In an 87‑year‑old stable patient with generalized weakness, cough, interstitial markings and cardiomegaly on chest radiograph, normal complete blood count, and mildly elevated serum creatinine, what is the most likely diagnosis and the initial diagnostic and therapeutic steps?

Diagnosis and Management of an 87-Year-Old with Weakness, Cough, Interstitial Markings, and Cardiomegaly

Most Likely Diagnosis

The most likely diagnosis is heart failure with pulmonary congestion, given the combination of cardiomegaly and interstitial markings on chest X-ray in an elderly patient with cough and weakness. 1

Diagnostic Approach

Immediate Laboratory Testing

• Obtain B-type natriuretic peptide (BNP) or NT-proBNP immediately to confirm or exclude heart failure; a normal level (<100 pg/mL for BNP or <400 pg/mL for NT-proBNP) makes heart failure unlikely with a negative predictive value >90%, while elevated levels strongly support the diagnosis. 1

• The mildly elevated creatinine at 1.10 mg/dL is common in elderly patients with heart failure and requires monitoring but does not exclude the diagnosis. 1

Echocardiography

• Perform transthoracic echocardiography within 48 hours as the most useful method for evaluating both systolic and diastolic dysfunction, determining ejection fraction, and assessing chamber sizes and valvular function. 1

• Cardiomegaly on chest X-ray has only 56% positive predictive value for true cardiomegaly, with 44% false positive rate, making echocardiography essential for definitive cardiac assessment. 2

Electrocardiogram

• Obtain a 12-lead ECG immediately; a completely normal ECG makes heart failure unlikely (<10% probability), while abnormalities support but do not confirm the diagnosis. 1

Key Diagnostic Considerations

Chest Radiograph Interpretation

• Interstitial markings with cardiomegaly strongly suggest pulmonary venous congestion from elevated left ventricular filling pressures, confirming left heart failure. 1

• However, approximately 19% of patients with acute decompensated heart failure have no radiographic signs of congestion, so negative findings do not exclude the diagnosis. 3

• Chest radiography has moderate accuracy for cardiopulmonary abnormalities but is essential for detecting alternative diagnoses such as pneumonia, pleural effusions, or pulmonary masses. 4

Alternative Diagnoses to Consider

• Interstitial lung disease must be considered if symptoms have been progressive over months rather than acute/subacute; however, this typically presents with exertional dyspnea rather than generalized weakness. 5, 6

• Chronic cough with interstitial abnormalities may indicate bronchiectasis, bronchial wall thickening, or early interstitial lung disease, which chest X-ray detects with only 64% negative predictive value compared to CT. 1

• If heart failure is excluded by normal natriuretic peptides and echocardiography, obtain high-resolution CT chest to evaluate for interstitial lung disease, as chest radiography has only 62% sensitivity for detecting ILD compared to HRCT. 6

Initial Therapeutic Management

If Heart Failure is Confirmed

• Initiate diuretic therapy (typically furosemide) to reduce pulmonary congestion and improve symptoms. 1

• Assess volume status clinically and adjust diuretics based on response, monitoring creatinine and electrolytes closely given baseline renal impairment. 1

• Consider ACE inhibitor or ARB therapy once volume status is optimized, with careful monitoring of renal function and potassium. 1

Monitoring Parameters

• Repeat chest X-ray after 48-72 hours of diuretic therapy to assess radiographic improvement; resolution of interstitial markings supports heart failure diagnosis. 7

• Monitor daily weights, intake/output, and clinical signs of congestion (jugular venous pressure, peripheral edema, lung crackles). 1

Critical Pitfalls to Avoid

• Do not rely solely on chest radiography to exclude heart failure; up to 19% of patients with acute decompensated heart failure have normal or non-diagnostic chest X-rays. 3

• Do not assume cardiomegaly on chest X-ray represents true cardiac enlargement; echocardiography is required for definitive assessment, as radiographic cardiomegaly has 44% false positive rate. 2

• Do not delay natriuretic peptide testing; this simple blood test has high diagnostic accuracy and should guide initial management decisions. 1

• Do not empirically treat for common causes of chronic cough (upper airway cough syndrome, asthma, GERD) without first excluding cardiopulmonary disease in an elderly patient with abnormal chest imaging. 1

• If initial workup excludes heart failure and symptoms persist, do not continue empiric treatment without obtaining chest CT, as radiography misses significant pulmonary pathology including bronchiectasis (34% false negative rate), early ILD, and small nodules. 1