Cardiac Syncope

What is Cardiac Syncope?

Syncope, or fainting, which is a sudden, temporary loss of consciousness and balance, is thought to affect around 30% to 40% of people. However, many believe this is an underestimation since a lot of people who faint don’t seek medical help at a hospital or urgent care facility. In the United States alone, fainting causes around 740,000 visits to the emergency department and results in about 250,000 hospital admissions annually.

The reasons why a person might faint can vary greatly, from a simple, harmless faint (vasovagal syncope) triggered by factors like the sight of blood or standing for long periods, to something more serious like a neurological disorder, metabolic issue, lung disease, blood volume decrease, or heart problem.

It’s vital to note that fainting due to a problem with the heart (cardiac syncope) can sometimes signify a potentially deadly underlying health condition and has a 30% chance of death in a year. This occurs when there’s a problem in the heart preventing it from providing the brain with enough nutrients and oxygen, causing you to lose consciousness. The heart problem could be due to a heart rhythm issue, a physical defect in the heart, or a physical defect that makes a patient prone to a rhythm disturbance. It’s estimated that cardiac syncope causes around 15% of all fainting episodes.

Determining whether fainting is due to a heart problem among many other possible causes can be quite difficult. So, it’s crucial for everyone in the medical field, and even those outside it, to have a basic understanding of cardiac syncope and how to recognize it.

What Causes Cardiac Syncope?

Syncope, or fainting, occurs when your brain temporarily doesn’t receive enough blood flow. This often happens when your heart is not able to pump enough oxygen-rich blood to your brain. The reason behind this might be related to a problem with the heart’s structure or function or due to an abnormal heart rhythm, known as an arrhythmia. Interestingly, it’s usually arrhythmias that cause the issue, but these can be triggered by problems with the heart itself. So, the two conditions can be closely connected.

There are many different reasons why your heart might not pump enough blood to the brain. The are listed below:

Structural causes might include:

• Ischemic cardiomyopathy, a disease that weakens and enlarges your heart
• Abnormal heart valves, especially aortic stenosis which is a narrowing of the heart valve that controls blood flow from your heart
• Nonischemic/Dilated cardiomyopathy, heart muscle disease not caused by reduced blood flow
• Situations where the heart becomes obstructed, like hypertrophic obstructive cardiomyopathy, aortic dissection, and cardiac tamponade
• Diseases around the heart, like pericardial disease
• Conditions affecting the lung’s blood flow and pressure, like pulmonary hypertension and pulmonary emboli

Electrical causes include:

• Tachyarrhythmia, which is an abnormally fast heartbeat that includes varying conditions like atrial fibrillation, atrial flutter, and supraventricular tachycardia
• Bradyarrhythmia, which is the opposite, an abnormally slow heartbeat
• Problems with the pathways that transmit electrical signals in the heart, known as conduction pathways
• Inherited conditions that affect the electrical system of the heart
• Drugs those lead to abnormal heart rates and rhythms

In summary, syncope can happen due to a range of structural or electrical problems in your heart, which disrupt the flow of blood to your brain.

Risk Factors and Frequency for Cardiac Syncope

Syncope, also known as fainting, is quite common and can happen to anyone, regardless of age, race, religious belief, or wealth. The second leading cause of fainting is cardiovascular (heart-related) disease, particularly irregular heart rhythms (arrhythmias) rather than physical heart problems. For instance, a type of irregular heart rhythm called ventricular tachycardia is responsible for about 11% of fainting events.

• Heart-related fainting is more common in older people than in younger ones. In fact, 10% to 30% of people over 60 who faint do so because of a heart problem.
• It also tends to be more common in men than in women.
• Physical heart problems are more common in people who have other health conditions like diabetes, high blood pressure, high cholesterol, and in those who smoke.
• Women are more likely to have pre-excitation syndromes, a specific type of irregular heart rhythm.
• Brugada syndrome, a potentially life-threatening heart rhythm disorder, is more common in men and people of Southeast Asian descent.

Signs and Symptoms of Cardiac Syncope

Assessing whether a fainting episode (known as syncope) is due to a heart-related cause involves examining a patient’s health history and conducting a physical exam. Combined with a physical examination, the patient’s history can help determine the cause of their fainting in almost half of the cases. Doctors will focus on certain details, such as a patient’s age (especially if over 60), gender, previous heart disease, heart valve disease, blocked heart arteries, lung clots or risk factors for lung clots. Risk factors can include having cancer, being immobile, being pregnant, taking birth control pills, and more. A type of fainting called cardiovascular syncope often occurs during physical exertion, while lying flat, or immediately following feelings of heart palpitations or chest pain. This type of fainting usually lacks warning signs associated with the body’s “fight or flight” response. It’s also crucial to find out if the patient has a family history of abnormal heart rhythms, fainting, or sudden unexplained deaths.

