Cardiac Emergencies: Sudden Death - 1 Contact Hours
This course is approved through the California Board of Registered Nursing Provider #CEP 13509.
This course discusses conditions and diseases that can cause sudden cardiac death (SCD).
After completing this module, the learner will be able to:
Identify the correct definition of sudden cardiac death.
Discuss the prevalence of sudden cardiac death.
Discuss five warning signs of sudden cardiac death.
Describe risk factors and triggers for sudden cardiac death.
Identify causes of sudden cardiac death.
Sudden cardiac death (SCD) is typically defined as “an unexpected death without obvious extracardiac causes that occurs in association with a witnessed rapid collapse or within 1 h of symptom onset.” (Albert & Sauer, 2022). It is usually presumed that SCD is preceded by a cardiac arrest that was caused by sustained ventricular tachycardia (V.T.) or ventricular fibrillation (V.F.) (Podrid, 2022). However, most cases of SCD are unwitnessed, an autopsy is not done, and the cause of the SCD remains unknown (Albert & Sauer, 2022). In addition, some deaths are classified as SCD if in the preceding 24 hours the patient had been healthy (Albert & Sauer, 2022), and many non-cardiac conditions can cause SCD (Podrid, 2022), and this could complicate determining the cause of SCD.
Sudden cardiac death is a significant public health problem in the United States (Albert & Sauer, 2022; Podrid, 2022). It has been estimated that each year in the United States, there are 350,000 cases of SCD (Albert & Sauer, 2022), and information from death certificates suggests that SCD accounts for ~ 13% to 15% of the total mortality in the United States (Podrid, 2022). There is no national surveillance system or requirements for reporting SCD (Albert & Sauer, 2022). Cases of SCD may go undetected or unconfirmed, or death may be mistakenly categorized as an SCD. Given these limitations, the true incidence of SCD is unknown (Albert & Sauer, 2022).
- The incidence of SCD is lower in women (Albert & Sauer,2022).
- African Americans are more likely to have unwitnessed SCD (Albert & Sauer, 2022).
- Asian and Hispanic Americans are less likely than African Americans and white Americans to suffer SCD (Albert & Sauer, 2022).
Warning Signs of Sudden Cardiac Death
Sudden cardiac death is, by definition, sudden and unexpected, but SCD is often preceded by warning signs (Podrid, 2022). Commonly occurring warning signs of SCD are:
- Chest pain
- Exertional dyspnea
- Syncope (González et al., 2022; Podrid et al., 2022; Mellor & Behr, 2021; Tsang & Link, 2021; Wylie & Garlitski, 2021)
Some conditions like epilepsy may cause SCD, which is preceded by signs and symptoms specific to the disease. SCD can occur without warning signs and symptoms, it can occur during sleep, and in some conditions/diseases, SCD may be the first indication of the presence of a condition or illness (Han et al., 2020; O’Gara et al., 2022; Minners et al., 2020).
Risk Factors and Triggers of Sudden Cardiac Death
Some of the factors that increase the risk of SCD and factors that can trigger SCD are:
- Alcohol abuse
- Cigarette smoking
- Emotional stress
- Family history of SCD
- Obstructive sleep apnea
Binge drinking and heavy alcohol drinking increase the risk of SCD (Tu et al., 2022). Binge drinking is defined as having five or more drinks (men) or four or more drinks (women) at the same time, at least one day a month (National Institute on Alcohol Abuse and Alcoholism (N.D.). Heavy drinking is defined as > 4 drinks on any or > 14 drinks per week (men), > 3 drinks on any day, or > 7 drinks per week (women) (National Institute on Alcohol Abuse and Alcoholism (N.D.).
Cigarette smoking significantly increases the risk of SCD (Albert & Sauer, 2022; Ip et al., 2022), even in people who do not have coronary heart disease (CHD) (Albert & Sauer, 2022). In the United States, cigarette smoking is the most preventable cause of SCD (Ip et al., 2022). The risk of SCD associated with cigarette smoking can be reversed with smoking cessation (Ip et al., 2022).
