What is the diagnosis for a pregnant woman at 37 weeks gestation presenting with a 1 week history of cough and expectoration, severe hypoxia, and an ejection fraction (EF) of 40% post-delivery, who improved with Lasix (furosemide) and broad-spectrum antibiotics?

Diagnosis: Peripartum Cardiomyopathy with Superimposed Respiratory Infection

The most likely diagnosis is peripartum cardiomyopathy (PPCM) with a concurrent respiratory infection that required treatment with broad-spectrum antibiotics. The European Society of Cardiology explicitly defines PPCM as a diagnosis of exclusion where "no other cause of heart failure is found," making it essential to rule out infectious etiologies before confirming PPCM 1.

Why This Represents PPCM with Infection

Diagnostic Criteria Met for PPCM

• Timing: The patient presented at 37 weeks gestation and developed heart failure post-delivery, which falls within the classic PPCM window (last month of pregnancy through 5 months postpartum) 1
• Ejection Fraction: EF of 40% meets the diagnostic threshold of <45% required by the European Society of Cardiology 1, 2
• Post-delivery worsening: The development of hypertension and worsening hypoxia after delivery is consistent with PPCM, as 78% of cases present in the first 4 months postpartum 2, 3

Why Infection Must Be Ruled Out

• PPCM is a diagnosis of exclusion: The European Society of Cardiology emphasizes that PPCM can only be diagnosed "where no other cause of heart failure is found" 1, 2
• Viral myocarditis consideration: The guidelines specifically note that "viral infection of the heart is another possible cause of peripartum inflammation," though clinical data are not conclusive 1
• Initial respiratory symptoms: The 1-week history of cough and expectoration with severe hypoxia requiring intubation suggests a primary respiratory/infectious process that may have triggered or coexisted with cardiac dysfunction 4

Clinical Response Pattern

• Improvement with antibiotics AND diuretics: The patient's improvement with both Lasix and broad-spectrum antibiotics suggests two concurrent processes:
  • Heart failure (responding to diuretics) 1
  • Respiratory infection (responding to antibiotics) 4
• This dual response pattern supports PPCM complicated by infection rather than infection alone causing the cardiac dysfunction 5

Differential Diagnosis Considerations

The European Society of Cardiology provides specific guidance on excluding other conditions 1:

• Pulmonary embolism: Must be excluded with appropriate imaging (D-dimers, CT pulmonary angiogram) 1
• Pregnancy-associated myocardial infarction: History and ECG findings help differentiate 1
• Pre-existing cardiomyopathy unmasked by pregnancy: These typically present by the second trimester, not at 37 weeks 1, 3
• Hypertensive heart disease: The patient was initially normotensive, making this less likely 1

Critical Diagnostic Pitfall

The key clinical teaching point is that PPCM requires exclusion of other causes, particularly infection. The European Society of Cardiology's definition explicitly states this is "an idiopathic cardiomyopathy...where no other cause of heart failure is found" 1. The initial presentation with cough, expectoration, and severe hypoxia requiring intubation strongly suggests a respiratory infection that needed treatment before the PPCM diagnosis could be confirmed 4.

Management Implications

• Immediate treatment: The patient correctly received both heart failure management (Lasix) and infection treatment (broad-spectrum antibiotics) 1
• Anticoagulation consideration: With EF of 40%, anticoagulation should be considered given the increased risk of thromboembolism in PPCM, particularly with EF <35% 1, 6
• Follow-up echocardiography: Repeat assessment at 6 weeks, 6 months, and annually is recommended to evaluate for recovery, as 50% of PPCM patients show spontaneous recovery 1, 6
• Guideline-directed heart failure therapy: Once infection is controlled and the patient is postpartum, standard heart failure medications (ACE inhibitors, beta-blockers) should be initiated 1, 7