon-like peptide-1 receptor agonists has shown improved outcomes in HFpEF patients 1
Non-Pharmacological Management
- Patient education about heart failure, symptom recognition, and self-monitoring 4
- Daily monitoring of symptoms and weight fluctuations 4
- Sodium restriction in patients with severe heart failure 5
- Avoidance of excessive fluid intake in severe heart failure 5
- Limitation of alcohol consumption 5
- Regular physical activity to prevent muscle deconditioning 5
- Smoking cessation 5
- Exercise training programs for stable NYHA class II-III patients 5
Transitional and Team-Based Care
- Multidisciplinary heart failure disease management programs for high-risk patients 4
- Patient-centered discharge instructions with clear transitional care plan 4
- Early follow-up within 7 days of hospital discharge 4
Management of Right Heart Failure
- Monitoring heart rate, rhythm, blood pressure, and oxygen saturation continuously for at least the first 24 hours of admission 7
- Maintaining oxygen saturation above 90% 7
- Loop diuretics for managing fluid retention 7
- Consider inotropic support with dobutamine (2.5-5.0 μg/kg/min) or milrinone (0.25-0.75 μg/kg/min) for improving right ventricular output 7
- Pulmonary vasodilators like sildenafil may be considered for right heart failure associated with pulmonary hypertension 7
Common Pitfalls and Caveats
- Inadequate diuresis in volume-overloaded patients 4
- Failure to uptitrate medications to target doses 4
- β-blockers should be introduced in a "start-low, go-slow" manner, with careful monitoring of heart rate, blood pressure, and clinical status after each dose titration 5
- Avoid excessive fluid administration in patients with a massively dilated right ventricle as this may increase right ventricular distention and compromise left ventricular filling 7
- Ensure the acute episode of heart failure has resolved, congestion is absent, and a stable oral diuretic regimen has been established for at least 48 hours before discharge 7