Can heart murmurs be seen on an electrocardiogram (EKG)?

Heart Murmurs Cannot Be Directly Detected on EKG

Heart murmurs cannot be directly visualized or detected on an electrocardiogram (EKG). 1

Relationship Between EKG and Heart Murmurs

• EKG provides information about the heart's electrical activity but cannot directly detect the turbulent blood flow that causes murmurs 1
• While EKG cannot show murmurs, it may show secondary changes associated with conditions that cause murmurs, such as:
  • Ventricular hypertrophy
  • Atrial enlargement
  • Arrhythmias
  • Conduction abnormalities
  • Evidence of prior myocardial infarction
  • Active ischemia 1

Diagnostic Value of EKG in Murmur Evaluation

• A normal EKG in a patient with a heart murmur provides useful negative information at relatively low cost 1
• Abnormal EKG findings in a patient with a heart murmur should lead to a more extensive evaluation that includes echocardiography 1
• The absence of left ventricular hypertrophy on EKG may be reassuring in patients with suspected aortic valve sclerosis, but echocardiography is frequently necessary for definitive diagnosis 1

Limitations of EKG in Murmur Evaluation

• EKG and chest radiography rarely assist in the diagnosis of heart murmurs in children 2
• A retrospective study found that routine use of EKG in evaluating asymptomatic cardiac murmurs in children is not useful 3
• Even with abnormal EKG findings, echocardiography is still required for definitive diagnosis of the cause of a heart murmur 4

Appropriate Diagnostic Approach for Heart Murmurs

• Echocardiography with color flow and spectral Doppler evaluation is the definitive test for assessing the significance of cardiac murmurs 1
• Echocardiography is recommended for:
  • All diastolic murmurs (always pathologic)
  • Continuous murmurs
  • Holosystolic murmurs
  • Late systolic murmurs
  • Murmurs associated with ejection clicks
  • Murmurs that radiate to the neck or back 5
• Echocardiography is also recommended for patients with heart murmurs and symptoms/signs of heart failure, myocardial ischemia, syncope, thromboembolism, or infective endocarditis 5
• Grade 3 or louder midpeaking systolic murmurs in asymptomatic patients require echocardiography 5

When EKG May Be Helpful

• When murmurs are associated with abnormal cardiac physical findings, an EKG may provide additional information that guides further evaluation 5
• In patients with suspected valvular heart disease, an abnormal EKG showing ventricular hypertrophy or prior infarction should prompt echocardiographic evaluation 1
• The correlation between clinical examination (including EKG) and echocardiographic findings is generally poor, particularly for diastolic murmurs 4

Clinical Implications

• Relying solely on EKG to evaluate heart murmurs is inadequate and may miss significant cardiac pathology 6
• In adults with systolic murmurs of unknown cause, echocardiography should be performed when significant heart disease is suspected, as the cardiac examination (including EKG) has limited ability to assess the exact cause of the murmur 7
• For asymptomatic patients with grade 2 or softer midsystolic murmurs identified as innocent by an experienced clinician, neither EKG nor echocardiography is routinely recommended 1