During a physical examination, the doctor will check the patient’s heart rate and rhythm to detect any abnormalities that may indicate heart rhythm disorders. The doctor will also look for signs of lung clot (pulmonary embolism) like high respiration rate or lack of oxygen in the blood. Symptoms such as vein swelling in the neck and low blood pressure could hint at an obstruction in the heart. The presence of unusual heart murmurs could suggest a cause related to heart valves, heart muscle thickening, or intracardiac obstruction. Muffled heart sounds could indicate a condition called pericardial tamponade, where fluid builds up around the heart. Lastly, signs such as swollen feet or evidence of deep vein clots would increase a patient’s chances of having lung clots.

Testing for Cardiac Syncope

If a fainting episode is thought to be due to a heart issue, more tests need to be done. These can include a 12-lead EKG, which monitors your heart rhythm, and other tests like an echocardiogram, an implantable heart monitor, or a Holter monitor or stress test.

An EKG is very useful for spotting heart rhythm problems. It can pick up issues like very slow heart rates (which can cause the heart to pause for more than 3 seconds) or very fast heart rhythms. The EKG can also pick up signs of other problems, like blockages in the electrical signals in the heart, signs of previous heart attacks, or conditions that can cause heart rhythm problems (like Wolff-Parkinson-White syndrome, Brugada syndrome, Long-QT syndrome, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy).

When you first go to the hospital with symptoms, basic blood tests are usually done. However, these don’t really tell the doctor if the fainting episode is due to a heart problem. A troponin test, which measures a protein found in the bloodstream after a heart attack, is also not very good at diagnosing fainting due to heart problems. One test that’s been shown to be useful is a natriuretic peptide test, which can help identify whether your fainting was due to a heart issue and if you are at risk of future heart problems.

If a heart rhythm issue isn’t picked up when having symptoms, an echocardiogram can be very useful. This test can spot physical issues with your heart structure. In fact, in a study of 128 patients who were thought to have heart-related fainting, an echocardiogram confirmed the diagnosis in almost half of them. CT scans and MRIs can also be used to identify physical issues with the heart.

If a physical problem with the heart structure isn’t causing the fainting and no heart rhythm problem has been detected, stress testing and longer-term heart monitoring can help catch the diagnosis. If the fainting is brought on by exercise, a stress test can often uncover the cause. If your symptoms are recurrent and frequent, a Holter monitor (which records your heart’s electrical signals) is recommended. If your symptoms are less frequent, a device called an external loop recorder or an implanted cardiac monitor can be used to catch the problem.

Another method that’s sometimes used is an electrophysiologic study. In this procedure, the doctor places catheter tips at multiple locations within the heart to stimulate different parts of the heart’s electrical system and try to reproduce an irregular heart rhythm. This test can pinpoint the exact source of any irregular electrical activity and allows for treatment at the same time. However, this test has certain limitations in that it’s not always accurate, and is only recommended in certain patients. Electrophysiologic studies are only considered diagnostic if they show certain specific signs on the tests.

Treatment Options for Cardiac Syncope

The goal of treating fainting that is caused by a heart condition, otherwise known as cardiac syncope, is to prevent further harm, injury, or unexpected expenses related to recurrent fainting incidents. The treatment approach differs depending on the specific condition that led to fainting.

Abnormal heart rhythms, or arrhythmias, are a common cause of fainting. When arrhythmias cause the heart rate to slow down, the condition is called sinus bradycardia. The first step in managing sinus bradycardia is to check if it’s being caused by medications that slow down the heart. If this is the case and the medication is unnecessary, it will be stopped. If not, doctors may recommend the installation of a pacemaker, a device that helps the heart to maintain a normal rhythm. However, it’s important to note that while a pacemaker can prevent future fainting episodes, it might not increase the overall lifespan and fainting might recur in some people even after receiving a pacemaker.

If the irregular heart rhythm involves either Mobitz type 2 second-degree or third-degree AV block, a pacemaker can also help to prevent future fainting spells. People with heart failure, reduced left ventricular ejection efficiency, or unusually long QRS segments (a part of the heart rhythm cycle) may benefit from a specific pacemaker mode called biventricular pacing.

