What is the most likely diagnosis for a previously healthy 20-year-old primigravida (first-time pregnant woman) at 37 weeks gestation presenting with fatigue, shortness of breath, and an enlarged heart on chest X-ray?

Peripartum Cardiomyopathy (PPCM)

The most likely diagnosis is D- Peripartum cardiomyopathy (PPCM), which is an idiopathic cardiomyopathy presenting with heart failure and left ventricular systolic dysfunction toward the end of pregnancy or in the months following delivery, and is a diagnosis of exclusion when no other cause of heart failure is found. 1

Why PPCM is the Most Likely Diagnosis

Clinical Presentation Matches PPCM Perfectly

• PPCM presents with heart failure symptoms (fatigue, shortness of breath) and cardiomegaly on chest X-ray at 37 weeks gestation, exactly as described in this case 1
• The rapid progression to death despite intensive measures is consistent with PPCM's ability to progress rapidly to end-stage heart failure, often within a few days 1
• The patient was previously healthy with no known cardiovascular disease, which is a defining feature of PPCM 1

Timing is Critical

• Only 9% of PPCM cases present during the last month of pregnancy (approximately 36-40 weeks gestation), but this is still within the recognized diagnostic window 2
• The majority (78%) of PPCM cases are diagnosed postpartum, with a peak 2-62 days after delivery, but antepartum presentation at term is well-documented 2
• PPCM is defined as developing during the last month of pregnancy or within 5 months of delivery 1

Why Other Options Are Unlikely

Myocardial Infarction (Option A)

• Myocardial infarction in a previously healthy 20-year-old woman without traditional cardiovascular risk factors is extremely rare 1
• The presentation with progressive fatigue and cardiomegaly over time is more consistent with cardiomyopathy than acute coronary syndrome
• No mention of chest pain, which would be expected in MI

Valvular Heart Disease (Option B)

• Valvular heart disease severe enough to cause acute decompensation would have been detected earlier in pregnancy or would have pre-existed with symptoms 1
• The patient was previously healthy, making undiagnosed severe valvular disease unlikely
• Pregnancy-related hemodynamic stress peaks before delivery, not at 37 weeks with progressive symptoms 1

Ischemic Heart Disease (Option C)

• Ischemic heart disease in a 20-year-old previously healthy woman is exceptionally rare 1
• This would require significant atherosclerotic disease or coronary anomalies, which would typically manifest earlier or with different presentation
• The clinical picture of progressive heart failure with cardiomegaly is not typical for acute ischemic heart disease

Key Diagnostic Features of PPCM

Clinical Characteristics

• PPCM presents with left ventricular systolic impairment (ejection fraction <45%) and is a diagnosis of exclusion 1
• High index of suspicion is required because shortness of breath and ankle swelling are common in normal pregnancy 1, 3
• The condition is associated with high morbidity and mortality but also with possibility of full recovery 1

Risk Factors Present in This Case

• First pregnancy (primigravida) is a recognized presentation pattern for PPCM 1
• Age 20 years falls within the typical demographic for PPCM 1
• Late third trimester presentation (37 weeks) is within the diagnostic window 1, 2

Critical Pitfall to Avoid

PPCM is a diagnosis of exclusion, and confusion commonly arises when cardiac changes accompany pregnancy-induced hypertension (pre-eclampsia) 2. However, this case describes a previously healthy patient with progressive symptoms and rapid deterioration, which is more consistent with primary PPCM rather than pre-eclampsia with cardiac involvement. The absence of mention of hypertension or pre-eclampsia features supports PPCM as the primary diagnosis 2.