Families coping with a sudden death of a family member often worry about their own health and whether they may be at risk for serious health problems. We hope the following provides further information to address your concerns, understand possible risks, and empower you to take the steps to live a long, healthy, active life.

Background Cardiology

Cardiovascular Conditions

Please click on a topic to learn more.

Heart Healthy Lifestyle

Adopting a heart-healthy lifestyle continues to be the first and best way to lower your risk of heart problems. Doing so can also help control or prevent other risk factors (for example: high blood pressure or diabetes).

Other Causes of Unexpected (Sudden) Death

While most causes of unexpected death is thought to be due to heart-related causes, there are some causes that are not heart-related. These are usually found during an autopsy, if a complete autopsy is done. 

Cardiovascular Conditions Definitions


Electrical problems are called “arrhythmias” or heart rhythm disturbances. There are many specific types of arrhythmias, some more serious than others. Just like a short in an electrical circuit, these problems can occur suddenly without warning. They are often very unpredictable and intermittent (come and go). Arrhythmias are often called “silent” because they cannot be seen in imaging tests nor when examining the heart on autopsy after a sudden death. Symptoms of arrhythmias vary from person to person but are often described as “irregular” or “fast” heart beat (palpitations), dizziness or lightheadedness, fainting or nearly fainting (syncope), and SCD.

Some life-threatening arrhythmias are genetic and run in families. The genetic forms that predispose to SCD often, but not always, occur in younger people (under 50 years of age) without other types of heart disease or prior medical conditions. These conditions are caused by a mutation, or an inherited change, in a gene. As you may know, our genes tell our bodies how to grow and function. Some of our genes are responsible for heart development and function. If one of these cardiac genes has a change in it that makes it unable to perform its job then it can cause genetic heart disease. These gene mutations are typically inherited from one generation to the next. Many of the genes that cause genetic heart disease are known so people with these conditions and their family members can be tested to find out if they are at risk to develop these conditions.

Long QT Syndrome:

Long QT syndrome (LQTS) is an inherited heart rhythm disorder characterized by a specific pattern on an electrocardiogram (ECG)—a prolonged QT interval—that can cause dangerous heart rhythms. People with LQTS may experience palpitations, syncope (fainting), or even sudden death. Diagnosing LQTS can be difficult because individuals with the condition have normal heart structure and the abnormal heart rhythm can be intermittent. LQTS is relatively common affecting approximately 1 in 2500 people. LQTS is caused by mutations in genes that regulate the electrical activity in the heart. Immediate relatives (parents, siblings, and children) of those with LQTS each have a 50% chance of developing the condition and must be evaluated accordingly.

Short QT Syndrome:

Short QT syndrome (SQTS) is an inherited heart rhythm disorder characterized by a specific pattern on an ECG (electrocardiogram)—a short QT interval—that can cause dangerous heart rhythms, often at young ages. People with SQTS may experience palpitations, syncope (fainting), or even sudden death. SQTS is a rare condition caused by mutations in genes that regulate the electrical activity in the heart. Immediate relatives (parents, siblings, and children), of those with SQTS each have a 50% chance of developing the condition and must be evaluated accordingly.

Brugada Syndrome

Brugada syndrome is a genetic arrhythmia associated with fainting, fast heart rate, dangerous heart rhythms, cardiac arrest, and/or SCD. The diagnosis of Brugada syndrome is based on a specific pattern on an ECG called “Brugada type 1 pattern”. Brugada can also be hard to diagnose because the abnormal ECG pattern can be intermittent and people with Brugada have normal heart structure. The severity of Brugada syndrome varies from person to person even between members of the same family. Some people never experience symptoms or Brugada ECG pattern. Others may have serious symptoms, including frequent syncope (fainting) or sudden cardiac death. The risk for life-threatening arrhythmias tends to be higher in males, in young adulthood, and in those who have had previous symptoms. Immediate relatives (parents, siblings, children) of someone with Brugada syndrome each have a 50% chance of developing the condition and should be evaluated.

Catecholaminergic Polymorphic Ventricular Tachycardia

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited condition that results in abnormal heart rhythms during exercise or activities associated with high adrenaline levels. These abnormal rhythms are absent at rest but can cause palpitations, fainting, or SCD with physical exertion or emotional stress. CPVT is not associated with abnormal heart structure so cardiac imaging studies usually appear normal. ECGs measured while resting are also normal since the abnormal heart rhythms typically occur with exercise. CPVT is diagnosed by cardiac stress (treadmill) tests. Immediate relatives (parents, siblings, and children) of someone with CPVT each have a 50% chance of developing the condition and must be evaluated accordingly.

