When should an echocardiogram be ordered for a heart murmur?

When to Order an Echocardiogram for a Heart Murmur

Echocardiography should be ordered immediately for any diastolic murmur, continuous murmur (except venous hums and mammary souffles), holosystolic murmur, late systolic murmur, grade 3 or louder systolic murmur, or any murmur accompanied by symptoms, regardless of intensity. 1

Absolute Indications for Echocardiography (Class I Recommendations)

Based on Murmur Characteristics Alone

All diastolic murmurs require echocardiography because they are virtually always pathologic, regardless of grade or intensity. 1, 2

Continuous murmurs require echocardiography (except innocent venous hums in children and mammary souffles during pregnancy), as they suggest patent ductus arteriosus or other shunt lesions. 1, 2

Holosystolic (pansystolic) murmurs require echocardiography as they indicate mitral regurgitation, tricuspid regurgitation, or ventricular septal defect. 1, 3

Late systolic murmurs require echocardiography because they suggest mitral valve prolapse with regurgitation. 1, 3

Grade 3 or louder midsystolic murmurs require echocardiography due to higher likelihood of organic heart disease. 1, 2

Murmurs with ejection clicks require echocardiography as they indicate bicuspid aortic valve or pulmonary stenosis. 1, 2

Murmurs radiating to the neck or back require echocardiography because they suggest aortic stenosis or coarctation. 1, 2

Based on Associated Clinical Features

Any murmur with symptoms requires immediate echocardiography, including: 1, 3

• Syncope (suggests severe aortic stenosis or hypertrophic cardiomyopathy)
• Chest pain or angina (indicates hemodynamically significant valve disease)
• Heart failure symptoms (dyspnea, orthopnea, edema)
• Thromboembolism (raises concern for atrial fibrillation or endocarditis)
• Signs of infective endocarditis (fever, new murmur, embolic phenomena)

Murmurs with abnormal cardiac physical findings require echocardiography, including: 1, 4

• Abnormal S2 (widely split, paradoxically split, or single)
• S3 or S4 gallop
• Displaced or hyperdynamic apical impulse
• Abnormal peripheral pulses

Based on Dynamic Auscultation Findings

Echocardiography is indicated when murmurs demonstrate specific dynamic responses: 1

• Increased intensity with Valsalva maneuver (suggests hypertrophic cardiomyopathy or mitral valve prolapse)
• Louder when standing from squatting position (suggests hypertrophic cardiomyopathy or mitral valve prolapse)
• Increased intensity during sustained handgrip exercise (suggests mitral regurgitation or ventricular septal defect)
• No increase after premature ventricular contraction or long R-R interval in atrial fibrillation (suggests mitral regurgitation or ventricular septal defect)

Reasonable Indications for Echocardiography (Class IIa Recommendations)

Echocardiography can be useful for murmurs associated with abnormal ECG findings, such as ventricular hypertrophy, atrial enlargement, or prior infarction. 1, 4

Echocardiography can be useful for murmurs associated with abnormal chest X-ray findings, such as cardiomegaly or abnormal pulmonary vascularity. 1, 4

Echocardiography can be useful when symptoms are likely noncardiac but a cardiac basis cannot be excluded by standard evaluation. 1

When Echocardiography is NOT Recommended (Class III)

Echocardiography is not recommended for grade 2 or softer midsystolic murmurs identified as innocent by an experienced observer in asymptomatic patients with completely normal physical examination findings. 1, 4

Characteristics of Innocent Murmurs That Do Not Require Echocardiography

An innocent murmur can be confidently diagnosed without echocardiography when ALL of the following are present: 1

• Grade 1-2 intensity at the left sternal border
• Systolic ejection pattern (midsystolic, crescendo-decrescendo)
• Normal intensity and splitting of S2
• No other abnormal cardiac sounds (no clicks, gallops, or abnormal S2)
• No symptoms
• No evidence of ventricular hypertrophy or dilatation
• No increase with Valsalva maneuver or standing from squatting
• Common in high-output states (anemia, pregnancy, fever, hyperthyroidism)

Critical Pitfalls to Avoid

Never dismiss an ejection systolic murmur in a patient with exertional syncope as "innocent" - this combination requires immediate echocardiography until structural heart disease is excluded. 2

Do not rely on murmur intensity alone - even grade 2/6 holosystolic murmurs can represent severe chronic mitral regurgitation. 3

Recognize that severe aortic stenosis can be misjudged when left ventricular ejection fraction is severely reduced, as the murmur may be softer than expected. 2

Be aware that trivial valvular regurgitation may be detected by echocardiography in many normal patients with no audible murmur - interpret echo findings in clinical context. 1, 2

Combined valvular lesions (especially aortic and mitral disease) are commonly missed on clinical examination, with sensitivity only 55% for detecting combined lesions. 2

Role of ECG and Chest X-Ray

Routine ECG and chest radiography are not recommended for asymptomatic patients with isolated grade 2 or softer midsystolic murmurs at the left sternal border, as they rarely change management and add unnecessary cost. 1, 4

However, if ECG or chest X-ray have already been obtained and show abnormalities, echocardiography should be performed. 1, 4

Emergency Indications

In emergency settings, echocardiography is recommended for new murmurs with: 1

• Symptoms or signs of heart failure
• Myocardial ischemia/infarction
• Syncope
• Thromboembolism
• Infective endocarditis
• Clinical evidence of structural heart disease