Atrial Fibrillation Guidelines
A healthy heart muscle pulses with electricity in orderly and regular intervals. The electrical pulses contract and relax the heart organ and propagate blood throughout the body. With cardiac arrhythmias, the electrical pulses are chaotic and the heart does not work reliably. The most common cardiac arrhythmia is Atrial Fibrillation (AF). The quivering heart beats erratically, causing the two upper chambers to pump blood unevenly and inefficiently. AF happens in episodes, minutes, weeks, or all the time. When the heart beats fast or is not operating efficiently, an individual can feel lightheaded, fatigued, short of breath, have chest pains or palpitations. Often, atrial fibrillation can go undiagnosed.
Coordinated contraction of the heart ensures blood flow to the ventricles, the heart’s main pumps. Abnormal, rapid heartbeats cause the upper chamber of the heart (the atria, right atrium and left atrium), and the lower chamber of the heart (the ventricles, left ventricle and right ventricle) to cause inefficient blood pumping. When blood is not pumped effectively, blood can pool within the atria and form blood clots in the heart. The risk of stroke or heart attack increases. A blood clot can escape from the heart and block an artery in the brain, legs, arms, or lungs causing a stroke or thromboembolism.
AF is considered a new epidemic. Increasing numbers of people have heart rhythm disturbances. AF is responsible for heart failure, stroke, and significant risk of early death. In addition, AF patients have a reduced quality of life, increased medical costs and more frequent hospitalizations. World-wide efforts are underway to identify the complex cardiovascular mechanisms associated with AF. Scientific organizations and physicians feel that AF incidence is, “unacceptably high.” They seek to improve outcomes, prevent stoke, help patients and families, and inform policy makers to make better decisions.
Atrial fibrillation has a documented heritable or genetic component. Experts say that the obesity epidemic is directly causing increases in AF incidence. While AF can strike any person at any age, it is more common as people get older. 5-10% of people over the age of 65 have atrial fibrillation. In others, there is no apparent cause or underlying heart abnormalities. Sometimes alcohol, tobacco, drug use and stress can bring on episodic AF. The condition itself is not life threatening, but it often leads to poor outcomes.
When an individual is diagnosed with AF, the chance of having a stroke increases. AF is responsible for about 15 percent of all strokes. About 70, 000 people in the U.S. die from a stroke each year as a direct result of AF. Individuals with AF can expect to have a 2-7 times increased risk of stroke than the general population. Stroke symptoms include sudden weakness, numbness and paralysis. Walking may become difficult with dizziness and loss of balance. An individual may have trouble seeing, speaking or understanding others. Personality may change and memory recall may be impaired. Emergency health services should be called immediately.
AF is now leading hospital admissions, surpassing heart failure. In Australia, hospitalizations for AF have tripled. Older, overweight men are most at risk for hospitalizations. 3 million people in the U.S. have AF. Canada has a quarter million AF patients and the U.K. has 800,000 AF patients. Atrial Fibrillation is mostly intermittent, however 25% of patients have chronic and long-term AF.
Finding individualized and customized treatment for each patient is critical. No current method is uniformly effective for all patients. Drug therapy is difficult as frequent blood tests and dosage levels must be monitored closely. A monitoring schedule to ensure therapeutic dosing levels appears to be difficult for a third of patients who are eligible for medications. Elderly patients may not have the resources to visit the physician for frequent monitoring. Food and drug interactions often interfere with AF drugs. Medication just fails in a majority of cases, as well. More aggressive treatment is likely to be needed. Electrical stimulations devices may need to be implanted to stimulate the heart. Ablation or removal of tissues or cells may be necessary. All available drugs and therapies have the potential to cause harm.
What Could Cause Atrial Fibrillation?
Men and women receive different levels of care according to researchers. Women are less likely to be tested for ejection fraction, the measurement of how efficiently the heart pumps blood. Women are less likely to be implanted with cardioverter defibrillators (ICDs), to find and correct AF events. Women are less likely to receive blood thinners, even though women have a higher risk of stroke. Men also do not always receive blood thinners. A quarter of the male patients admitted to hospitals have procedures performed for AF while women only had procedures performed 18% of the time. Women also have a 10% higher chance of being hospitalized for more than a week. The chance of dying in the hospital, however, is the same for men and women. About 3% of men and women die in the hospital. The gender gap is clear for both differences in disease states, and also the level of care received. Other gender differences include:
- Heart problems – average age is 74 for women vs. 69 for men.
