Sudden Cardiac Death


Article Author:
Allison Yow
Venkat Rajasurya


Article Editor:
Sandeep Sharma


Editors In Chief:
Kranthi Sitammagari
Mayank Singhal


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Kyle Blair
Trevor Nezwek
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Abbey Smiley
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Daniyal Ameen
Altif Muneeb
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes
Komal Shaheen
Sandeep Sekhon


Updated:
7/30/2019 3:36:50 PM

Introduction

Sudden cardiac death (SCD) is death due to a cardiovascular cause that occurs within one hour of the onset of symptoms. A sudden cardiac arrest occurs when the heart stops beating or is not beating sufficiently to maintain perfusion and life. 

Etiology

Coronary artery disease is the most common cause of sudden cardiac death, accounting for up to 80% of all cases. Cardiomyopathies and genetic channelopathies account for the remaining causes. The most common causes of non-ischemic sudden cardiac death are cardiomyopathy related to obesity, alcoholism, and fibrosis. 

In patients younger than 35, the most common cause of sudden cardiac death is a fatal arrhythmia, usually in the context of a structurally normal heart. In patients from birth to 13 years, the primary cause is a congenital abnormality. In patients aged 14 to 24 years, the cause of sudden cardiac death is attributed to hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular cardiomyopathy (ARVC), congenital coronary anomalies, genetic channelopathies, myocarditis, Wolff-Parkinson-White syndrome, and Marfan syndrome. 

Common Causes of Sudden Cardiac Arrest[1][2][3]

Ischemic Heart disease

  • Myocardial infarction
  • Anomalous coronary origin
  • coronary spasm

Inherited Channelopathies 

  • Long QT syndrome (LQTS)
  • Short QT syndrome (SQTS)
  • Brugada syndrome
  • Early repolarization syndrome
  • Catecholaminergic polymorphic ventricular tachycardia (CPVT)

Cardiomyopathies

  • Alcoholic
  • Hypertrophic
  • Idiopathic
  • Obesity-related
  • Fibrotic
  • Arrhythmogenic right ventricular cardiomyopathy (ARVC)
  • Myocarditis

Heart Failure

  • Nonpreserved  ejection fraction (EF) systolic heart failure (EF less than 35%)

Valve disease

  • Aortic stenosis

Congenital diseases

  • Tetraology of Fallot

Epidemiology

Each year, approximately 0.1% of the United States population experiences a medical services-assessed, out-of-hospital cardiac arrest. European studies have a similar incidence ranging from 0.04% to 0.1% of the population. The median age in the US is between age 66 and 68. Males are more likely to suffer from sudden cardiac arrest. 

While rare, sudden cardiac death is the leading cause of nontraumatic cause of death among young athletes. In the general population, sports-related, sudden death from any cause is 0.5 to 2.1 per 100,000 yearly. Sports-related, sudden deaths are higher in elite athletes with an incidence of 1:8,253 per year per the National Collegiate Athletic Association (NCAA). NCAA Division I male basketball players have a 1:5200 incidence of sudden death. 

A circadian peak of sudden cardiac death occurs between 6 am and noon, and a smaller peak occurs in the late afternoon. The overall incidence of sudden cardiac death is higher on Mondays. [1]

Pathophysiology

After a myocardial infarction, the risk of sudden cardiac death is highest during the first months due to fatal tachyarrhythmias, re-infarction, or myocardial rupture. [2]

Ventricular fibrillation (VF) and ventricular tachycardia (VT) were initially thought to be the most common causes of out-of-hospital cardiac arrest. More recent studies show pulseless, electrical activity (PEA) and asystole as more frequent. Approximately 50% of patients initially have asystole, and 19% to 23% have PEA as the first identifiable rhythm. 

Immediately following OHCA the blood flow to the brain slows to essentially zero and ultimately leading to death.

History and Physical

Some patients experience palpitations, dizziness, or near syncope prior to sudden cardiac arrest. Almost half of the patients who have sudden cardiac arrests report no symptoms prior to collapse. 

