What is the best management approach for a patient with ischemic cardiomyopathy, heart failure with mid-range ejection fraction (HFmrEF), and severe coronary artery disease (CAD) who develops bilateral pleural effusion, particularly on the left, after being treated for acute coronary syndrome (ACS) with ST-elevation myocardial infarction (STEMI) and percutaneous coronary intervention (PCI)?

Management of Bilateral Pleural Effusion Post-STEMI in HFmrEF

The bilateral pleural effusion in this post-STEMI patient with HFmrEF (LVEF 44%) is most likely due to heart failure-related fluid overload and should be managed primarily with aggressive intravenous loop diuretics, with therapeutic thoracentesis reserved only for large effusions causing significant respiratory compromise. 1, 2

Understanding the Etiology

• Heart failure-associated pleural effusions result from elevated pulmonary capillary pressure causing increased interstitial lung fluid that crosses into the pleural space. 2
• These effusions are typically bilateral, but when unilateral, they favor the right side more commonly—making the left-sided predominance in this case somewhat atypical but still consistent with HF. 2
• The fluid is usually a transudate, though in 25% of cases it may appear exudative, particularly after diuretic therapy (creating a "pseudoexudate"). 2, 3

Immediate Diuretic Management Strategy

Door-to-diuretic time should not exceed 60 minutes from identification of congestion. 1

Initial Dosing Approach:

• If the patient was already on oral loop diuretics pre-admission, start with double the home oral dose given intravenously. 1
• If loop diuretic-naïve, initiate 20-40 mg furosemide equivalents IV. 1
• In this patient with severe CAD and recent multi-vessel stenting, renal function must be carefully monitored, as contrast-induced nephropathy may be present. 4

Monitoring Response (Critical Time Points):

At 2 hours post-diuretic:

• Check spot urinary sodium—target ≥50-70 mmol/L. 1

At 6 hours post-diuretic:

• Assess urine output—target ≥100-150 mL/hour. 1

If targets are not met:

• Double the original diuretic dose, up to maximum 400-600 mg furosemide daily (or up to 1000 mg daily if severely impaired renal function exists). 1

Early Combination Diuretic Therapy

If inadequate response to loop diuretics alone, add acetazolamide 500 mg IV once daily, particularly if baseline bicarbonate ≥27 mmol/L. 1

• Acetazolamide remains effective even with worsening renal dysfunction but should be limited to the first 3 days to prevent severe metabolic disturbances. 1
• Alternative combination: hydrochlorothiazide can be added if acetazolamide is contraindicated. 1
• Continuous infusion of loop diuretics offers no advantage over intermittent boluses. 1

Role of Therapeutic Thoracentesis

Therapeutic thoracentesis should be performed only for very large effusions causing significant respiratory distress that requires immediate relief. 2

• Loop diuretics remain the mainstay of therapy; thoracentesis is not a substitute for adequate diuresis. 2
• If thoracentesis is performed, fluid should be sent for protein, LDH, and consider NT-proBNP measurement to confirm HF etiology. 2

Critical Pitfall: Pseudoexudate Formation

Treatment of heart failure with diuretics causes significant changes in pleural fluid chemistry—transudates can convert to "pseudoexudates" after diuresis. 3

• Weight loss per day correlates significantly with increased pleural fluid protein concentration (r=0.715). 3
• If fluid appears exudative after diuretic therapy, calculate serum-to-pleural fluid albumin gradient or measure pleural fluid NT-proBNP to confirm HF etiology rather than pursuing alternative diagnoses. 2

Guideline-Directed Medical Therapy Optimization

This patient with LVEF 44% (HFmrEF) and ischemic cardiomyopathy requires aggressive GDMT initiation before discharge:

Essential Medications:

ACE inhibitor (or ARB if ACE-I not tolerated):

• Recommended for all patients with LVEF ≤40% after stabilization to reduce death, recurrent MI, and HF hospitalization. 4
• Should be initiated within first 24 hours in patients with evidence of heart failure, LV dysfunction, diabetes, or anterior infarct. 4

Beta-blocker:

• Mandatory in patients with LVEF ≤40% after stabilization to reduce death, recurrent MI, and HF hospitalization. 4

Mineralocorticoid receptor antagonist (MRA):

• Recommended for patients with LVEF <40% and heart failure or diabetes who are already on ACE-I and beta-blocker, provided no renal failure (creatinine >221 μmol/L in men, >177 μmol/L in women) or hyperkalemia exists. 4
• Requires routine serum potassium monitoring. 4

Dual antiplatelet therapy (DAPT):

• Continue aspirin plus potent P2Y12 inhibitor (prasugrel or ticagrelor preferred over clopidogrel) for 12 months post-stent implantation. 5

High-intensity statin:

• Atorvastatin 40-80 mg or rosuvastatin 20-40 mg for secondary prevention. 5

Discharge Criteria and Follow-Up

The patient should NOT be discharged while still congested—complete decongestion must be achieved before hospital discharge. 1

Signs of Adequate Decongestion:

• Resolution of dyspnea at rest
• Absence of orthopnea
• Jugular venous pressure normalization
• Resolution or significant reduction of peripheral edema
• Stable or improving renal function

Early follow-up visit within 2 weeks is mandatory to up-titrate GDMT to target doses (STRONG-HF protocol). 1

Special Consideration: Renal Function Monitoring

Given recent contrast exposure from PCI and potential contrast-induced nephropathy, careful attention to renal function is essential during aggressive diuresis. 4

• Hydration with isotonic saline was recommended peri-PCI to prevent contrast nephropathy. 4
• Monitor creatinine and electrolytes daily during aggressive diuresis. 1
• Worsening renal function should not automatically halt diuretic therapy if patient remains congested—acetazolamide remains effective even with renal dysfunction. 1