- Hypertension – 77 percent for women vs. 72 percent for men.
- Coronary disease – 44 percent for women vs. 53 percent for men.
- Renal insufficiency – 18 percent for women vs. 23 percent for men.
Genetic variants or heritability is associated with AF risk. People with atrial fibrillation may have a 30% chance of having inherited the genes that cause AF. A variety of genes influence heart diseases such as atrial fibrillation. The heart cell’s nucleus contains DNA and hereditary information coding for the behavior of other genes. The gene MLIP (Muscle enriched A-type Lamin Interacting Protein), can become mutated. Degenerative heart muscle disease mutations are associated with the Lamin gene family. The KCNE2, KCNJ2, and KCNQ1 genes may also be implicated in AF. Understanding the loss of cardiac function is improving with the discovery of genes that increase the risk.
- Stroke –the major risk factor for patients with AF and the third leading cause of death overall. Medication for AF often comes with a side effect of bleeding. Vitamin K antagonists, including the well known drug Warfarin can reduce blood clotting, but Warfarin has downsides including frequent monitoring and negative interactions with food and drugs. The dosage of Warfarin has to be just right. Not enough of the drug could cause a stroke and too much could cause a serious or fatal hemorrhage. Newer drugs may overcome those difficulties and reduce the need for regular and lifelong blood testing. An ischemic stroke is the most common type of stroke. When an artery to the brain becomes blocked, a stroke or thromboembolism occurs.
- Congestive Heart Failure (CHF) – an older term, currently replaced with just heart failure. When the heart’s blood pumping mechanisms are inadequate, the whole body suffers. Muscles and coordination decline. The brain also needs an adequate supply of blood to control bodily functions and cognition. Heart failure can be a contraction problem or a filling problem or both. When the heart does not fill up with enough blood, it is considered a filling problem. When the heart does not contract enough to send blood out, it is considered a contraction problem. Patients with AF are more likely to have some variety of heart failure.
- Cognitive Dysfunction – AF can lead to stroke which can often lead to dementia. AF also can contribute to dementia in the absence of stroke, as well. Researchers find that dementia and AF are more likely with increased age. When the heart is pumping inefficiently, less blood supplies the brain and cognitive abilities decline. Subtle differences in the way the brain conserves energy can contribute to dementia. Small blood clots in the brain can go undetected and inflammation may lead to dementia as well.
- Osteoporosis – people with atrial fibrillation are twice as likely to have vertebral fractures as the general population. Spinal compression fractures are frequently underestimated as a complication of heart failure and AF. Osteoporosis, along with AF and dementia, also increases with age. Clinicians often do not detect osteoporosis, because the most common form of osteoporosis, vertebral fractures, go unnoticed. Vertebral compression fractures can lead to more vertebral fractures, and even more devastating hip fractures.
Preventing Atrial Fibrillation
Uncovering and correcting behaviors and conditions that may cause AF is an important first step. Stimulant drugs, hypertension and hyperthyroidism can cause atrial fibrillation. Obesity is directly responsible for atrial fibrillation. Other steps for prevention include:
Stimulant drugs, Smoking and Alcohol – cardiac arrhythmias due to these behaviors are usually not associated with long-standing heart disease. Arrhythmias tend to stop when these behaviors are discontinued.
High blood pressure – hypertension is implicated for more than one-fifth of all cases of AF. Reducing or controlling high blood pressure may resolve AF.
Hyperthyroidism – too much thyroid hormone can cause AF symptoms. 5-15% of hypothyroidism patients have AF symptoms, which can be resolved.
Diabetes – AF incidence is higher in diabetic vs. non-diabetic patients. Researchers are not sure why people with diabetes are more likely to have AF. Diabetics have larger left atria, increased inflammation, diastolic dysfunction, and sleep apnea. Seeking treatment for diabetes may reduce AF incidence.
