What is the most appropriate diagnostic test for a patient with fever, fatigue, cough with hemoptysis, and a new heart murmur, with a history of intravenous (IV) drug use?

Transoesophageal Echocardiography (TEE) is the Most Appropriate Diagnostic Test

The most appropriate diagnostic test for this patient is transoesophageal echocardiography (TEE) as it provides the highest sensitivity for detecting vegetations and complications of infective endocarditis in this high-risk patient with clinical features strongly suggestive of endocarditis with septic emboli.

Clinical Presentation Analysis

This 45-year-old male presents with classic features of infective endocarditis:

• Fever for one week (temperature 102.2°F)
• Fatigue
• Hemoptysis (blood-tinged sputum)
• New holosystolic murmur at the lower left sternal border
• History of intravenous drug use (major risk factor)
• Tachycardia (pulse 130/min)
• Multiple small lesions across both lung fields (likely septic emboli)

Diagnostic Approach

First-Line Testing

While transthoracic echocardiography (TTE) is recommended as the first-line imaging modality in suspected infective endocarditis 1, this patient has several high-risk features that warrant proceeding directly to TEE:

1. History of IV drug use (high-risk population)
2. New murmur with fever (classic presentation)
3. Evidence of likely septic pulmonary emboli on chest radiograph
4. Clinical presentation strongly suggestive of right-sided endocarditis

Superiority of TEE in This Case

TEE is significantly more sensitive than TTE for detecting:

• Vegetations (96% vs 70% sensitivity for native valves) 1
• Abscesses and other perivalvular complications
• Right-sided endocarditis, particularly in IV drug users

The European Society of Cardiology guidelines specifically recommend TEE when there is a high clinical suspicion of IE, even with a positive TTE, to rule out local complications 1. The American Heart Association guidelines similarly recommend TEE for patients with high-risk features 1.

Diagnostic Algorithm for Suspected IE

1. Obtain blood cultures (at least 3 sets from separate venipuncture sites)

2. Assess clinical probability of IE based on:

   • Risk factors (IV drug use in this case)
   • Clinical presentation (fever, new murmur, embolic phenomena)
   • Laboratory findings

3. Proceed with imaging:

   • For high-probability cases with evidence of complications (like this patient): TEE is the preferred initial test
   • For lower-probability cases: TTE first, followed by TEE if TTE is negative or non-diagnostic

Common Pitfalls to Avoid

1. Relying solely on TTE in high-risk patients - TTE has limited sensitivity (only 70% for native valves) and may miss small vegetations or perivalvular complications
2. Delaying appropriate imaging - echocardiography should be performed expeditiously when IE is suspected
3. Failing to recognize septic pulmonary emboli - the multiple small lesions on chest radiograph in this IV drug user strongly suggest right-sided endocarditis with septic emboli

Conclusion

While blood cultures are essential in the workup of infective endocarditis, TEE represents the most appropriate next diagnostic test for this patient given the high clinical suspicion for IE with complications. TEE will provide the most definitive assessment of valve involvement, vegetation size, and potential complications, which will guide both antimicrobial therapy and potential surgical intervention decisions.