What are the electrocardiogram (ECG) abnormalities?

From the Guidelines

ECG abnormalities should be evaluated and managed based on the specific abnormality and clinical context, with a focus on identifying and treating underlying cardiac conditions that may be life-threatening, as recommended by the 2017 international recommendations for electrocardiographic interpretation in athletes 1.

Common ECG Abnormalities

• Arrhythmias (irregular heart rhythms)
• Conduction disorders
• Signs of cardiac damage or disease

Evaluation and Management

• Echocardiography is the most commonly used imaging technique for evaluating myocardial, valvular, and congenital heart disorders associated with ventricular arrhythmias and sudden cardiac death, as recommended by the 2015 ESC guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.
• Cardiac magnetic resonance (CMR) is useful for evaluating the structure and function of the beating heart, particularly in patients with suspected arrhythmogenic right ventricular cardiomyopathy (ARVC), as recommended by the 2017 international recommendations for electrocardiographic interpretation in athletes 1.
• Ambulatory electrocardiographic monitoring is useful for detecting ventricular tachyarrhythmias and identifying patients at risk of sudden cardiac death, as recommended by the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline for the management of hypertrophic cardiomyopathy 1.

Key Considerations

• ECG abnormalities require interpretation in clinical context, as some findings may be normal variants in certain populations while indicating serious pathology in others.
• Management depends on the specific abnormality and may include medication, device therapy, or addressing underlying causes like electrolyte imbalances or medication effects.
• The 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay recommends the use of electrocardiography, echocardiography, and ambulatory electrocardiographic monitoring for the evaluation and management of patients with conduction system disease 1.

From the Research

ECG Abnormalities in Acute Coronary Syndromes

• ECG abnormalities are a key diagnostic tool in acute coronary syndromes (ACS), which include ST-segment elevation myocardial infarction (STEMI), non-STEMI (NSTEMI), and unstable angina 2.
• The ECG can distinguish between STEMI and non-ST-segment elevation ACS (NSTE-ACS), with STEMI characterized by complete coronary artery occlusion and NSTE-ACS characterized by partial or intermittent occlusion of the artery 2.
• ECG patterns in ACS can include ST-segment elevation, ST-segment depression, T-wave inversions, and QRS complex changes, which can indicate the presence and severity of myocardial ischemia 3, 4.

Diagnostic Evaluation of ACS

• The evaluation of ACS begins with an electrocardiogram (ECG) obtained within 10 minutes of presentation, which can diagnose STEMI if ST-segment elevation is present 5.
• If STEMI is not present, troponin levels should be measured to diagnose NSTEMI, and risk stratification should be calculated using the Thrombosis in Myocardial Infarction (TIMI) or HEART score 5.
• Further evaluation to exclude coronary artery disease (CAD) can be completed during hospitalization or after discharge using exercise treadmill testing, stress echocardiography, myocardial perfusion scintigraphy, or coronary computed tomography angiography 5.

ECG Interpretation and Classification

• ECG interpretation is an essential part of the initial evaluation of patients with symptoms suspected to be related to myocardial ischemia, along with focused history and physical examination 4.
• The ECG can provide important information about the presence, extent, and severity of myocardial ischemia, and can help diagnose STEMI and NSTEMI 4.
• Up-sloping ST-segment depression with positive T waves can be a sign of regional subendocardial ischemia associated with severe obstruction of the left anterior descending coronary artery, while widespread ST-segment depression can represent diffuse subendocardial ischemia caused by severe coronary artery disease 4.

Screening for Heart Disease

• The resting electrocardiogram (ECG) has been reviewed as a screening technique for heart disease, with conventional risk factors relating to long-term risk and ECG abnormalities being better predictors of short-term risk 6.
• However, the sensitivity of the ECG for future events is too low for it to be practical as a screening tool, although ECG abnormalities can increase with age and pre-test risk 6.