Most Common Causes of Sudden Death: Recognize the Signs

Updated October 25, 2018
Heart with heartbeat

The most frequent causes of sudden death in adults result from catastrophes in the heart, blood vessels, lungs, and brain, according to Forensic Pathology. Sudden collapse and death can occur in people with known medical risks as well as in seemingly healthy, even young people.

Sudden Death From Cardiac Arrhythmia

Cardiac arrest from arrhythmias is the leading cause of sudden death in adults from natural causes, though it can also affect younger people according to the Cleveland Clinic. A review in the Journal of Electrocardiology notes about 80% of sudden cardiac deaths in the U. S. and worldwide are from cardiac arrhythmias.

An arrhythmia is a change in the normal, regular rhythm of the heart, as illustrated by the American Heart Association. Disruption of the heart's pacemakers - the sinoatrial (SA) and atrioventricular (AV) nodes - and the nerve electrical conduction system, prevents the heart from pumping blood and delivering oxygen. The heart acutely stops beating, leading to cardiac arrest and sudden death if not immediately treated.

Causes and Risk Factors

The Mayo Clinic lists several causes of and risk factors for cardiac arrhythmias, including:

  • Defects in the nerve fibers of the heart because of an inherited problem or a previous heart attack
  • Diseased heart muscle or cardiomyopathy from a previous heart attack, infection, or alcohol or drug abuse
  • Electrolyte imbalance
  • Thyroid disease
  • Sleep apnea
  • High blood pressure or stress
  • Medications
  • Trauma to heart tissue

Symptoms and Signs

Many people have no symptoms just before a sudden cardiac arrest from an arrhythmia. Others might have had prior symptoms which recur just before the sudden death. According to the American Heart Association, symptoms of arrhythmia include the following:

  • Fluttering in the chest
  • Fast heartbeat
  • Skipped heartbeats
  • Palpitations
  • Chest pain
  • Shortness of breath
  • Dizziness or loss of consciousness

Consider the possibility of a cardiac arrhythmia in anyone with these symptoms. Treatment may prevent sudden death. Note any symptoms especially in the young and athletes as this demographic tends to ignore signs.

Heart Attack From Coronary Heart Disease

Businesswoman having heart attack

Heart disease is the number one cause of death in the U. S., according to the Centers for Disease Control and Prevention. An acute heart attack from coronary heart disease (CHD) is a leading cause of sudden death. Based on a review in the journal Circulation, 50% of all deaths from CHD are sudden deaths. The National Heart, Lung, and Blood Institute (NHLBI) notes a major blockage of an artery or arteries from coronary artery disease decreases blood flow and oxygen supply to heart tissue.

Insufficient blood and oxygen cause tissue damage and a heart attack, or acute myocardial infarction (AMI), which can lead to sudden cardiac arrest and death if not immediately treated. The damage to heart tissue from lack of oxygen supply can also disrupt the electrical system of the heart and cause unstable rhythms which could also be the cause of the cardiac arrest.

Causes and Risk Factors

Many people who die from a sudden heart attack had a previous history of CHD and heart attacks. Others have a history of known risk factors for heart disease. The NHLBI lists the following causes and risk factors:

  • Smoking
  • Drinking
  • Being overweight
  • Age
  • Family history
  • Lack of exercise
  • High blood pressure
  • Diabetes
  • Alcohol and drug abuse

Change in lifestyle habits and regimented treatment of risk factors and symptoms may prevent an acute heart attack.

Symptoms and Signs

A sudden heart attack and death can occur without warning in many people. For others, symptoms of a heart attack might immediately precede the sudden death. According to MedlinePlus symptoms of a heart attack include:

  • Chest pain (angina), which can radiate to arms, jaw, upper back
  • Heaviness in the chest
  • Shortness of breath or a cough
  • Anxiety
  • Nausea or vomiting
  • Dizziness

Many people ignore recurrent episodes of these symptoms and the next thing you know they faint, collapse, and die.

Pulmonary Embolism

Death from a pulmonary embolus (PE) can be sudden and devastating. According to MedlinePlus, a PE occurs when a piece, or pieces, of a blood clot from a leg vein (or pelvic vein) breaks off and travels through the main vein (vena cava) to the right side of the heart. From there the embolus goes to the lungs and blocks one or more arteries there and cut off the blood supply to the affected area of the lung.

A significant loss of lung tissue decreases oxygen supply to the brain and the rest of the body. When this happens, a person will collapse and can die. Decreased blood flow from the lungs to the left side of the heart also interferes with the function of the heart and diminishes the blood flow from the left ventricle to the rest of the body, contributing to sudden death.

