What is the management approach for abnormal electrocardiograms (ECGs)?

Management of Abnormal ECGs

All abnormal ECG findings require systematic evaluation with echocardiography as the initial diagnostic test, followed by risk-stratified additional testing based on the specific abnormality identified. 1

Initial Risk Stratification

Abnormal ECGs predict significantly worse outcomes and mandate immediate evaluation rather than observation alone. The presence of any ECG abnormality increases risk of serious cardiac events, with specific patterns carrying different prognostic implications 1:

• ST-segment elevation or depression indicating acute ischemia: 54.2% risk of myocardial infarction—requires immediate hospital admission and consideration for emergent reperfusion therapy 2, 3
• Nonspecific ST-T wave changes: 14.6% risk of MI—warrants inpatient evaluation with serial troponins and continuous monitoring 2
• Bundle branch blocks or conduction abnormalities without clear ischemia: 3.6% risk of MI but associated with increased heart failure hospitalization risk 2, 4
• Normal ECG with chest pain: 1.3% risk of MI—may be evaluated as outpatient based on cardiac risk profile 2

Specific ECG Abnormalities and Required Workup

T-Wave Inversions

T-wave inversion ≥1 mm in depth in two or more contiguous leads (excluding aVR, III, V1) is definitively abnormal and requires comprehensive cardiac evaluation. 1, 5

Mandatory initial testing:

• Echocardiography to exclude hypertrophic cardiomyopathy, dilated cardiomyopathy, left ventricular noncompaction, and arrhythmogenic right ventricular cardiomyopathy 1
• 24-48 hour ambulatory ECG monitoring 1
• Cardiac biomarkers (troponin) to exclude acute myocardial injury 5

If echocardiography is non-diagnostic but clinical suspicion remains high:

• Cardiac MRI with gadolinium to detect subtle myocardial abnormalities, fibrosis, or edema 1, 5
• Exercise ECG testing 1

Critical exception: T-wave inversions in V1-V4 preceded by J-point/ST-segment elevation in Black athletes are normal variants and do not require further workup 1. However, lateral lead (I, aVL, V5-V6) T-wave inversions are abnormal even in Black athletes 5.

Pathological Q Waves

Q waves with Q/R ratio ≥0.25 or ≥40 ms duration in two or more contiguous leads (except III and aVR) require evaluation for cardiomyopathy or prior myocardial infarction. 1

Required evaluation:

• Repeat ECG with careful lead placement to exclude technical error 1
• Echocardiography to exclude cardiomyopathy 1
• In patients ≥30 years with coronary risk factors: stress testing to evaluate for coronary artery disease 1
• If echocardiography is normal but high clinical suspicion: cardiac MRI 1

Conduction Abnormalities

Complete left bundle branch block:

• Echocardiography (mandatory) 1
• Cardiac MRI with perfusion study (mandatory) 1

Profound nonspecific intraventricular conduction delay (QRS ≥140 ms):

• Echocardiography to evaluate for myocardial disease 1
• Additional testing based on echocardiographic findings 1

Advanced second-degree or third-degree AV block:

• Echocardiography 1
• Minimum 24-hour ECG monitoring 1
• Exercise ECG testing 1
• Laboratory screening and cardiac MRI based on echocardiography findings 1

Ventricular Arrhythmias

Multiple premature ventricular contractions, couplets, triplets, or nonsustained ventricular tachycardia require comprehensive evaluation for myocardial disease. 1

Mandatory testing:

• Echocardiography 1
• Cardiac MRI (especially if >2,000 PVCs or nonsustained VT present) 1
• 24-hour ECG monitoring 1
• Exercise ECG testing 1
• Consider signal-averaged ECG 1

Ventricular Pre-excitation (Wolff-Parkinson-White Pattern)

Required evaluation:

• Exercise ECG test to assess for abrupt cessation of delta wave (indicates low-risk pathway) 1
• If low-risk pathway cannot be confirmed non-invasively: electrophysiology study for risk assessment 1
• Consider EP study for moderate to high-intensity sports participation 1

Prolonged QTc

QTc ≥500 ms warrants direct referral to heart rhythm specialist or sports cardiologist. 1

Initial evaluation:

• Repeat resting ECG on separate day 1
• Exercise ECG testing 1
• Laboratory screening (electrolytes) 1
• Family screening with ECGs of first-degree relatives 1
• Genetic testing when clinical suspicion is high 1

Brugada Type 1 Pattern

Immediate referral to cardiologist or heart rhythm specialist is required. 1

Additional evaluation:

• High precordial lead ECG with V1-V2 in second intercostal space 1
• Sodium channel blockade if Brugada pattern is indeterminate 1
• Genetic testing and family screening 1

Profound Bradycardia or First-Degree AV Block

Profound sinus bradycardia <30 bpm or first-degree AV block ≥400 ms:

• Repeat ECG after mild aerobic activity 1
• Additional testing based on clinical suspicion 1

Athletes with Abnormal ECGs

Temporary restriction from athletic activity should be implemented until secondary investigations are completed for any abnormal ECG finding. 1

Two or more borderline ECG findings together warrant:

• Echocardiography 1
• Additional testing based on clinical suspicion 1

Long-term surveillance is critical: Markedly abnormal ECGs in young athletes may represent initial expression of cardiomyopathy that becomes evident only after many years, with 6% developing overt cardiomyopathy during 9-year follow-up 6. Serial clinical, ECG, and echocardiographic monitoring every 1-2 years is essential even when initial comprehensive evaluation is normal 1, 5, 6.

Patients with Known or Suspected Cardiac Disease

Repeat ECG is mandatory for any change in clinical status: 1

• Syncope or near-syncope 1
• New or worsening dyspnea 1
• Change in anginal pattern 1
• Palpitations 1
• Extreme unexplained fatigue or weakness 1

For patients with known cardiovascular disease, serial ECGs every 1-2 years are recommended for ongoing monitoring, with more frequent testing if symptoms change. 1

Critical Pitfalls to Avoid

Do not dismiss minor T-wave changes (<2 mm) as benign—while they have unclear significance, they are rare in healthy individuals (<0.5%) yet common in cardiomyopathy, suggesting potential pathological basis 5. These warrant at minimum echocardiography and consideration for serial monitoring.

Do not rely solely on initial negative workup—T-wave abnormalities and other ECG changes may represent initial phenotypic expression of cardiomyopathy before structural changes become detectable on imaging 5, 6. Serial monitoring is essential.

Emergency physicians miss clinically significant ECG abnormalities in 17.5% of cases (25 of 143 abnormal ECGs), most commonly anterior wall ischemia/infarct and atrial fibrillation 7. When uncertainty exists, obtain cardiology consultation rather than discharging based solely on emergency department interpretation.