Idiopathic Ventricular Fibrillation

The most common heart rhythm that leads to SCD is called “ventricular fibrillation” or VF. VF is a very fast, irregular and dangerous heart rhythm that causes SCD if not treated within minutes. VF is treated with electrical shock via a defibrillator (paddles) that doctors or emergency medical service (EMS) providers administer. You’ve probably even seen automated emergency defibrillators (AEDs) at public places like airports, gyms, theaters, sports arenas, etc. These lifesaving devices can be used by anyone without special training.

When someone survives defibrillation, they undergo extensive medical testing to look for the cause of the life-threatening heart rhythm. If the underlying cause of VF cannot be determined, the patient is diagnosed with “idiopathic ventricular fibrillation (iVF)”. Some people with iVF actually have a genetic arrhythmia syndrome such as LQTS, Brugada or CPVT. Because the dangerous heart rhythms associated with iVF can run in families, FDRs must be evaluated to determine if they are risk. There are other forms of VF that caused by other abnormalities in the heart and not inherited in families. 

Accessory Pathways (WPW, etc.)

Not all arrhythmias that cause SCD are inherited. Some people are born with an extra piece of heart tissue that connects directly between the upper and lower parts (chambers) of the heart. This abnormal piece of muscle is called a bypass tract or accessory pathway and may cause dangerous heart rhythms and SCD. Typically, abnormal accessory pathways do not run in families. Often, these pathways can be cured with cardiac procedures or medications. Rarely, accessory pathways do run in families so it may be important for FDRs to be evaluated.


Heart muscle problems are called “cardiomyopathies” (cardio=heart, myo=muscle, pathy=disease). Cardiomyopathies are characterized by abnormal heart size, thickness and function, and are diagnosed by cardiac imaging tests and autopsy. Importantly, these abnormalities can be seen at autopsy, unlike the arrhythmic causes described above. Some types of cardiomyopathy that cause SCD are genetic while others are due to pre-existing medical problems.

Hypertrophic Cardiomyopathy (HCM):

HCM is an inherited heart disorder characterized by an abnormally thickened heart. It affects approximately 1 in 500 people in the United States. People with HCM may experience palpitations, chest pain, shortness of breath, or fainting. They also carry a higher risk of stroke and sudden cardiac death than the general population. In fact, HCM is among the top causes of sudden death in young athletes but can also cause SCD at any age.

HCM is caused by mutations in genes that make up the structural proteins of heart muscle. The first-degree relatives (parents, siblings, and children) of someone with HCM each have a 50% chance of developing the condition.

Other forms of hypertrophy (thickening of the muscle) are not inherited. These can be caused by high blood pressure, abnormalities of one of the heart valves (the aortic valve) or extreme conditioning and training (as in athletes).

Dilated Cardiomyopathy (DCM)

DCM is characterized by an enlarged heart with weak pumping function. People with DCM may experience palpitations, shortness of breath, severe fatigue, and/or  excess build up of fluid in their body, particularly in the legs. DCM can progress to severe heart failure and can sometimes trigger life-threatening arrhythmias resulting in sudden death. There are genetic and non-genetic forms of DCM. Non-genetic forms are due other cause such as blockages in blood vessels, toxins (eg. certain chemotherapy drugs), excessive drug or alcohol intake, viral infection in the heart, heart valve abnormalities and some other causes. When an underlying cause cannot be identified, it is called primary (or idiopathic) DCM. Sometimes, primary DCM runs in families and is referred to as “familial DCM”. Familial DCM affects at least 1 in 2500 people in the United States and may be much more common as it is often unrecognized and/or misdiagnosed. The immediate family members (parents, siblings, children) of someone with familial DCM each have a 50% chance of developing the condition and should be evaluated.

Arrhythmogenic Right Ventricular Cardiomyopathy or Dysplasia

ARVC or ARVD is an inherited heart disorder that is characterized by gradual replacement of the right heart muscle with fatty tissue. Symptoms of ARVC include very fast heart rate (palpitations), shortness of breath, fainting, and SCD. ARVC is typically diagnosed with a variety of cardiac tests. However, because arrhythmias can occur before muscle changes, the structural changes of ARVC are not always seen. Also, not all medical examiners are trained to diagnose ARVC so second opinions are sometimes needed to make the diagnosis at autopsy.