The American Heart Association recommends cardiovascular screening for high school and collegiate athletes. This includes an evaluation of the athlete's personal and family history and a physical exam. [4] Screening should follow the AHA guidelines:

Personal History

  1. Chest pain/discomfort/tightness/pressure related to exertion
  2. Unexplained syncope or near syncope
  3. Excessive exertional and unexplained dyspnea/fatigue or palpitations, associated with exercise
  4. Prior recognition of a heart murmur
  5. Elevated systemic blood pressure
  6. Prior restriction from participation in sports
  7. Prior testing for the heart, ordered by a physician

Family History

  1. Premature death (sudden and unexpected) before age 50 attributed to heart disease in > 1 relative
  2. Disability from heart disease in close relative less than age 50
  3. Hypertrophic or dilated cardiomyopathy, long-QT syndrome, or other ion channelopathies, Marfan syndrome, or clinically significant arrhythmia specific knowledge of certain cardiac conditions in family members

Physical Examination

  1. Heart murmur should be evaluated with the patient both supine and standing or with Valsalva
  2. Femoral pulses to exclude aortic coarctation
  3. Physical stigmata of Marfan syndrome
  4. Brachial artery blood pressure (sitting position), prefer both arms

Routine ECG testing is not recommended for student-athletes. Students found to have an abnormal exam or those with a positive personal or family history may be referred for cardiac testing including ECG and echocardiogram.

Sudden cardiac arrest patients may demonstrate brief myoclonic or seizure-like activity.

Evaluation

Before transportation to a hospital, emergency medical services (EMS) or lay people may utilize an automated external defibrillator (AED). Once EMS arrives cardiac monitoring via ECG should occur. 

Full cardiac assessment is required for cardiac arrest survivors. The following tests should be completed to establish a cause [2]:

  • ECG
  • Echocardiogram
  • Coronary angiography
  • Exercise test
  • Electrophysiology testing
  • Cardiac MRI
  • Genetic testing if ARVC, Brugada syndrome, CPVT, or LQTS are found
  • Cardiac biopsy may be considered if no other cause is found

ECG testing helps determine a diagnosis of ischemic heart disease, myocardial infarction, and inherited channelopathies. Echocardiograms evaluate for evidence of heart failure, cardiomyopathy, valvular heart disease, and congenital heart disease. Coronary angiography further evaluates coronary artery disease, congenital coronary anomalies, and coronary spasms. Exercise testing is helpful for diagnosis of ischemic heart disease, LQTS, and CPVT. Electrophysiology studies can detect the suspected arrhythmia. Procainamide can provoke Brugada syndrome regardless of the findings on the initial ECG. Cardiac MRI can detect ARVC, sarcoidosis (fibrotic cardiomyopathy), myocarditis, and myocardial injury from coronary spasms. 

Treatment / Management

Treatment for sudden cardiac arrest should be initiated immediately by lay people and EMS. Treatment includes the use of an automated external defibrillator and cardiopulmonary resuscitation (CPR). CPR provides enough oxygen to the brain until a stable electrical rhythm can be established.  

After transfer to a hospital, therapeutic hypothermia can be induced to limit neurologic injury and reperfusion injuries. Therapeutic hypothermia is more effective for the management of ventricular tachycardia and ventricular fibrillation but can also be used in PEA and asystole. Limitations to therapeutic hypothermia include a tympanic membrane temperature below 30 degrees at presentation, being comatose before the sudden cardiac arrest, pregnancy, inherited coagulation disorder, and the terminally ill patient. 

If a patient survives the out-of-hospital cardiac arrest, long-term treatment is aimed at the underlying cause.

An implantable cardioverter defibrillator (ICD) is used for secondary prevention of sudden cardiac death in any person who has experienced arrhythmia-related syncope or survived sudden cardiac arrest. 

Medication is targeted at the underlying cause of sudden cardiac arrest.

Prognosis

The overall out-of-hospital survival for sudden cardiac arrest is around 7%. 

