What ECG abnormality is associated with methadone use?

Methadone use is notably associated with QT interval prolongation on an electrocardiogram (ECG). This prolongation can lead to an increased risk of serious arrhythmias, such as Torsades de Pointes, which can be life-threatening. Methadone, a long-acting opioid agonist commonly used for pain management and as a part of drug addiction detoxification programs, has effects on cardiac repolarization due to its influence on ion channels, particularly potassium channels responsible for repolarizing the heart during the cardiac cycle.

QT interval prolongation indicates that the time it takes for the heart's electrical recharging process after each heartbeat is extended, which can lead to instability in the heart's rhythm. Therefore, monitoring of the QT interval in patients receiving methadone treatment is critical to prevent potential cardiac complications. This characteristic makes option B the correct answer.

In contrast, other choices do not specifically correlate with the effects of methadone. DR interval prolongation, PR interval shortening, and ST segment elevation are not typical ECG changes directly associated with methadone use. Each of these abnormalities may be linked to different physiological or pharmacological effects not related to methadone exposure.