What are the preventive measures and treatments for sudden cardiac death?

Sudden Cardiac Death: Prevention and Treatment

Primary Prevention Strategy

The implantable cardioverter-defibrillator (ICD) is the most effective treatment currently available for preventing sudden cardiac death, demonstrating superior efficacy compared to drug-based treatments in high-risk populations. 1

Risk Stratification and ICD Candidacy

• Left ventricular ejection fraction (LVEF) assessment is mandatory in all patients with acute myocardial infarction before discharge to identify those at highest risk for sudden cardiac death 1
• ICD implantation should be considered for patients with LVEF <35% and symptomatic heart failure, provided meaningful survival >1 year is expected with reasonable quality of life 1
• Early ICD implantation immediately after acute myocardial infarction does not improve prognosis due to competing causes of death; optimal timing is after medical therapy optimization and reassessment 1
• Wearable cardioverter-defibrillators may serve as a bridge in patients awaiting transplant or during the post-infarction period when prognosis remains uncertain 1

Medical Therapy for Primary Prevention

Beta-blockers are first-line therapy for reducing sudden cardiac death risk in patients with coronary artery disease, post-myocardial infarction, and heart failure. 2, 3, 4

• Beta-blockers reduce mortality in post-MI patients and those with congestive heart failure through antiarrhythmic and cardioprotective effects 2, 3
• In patients with heart failure and reduced ejection fraction (HFrEF), combination therapy with beta-blocker, mineralocorticoid receptor antagonist (MRA), and either ACE inhibitor, ARB, or sacubitril/valsartan reduces sudden cardiac death and all-cause mortality 2
• ACE inhibitors and ARBs should be used in patients at high risk for sudden cardiac death, particularly those with structural heart disease 2, 4
• Statins improve survival in high-risk populations through plaque stabilization and anti-inflammatory effects 4

Routine prophylactic use of Class I or III antiarrhythmic drugs is not recommended for asymptomatic ventricular arrhythmias due to lack of efficacy and potential for harm, with the possible exception of amiodarone in selected cases. 2, 3

Secondary Prevention (Post-Cardiac Arrest)

ICD implantation is the treatment of choice for patients who have survived sustained ventricular tachyarrhythmias or cardiac arrest not due to reversible causes. 1, 3

Acute Management of Cardiac Arrest

• Immediate recognition and activation of emergency medical services is critical for survival 1
• Early high-quality CPR maintains coronary and cerebral perfusion pressure >60 mmHg systolic until definitive therapy 1, 5
• Early defibrillation within minutes of ventricular fibrillation onset is lifesaving; all emergency personnel should be trained and equipped with defibrillators 1
• Automated external defibrillators (AEDs) should be widely available in public settings, with survival to hospital discharge nearly twice as high when AEDs are applied for out-of-hospital cardiac arrest 1

Management of Recurrent Ventricular Arrhythmias

For recurrent sustained ventricular tachycardia or ventricular fibrillation despite optimal medical therapy, immediate coronary angiography should be performed to assess for incomplete revascularization or recurrent ischemia. 1

• Amiodarone 150-300 mg IV bolus should be administered to acutely suppress recurrent hemodynamically significant ventricular arrhythmias 1, 6
• Beta-blockers are effective for polymorphic ventricular tachycardia due to myocardial ischemia 2
• Deep sedation may reduce episodes of ventricular tachycardia or fibrillation in electrical storm 1
• Other antiarrhythmic drugs (procainamide, propafenone, ajmaline, flecainide) are not recommended in acute coronary syndromes 1

Catheter Ablation

In patients with bundle-branch reentrant VT, catheter ablation is the preferred therapy and is usually curative. 1

• For recurrent ventricular tachycardia or fibrillation despite complete revascularization and optimal medical therapy, radiofrequency catheter ablation should be considered 1
• Early referral to specialized ablation centers is recommended for patients presenting with ventricular tachycardia or fibrillation storms 1
• Epicardial catheter ablation can be useful in patients with structural heart disease who have failed endocardial ablation 1

Special Populations and Conditions

Post-Myocardial Infarction

• Optimal revascularization and medical therapy (beta-blockers, dual antiplatelet therapy, statins) are the mainstays of sudden death prevention 1
• Early ventricular fibrillation (within 48 hours) is associated with up to five-fold increase in hospital mortality but does not automatically mandate ICD implantation without additional risk factors 1
• Programmed electrical stimulation may identify low-risk patients (those without inducible monomorphic VT) early after acute MI 1

Young Patients and Athletes

• Anomalous origin of the left coronary artery from the right or non-coronary sinus of Valsalva is a major cause of sudden cardiac death in young males during physical activity 1
• Surgical intervention (direct reimplantation or bypass grafting) is appropriate for symptomatic patients or those resuscitated from cardiac arrest 1
• Stress testing, Doppler echocardiography, and coronary angiography are indicated in young patients with exertional chest pain or syncope 1

Hypertrophic Cardiomyopathy and Structural Heart Disease

• Myocardial bridges occur in 30-50% of patients with hypertrophic cardiomyopathy and may cause sudden cardiac death 1
• Beta-blockers are first-line therapy; nitrates should be avoided as they worsen systolic narrowing 1
• Comprehensive evaluation for structural heart disease is mandatory in all patients with sustained ventricular arrhythmias 1

Critical Pitfalls to Avoid

• Do not implant ICDs within 40 days of acute myocardial infarction unless there are specific high-risk features, as early implantation does not improve survival 1
• Avoid hypokalemia and QT-prolonging drugs in patients with left ventricular hypertrophy or structural heart disease 2
• Do not use calcium channel blockers (verapamil, diltiazem) for wide-QRS tachycardia of unknown origin, especially in patients with myocardial dysfunction 7
• Monitor QTc interval during amiodarone infusion; combination with other QTc-prolonging agents (fluoroquinolones, macrolides, azoles) increases risk of torsades de pointes 6
• Amiodarone infusion rate must not exceed recommended dosing to avoid acute hepatocellular necrosis and hypotension 6
• Approximately 70% of sudden cardiac arrests occur at home where survival rates are significantly lower (12%) compared to public settings (34%); home AED placement has not been shown to improve survival 1

Community-Based Prevention

• Coordinated placement of AEDs in high-risk geographic locations (schools, organized sports arenas, fitness clubs) substantially increases the proportion of patients receiving timely defibrillation 1
• All emergency ambulances responding to cardiac patients must be equipped with defibrillators 1
• Defibrillation should be a core competence of all healthcare professionals including nurses, with devices widely available on general hospital wards 1