Final answer:
The standard treatment for a serious arrhythmia at risk of sudden death is an implantable cardioverter-defibrillator (ICD) which continuously monitors the heart's rhythm and delivers electrical shocks if necessary.
Step-by-step explanation:
The standard treatment for any patient with a serious arrhythmia who is at risk of sudden death from cardiac arrest is an implantable cardioverter-defibrillator (ICD).
ICDs are small devices that are surgically implanted under the skin of the chest and are connected to the heart through leads. They continuously monitor the heart's rhythm and deliver electrical shocks to restore normal sinus rhythm if a life-threatening arrhythmia is detected.
ICDs are highly effective in preventing sudden cardiac death in high-risk patients with serious arrhythmias.