INTERCHEST Clinical Prediction Rule for Chest Pain in Primary Care

INTERCHEST Calculator

History of Coronary Artery Disease

Known Clinical Vascular Disease

Female ≥65 or Male ≥55 Years

Pain Worse with Exercise

Pain Not Reproducible by Palpation

Patient Believes Pain Is Cardiac

INTERCHEST Score: 0

Low Risk

Score 0: Low probability of ischemic chest pain. Consider non-cardiac etiologies.

Rules out coronary artery disease (CAD) in primary care patients with chest pain.

Why Use

Only ~1.5% of patients seen in primary care for chest pain have unstable CAD ( Cayley 2005 , Klinkman 1994 ); the most common causes of chest pain in primary care are chest wall pain, gastrointestinal disease, and stable heart disease. Helps determine which outpatients with chest pain are at sufficiently low risk of unstable CAD to allow for further follow-up; testing and management to be done on a non-urgent outpatient basis (scores ≤1) or on an urgent or inpatient basis (scores ≥2). Better at predicting presence of CAD (higher PPV) than the Marburg Heart Score , but has been less well studied (see Evidence for details).

When to Use

Patients ≥30 years old presenting with chest pain in a primary care setting. Should not be used in patients with a readily apparent cause of chest pain (e.g. trauma, infection), clear anginal equivalent symptoms (e.g. jaw pain, dyspnea on exertion, arm pain), or if other testing (e.g. electrocardiography, lab testing) has suggested a clearly cardiac etiology.

Formula

Addition of the selected points: Variable Points History of CAD 1 Female ≥65 years or male ≥55 years 1 Chest pain related to effort 1 Pain reproducible by palpation -1 Physician initially suspected a serious condition 1 Chest discomfort feels like “pressure” 1

Pearls / Pitfalls

Not to be used for a positive diagnosis of angina or CAD, but as a negative tool to help assess who is low-enough risk to not need further evaluation. While scores ≤1 make unstable CAD highly unlikely ( NPV 98%), scores ≥2 are only modestly predictive of CAD ( PPV 43%). Most applicable to patients 30 years or older.

Management

For any primary care patient with chest pain, clinical stability can quickly be determined by evaluating the ABCs (airway, breathing, and circulation). A patient who shows no signs of respiratory distress and has appropriate vital signs is unlikely to be acutely unstable and can be further evaluated the office with appropriately targeted history, physical examination, and testing. If there is a readily apparent cause of chest pain other than CAD (e.g. trauma, infection), attention should be directed to these causes. If there are clearly anginal equivalent symptoms (e.g. jaw pain, dyspnea on exertion, arm pain), or if there are ischemic changes on the ECG, then the INTERCHEST score does not apply and urgent inpatient admission is warranted. A patient with undiagnosed chest pain and a low risk INTERCHEST score (≤1) can have further testing, including chest x-ray and stress testing, electively as an outpatient. A patient with a higher risk INTERCHEST score (≥2) does not necessarily have unstable CAD, but since unstable CAD cannot be excluded if the INTERCHEST score is ≥3, such patients generally warrant more urgent evaluation or inpatient admission.

Critical Actions

No decision rule should trump clinical gestalt, and any patient with chest pain who is clinically unstable (respiratory distress or abnormal vital signs) warrants urgent or emergency inpatient admission.

Advice

When evaluating patients with chest pain in primary care, INTERCHEST scores ≤1 mean the chest pain is highly unlikely to be due to unstable CAD (NPV 98%), and further outpatient evaluation is generally safe and appropriate. A primary care patient with an INTERCHEST score of ≤1 generally does not need urgent evaluation of chest pain (unless there is clear evidence of clinical instability), and further evaluation may be done through non-urgent outpatient follow up. A primary care patient with an INTERCHEST score ≥2 does not necessarily have unstable CAD, but should have further testing done more urgently.

More Information

Interpretation: Score CAD risk Probability of CAD ≤1 Low 2.1% 2-5 Not low 43.0% From Aerts 2017 .