ARVC affects approximately 1 in 5000 people in the United States, men more commonly than woman. Immediate relatives (parents, siblings, and children) each have a 50% chance of developing the condition and should be evaluated.

Aortic Aneurysm and Dissection

The aorta is the large blood vessel that delivers blood to the entire body. The aorta starts in the heart and travels down to the pelvis feeding blood vessels throughout the body. An aneurysm is an enlargement, or ballooning, of a blood vessel. When aneurysms get too large, the blood vessel becomes very weak and can burst (“rupture”) or tear (“dissect”). Aneurysms can occur anywhere along the length of the aorta. Those that occur at the beginning of the aorta in the chest are termed “thoracic” aortic aneurysms. Those in the lower portion of the aorta are referred to as “abdominal” aortic aneurysms. While both thoracic and abdominal aortic aneurysms are serious medical conditions that should be treated, thoracic aortic aneurysms are generally more serious and immediately life-threatening because it causes catastrophic internal bleeding and death unless repaired via emergency surgery. SCD caused by thoracic aortic dissection occurs after an aneurysm dissects and blood is unable to reach the rest of the body.

Aortic aneurysms generally do not produce symptoms. However, symptoms of aortic rupture/dissection include the sudden onset of acute, sustained pain, most commonly in the back or chest. Thoracic aortic dissection is life-threatening which is why it is extremely important for individuals at increased risk to be checked for aortic enlargement before they experience any symptoms. Aortic aneurysms and dissections are treatable with medication and surgery when necessary. Sudden death is preventable with close monitoring and, when necessary, appropriately timed surgery.

There are genetic and non-genetic forms of thoracic aortic aneurysm/dissection. Genetic forms can either occur alone (“isolated”) or in conjunction with other physical differences and/or medical problems (syndromic). Unfortunately, it can be difficult to determine whether or not someone has an inherited form of aortic disease unless other family members are known to have aneurysms or they have medical and/or physical features of a genetic syndrome. Therefore, the first-degree relatives (parents, siblings, and children) of anyone with thoracic aortic aneurysm, dissection, or sudden death due to aortic dissection should be screened with cardiac imaging tests. Non-genetic forms generally occur in older people, people with hypertension, elevated cholesterol, significant smoking history, certain congenital heart defects, or a broad category of non-inherited diseases such as scleroderma or vasculitis. Abdominal aortic aneurysms are rarely genetic so typically family members would not be at increased risk.

Aortopathy Screening Recommendations:​

Immediate relatives (parents, siblings, children) of anyone with familial aortic disease should have baseline imaging of the thoracic aorta by echocardiogram, CT, or MRI. The variable age of onset of the aortic disease in familial aortic disease makes it necessary to begin imaging the aorta of individuals at risk at a relatively young age. Experts recommend that imaging begin when a child can undergo an echocardiogram without sedation (usually age 6-7 years) unless onset in the family has been at a younger age ( ). At-risk relatives should be monitored once every few years for aortic abnormalities if the initial assessment is normal. Individuals with aortic aneurysm should be followed closely by a cardiologist familiar with aortic diseases.

Aortopathy Syndromes:

Other genetic causes of thoracic aortic aneurysm/dissection affect other parts of the body and are called “syndromes”. There are many different genetic syndromes predisposing to aortic disease, but the most common include Marfan/Marfan-related syndromes and vascular Ehlers-Danlos syndrome. 