When it comes to arrhythmias that speed up the heart rate, dealing with the underlying cause is often more challenging. For instance, supraventricular tachycardia, a certain type of fast heart rate, can often be treated by destroying the pathway responsible for the excess speed using a procedure called catheter ablation. If the procedure can’t be performed immediately, certain medications may be used as temporary alternatives. Syncope caused by a rapid heart rate due to conditions like atrial fibrillation and nonsustained ventricular tachycardia might be managed with heart rate lowering medications. If syncope episodes continue to occur despite medication, the doctors might consider conducting an ablation procedure or installing an implantable cardioverter-defibrillator (ICD), a device that helps monitor and correct irregular heart rhythms.

Another cause of fainting spells can be issues with a previously installed pacemaker. In such cases, the device needs to be assessed by a specialist. Problems like battery exhaustion or issues with the leads (wires that connect the pacemaker to the heart) might be resolved by replacing the device or the wires.

When it comes to fainting spells caused by some form of structural heart abnormality, the treatment will vary depending on the specific problem. For instance, aortic stenosis (narrowing of the aortic valve) might require valve replacement surgery, whereas heart failure or heart enlargement might be managed with medications such as nitrates and diuretics.

Patients who have experienced fainting spells due to a heart condition and have not yet received a definitive intervention to prevent future incidents should avoid driving. Studies indicate these individuals are 2 to 4 times more likely to be involved in car accidents.

What else can Cardiac Syncope be?

When people suddenly lose consciousness, it may be due to a condition known as cardiac syncope. But, there are other reasons that can cause a person to blackout. If they have hit their head and then lost consciousness, that means they have had a concussion. If there’s no injury involved, the cause can still vary. It could be a seizure, a sudden drop in blood sugar or sodium, lack of oxygen, too low carbon dioxide in the blood, a temporary interruption of blood flow to certain parts of the brain, alcohol or certain substances that slow down brain activity, fake seizures, or a psychological response.

However, blackout is not always due to a decrease in blood flow to the brain as happens in syncope. If the blackout is classified as syncope, it can be because something is affecting the heart’s ability to pump blood or altering the body’s normal control of blood pressure.

Below are other causes for blackouts not related to heart problems:

• Reflex (Neurogenic)
  • Vasovagal: usually happens after intense fear, seeing blood, hearing bad news, emotional stress, or pain
  • Situational: happens after specific actions like sneezing, laughing, coughing, urinating, pooping, eating, or exercising
  • Carotid sinus stimulation: an unusual reflex that happens when the carotid sinus in the neck is stimulated
• Orthostatic Hypotension
  • Autonomic dysfunction: usually a symptom of another degenerative disease such as Parkinson disease, multiple system atrophy, Lewy body dementia or can be a primary disease on its own; can also be a side effect of diabetes, amyloidosis, and spinal cord trauma
  • Drug-induced: it could happen due to some medications like diuretics, vasodilating agents, alcohol, antidepressants, or any other medications that affect the heart or blood pressure
  • Volume depletion: could be due to severe bleeding (due to injury or not), diarrhea, vomiting, sweating, not drinking enough fluid

What to expect with Cardiac Syncope

Patients with cardiac syncope, a condition that causes fainting due to a temporary decrease in blood flow to the brain, often have a good outlook if the cause of the fainting spells can be easily treated. However, those with advanced heart failure and syncope face a more serious prognosis, with nearly half not surviving past a year.

It’s also worth noting that patients with this condition are more prone to recurring fainting episodes, with about a third likely to experience a recurrence within three years. These repeated fainting spells can significantly affect a person’s quality of life, especially if they result in physical harm such as broken bones or brain bleeding due to falls or other accidents.

Possible Complications When Diagnosed with Cardiac Syncope

When a cardiac syncope, or fainting episode related to the heart, occurs, we do everything we can to prevent a future one from happening. However, these fainting episodes can have immediate consequences too. These can include the expense of a hospital stay, any treatments, and time missed from work. Plus, there can be physical injuries from falling when the fainting episode happens.

Possible Consequences:

• Hospitalization costs
• Costs of treatment
• Lost work time
• Physical injuries from falling during the fainting episode

Preventing Cardiac Syncope

People who are on multiple medications are more likely to faint, a condition known as syncope. Drinking alcohol can also cause a sudden drop in blood pressure when standing up (this is called orthostatic hypotension), which can lead to fainting. People with heart conditions should be aware of the signs of fainting and know when to get help. This is particularly important as fainting related to heart problems can be very serious and even life-threatening, especially if the heart condition is severe.