What tests are indicated for a patient with an S4 (fourth heart sound)?

From the Guidelines

If a patient has an S4 heart sound, I would order an electrocardiogram (ECG), echocardiogram, cardiac biomarkers (troponin, BNP), and comprehensive metabolic panel. The ECG helps identify left ventricular hypertrophy, ischemia, or arrhythmias that may cause diastolic dysfunction 1. An echocardiogram provides direct visualization of cardiac structure and function, particularly assessing ventricular compliance and filling pressures 1. Cardiac biomarkers help evaluate for myocardial injury (troponin) or heart failure (BNP/NT-proBNP) 1. A comprehensive metabolic panel assesses electrolyte abnormalities and renal function that might contribute to cardiac dysfunction 1. These tests are crucial because an S4 gallop typically indicates decreased ventricular compliance during late diastole, often due to conditions like hypertension, coronary artery disease, aortic stenosis, or hypertrophic cardiomyopathy 1. Additional testing might include stress testing or cardiac catheterization depending on the initial results and clinical suspicion 1. The goal is to identify the underlying cause of the decreased ventricular compliance that's producing the S4 sound, as this will guide appropriate treatment.

Some key points to consider when evaluating a patient with an S4 heart sound include:

• The presence of symptoms such as chest pain, shortness of breath, or palpitations
• The patient's medical history, including any previous cardiac conditions or procedures
• The results of the ECG, echocardiogram, and cardiac biomarkers
• The presence of any electrolyte abnormalities or renal dysfunction
• The need for additional testing, such as stress testing or cardiac catheterization, to further evaluate the patient's condition.

It's also important to note that the evaluation and management of a patient with an S4 heart sound should be individualized based on the patient's specific clinical presentation and medical history.

From the Research

Indications for Testing with an S4

The presence of an S4, or fourth heart sound, can be an indicator of various cardiac conditions. The following tests may be indicated for a patient with an S4:

• Echocardiography and Doppler studies to assess left ventricular diastolic function 2
• Electrocardiogram (ECG) to diagnose acute myocardial ischemia, although it may not be diagnostic in all cases 3
• Computerized acoustic cardiography to measure diastolic heart sounds, including S3 and S4 3
• Transthoracic phonocardiograms and Doppler A waves to characterize S4 production 4
• Hilbert-Huang Transform (HHT) analysis of heart sound signals to detect the presence of S3 and S4 5

Relationship Between S4 and Cardiac Conditions

The S4 is thought to be related to cardiohemic vibrations powered by deceleration of transmitral blood flow, and its presence can be an indicator of:

• Myocardial ischemia 3
• Left ventricular diastolic dysfunction, although its sensitivity and specificity are limited 2
• Decreased ventricular distensibility 6
• Atrial systolic transmitral flow deceleration 4

Diagnostic Considerations

When interpreting the results of these tests, it is essential to consider the following:

• The S4 can be present in normal individuals, particularly the elderly 2
• The S4 can be absent in individuals with severe diastolic dysfunction 2
• The combination of diastolic heart sounds with standard ECG may improve the noninvasive diagnosis of myocardial ischemia 3, 5