What is the recommended management for a patient with an abnormal 12-lead electrocardiogram (ECG) showing sinus rhythm, probable left atrial enlargement, left axis deviation, low voltage in extremity leads, and consideration of anteroseptal infarct?

Management of Abnormal ECG Findings: Sinus Rhythm, Left Atrial Enlargement, Left Axis Deviation, Low Voltage, and Possible Anteroseptal Infarct

The patient with an abnormal ECG showing sinus rhythm, probable left atrial enlargement, left axis deviation, low voltage in extremity leads, and consideration of anteroseptal infarct should undergo immediate cardiac evaluation including cardiac biomarker testing, additional ECG monitoring, and cardiac imaging to rule out acute coronary syndrome and structural heart disease. 1, 2

Initial Assessment and Risk Stratification

• The ECG findings of left axis deviation, left atrial enlargement, and possible anteroseptal infarct represent abnormal findings that require further evaluation, as they may indicate underlying cardiac pathology 1
• Low voltage in extremity leads may suggest various conditions including pericardial effusion, infiltrative cardiomyopathy, obesity, emphysema, or prior myocardial infarction 1, 3
• The consideration of anteroseptal infarct on ECG requires urgent evaluation to rule out acute coronary syndrome, as this finding may represent acute myocardial ischemia or infarction 1, 2
• The combination of these ECG abnormalities places the patient at higher risk for adverse cardiac events compared to those with normal ECGs 4, 3

Immediate Management Steps

• Obtain cardiac biomarkers (troponin) immediately and serially at 3-6 hours to evaluate for myocardial injury 1
• Perform continuous cardiac monitoring to detect dynamic ECG changes or arrhythmias 1, 2
• If the patient has chest pain or other symptoms concerning for acute coronary syndrome, administer aspirin, consider nitroglycerin for ongoing pain, and initiate other appropriate ACS therapies 1
• Compare the current ECG with previous ECGs if available, as this significantly improves diagnostic accuracy 1, 2
• If initial cardiac biomarkers are negative but clinical suspicion remains high, obtain serial ECGs at 15-30 minute intervals during the first hour, especially if symptoms recur 2

Further Diagnostic Evaluation

• Echocardiography should be performed to assess:

  • Left ventricular function and wall motion abnormalities
  • Left atrial size (to confirm left atrial enlargement)
  • Presence of structural heart disease
  • Evidence of prior myocardial infarction 1

• Consider coronary evaluation based on clinical presentation and risk factors:

  • For patients with elevated troponin or ongoing symptoms, coronary angiography is indicated 1
  • For lower-risk patients with negative biomarkers, a stress test (exercise or pharmacological) within 72 hours may be appropriate 1
  • Coronary CT angiography may be considered as an alternative to stress testing in appropriate patients 1

Specific Management Based on ECG Findings

Left Axis Deviation

• Left axis deviation is considered a "borderline" ECG finding in athletes but may indicate underlying cardiac disease in non-athletes 1
• Evaluate for left ventricular hypertrophy, conduction system disease, or prior inferior myocardial infarction 1

Left Atrial Enlargement

• Assess for underlying causes including hypertension, valvular heart disease, heart failure with preserved ejection fraction, or atrial fibrillation 1, 3
• Echocardiography is essential to confirm the presence and determine the severity of left atrial enlargement 1

Low Voltage in Extremity Leads

• Consider additional diagnostic testing for conditions associated with low voltage:
  • Chest X-ray to evaluate for pulmonary disease
  • Echocardiography to assess for pericardial effusion or infiltrative cardiomyopathy
  • Laboratory testing for thyroid disorders 1, 3

Possible Anteroseptal Infarct

• This finding requires urgent evaluation as it may represent acute myocardial injury 1, 2
• If cardiac biomarkers are elevated, manage as NSTEMI with appropriate antiplatelet therapy, anticoagulation, and consideration for early invasive strategy 1
• If biomarkers are negative but the ECG finding persists, consider cardiac MRI to differentiate between old infarct and other causes of Q waves 1, 2

Follow-up Recommendations

• For patients with negative initial evaluation but persistent ECG abnormalities:

  • Schedule follow-up with a cardiologist within 1-2 weeks 1
  • Consider ambulatory ECG monitoring (24-48 hours) to detect intermittent arrhythmias 1
  • Repeat ECG in 1-2 months to assess for dynamic changes 1

• For patients with confirmed cardiac pathology:

  • Initiate appropriate disease-specific therapy
  • Schedule regular cardiac follow-up
  • Consider implantable cardiac monitor or event recorder if symptoms suggest arrhythmias 1

Common Pitfalls to Avoid

• Do not dismiss abnormal ECG findings even if the patient is asymptomatic, as they may indicate underlying cardiac disease 4, 5
• Avoid overreliance on a single ECG; serial ECGs increase diagnostic accuracy 2, 6
• Remember that 1-4% of patients with chest pain and normal ECGs may still have acute myocardial infarction; clinical history remains crucial 6
• Do not assume all Q waves represent prior infarction, as they may be due to conduction abnormalities, cardiomyopathy, or normal variants 2
• Be aware that left axis deviation with LBBB can occasionally show intermittent right axis deviation during acute myocardial infarction 7