**Core Concept**
Recurrent sustained monomorphic ventricular tachycardia (VT) in a patient with heart failure poses a high risk of sudden cardiac death, necessitating a treatment strategy that focuses on immediate restoration of normal heart rhythm and prevention of further episodes.

**Why the Correct Answer is Right**
Intracardiac defibrillators, such as implantable cardioverter-defibrillators (ICDs), are the preferred treatment for recurrent sustained monomorphic VT in patients with heart failure. ICDs can detect life-threatening arrhythmias and deliver a shock or anti-tachycardia pacing to restore a normal heart rhythm. This approach has been shown to significantly reduce mortality in patients with heart failure and a history of VT. The effectiveness of ICDs in preventing sudden cardiac death has been demonstrated in numerous clinical trials, including the MADIT-II and SCD-HeFT studies.

**Why Each Wrong Option is Incorrect**
**Option A:** Encainide and flecainide are Class IC anti-arrhythmic medications that can be effective in treating certain types of VT, but they are not the preferred choice for recurrent sustained monomorphic VT in patients with heart failure due to their potential pro-arrhythmic effects and lack of proven mortality benefit in this population.

**Option B:** Flecainide, like encainide, is a Class IC anti-arrhythmic medication that can be effective in treating certain types of VT, but it is not the preferred choice for recurrent sustained monomorphic VT in patients with heart failure due to its potential pro-arrhythmic effects and lack of proven mortality benefit in this population.

**Option D:** Beta-blockers are an essential component of heart failure management, but they are not effective in treating recurrent sustained monomorphic VT. Beta-blockers can actually worsen VT in some cases by increasing sympathetic tone and heart rate.

**Clinical Pearl / High-Yield Fact**
In patients with heart failure and a history of VT, the presence of a sustained monomorphic VT on a 24-hour Holter monitor or an event monitor is a strong indication for ICD implantation.

**✓ Correct Answer: C. Intracardiac Defibrilator. Implantable cardioverter-defibrillator.**