Enhancing Healthcare Team Outcomes

To reduce the risk of sudden death, healthcare workers should educate the family members of young sudden cardiac death victims that they may also be at an increased risk for ischemic heart disease and ventricular arrhythmias. First-degree relatives, particularly those younger than 35, should be screened. If cardiomyopathy or a genetic channelopathy is present, the evaluation of other family members should also occur. For the most part, the evaluation should be done by a cardiologist or an internist.


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Sudden Cardiac Death - Questions

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What is the most common disease associated with sudden cardiac death?



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Which condition requires further inquiry prior to sport participation?



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What is the most common rhythm found during a sudden cardiac arrest?



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A 62-year-old male with a positive past medical history for DM, HTN, CKD stage 3 and COPD comes in with left-sided chest pain and shortness of breath for the past 2 hours. The pain is pressure like and is radiating to the jaw. Physical examination is positive for tachycardia, otherwise negative — Vitals, BP 160/45, Respiratory rate 32/min, Pulse 110/min, and afebrile. Labs show mild leukocytosis and elevated cardiac enzymes. EKG shows ST-segment elevation in lateral leads. STEMI alert is called, and the patient undergoes cardiac catheterization. He got 2 stents in LAD and was started on appropriate medical treatment. After 3 days he is discharged home and was told to follow up with the primary care physician. Two weeks later he undergoes sudden cardiac arrest and dies. What is the likely cause of patients sudden cardiac death?



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A 65-year-old male with a past medical history of diabetes, hypertension, dyslipidemia who lives a sedentary lifestyle was brought to the emergency department after he was found unresponsive at home by his son. The patient had exertional dyspnea prior to the event and when emergency medical services arrived, he was found unresponsive in his bathroom. He was in full cardiac arrest and advanced cardiac life support (ACLS) protocol was initiated. The patient was intubated in the field and received 3 rounds of epinephrine with ongoing chest compressions when he arrived in the emergency department. In the emergency department, the patient had pulseless electrical activity (PEA) on the monitor. After 50 minutes of unsuccessful resuscitation, the patient was pronounced dead. What is the most common disease associated with this sudden death?



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A 17-year-old athlete presents for a regular wellness visit. He has no past medical history. He does not take any medications on a regular basis. He denies any complaints. His BMI is 25 kg/m2. He has started preparing for a marathon that will take place in 6 months. He plans on joining an intense marathon preparation program to improve his endurance. On physical examination, his vital signs are normal. Which condition requires further inquiry prior to sport participation?



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A 17-year-old student who suddenly collapsed while playing soccer was brought to the emergency department by emergency medical services. On arrival, he had no pulse and was in full cardiac arrest with an ongoing cardiopulmonary resuscitation (CPR). He has no past medical history according to his family member. He is intubated in the emergency department where good quality CPR is being monitored by waveform capnography. The patient is connected to the cardiac monitor. What is the most common rhythm that will be found in this condition?

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Sudden Cardiac Death - References

References

The spectrum of epidemiology underlying sudden cardiac death., Hayashi M,Shimizu W,Albert CM,, Circulation research, 2015 Jun 5     [PubMed]
The inter-association task force for preventing sudden death in secondary school athletics programs: best-practices recommendations., Casa DJ,Almquist J,Anderson SA,Baker L,Bergeron MF,Biagioli B,Boden B,Brenner JS,Carroll M,Colgate B,Cooper L,Courson R,Csillan D,Demartini JK,Drezner JA,Erickson T,Ferrara MS,Fleck SJ,Franks R,Guskiewicz KM,Holcomb WR,Huggins RA,Lopez RM,Mayer T,McHenry P,Mihalik JP,O'Connor FG,Pagnotta KD,Pryor RR,Reynolds J,Stearns RL,Valentine V,, Journal of athletic training, 2013 Jul-Aug     [PubMed]
A Clinical Perspective on Sudden Cardiac Death., Katritsis DG,Gersh BJ,Camm AJ,, Arrhythmia & electrophysiology review, 2016     [PubMed]
Inherited arrhythmias: The cardiac channelopathies., Behere SP,Weindling SN,, Annals of pediatric cardiology, 2015 Sep-Dec     [PubMed]

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