Testing considerations for all patients at risk of SCD

    • tests indicated in all patients at risk for SCD
      • electrocardiography (ECG)
        • resting ECG
        • ambulatory ECG for detection and diagnosis of arrhythmias
        • signal-averaged ECG to improve diagnosis of arrhythmogenic right ventricular dysplasia (ARVD)
        • cardiac event recorders to determine if transient arrhythmias are cause of sporadic symptoms 
        • implantable loop recorders to establish cause of sporadic symptoms (such as syncope) if rhythm-­symptom correlation not identified using conventional diagnostic techniques and if arrhythmia relation suspected 
      • transthoracic echocardiography (TTE) for assessment of left ventricular (LV) function and detection of structural heart disease
        • tests to consider for all patients at risk for SCD, if TTE uninformative of left ventricular function
          • cardiac magnetic resonance imaging (cMRI)
          • cardiac computed tomography (CT)
    • consider coronary angiography to identify or rule out significant obstructive coronary artery disease (CAD) in
      • patients with life-threatening ventricular arrhythmias
      • SCD survivors with moderate-to-high risk of CAD according to age and symptoms
    • general findings associated with increased risk in some patient populations
      • decreased left ventricular ejection fraction (LVEF)
      • ECG findings
        • prolonged QRS interval
        • prolonged QT interval
        • presence of QT dispersion
        • abnormal signal-averaged ECG
        • low-frequency short-term heart rate variability (HRV)
    • abnormal long-term ambulatory ECG (Holter monitoring)
      • nonsustained ventricular tachycardia
      • long-term HRV
      • heart rate turbulence
    • abnormal exercise test/functional status
      • exercise capacity
      • New York Heart Association (NYHA) functional class
      • heart rate recovery
      • recovery ventricular ectopy
      • T-wave alternans
    • baroreceptor sensitivity (BARS)

    Prevention and treatment 

    • primordial prevention
      • preventing development of risk factors for cardiovascular disease
      • may include lifestyle interventions to optimize
        • blood pressure
        • weight
        • glucose
        • physical activity
    • primary prevention—prevention in patients who are at risk for but have not yet experienced episodes of sustained ventricular tachycardia, ventricular fibrillation, or resuscitated cardiac arrest
      • implantable cardioverter defibrillator recommended for primary prevention of SCD in selected patients with nonischemic dilated cardiomyopathy or ischemic heart disease if all of
        • ≥40 days postmyocardial infarction
        • left ventricular ejection fraction (LVEF)
          • ≤35% if New York Heart Association (NYHA) Class II or III symptoms on chronic guideline-directed medical therapy
          • ≤30% if NYHA Class I symptoms on chronic guideline-directed medical therapy
        • reasonable expectation of meaningful survival for >1 year
      • beta blockers recommended, unless contraindicated, for patients with
        • coronary artery disease and heart failure or prior myocardial infarction with
          • left ventricular ejection fraction ≤40%
          • normal left ventricular function
        • asymptomatic heart failure with reduced ejection fraction with or without history of myocardial infarction or acute coronary syndrome
        • symptomatic heart failure with reduced ejection fraction to reduce mortality
      • angiotensin-converting enzyme (ACE) inhibitors recommended, unless contraindicated, for patients with atherosclerotic cardiovascular disease and any of
        • left ventricular ejection fraction ≤40%
        • hypertension
        • diabetes
        • chronic kidney disease
      • angiotensin II receptor blockers (ARBs) recommended for patients intolerant of ACE inhibitors
      • aldosterone blockade recommended for
        • postmyocardial infarction patients with all of
          • heart failure and/or diabetes
          • already receiving therapeutic doses of ACE inhibitor plus beta blocker
          • left ventricular ejection fraction ≤40%
          • no significant renal dysfunction
          • no hyperkalemia
        • patients with NYHA Class III and IV heart failure and left ventricular ejection fraction ≤35%
        • patients with NYHA Class II heart failure and history of prior cardiovascular hospitalization or increased plasma natriuretic peptide levels and left ventricular ejection fraction ≤35%
      • statins indicated for virtually all patients with known cardiovascular disease
      • antiarrhythmic medications, such as amiodarone, generally not recommended
      • antihypertensive medications: do not reduce sudden cardiac death but may reduce fatal myocardial infarction
    • secondary prevention—prevention in patients who have survived prior sustained ventricular tachycardia or cardiac arrest
    • implantable cardioverter defibrillator (ICD) therapy indicated in patients with
      • history of cardiac arrest due to ventricular fibrillation or hemodynamically unstable ventricular tachycardia, after evaluation to exclude reversible causes
        • structural heart disease and spontaneous sustained ventricular tachycardia
        • syncope of undetermined origin and clinically relevant sustained ventricular tachycardia or ventricular fibrillation induced at electrophysiologic study
      • addition of amiodarone to implantable cardiac defibrillator may increase mortality in patients with previous cardiac arrest or syncope due to ventricular tachycardia/ventricular fibrillation


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    Dr Drabkin is a senior clinical writer for DynaMed, a database of comprehensive updated summaries covering more than 3,200 clinical topics, and assistant clinical professor of population medicine at Harvard Medical School.