An abnormal electrocardiogram (ECG) indicates deviations from normal cardiac electrical conduction or myocardial activity. ECG abnormalities may reflect arrhythmias, ischemia, myocardial hypertrophy, electrolyte imbalances, conduction blocks, or prior myocardial injury.

Common findings include ST-segment changes, T-wave inversions, prolonged QT intervals, bundle branch blocks, atrial or ventricular arrhythmias, and axis deviations. While some ECG changes may be benign or transient, others signify potentially life-threatening cardiac pathology.

Importantly, an abnormal ECG is not a diagnosis but a diagnostic clue requiring further evaluation. Correlation with symptoms, clinical history, and additional investigations is essential. Diagnostic pathways may include Holter monitoring, stress testing, echocardiography, cardiac MRI, or electrophysiological studies.

Timely evaluation of abnormal ECG findings enables early intervention, risk stratification, and prevention of adverse cardiac events such as stroke, heart failure, or sudden cardiac arrest.