Causes and Risk Factors

A pulmonary embolus mostly occurs in the elderly and people with risk factors. The most common causes and risk factors, according to the Mayo Clinic, include:

  • Individuals who are immobilized for awhile such as someone who is in a wheelchair or on bed rest
  • Blood vessel injury from surgery or other trauma
  • Inherited causes of hypercoagulable states which increase the risk of blood clots
  • A previous history of deep vein thrombosis (DVT)
  • Estrogen therapy which increases the risk for DVT
  • Pregnancy and childbirth
  • Cardiovascular disease (CVD) and risks for CVD, such as smoking
  • Some cancers, such as those of the lungs, pancreas, and ovaries

Symptoms and Signs

Many people who die from a PE had no immediate prior symptoms. In others, symptoms can occur just before the sudden death. According to the above Mayo Clinic reference, common symptoms of a pulmonary embolus include:

  • Sudden onset of shortness of breath and cough
  • Sudden chest pain
  • A rapid, or irregular, heartbeat
  • Sweating, lightheadedness, and dizziness

Prompt treatment can prevent death from a PE.

Acute Respiratory Arrest


Acute respiratory arrest can cause sudden death if breathing can't be restored. When breathing stops for more than five minutes, it causes damage to vital brain function and leads to death. The interference with oxygen supply can also lead to cardiac arrest which contributes to brain damage and death.

Causes and Risk Factors

According to a Merck Manual Professional review, the following are some known causes and risk factors for sudden death from respiratory arrest:

1. Acute upper airway obstruction of the throat, epiglottis, vocal chords, pharynx, or trachea with:

  • A mucus plug, food, or vomit
  • Blood, inflammation, infection
  • Tumor, foreign body, airway spasm, edema, or trauma

2. Lower airway obstruction of the lower pharynx, bronchi, and lung spaces from problems such as:

  • Aspiration of food or vomit
  • Bronchospasm from diseases such as asthma or an allergic reaction
  • Pneumonia, pulmonary edema, or pulmonary hemorrhage

3. Depression of the natural drive to breathe, which can be caused by:

  • CNS disorders such as a tumor, infection, bleeding, which can depress the brain's breathing and sleep arousal centers
  • Drug overdose
  • Metabolic disorders such as hypoglycemia, hypotension, electrolytes

Symptoms and Signs

Impending acute respiratory arrest may occur while a person is sleeping or unconscious, or may be preceded by signs and symptoms of acute respiratory failure. According to the NHBLI, symptoms and signs include:

  • Agitation, anxiety, and confusion
  • Struggle to breathe, choking, or fatigue
  • Tachycardia, sweating
  • Wheezing on inhaling (inspiratory stridor) and respiratory distress

In many cases, a person might be saved if the underlying cause of the acute respiratory arrest is promptly treated.

Hemorrhagic Stroke

According to the American Stroke Association (ASA), a hemorrhagic stroke is a rupture of a blood vessel in or over the brain. The hemorrhage can cause damage to vital brain tissue and a sudden, catastrophic death.

Sudden death occurs from the disruption of the normal blood flow and oxygenation to the affected area of the brain. Increased pressure caused by the hemorrhage on the brain, can also lead to death. Other factors that can contribute to death include accompanying cardiac arrhythmias and depression of the brain's breathing center.

Causes and Risk Factors

Risk factors and causes of hemorrhagic stroke, according to an ASA review include:

  • A history of high blood pressure
  • An intracranial blood vessel aneurysm
  • An arteriovenous malformation - a cluster of abnormal blood vessels
  • Smoking, alcohol or drug misuse, and birth control pills
  • Traumatic brain injury

Symptoms and Signs

People with sudden death from a hemorrhagic stroke may have no history of previous symptoms that might indicate an impending problem. According to a Mayo Clinic review, warning signs and symptoms of a stroke include:

  • A new headache or one that gets worse
  • A change in mental status
  • Incoherent speech
  • A one-sided facial numbness of droop
  • One-sided limb weakness, numbness or paralysis
  • Blurred or loss of vision

Loss of consciousness and sudden death then ensues if treatment is unavailable or not helpful.

Acute Aortic Dissection or Ruptured Aneurysm

An acute dissection or rupture of the aorta (the major artery of the heart) is a common cause of sudden, catastrophic death. According to a review by the Journal of Emergency Medical Services, an "aortic catastrophe" (a dissection or a rupture) is one of the five most common causes of sudden death. An aortic dissection or rupture occurs because of a weakening of the muscle wall of the aorta, anywhere along its route from chest to abdomen.

In an aortic dissection, blood dissects in between the inner and middle layers of the three layers of the muscle wall of the aorta. In a rupture, blood bursts through the bulging aneurysm of all three muscle layers. A dissection or a rupture can lead to significant internal blood loss, cardiac arrest, and sudden death.

