What is the best course of action for a patient presenting with nocturnal cough, tachycardia (heart rate 127), and a chest X-ray showing no evidence of gross cardiac failure, pneumonic infiltrate, or pleural effusion?

Diagnostic Approach and Management

This patient requires immediate evaluation for pulmonary embolism (PE) given the combination of nocturnal cough, tachycardia (HR 127), and a chest X-ray that excludes common alternative diagnoses. 1, 2

Why Pulmonary Embolism Must Be Ruled Out First

The clinical presentation is concerning for PE based on several key features:

• Tachycardia (HR 127) is present in 26% of PE cases and represents a minor Framingham criterion for heart failure, but more importantly, it's a common sign of PE 3, 2
• Nocturnal cough occurs in 20% of PE cases and is also a minor Framingham criterion for heart failure 3, 2
• The chest X-ray showing no infiltrate, effusion, or gross failure does NOT exclude PE - in fact, a normal or near-normal chest X-ray in a patient with acute dyspnea and tachycardia should heighten suspicion for PE 1, 2
• Up to 40% of PE patients have normal oxygen saturation, so lack of documented hypoxemia doesn't rule it out 2

Immediate Next Steps

Assess clinical probability for PE using a validated scoring system (Wells or Geneva score) and obtain D-dimer if low-to-intermediate probability. 1

• If D-dimer is negative in low-to-intermediate probability patients, PE is excluded and no further imaging is needed 1
• If D-dimer is positive OR clinical probability is high, proceed directly to CT pulmonary angiography (CTPA) within 24 hours 1
• Do not obtain D-dimer in high-probability patients - they should go straight to CTPA 1

Alternative Diagnoses to Consider Simultaneously

Heart Failure with Preserved Ejection Fraction (HFpEF)

The combination of nocturnal cough and tachycardia >120 bpm meets Framingham minor criteria for heart failure, but requires additional evaluation:

• Obtain BNP or NT-proBNP levels - ambulatory patients need BNP >35 pg/mL or NT-proBNP >125 pg/mL to support HFpEF diagnosis 3
• Order echocardiography to assess for structural/functional cardiac abnormalities and measure ejection fraction 3
• The absence of pleural effusion on chest X-ray makes heart failure less likely but doesn't exclude it, as pericardial effusion (which forms with elevated right-sided pressures) can occur without pleural effusion 4

Acute Bronchitis

This diagnosis is less likely given the clinical context, but can be considered if:

• The patient lacks all four findings that suggest pneumonia: heart rate >100 bpm (this patient HAS tachycardia), respiratory rate >24 breaths/min, temperature >38°C, and focal consolidation on exam 3
• Since this patient already has tachycardia >100 bpm, acute bronchitis is less probable 3
• If acute bronchitis is diagnosed, do NOT prescribe antibiotics routinely - they are ineffective for this predominantly viral illness 3

Cardiac Arrhythmia-Triggered Cough

• Cough can be directly caused by cardiac arrhythmias, particularly in the presence of tachycardia 5
• This is rare but underrecognized, and the cough typically resolves with successful arrhythmia treatment 5
• Obtain a 12-lead ECG to evaluate for arrhythmias, especially given the heart rate of 127 5

Diagnostic Algorithm Summary

1. Immediately assess hemodynamic stability - check blood pressure, respiratory rate, oxygen saturation 1, 2

2. Calculate PE clinical probability using Wells or Geneva score 1

   • Low/intermediate probability → obtain D-dimer
   • High probability → proceed directly to CTPA
   • Positive D-dimer → proceed to CTPA

3. Obtain 12-lead ECG to evaluate for:

   • Arrhythmias that could explain tachycardia and trigger cough 5
   • Signs of right ventricular strain (S1Q3T3 pattern, T-wave inversions in V1-V4, right bundle branch block) suggesting PE 2

4. Obtain BNP/NT-proBNP and order echocardiography if PE is excluded and heart failure remains in the differential 3

5. If all cardiac and PE workup is negative, consider acute bronchitis but remember this patient has tachycardia which makes pneumonia more likely than simple bronchitis 3

Critical Pitfalls to Avoid

• Do not dismiss PE based on normal chest X-ray alone - chest X-ray is rarely diagnostic for PE and its main value is excluding alternative diagnoses 1, 2
• Do not assume normal oxygen saturation rules out PE - up to 40% of PE patients have normal arterial oxygen saturation 2
• Do not delay CTPA in hemodynamically stable patients with high clinical probability - imaging should occur within 24 hours 1
• Do not prescribe antibiotics empirically for presumed bronchitis without first excluding more serious diagnoses like PE and heart failure 3
• Do not rely on the absence of dyspnea to exclude serious pathology - some patients with PE present primarily with cough rather than dyspnea 2