What is the best course of action for a patient with acute left-sided pain that began 3 days ago, worsens with turning and lifting arms, and has no known past medical history or demographic factors?

Evaluation and Management of Acute Left-Sided Pain with Movement-Related Symptoms

This presentation is most consistent with musculoskeletal chest wall pain, but cardiac causes must be excluded first given the potential for life-threatening disease.

Immediate Cardiac Risk Assessment Required

While the clinical features favor a musculoskeletal etiology, you must obtain a 12-lead ECG within 10 minutes of presentation to exclude acute coronary syndrome (ACS), as the American Heart Association mandates this for any chest/thoracic pain presentation 1, 2. The absence of classic cardiac features does not eliminate risk:

• Pain with arm lifting can mimic radiation to the arm, a high-risk ACS feature 2
• Left-sided location overlaps with cardiac pain distribution 1, 3
• Obtain immediate cardiac troponin and repeat at 3-6 hours if initial value is negative, as a single measurement is insufficient to exclude myocardial injury 1, 2

Critical pitfall to avoid: The American College of Cardiology warns against relying on pain characteristics alone to determine urgency, as pain severity and quality are poor predictors of cardiac events 3. Even with completely normal peripheral pulses and physical examination, STEMI or NSTE-ACS remains possible 3.

High-Risk Features That Would Mandate Cardiac Protocol

If ANY of the following are present, activate ACS protocol immediately 1, 3:

• ST-segment elevation, depression, or new left bundle branch block on ECG 1, 2
• Elevated troponin levels 1, 2
• Pain duration >20 minutes at rest 2, 3
• Associated diaphoresis, nausea, dyspnea, or lightheadedness 1, 3
• Hemodynamic instability 1, 3

Musculoskeletal Pain Diagnosis

If cardiac workup is negative (non-ischemic ECG and two negative troponins at least 6 hours apart), the clinical presentation strongly suggests musculoskeletal chest wall pain 1, 4:

• Pain reproducible with specific movements (turning, arm lifting) is the hallmark of musculoskeletal origin 2, 4
• Three-day duration with positional triggers without systemic symptoms supports this diagnosis 4, 5
• Patient history is the single most valuable diagnostic source for musculoskeletal disorders 4

Physical examination findings to confirm musculoskeletal etiology 4, 5:

• Palpate the chest wall, ribs, and intercostal spaces for point tenderness
• Reproduce pain with specific movements or palpation
• Assess for costochondral junction tenderness (costochondritis)
• Evaluate for muscle spasm or trigger points

Management Algorithm

Once cardiac causes are excluded:

1. Pain control with NSAIDs as first-line therapy for musculoskeletal pain 6
2. Activity modification - avoid movements that provoke pain initially, then gradual return to normal activity 7, 5
3. Local heat application may provide symptomatic relief 6
4. Reassurance that symptoms are self-limited, as 90% of acute musculoskeletal pain resolves within one month 7

Do not over-evaluate or over-treat once serious causes are excluded, as this yields inferior clinical outcomes and wastes resources 7.

Red Flags Requiring Further Evaluation

Beyond cardiac causes, assess for 8:

• Aortic dissection: Check blood pressure in both arms; pulse differential suggests dissection, though its absence does not exclude it 8, 3
• Pulmonary embolism: Assess for dyspnea, tachycardia, pleuritic pain 3
• Intra-abdominal pathology: If pain is truly in the left lower quadrant rather than chest wall, consider diverticulitis in older patients with fever and leukocytosis 8

The key clinical decision point is whether the ECG and serial troponins are normal - if yes, treat as musculoskeletal pain with conservative management and close outpatient follow-up 1, 2.