In a 70-year-old patient with chest pain that worsens on deep breathing, normal ECG, negative D-dimer, and a high-sensitivity troponin T of 13 ng/L, what is the most likely diagnosis and appropriate initial management?

Most Likely Diagnosis: Costochondritis (Musculoskeletal Chest Pain)

In this 70-year-old patient with pleuritic chest pain, normal ECG, negative D-dimer, and a high-sensitivity troponin T of 13 ng/L (below the 99th percentile threshold of ~14 ng/L for most assays), the most likely diagnosis is costochondritis or another musculoskeletal cause of chest wall pain, though acute coronary syndrome must still be formally excluded with serial troponin measurements.

Immediate Diagnostic Actions Required

• Obtain a second high-sensitivity troponin at 3–6 hours from symptom onset because a single normal troponin drawn <6 hours after pain onset may miss evolving myocardial injury, and 30–40% of acute myocardial infarctions present with normal or nondiagnostic initial ECGs. 1, 2

• Perform serial ECGs every 15–30 minutes if chest pain persists or recurs, as ischemic changes may evolve over time even when the initial ECG is normal. 1, 2

• Palpate the costochondral junctions systematically to reproduce the pain; tenderness over these joints with pain worsened by chest wall movement, deep breathing, or arm motion strongly supports costochondritis, which accounts for ~43% of chest pain presentations in primary care after cardiac causes are excluded. 3, 4

Why Acute Coronary Syndrome Is Unlikely (But Not Yet Excluded)

• Pleuritic pain that worsens with breathing is atypical for myocardial ischemia, yet approximately 13% of patients with pleuritic-type chest pain still have acute myocardial ischemia, so ACS cannot be dismissed based on pain character alone. 3, 4

• The troponin of 13 ng/L is below the diagnostic threshold (typically 14 ng/L for the 99th percentile in most high-sensitivity troponin T assays), but serial measurement is mandatory because troponin may rise over the first 6–12 hours. 2

• A normal ECG does not exclude ACS; 30–40% of acute MIs present with a normal or nondiagnostic initial ECG, and up to 5% of ACS patients have a completely normal first ECG. 1, 4, 2

Why Pulmonary Embolism Is Effectively Ruled Out

• A negative D-dimer in a patient with pleuritic chest pain makes pulmonary embolism highly unlikely (negative predictive value >95% when clinical probability is low-to-intermediate). 3

• Tachycardia is present in >90% of PE patients, and the absence of tachycardia further reduces the probability of PE. 3, 4

Why Pericarditis Is Less Likely

• Pericarditis typically presents with sharp, pleuritic pain that worsens when lying supine and improves when sitting forward, not pain that worsens specifically with breathing alone. 1, 3

• The ECG in pericarditis usually shows diffuse concave ST-elevation with PR-segment depression, which is absent in this patient. 3, 4

• A pericardial friction rub is present in many cases of acute pericarditis, and its absence makes pericarditis less likely (though not excluded). 3, 4

Algorithmic Management Pathway

Step 1: Complete ACS Rule-Out Protocol

1. Draw a second high-sensitivity troponin at 3–6 hours from the first sample (or from symptom onset if >3 hours have elapsed). 2
2. If the second troponin remains normal (<14 ng/L) and serial ECGs show no ischemic changes, acute coronary syndrome is effectively excluded. 2
3. If troponin rises above the 99th percentile or new ischemic ECG changes appear, activate emergency medical services immediately and transfer to a facility with 24/7 cardiac catheterization capability. 4, 2

Step 2: Confirm Musculoskeletal Etiology

1. Palpate all costochondral junctions bilaterally and attempt to reproduce the pain with direct pressure, chest wall movement, or full-range arm motion. 3, 4
2. If pain is reproducible with palpation and worsens with movement, the diagnosis of costochondritis is confirmed. 3, 4

Step 3: Initiate Treatment for Costochondritis

1. Prescribe ibuprofen 600–800 mg three times daily for 1–2 weeks to reduce inflammation and provide symptom relief. 3
2. Advise temporary avoidance of movements that exacerbate chest wall pain (e.g., heavy lifting, reaching overhead). 3
3. Provide reassurance that costochondritis is a benign, self-limited condition. 5, 6

Step 4: Arrange Outpatient Cardiac Risk Stratification

1. Schedule outpatient stress testing or coronary CT angiography within 72 hours because age 70 years with cardiovascular risk factors warrants objective exclusion of obstructive coronary disease, even when troponin and ECG are normal. 3, 4

Critical Pitfalls to Avoid

• Do not rely on nitroglycerin response to differentiate cardiac from musculoskeletal chest pain, as esophageal spasm and other non-cardiac conditions may also improve with nitroglycerin. 3, 4

• Do not assume that reproducible chest wall tenderness rules out ACS; up to 7% of patients with palpable tenderness still have acute coronary syndrome. 3, 4

• Do not discharge the patient based on a single normal troponin drawn <6 hours from symptom onset, as this may miss evolving myocardial injury. 2

• Do not dismiss chest pain in a 70-year-old patient based on atypical features; older adults frequently present with atypical symptoms such as isolated dyspnea, syncope, or pleuritic pain. 1, 4

Special Considerations for This Patient

• Age 70 years is a high-risk feature that mandates completion of the full ACS rule-out protocol (serial troponins, serial ECGs) before attributing pain to a benign cause. 1, 4

• Pain worsening with breathing is a classic feature of costochondritis, but it also occurs in pericarditis, pleuritis, and pulmonary embolism, so systematic exclusion of these conditions is required. 3, 5, 6

• The negative D-dimer effectively rules out pulmonary embolism in this clinical context (low-to-intermediate pre-test probability), allowing focus on cardiac and musculoskeletal etiologies. 3