**Question:** In the ECG shown below which drug is not to be given?

A. Amiodarone
B. Beta-blockers
C. Calcium channel blockers
D. Digoxin

**Core Concept:** Understanding the ECG changes induced by different medications is crucial in clinical practice, particularly when prescribing medications to patients with cardiac disorders. The provided ECG represents a patient on beta-blockers.

**Why the Correct Answer is Right:** Amiodarone is a class III antiarrhythmic drug that causes QT interval prolongation, which can lead to an increased risk of life-threatening torsades de pointes arrhythmias.

**Why Each Wrong Option is Incorrect:**

1. Beta-blockers (A): These drugs, particularly when used in the presence of pre-existing bradycardia or heart block, can lead to profound bradycardia and even asystole, causing a significant risk of cardiac arrest.
2. Calcium channel blockers (C): These drugs are primarily used for hypertension management and angina, not directly affecting the ECG. QT interval prolongation can occur as a side effect, but it is less severe compared to amiodarone.
3. Digoxin (D): While digoxin may cause ECG changes like QT prolongation, it does not lead to the significant prolongation of the T wave and U wave as seen in the ECG and is typically used for heart failure management.

**Why each wrong option is incorrect:**

1. Beta-blockers (A): These drugs, particularly when used in the presence of pre-existing bradycardia or heart block, can lead to profound bradycardia and even asystole, causing a significant risk of cardiac arrest.
2. Calcium channel blockers (C): These drugs are primarily used for hypertension management and angina, not directly affecting the ECG. QT interval prolongation can occur as a side effect, but it is less severe compared to amiodarone.
3. Digoxin (D): While digoxin may cause ECG changes like QT prolongation, it does not lead to the significant prolongation of the T wave and U wave as seen in the ECG and is typically used for heart failure management.

**Clinical Pearl:** When prescribing medications, it is essential to consider the potential cardiac side effects and their ECG manifestations. A thorough assessment of the patient's medical history, co-morbidities, and potential drug interactions is crucial when prescribing medications. In this case, the ECG changes seen in the provided ECG suggest using amiodarone, a class III antiarrhythmic agent, which is indicated for treating life-threatening arrhythmias like atrial fibrillation, ventricular arrhythmias, and supraventricular tachycardias.

**Correct Answer: C** (Calcium channel blockers)

**Clinical Pearl:** When prescribing medications, it is essential to consider the potential cardiac side effects and their ECG manifestations. A thorough assessment of the patient's medical history, comorbidities, and potential