The incidence of SCD in a diabetic patient is 3- to 8-fold higher than in the general population (Remme, 2022). Cardiovascular (CV) diseases are common in diabetic patients, but diabetes appears to be an independent risk factor for SCD (Remme, 2022). Lynge et al. (2020) found that in diabetic patients ages 1 to 35 (presumably many without significant cardiac disease), the presence of diabetes increased the risk of SCD by 8-fold. In the Lynge study, 26% of cases of SCD in diabetic patients in which an autopsy was performed, no evidence of cardiac disease was found (Lynge et al., 2020).
Emotional stress can cause SCD In patients with certain cardiac diseases, e.g., catecholaminergic polymorphic ventricular tachycardia and stressed-induced cardiomyopathy (Giudicessi et al., 2021; Singh et al., 2022). Sudden death is a leading cause of death in patients who have epilepsy (González et al., 2022) and accounts for approximately 2% to 18% of all deaths in epileptic patients (Suna et al., 2021).
In certain patient populations (young athletes) and patients with certain cardiac diseases like an inherited arrhythmia syndrome, SCD can happen during or after heavy exercise (Albert & Sauer, 2022; Kim & Chelu, 2021). A family history of SCD increases the risk of SCD (Albert & Sauer, 2022), and many non-structural heart diseases that can cause SCD have a strong heritable component. Obstructive sleep apnea (OSA) increases the risk of developing cardiovascular morbidities like arrhythmias and H.F. (Heilbrunn et al., 2021), and OSA is an independent risk factor for SCD (Gami et al., 2013; Ottaviani & Buja, 2020).
Causes of Sudden Cardiac Death
Most cases of SCD happen in patients with common structural heart diseases like heart failure (H.F.) or coronary heart disease (Albert & Sauer, 2022). Non-structural heart disease and non-cardiac conditions, e.g., epilepsy, can also cause SCD (Albert & Sauer, 2022), but they account for only a small percentage of SCDs.
Structural heart diseases are the most common cause of SCD. Some of the structural heart diseases that can cause SCD are:
- Aortic Stenosis
- Congenital Coronary Artery Anomalies
- Coronary Heart Disease
- Heart Failure
- Left Ventricular Hypertrophy
- Mitral Valve Prolapse
- Spontaneous Coronary Artery Dissection (Albert & Sauer, 2022; Podrid, 2022)
Non-structural arrhythmic diseases and channelopathies associated with SCD are:
- Acquired Long QT Syndrome
- Brugada Syndrome
- Catecholaminergic Polymorphic Ventricular Tachycardia
- Congenital Long QT Syndrome
- Early Repolarization
- Idiopathic Ventricular Fibrillation
- Short QT Syndrome
- Wolff- Parkinson-White (Albert & Sauer, 2022; Podrid, 2022)
These conditions and diseases are uncommon causes of SCD.
The CredibleMeds® website lists drugs that can cause QT interval prolongation or Torsades de Pointes (TDP), and the list is continually updated. The site can be accessed with this link: www.crediblemeds.org. Examples of drugs that can prolong the QT interval are:
- Antiarrhythmics, e.g., procainamide, quinidine, sotalol
- Antidepressants, e.g., selective serotonin reuptake inhibitors, tricyclic antidepressants
- Antiemetics, e.g., droperidol, ondansetron
- Antipsychotics, atypical and typical, e.g., chlorpromazine, iloperidone
- HIV antiretrovirals
- Macrolide antibiotics
- Methadone (Berul, 2020; Campleman et al., 2020; Khatib et al., 2021; Li & Ramos, 2017).