  • Marfan Syndrome
    • Marfan syndrome is a connective tissue disorder associated with heart, skeletal and eye manifestations. Cardiovascular abnormalities include aortic aneurysm/dissection and mitral valve prolapse. Ocular lenses can move out of place causing severe vision problems or blindness. Some people with Marfan can have severe nearsightedness. Skeletal features may include tall, thin statures with disproportionately long limbs, long fingers, chest that sticks out or caves in, high arched palate and dental crowding, and scoliosis (spine curvature). Marfan syndrome is caused by mutations (change or mistake) in the FBN1 gene. As you may know, our genes tell our bodies how to grow and function, and if a gene has a change in it that makes it unable to perform its job then it can cause a disease like Marfan syndrome. FBN1 mutations can be passed on from one generation to the next and follow an autosomal dominant pattern, meaning that the children of a mutation carrier each have a 50% risk to inherit the mutation.
    • The severity of Marfan syndrome is quite variability in families. Thus, individuals with FBN1 mutations can have a wide variety of physical features associated with Marfan syndrome but all will have at least some manifestations of the condition. With proper medical care, individuals with Marfan syndrome have a normal life span. 
    • There are many rare connective tissues disorders that have many of the same features as Marfan syndromes. Someone undergoing genetic evaluation for Marfan syndrome will be evaluated for these less common Marfan-related syndromes as well.
  • Vascular Ehlers-Danlos Syndrome
    • Vascular Ehlers-Danlos Syndrome, or type IV (EDSIV) is characterized by abnormalities of the skin, joints, and blood vessels. People with vascular EDS have thin, translucent skin that bruises easily. Wounds heal slowly and often result in surgical complications and abnormal scarring. Joints are often extremely flexible, especially the fingers, and prone to dislocation and chronic pain. The aorta as well as other blood vessels and internal organs are fragile thus at risk for dissection or rupture. Pregnancy results in significant risk for uterine rupture and sudden death.
    • Vascular EDS is caused by mutations (change or mistake) in the COL3A1 gene. As you may know, our genes tell our bodies how to grow and function, and if a gene has a change in it that makes it unable to perform its job then it can cause a disease like vascular EDS. COL3A1 mutations can be passed on from one generation to the next and follow an autosomal dominant pattern, meaning that the children of a mutation carrier each have a 50% risk to inherit the mutation.
    • ***It’s important to be aware that there are many forms of Ehlers-Danlos syndrome (EDS) some of which are very common. SCD due to serious bleeding events is only associated with the vascular form of EDS, termed “EDS IV”.
    • Some patients with Marfan, Loeys-Dietz, and vascular Ehlers-Danlos syndromes are the only people in their family with the condition. Even without a family history, their children still have a 50% chance to develop the condition. Since these syndromes can be subtle, the FDRs (including siblings and parents) of someone who died suddenly from any of these syndrome should be formally evaluated by a medical geneticist. To find a geneticist near you, click here.

Coronary Artery Disease / Myocardial Infarction

A “myocardial infarction (MI)”, commonly called “heart attack”, is due to a blockage in one or more arteries that supply blood to the heart. The blockages are caused by plaque that builds up in the blood vessels over many years. This is called coronary artery disease (CAD). If untreated, heart attacks can cause SCD. Screening for CAD involves routine blood tests that measure cholesterol and other lipids. Risk factors for CAD include high (LDL) cholesterol and triglyceride levels. Modifiable risk factors for CAD include smoking, high blood pressure, diabetes, being overweight, and a sedentary lifestyle. Non-modifiable risk factors include increasing age, male gender and family history of CAD.

Most CAD is thought to be due to a combination of genetic factors and environmental factors. The greater number of risk factors a person has, the higher the risk for CAD. For those with a family history of CAD, the risk is higher if you have:

  • Close relative (parent, siblings or child) compared to a distant relative (cousin, great uncle/aunt, etc.)
  • Family history of CAD or MI at young age (<50 for men, <65 for women) compared to those whose relatives were affected at older ages.
  • Female relative with CAD or MI versus male relative. This is because CAD is more common in men.
  • Affected relative(s) without CAD risk factors.
  • Many affected relatives especially if relatives in multiple generations on the same side of the family.

Coronary Artery Disease Risk Self-Assessment

Is important for everyone to know the risk factors for CAD, make heart-healthy lifestyle choices, and follow a doctor’s advice about recommended screening tests. Also, risk for heart disease changes as risk factors change. Some of these, like aging, are unavoidable. You can estimate your risk for CAD at CAD risk changes as risk factors change. For a current risk assessment, make sure to recalculate your risk every 3-5 years and sooner if your risk factors change.

Congenital Heart Defects

Congenital heart defects (CHDs) result from the abnormal formation of the heart or blood vessels that during pregnancy, while the fetus is developing in the uterus. CHDs are fairly common, affecting up to 1% of infants and 1/150 adults. There are many different types of CHDs and they range broadly in severity. Some CHDs are very mild and do not require medical intervention while others are complex, severe defects requiring surgery in infancy and lifelong medical management. Congenital heart defects may be diagnosed anytime from pregnancy to adulthood. Symptoms of CHDs in adults typically include shortness of breath and poor exercise tolerance, however, many adults with CHDs do not have symptoms. Most adults with CHDs should be monitored by a general cardiologist familiar with these conditions or congenital heart specialist.