cardiac arrest

Etiology

• ventricular fibrillation, primary or secondary to disorders below
• coronary artery disease (CAD)
  • most common cause of cardiac arrest
  • cardiac arrest is the initial manifestation in 20-25% of patients with CAD
  • chronic ischemia with or without underlying myocardial scarring
  • myocardial infarction:
    • 20% of out-of-hospital cardiac arrests are associated with myocardial infarction (MI)
    • attribute cardiac arrest to MI only if large, trans- mural or Q-wave infarction
  • within 48 hours of acute Q-wave MI
• left ventricular hypertrophy
• obstructive hypertrophic cardiomyopathy
• congestive heart failure
• prolonged QT interval
  • congenital (long QT syndrome)
  • drug-induced
    • antiarrhythmics
    • psychotropics
• Wolf-Parkinson-White syndrome
• Brugada syndrome
• commotio cordis
• toxic, metabolic or electrolyte disturbances
  • alcohol
  • illicit drugs
• proarrhythmic agents
  • ecainide
  • flecainide
• pulmonary embolism
• vigorous exercise heightens risk of cardiac arrest (see sudden death in competitive sports)

Epidemiology

• 300,000/year in the US
• 1/3 of survivors die within 1 year

Pathology

• cardiac ischemia
• reperfusion injury
• heart failure
• metabolic abnormalities
• cardiogenic shock

Clinical manifestations

• prodomal symptoms occur in 50% of patients within 4 weeks of cardiac arrest
  • may occur months prior to cardiac arrest
  • chest pain
  • palpitations
  • dyspnea
  • fatigue
  • lightheadedness
• signs of cardiac arrest
  • unresponsiveness
  • no pulse
  • apnea or agonal respirations
  • pallor or cyanosis
• gasping during CPR after cardiac arrest is associated with increased 1-year survival with good neurologic outcome
  • do NOT terminate chest compressions prematurely

Laboratory

• arterial blood gas (ABG)
  • hypoxia
  • acidosis
• electrolytes
  • hypokalemia or hyperkalemia
  • hypomagnesemia
• drug levels
• addition of long QT syndrome genotyping to autopsy identifies probable cause of death in 13% of young people with sudden cardiac death
• serum neurofilament light chain at 24 hours after cardiac arrest predicts long-term poor neurologic outcome
• other genetic testing ?

Diagnostic procedures

• electrocardiogram
  • ventricular tachycardia (VT) or ventricular fibrillation (VF)
  • pulseless electrical activity (PEA)
  • asystole
• echocardiogram
  • structural heart disease
  • LV dysfunction
  • cardiomyopathy
• electrophysiology study
  • indications
    • survivors of sudden cardiac death
    • suspected ventricular arrhythmias
    • syncope
    • structural heart disease
  • see management (follow-up)
• coronary angiography
  • no difference in survival between immediate vs delayed coronary angiography without ST-segment elevation

Complications

• pulmonary aspiration & aspiration pneumonia resulting from cardiopulmonary resuscitation, especially bag-mask ventilation & endotracheal intubation
• neurologic impairment in survivors of cardiac arrest generally does not affect ability to live independently
• return of spontaneous circulation in out-pf-hospital cardiac arrest lower during the COVID-19 pandemic