Risk factors for TPD are:
- Advanced age
- Drug-drug interaction, e.g., the use of 2 or more drugs that cause prolonged QT interval
- Female gender
- Electrolyte abnormalities: Hypocalcemia, hypokalemia, hypomagnesemia
- Heart disease, e.g., H.F. and LVH
- High drug dose
- QT interval > 500 msec (Berul, 2020; Khatib et al., 2021; Li & Ramos, 2017)
Miscellaneous causes of SCD include:
- Airway obstruction
- Chronic kidney disease
- Commotio Cordis
- Drug intoxication
- Near drowning
- Obstructive sleep apnea
- Pulmonary embolism
- Tension pneumothorax
A 65-year-old female self-referred to an emergency room because she had been feeling dizzy, had palpitations, and possibly had an episode of syncope.
The patient said she had several episodes of dizziness in the previous four weeks. Some of these were accompanied by palpitations, and she may have briefly lost consciousness during one episode. The last time the patient felt dizzy was one hour before she arrived. The dizziness began after she stood up, it continued for approximately 10 minutes after she returned to a sitting position, and she felt her heart fluttering. She did not have chest pain, shortness of breath, or other symptoms.
The patient has a past medical history of heart failure with reduced ejection fraction, hypertension, and depression. She takes furosemide 40 mg once a day, lisinopril 20 mg once a day, and fluoxetine 60 mg daily. Her psychiatrist had recently (approximately six weeks ago) prescribed escitalopram 10 mg once a day because the signs and symptoms of the patient’s depression had been worsening.
Temperature, 99°F, pulse 86, respiratory rate 16, and blood pressure, 146/74 mm Hg. Orthostatic vital signs were normal.
The patient is awake, alert, and oriented. Nothing abnormal was noted during the physical examination. Aside from the episodes of dizziness, the patient has been in good health, but she said she “had not been eating well lately.”
Laboratory test results:
- BUN and creatinine: 17 mg/dL and 1.0 mg/dl.
- Electrolytes: Sodium 142 mEq/L, potassium 3.0 mEq/L, chloride 104 mEq/L, carbon dioxide 26 mEq/L, anion gap of 12.
- AST and ALT: 12 IU/L and I14 IU/L.
- Serum calcium and magnesium: 8.4 mg/dL and 1.5.1 mg/dL.
- 12-lead ECG: Rate 89, PR interval 140 msec, QRS, 85 msec, QTc, 525 msec. No evidence of old or acute ischemia. A 12-lead ECG was done one year ago; at that time, the QTc was 430 msec.
- C.T. scan of the head was normal.
The patient was admitted and placed on continuous ECG monitoring. Potassium and magnesium supplementation was given, and continuous ambulatory ECG monitoring was started. The 24-hour ECG monitoring recorded one 30-second episode of TDP. It happened when the patient was resting, and the clinical staff did not see the arrhythmia on the telemetry monitor. The patient was found apneic and pulseless, and she could not be resuscitated.
Diagnosis: Sudden cardiac death caused by drug-induced QTc prolongation and TDP.
Analysis: The QTc was abnormally long, and TDP was documented. The patient had several contributing risk factors for QTc prolongation and TDP: Age, female gender, heart failure, hypokalemia, hypomagnesemia, a QTc > 500 msec, and QTc > 60 msec from the previous QTc duration. In addition, escitalopram can cause QTc prolongation, and it has a known risk of TDP. Fluoxetine can cause QTc prolongation, and it can, in certain circumstances, cause TDP, e.g., the presence of hypokalemia or the concurrent use of another drug that causes QTc prolongation.
Most cases of SCD happen in patients with common structural heart diseases like heart failure (H.F.) or coronary heart disease (CHD). Non-structural heart disease and non-cardiac conditions, e.g., epilepsy, can also cause SCD, but they account for only a small percentage of SCDs.
Sudden cardiac death is, by definition, sudden and unexpected, but SCD is often preceded by signs and symptoms, i.e., warning signs like chest pains, dizziness, palpitations, and syncope. However, SCD can occur without warning signs and symptoms.
Risk factors and triggers of SCD include alcohol abuse, cigarette smoking, diabetes, emotional stress, epilepsy, exercise, family history of SCD, and obstructive sleep apnea.
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