Guidelines on Sudden Cardiac Death Prevention and Management
The cornerstone of sudden cardiac death (SCD) prevention is early identification of high-risk patients through left ventricular ejection fraction (LVEF) assessment, followed by implantable cardioverter-defibrillator (ICD) therapy for those with LVEF ≤35% and appropriate clinical criteria, combined with aggressive management of underlying cardiac disease. 1
Pre-Hospital and Emergency Response
Immediate Response System
- Minimize time from symptom onset to first medical contact and from first contact to reperfusion in patients presenting with chest pain, as this directly impacts mortality 1
- Ambulance teams must be trained and equipped with ECG recorders, telemetry capability, and defibrillation equipment to identify acute coronary syndromes and treat cardiac arrest 1
- Follow European Resuscitation Council protocols for basic and advanced life support during cardiac arrest management 1
Public Access Defibrillation
- Establish public access defibrillation at high-risk sites including schools, sports stadiums, large stations, casinos, trains, cruise ships, and airplanes where cardiac arrest is relatively common or where no other defibrillation access exists 1
- Public access defibrillation linked with cardiopulmonary resuscitation is more effective than CPR alone, particularly in locations with trained volunteers 1
Acute Coronary Syndrome Management
Revascularization Strategy
Urgent reperfusion is the primary intervention for preventing SCD in the acute setting 1:
- STEMI patients require immediate reperfusion (Class I, Level A recommendation) 1
- High-risk NSTEMI patients with life-threatening ventricular arrhythmias need coronary angiography within 2 hours of hospital admission 1
- Patients with recurrent VT or VF require prompt and complete coronary revascularization to treat underlying myocardial ischemia 1
- New-onset ischemic AV conduction disturbances, especially AV block from inferior infarction, require prompt opening of infarct vessels even with late (>12 hours) presentation 1
Post-Cardiac Arrest Care
- Comatose survivors of out-of-hospital cardiac arrest with STEMI criteria should go directly to the catheterization laboratory without ICU delay 1
- Comatose survivors without ST-elevation should be evaluated in the ICU first to exclude non-coronary causes, followed by coronary angiography within 2 hours if no obvious non-coronary cause is identified, particularly in hemodynamically unstable patients 1
- Post-resuscitation care must occur in high-volume expert centers capable of multidisciplinary intensive care, primary coronary interventions, electrophysiology, cardiac assist devices, cardiac/vascular surgery, and therapeutic hypothermia 1
Primary Prevention with ICD Therapy
Heart Failure Patients
ICD therapy is the definitive primary prevention strategy for high-risk heart failure patients 1:
- Symptomatic HF (NYHA class II or III) with LVEF ≤35% after ≥3 months of optimal medical therapy who are expected to survive at least 1 year with good functional status (Class I recommendation) 1
- Re-evaluate LVEF 6-12 weeks after myocardial infarction to assess need for primary prevention ICD implantation 1
The SCD-HeFT trial demonstrated a 23% reduction in total mortality with ICD treatment compared to placebo in heart failure patients 1. Notably, empiric amiodarone showed no survival benefit and was associated with possibly increased mortality in NYHA class III patients 1.
Cardiac Resynchronization Therapy
CRT-D (cardiac resynchronization therapy with defibrillator) is recommended for specific heart failure subgroups 1:
- NYHA class II patients in sinus rhythm with QRS ≥130 ms, LVEF ≤30%, and LBBB despite ≥3 months optimal medical therapy (Class I recommendation) 1
- NYHA class III/ambulatory class IV patients with LVEF ≤35% and LBBB despite ≥3 months optimal therapy 1:
Pharmacological Considerations
What NOT to Use
- Asymptomatic non-sustained ventricular tachycardia (NSVT) should NOT be treated with antiarrhythmic medication in heart failure patients, as there is no evidence that suppression improves prognosis 1
- No Vaughan Williams class I or III antiarrhythmic drug has demonstrated prophylactic efficacy to reduce mortality, with the possible exception of amiodarone 2
Beta-Blockers
- Beta-adrenergic blocking agents are effective pharmacologic therapy in patients following myocardial infarction and in those with congestive heart failure 2
Acute Arrhythmia Management
- Intravenous procainamide is appropriate for early conversion of stable monomorphic VT when early slowing and termination are desired 1
- Intravenous amiodarone may facilitate defibrillation and prevent VT/VF recurrences in acute situations 1
- Lidocaine is effective when VT is thought to be related to myocardial ischemia 1
Risk Stratification Beyond LVEF
While LVEF ≤35% remains the primary criterion for ICD candidacy, LVEF is neither sensitive nor specific in identifying all individuals who will benefit from ICD therapy 3. The evidence suggests that left ventricular ejection fraction measured by echocardiography or cardiac imaging is the gold standard to detect high-risk patients, but additional noninvasive techniques including T-wave alternans, signal-averaged electrocardiography, heart rate variability, and heart rate turbulence have been proposed as useful adjunctive tools 4.
Inherited Arrhythmogenic Diseases
- Avoidance of competitive sports is mandatory in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) 1
- Comprehensive toxicology analysis of blood and body fluids is essential in all victims of unexplained sudden death to identify potential toxic substances or inherited conditions 1, 5
Quality of Life Considerations
Discussion of quality-of-life issues is mandatory before ICD implant and during disease progression in all patients 1. ICD implantation affects driving ability, intimate relations, sleep quality, body image (particularly in younger women), and participation in organized sports (particularly in children and adolescents) 1.
Common Pitfalls to Avoid
- Do not delay revascularization in acute coronary syndromes - up to 6% of ACS patients develop VT or VF within the first 48 hours, most often before or during reperfusion 1
- Do not assume wide-QRS tachycardia is supraventricular - it should be presumed to be VT if the diagnosis is unclear 1
- Do not implant ICD in the immediate post-MI period - wait 6-12 weeks to reassess LVEF, as early implantation is not indicated 1
- Do not use empiric amiodarone for primary prevention in heart failure patients, as it provides no survival benefit 1
- Correct electrolyte imbalances immediately as they contribute to arrhythmogenesis 1