• disease interaction(s) of HIV1 infection with cardiac arrest

Differential diagnosis

• aspiration of a foreign body 'cafe coronary'
• vasovagal syncope
• seizure

Management

• basic life support
  • early & effective bystander CPR is the goal for witnessed out-of-hospital cardiac arrests
  • cardiopulmonary resuscitation at the site of cardiac arrest with better ourcomes than immediate transport & resuscitation attempts on the way to the hospital
• defibrillation
• electrocardiography to identify cardiac arrhythmia
• defibrillation for ventricular fibrillation & other shockable rhythms prior to epinephrine
• public access defibrillators for out-of-hospital cardiac arrest
• a prearrest protocol is proposed for at-home use of fully automated external defibrillators reducimg arrest-to-shock interval to < 1 minute
  • defibrillator placed upon initial symptoms of acute coronary syndrome the defirillator senses & delivers shock autonomously if appropriate
• advanced cardiac life support (see ACLS)
  • combined vasopressin-epinephrine & methylprednisolone during CPR & stress-dose hydrocortisone in postresuscitation shock may improve survival to hospital discharge with favorable neurological status
  • vasopressin + methylprednisolone increases likelihood of return to spontaneous circulation in patients with in-hospital cardiac arrest
  • epinephrine every 3 to 5 minutes (guideline)
  • intervals shorter than 3 minutes may increase odds of survival with favorable neurologic outcome
  • epinephrine for out-of-hospital cardiac arrest
  • may be of no benefit
  • early epinephrine associated with better survival outcomes in adults with shockable & nonshockable out-of-hospital cardiac arrest
  • other ACLS medications: amiodarone ...
  • see ventricular fibrillation for persistent or recurrent VF/VT (i.e. 2nd shock)
  • of no benefit for out-of-hospital cardiac arrest
  • intravenous or intraosseous infusion of calcium no better than saline for sustained return of spontaneous circulation
• ventilation & oxygen for out-of-hospital cardiac arrest
  • bag mask ventilation vs endotracheal intubation
    • results of comparison inconclusive
  • laryngeal tube insertion vs endotracheal intubation
    • 72-hour survival 18.3% vs 15.4%
  • oxygen saturation target of 98%-100% better than or equal to target of 90%-94% in out-of-hospital resuscitation for cardiac arrest
• targetted temperature management
  • standard of care for patients who remain unconscious after cardiac arrest (MKSAP, NEJM)
  • mild induced hypothermia may (or may not) improve outcomes
  • targetted temperature of 33 C no better than 36 C or 37.5 C
  • may benefit patients with non-shockable rhythms
  • targetted temperature management = prevention of hyperthermia
  • targetted temperature management for at least 12 hours in patients who remain unconcious after out-of-hospital cardiac arrest from ventricular arrhythmia
  • may improve neurologic outcomes, survival
  • no difference in neurologic outcome or mortality 33 C vs 37.5 C
  • hypothermia does not improve mortality vs normothermia
  • 48 hours vs 24 hours of induced hypothermia not associated with better neurologic outcomes
  • prophylactic antibiotics prevents pneumonia with hypothermia after cardiac arrest but does not effect mortality, duration of mechanical ventilation, or length of intensive care stay
  • no benefit in neurological outcomes or mortality for maintenance of mild hypothermia for out-of-hospital cardiac arrest
  • hypothermia does not improve survival or function after out-of-hospital cardiac arrest with initial nonshockable rhythm
• prognosis:
  • see cardiopulmonary resuscitation
  • mortality, brain damage, & nursing home admission at 1 year lower if bystanders had jumped in to help in out-of-hospital cardiac arrest
• follow-up
  • stabilization of cardiac rhythm & hemodynamics
  • diagnose & treat underlying etiology
  • within 48 hours of acute Q-wave MI
  • prognosis is good
  • standard post-MI management
  • cardiac arrest not associated with acute MI
  • coronary angiography
    • no difference in survival between immediate vs delayed coronary angiography without ST-segment elevation
  • echocardiography
  • electrophysiologic testing
  • inducible VT or VF
    • antiarrhythmics if suppress VT/VF
    • automatic implantable cardioverter defibrillator (AICD)*
    • empiric amiodarone
      • 600 mg TID for 9 days, then
      • 400 mg QD
    • sotalol 160 mg BID
  • non-inducible VT or VF
    • AICD if left ventricular dysfunction (LVEF < 40%)
    • patient may only need treatment of reversible causes of cardiac arrest
  • electrophysiologic testing generally not required for reversible causes of cardiac arrest
  • 50% recurrence of ventricular tachycardia within 2 years
  • indications for AICD*
  • cardiac arrest without a reversible cause
    • includes cardiac arrest without an identifiable cause
  • hemodynamically significant, inducible, sustained VT/VF
  • MI with LVEF < 40% & inducible VT/VF
  • non-sustained VT, cardiomyopathy, LVEF 35%
  • high-risk hypertrophic cardiomyopathy
  • for patients receiving AICD after cardiac arrest
  • all-cause mortality: 22%
  • hospitalization: 65%
    • heart-failure hospitalization: 19%
  • skilled nursing facility admission: 22%
  • patients > 80 years have higher risks
• prevention
  • do not smoke
  • maintain BMI > 25 kg/m2
  • exercise at least 30 minutes/day
  • adhere to Mediterranean diet
  • screen for family history of sudden cardiac death
  • one 1st degree relative or >= 2 2nd degree relatives
  • assess left ventricular function if positive history
  • for patients hospitalized with high-risk cardiovascular conditions (MI, heart failure), refer family members to CPR & automated external defibrillator education
  • implantable cardioverter-defibrillator for patients with heart failure & LVEF < 35% expected to survive > 1 year
  • effective for prevention of sudden cardiac death
  • ACE inhibitor or ARB for patients with heart failure & reduced LVEF (LV systolic dysfunction)

* treatment of choice

* cardiac magnetic resonance imaging helpfuk to assess myocardial infiltration prior to ICD pacement

More general terms

• heart disease (cardiac disease)

Additional terms

• cardiopulmonary resuscitation (CPR)
• sudden death in competitive sports