When should I order a B-type natriuretic peptide (BNP) and a troponin level?

From the Guidelines

BNP and troponin tests should be ordered in patients with suspected acute coronary syndrome or heart failure, as they provide valuable diagnostic and prognostic information. When evaluating patients with symptoms suggestive of heart failure, such as shortness of breath, fatigue, and edema, a BNP test should be ordered, as elevated levels indicate cardiac strain and help distinguish between cardiac and non-cardiac causes of dyspnea 1. Troponin should be ordered when acute coronary syndrome or myocardial injury is suspected, particularly in patients presenting with chest pain, pressure, or discomfort that might indicate a heart attack, with serial measurements (typically at presentation, 3 hours, and sometimes 6 hours) necessary to detect rising or falling patterns indicative of acute myocardial injury 1. Some key points to consider when ordering these tests include:

• BNP levels above 100 pg/mL suggest heart failure, while troponin elevations above the 99th percentile upper reference limit indicate myocardial injury 1
• Both tests can be ordered simultaneously in emergency settings when patients present with symptoms that could indicate either heart failure or acute coronary syndrome, such as shortness of breath with chest discomfort 1
• Natriuretic peptides, such as BNP, provide prognostic information regarding the risk of death, acute heart failure, and the development of atrial fibrillation, in addition to cardiac troponin 1
• The pretest probability is important, and the result must be interpreted in the clinical context, with the test not needed if the clinical scenario is strongly suggestive of heart failure or points towards an alternative diagnosis 1

From the Research

Ordering BNP and Troponin Tests

When to order BNP and troponin tests is a crucial decision in the diagnosis and management of patients with suspected acute coronary syndrome (ACS) or heart failure. The following points summarize the key findings from relevant studies:

• BNP levels are elevated in patients with acute myocardial infarction (AMI) and have prognostic value 2, 3, 4.
• Troponin levels are regarded as markers of choice for the diagnosis of AMI, but BNP levels can provide additional prognostic information 2, 3.
• The combination of BNP and troponin tests can improve the sensitivity and negative predictive value for acute myocardial infarction, acute coronary syndrome, and 30-day adverse events 5.
• BNP testing can be helpful in establishing the diagnosis of ACS in patients presenting with chest pain, but its role in determining treatment has not yet been defined 4.
• The diagnostic accuracy of baseline troponin and troponin change for the diagnosis of myocardial infarction complicated with heart failure is influenced by the severity of heart failure 6.

Clinical Scenarios for Ordering BNP and Troponin Tests

The following clinical scenarios may warrant ordering BNP and troponin tests:

• Patients presenting with chest pain and suspected ACS 3, 5, 4.
• Patients with known heart failure and suspected acute myocardial infarction 2, 6.
• Patients with elevated troponin levels and suspected heart failure 2, 3.
• Patients with acute coronary syndrome and suspected heart failure 3, 4.

Key Considerations

When ordering BNP and troponin tests, the following key considerations should be taken into account:

• The clinical context and suspected diagnosis 2, 3, 5, 4, 6.
• The severity of heart failure, if present 6.
• The potential impact of BNP and troponin levels on treatment decisions 4.
• The need for additional testing and evaluation to confirm the diagnosis and guide management 2, 3, 5, 4, 6.