Which musculoskeletal strain, such as an intercostal or pectoral muscle pull, can mimic chest pain, and does nitroglycerin (nitro) relieve this type of pain?

Musculoskeletal Chest Pain Mimicking Cardiac Pain

Intercostal muscle strain, pectoral muscle strain, and costochondritis are the most common musculoskeletal conditions that mimic cardiac chest pain, but nitroglycerin does NOT reliably distinguish between them—relief with nitro is NOT diagnostic of cardiac ischemia and should not be used as a diagnostic criterion. 1

Which Muscle Strains Mimic Cardiac Pain

The following musculoskeletal conditions commonly present with chest pain that can be confused with angina:

Primary Musculoskeletal Causes

• Intercostal muscle strain - affects the muscles between the ribs 2
• Pectoral muscle strain - involves the chest wall muscles 3
• Costochondritis - inflammation of rib cartilages (accounts for ~42% of nontraumatic musculoskeletal chest wall pain) 4
• Cervical spine disorders - cervical radiculopathy can radiate to the chest and left arm, closely mimicking myocardial infarction 5
• Intercostal myofascial injury - trauma to connective tissues between ribs 6

Key Distinguishing Features

Characteristics Suggesting MUSCULOSKELETAL Origin (NOT Cardiac):

• Sharp, stabbing pain (rather than pressure/squeezing) 1, 7
• Pain reproduced by palpation or movement of chest wall or arms 8
• Positional pain - changes with body position 1, 9
• Pleuritic pain - increases with inspiration 1, 7
• Point tenderness - can be localized with one finger 8, 10
• Duration - either very brief (<5 seconds) or prolonged (>30 minutes) 10
• Pain increases with trunk or arm movement 10

Characteristics Suggesting CARDIAC Origin:

• Substernal pressure/squeezing that builds gradually over minutes 1
• Exertional trigger - precipitated by physical or emotional stress 1
• Radiation to left arm, jaw, neck, or back 1
• Associated symptoms - dyspnea, diaphoresis, nausea, lightheadedness 1, 7

The Nitroglycerin Myth: Critical Clinical Pitfall

Relief of chest pain with nitroglycerin is NOT predictive of cardiac origin and should NOT be used diagnostically. This is explicitly stated in the 2021 AHA/ACC Guidelines 1, 9.

Evidence Against Using Nitro as a Diagnostic Test:

The highest quality research demonstrates:

• Nitroglycerin relieved pain in only 35% of patients WITH documented acute coronary syndrome 8
• Nitroglycerin relieved pain in 41% of patients WITHOUT cardiac disease 8
• The positive likelihood ratio for coronary disease when nitro relieves pain is only 1.1 (essentially no diagnostic value) 11
• Sensitivity: 72%, Specificity: only 37% for cardiac chest pain 11

Why Nitro Can Relieve Non-Cardiac Pain:

• Esophageal spasm responds to nitroglycerin (smooth muscle relaxation) 1, 10
• Cervical root compression pain can be relieved by nitro 10
• Nitro causes vasodilation of all smooth muscle, not just coronary arteries 12

Clinical Approach Algorithm

Step 1: Characterize the Pain

• Quality: Pressure/squeezing vs. sharp/stabbing
• Duration: Gradual build (minutes) vs. sudden or fleeting
• Location: Diffuse substernal vs. point tenderness
• Triggers: Exertion/stress vs. movement/position

Step 2: Physical Examination

• Palpate chest wall - reproducible pain suggests musculoskeletal 8
• Test range of motion - pain with arm/trunk movement suggests musculoskeletal 10
• Assess for point tenderness - localizable pain less likely cardiac 8

Step 3: Risk Stratification (NOT Nitro Response)

Use objective criteria:

• ECG findings (ST changes, T-wave abnormalities) 8
• Cardiac biomarkers (troponin) 8
• Cardiovascular risk factors 1
• Age, sex, diabetes status 1, 7

Step 4: Do NOT Rely on Nitro Response

• If pain relieved by nitro: Still requires full cardiac workup if clinical suspicion exists 1, 11, 13
• If pain NOT relieved by nitro: Does NOT rule out cardiac disease 8

Common Clinical Pitfalls to Avoid

1. Assuming nitro relief = cardiac origin - This is FALSE 1, 11, 13
2. Assuming nitro failure = non-cardiac - Also FALSE 8
3. Using "atypical" terminology - Use "cardiac," "possibly cardiac," or "noncardiac" instead 7
4. Dismissing reproducible chest wall tenderness - While suggestive of musculoskeletal origin, 7% of patients with reproducible pain still had acute coronary syndrome 8

Special Populations

Women

• More likely to present with accompanying symptoms (nausea, fatigue, dyspnea) rather than classic substernal pressure 1, 7
• At risk for underdiagnosis - maintain high index of suspicion 9

Elderly (>75 years)

• May present with atypical symptoms: dyspnea, syncope, delirium, unexplained falls 9
• Higher likelihood of underlying coronary disease 8

Diabetics

• More likely to have atypical presentations 1, 7
• May have vague abdominal symptoms or throat discomfort 9

Bottom Line for Clinical Practice

When evaluating chest pain, focus on pain characteristics, physical examination findings, ECG, and cardiac biomarkers—NOT nitroglycerin response. Musculoskeletal causes (intercostal strain, pectoral strain, costochondritis) are distinguished by reproducible tenderness, positional changes, and sharp quality, but these features do not absolutely exclude cardiac disease. The 2021 AHA/ACC Guidelines explicitly state that relief with nitroglycerin should not be used as a diagnostic criterion because other entities (esophageal spasm, musculoskeletal pain) demonstrate comparable responses 1, 9.