Causes and Risk Factors

Aortic dissection or an aneurysm is more common in the elderly age 65 and over. The risks for both are the same risk factors for cardiovascular disease, which includes:

  • High blood pressure
  • Smoking
  • Obesity
  • Diabetes

Symptoms and Signs

An aortic aneurysm can continue without symptoms for years or cause back or abdominal pain as the aneurysm expands. Depending on the site, an acute expansion of the dissection or sudden rupture of the aneurysm might cause:

  • A sudden severe, "tearing" chest and back pain if there is a dissection
  • Severe pain in the flank, or abdomen, if there is a rupture

An abdominal aortic aneurysm might be seen on an imaging study or be large enough to be felt through the abdomen by a doctor and repaired by surgery before it ruptures.

Sudden Infant Death Syndrome

Heart in baby's crib

The death of a healthy infant during sleep from Sudden Infant Death Syndrome (SIDS) is devastating. The sudden, unexpected, unexplained crib death occurs in infants less than a year old, according to the National Institute of Child Health and Human Development (NICHD).

SIDS is the most common cause of death between ages one to 12 months, with more deaths occurring in boys. Most deaths occur before six months, and SIDS deaths tend to peak between four and six months. Based on 2014 statistics on SIDS from the CDC:

  • A total of 3,500 infant deaths were "sudden and unexpected infant deaths" or SUIDS - most from explainable causes, such as infections. Of the 3,500 cases, 1,500, or 43%, were SIDS, or unexplainable infant deaths.
  • Non-Hispanic African American infants were twice more likely than non-Hispanic Caucasian infants to die of SIDS.
  • Hispanic and Asian/Pacific Islander infants had the lowest rates of SIDS.

Causes and Risk Factors

The cause of SIDS is unknown. One risk factor is birth less than 39 weeks of gestation. Beyond that, little is known about what puts an infant at risk for this sudden unexplained death. Some causes and risks, according to the Mayo Clinic, may include:

  • Delayed or inadequate prenatal care
  • Premature birth and low birthweight
  • Immaturity of the brain centers which control breathing and sleep arousal
  • Putting an infant on his stomach to sleep
  • Accidental suffocation from soft toys or bedding
  • Bed sharing with parents or siblings, or overheating
  • Exposure to toxins, such as nicotine during pregnancy or after birth
  • An undiagnosed heart or genetic disorder

No other warning signs before a SIDS death have been described. The United States' NICHD Safe to Sleep campaign has decreased the incidence of SIDS by 50% since 1994 by encouraging parents to put an infant to sleep on his back instead of his stomach.

The #1 Most Common Cause of Death

The #1 most common cause of death among people, young and old, will vary depending on their specific age group. The following are the most common causes of death according to age group:


The #1 most common cause of death for teens is accidents. These unintentional injuries most often occur because of automobile accidents and could actually be preventable. According to the Centers for Disease Control and Prevention, six teens are killed every day from injuries due to a car accident.

Young Adults Under 35

The #1 most common cause of death for men and women under the age of 35 is accidents/unintentional injuries which are (again) mostly attributed to automobile accidents.

Middle-Aged Men and Women Under 65

The most common cause of death for both middle-aged men and women is heart disease with cancer closing the gap and coming in at a close second.


The most common cause of death for seniors is heart disease which includes heart attack, heart failure, and heart arrhythmia. This is typically associated with other ongoing health issues such as diabetes, high blood pressure, and smoking history.

Other Circumstances Associated With Sudden Death

Symptoms or unexpected circumstances that may occur or be associated with sudden death:

  • If vomiting occurred prior to sudden death, it may have been a warning sign for imminent cardiac arrest.
  • If sudden death occurred during sleep, there are multiple causes as to why it could have happened. Cardiac arrest, respiratory arrest, certain genetic conditions and sleep disorders such as obstructive sleep apnea.
  • If sudden death happened during exercise, this would typically be due to an undetected heart defect or advanced heart disease that the person was not aware of.
  • If there was a sudden death during pregnancy, there could be numerous reasons as to why it may have happened. A few of the possible causes include blood clots, hypertensive disorders, eclampsia, postpartum hemorrhage, and infection.

Symptoms, Signs and Risk Factors Infographic

This interesting infographic sums up symptoms, signs and risk factors you should be watching for to live a long and healthy life.

Sudden Death Infographic

Attention to Prevention and Treatment

The common causes of sudden death occur in the major vital organ systems of the body. If you or those you care about have risk factors, attention to prevention or treatment of these factors may prevent their sudden death. Also, putting your infant to sleep on her back can decrease the chance of losing your child to SIDS. Always remember to call 911 if you see someone collapse, or you can't wake up your baby.

Most Common Causes of Sudden Death: Recognize the Signs