What is the preliminary diagnosis for a patient with a 12-hour history of pleuritic chest pain radiating to the left shoulder and neck, recent viral illness, temperature of 99°F, tachycardia (heart rate 112 beats per minute), oxygen saturation at 97% on room air, and a pericardial friction rub, who uses contraceptives and vapes nicotine?

Preliminary Diagnosis: Acute Pericarditis

The preliminary diagnosis is acute pericarditis, based on the presence of pleuritic chest pain radiating to the left shoulder and neck, recent viral illness, and a pericardial friction rub on examination. 1, 2, 3

Diagnostic Criteria Met

This patient fulfills at least 2 of the 4 required diagnostic criteria for acute pericarditis 4, 5:

• Characteristic pleuritic chest pain that worsens with deep breaths and radiates to the left shoulder and neck (present in approximately 90% of cases) 3, 4
• Pericardial friction rub - the grating sound at the left sternal border that is louder on inhalation is pathognomonic for pericardial inflammation 2, 3
• Recent viral illness (cold symptoms) provides the typical viral prodrome seen before acute pericarditis 3, 5

Key Clinical Features Supporting This Diagnosis

Pain characteristics:

• Sharp, pleuritic quality that worsens with inspiration is characteristic of pericarditis and makes ischemic heart disease unlikely 3
• Radiation to the left shoulder and neck is typical for pericarditis, though the European Heart Society notes this pattern can also occur with myopericarditis 2

Physical examination findings:

• The pericardial friction rub is highly specific for pericardial inflammation when present, though it only occurs in 18-84% of cases and can be transient 4, 6
• The friction rub is best heard at the left lower sternal border with the patient sitting upright and leaning forward 2, 6
• Tachycardia (HR 112) is common with acute pericarditis due to pain and inflammation 1

Vital signs:

• Low-grade fever (99°F) supports acute inflammation 1
• Normal oxygen saturation (97%) helps exclude pulmonary embolism and pneumothorax 3
• Absence of lower extremity edema makes heart failure and deep vein thrombosis less likely 1

Important Differential Considerations

Myopericarditis must be excluded:

• The presence of left arm pain raises concern for myocardial involvement, as this is more typical of acute coronary syndromes 2
• Up to 50% of acute pericarditis cases have elevated troponin indicating myopericarditis, which does not predict worse outcomes when left ventricular function is preserved 7, 3
• The European Heart Journal notes that myopericarditis can present with chest pain having features of both pericarditis and myocardial ischemia 2

Risk factors requiring consideration:

• Oral contraceptive use combined with nicotine vaping increases thrombotic risk, making pulmonary embolism a consideration 1
• However, the presence of a pericardial friction rub and pleuritic pain pattern strongly favor pericarditis over PE 1

Immediate Diagnostic Workup Required

Essential immediate studies (to be performed within 10 minutes) 3:

• 12-lead ECG - look for widespread saddle-shaped ST elevation with PR segment depression, which is pathognomonic for pericarditis 3, 4
• Cardiac troponin - elevated in up to 50% of pericarditis cases, indicating myopericarditis 7, 3
• Inflammatory markers (CRP, ESR, WBC) - typically elevated in acute pericarditis 7
• Chest radiograph - to evaluate for cardiomegaly suggesting large effusion and rule out other intrathoracic causes 2

Urgent transthoracic echocardiography should be performed in all patients with suspected pericarditis to detect pericardial effusion (present in only 60% of cases) and evaluate for cardiac tamponade 2, 3, 4

Critical Pitfalls to Avoid

• Do not assume normal echocardiogram excludes pericarditis - pericardial effusion is only present in 60% of acute pericarditis cases 3, 4
• Do not dismiss the diagnosis if friction rub disappears - it is transient and can disappear and reappear during the course of disease 2, 6
• Do not withhold fibrinolysis consideration without confirming pericarditis - it is critical to consider pericarditis in every patient in whom fibrinolysis is considered for presumed STEMI 1
• Do not ignore elevated troponin - this indicates myopericarditis and requires hospital admission for monitoring 7, 3

Risk Stratification for Admission

This patient requires hospital admission if any of the following are present 2:

• Elevated troponin (indicating myopericarditis)
• Fever >100.4°F (38°C) - this patient has 99°F, borderline
• Large pericardial effusion or any signs of tamponade
• Hemodynamic instability
• Failure to respond to NSAIDs within 7 days

Cardiac MRI with gadolinium contrast is the most sensitive study (94-100% sensitivity) for confirming myocardial and pericardial inflammation and should be considered if myopericarditis is suspected based on troponin elevation or atypical features like prominent left arm pain 2, 7