Obesity – directly causes electrical abnormalities in the heart. More than half the cases of AF could be resolved with body mass index reductions. Overweight and obese people have changes in their hearts. Elevated body mass influences the size and structure of the heart muscle. These structural differences change the way the heart works. By 2020, researchers estimate that 75% of AF cases will be due to obesity. However, AF can be reversed when people lose weight.
NSAIDs or COX-2 inhibitors – nonsteroidal anti-inflammatory drugs are medications like aspirin and ibuprofen. They are used for pain relief, lowering fever, arthritis, blood thinning, and other prescribed uses. However, they are associated with increased AF. Older people, those with kidney disease and rheumatoid arthritis are at increased risk of AF when using NSAIDs.
Additional Risk Factors
Besides the validated risk factors for AF previously mentioned, additional predictors of cardiovascular disease, heart failure and AF include:
- Emotions – variations in personality and emotional response may make people susceptible to AF. High anxiety can increase stress hormones, making people more vulnerable to worsening heart symptoms.
- Mitral valve – disease between the left and right ventricle of the heart.
- Height – risk rises markedly with 10 cm. increments in height.
- Sleep apnea – oxygen deprivation at night, due to intermittent collapsed airway.
- Excessive endurance sports.
- Lung diseases – low amounts of oxygen in the blood from emphysema, asthma or chronic obstructive pulmonary disease (COPD).
Atrial Fibrillation Diagnosis
AF often goes unnoticed, undiagnosed and untreated. Many patients with atrial fibrillation have no symptoms at all. If symptoms are noticed, they can occur in episodes and vary in severity. A stroke is often the first sign of AF, unfortunately. Common validated symptoms are palpitations and shortness of breath. Dizziness, fainting, weakness, and fatigue may also or separately occur. The main symptoms of AF caused by inefficient blood flow include:
- Palpitations – rapid and irregular heartbeat.
- Dyspnea – shortness of breath or a hunger for air.
- Angina – chest pain due to reduced blood flow to the heart muscles.
Physicians rely on clinical judgment with routine physical examinations or ECG tests to identify AF risks. More efficient risk assessments have been developed:
CHADS2 index – the most accepted risk stratification model to tailor anticoagulation therapy. This screening index is also a valuable tool for predicting cerebrovascular events in high-risk patients. CHADS2 score is used for the evaluation of stroke risk in patients with AF. The presence of heart failure, hypertension, advanced age, diabetes and previous stroke are factored into the score. Each component gives a score of 1 and a stroke earns a score of 2. The higher the score, the greater the risk. A score of 2 or higher merits permanent treatment with oral anticoagulation drugs.
ISCORE – A new online tool for estimating risk factors. Researchers found the test has a high degree of accuracy and reliability for predicting stroke. Atrial fibrillation, heart disease, age, smoking, cancer, dementia and kidney disease incidence can predict the probability of stroke and death.
Many factors for AF remain unclear and therefore cannot be tested for. A physical exam of the patient can identify high blood pressure and heart failure. Blood tests are used to find biomarkers of thyroid levels, electrolytes, blood oxygen and carbon dioxide levels. Genetic testing may indicate some cardiovascular risk factors. Chest x-rays are often ordered for heart and lung evaluation. A treadmill test, where a patient walks or runs with EKG sensors is often useful. Common tests include:
- EKG (electrocardiogram) – if AF occurs during the test, this test can easily recognize electrical abnormalities. AF is definitively diagnosed with this test.
- Holter monitor – when AF does not show up with an EKG, a continuous, round the clock monitor may be given to the patient for later interpretation.
- Echocardiography – ultrasound waves are used to produce an image of the heart as it works. AF along with other heart problems can be diagnosed. AF treatment can also be tailored with this tool, according to how the atria is structured and functions.
- Delayed-enhancement magnetic resonance imaging (DE-MRI) – very useful for detecting left atrial fibrosis associated with stroke. This test can be used with the CHADS2 index for risk analysis and for tailoring treatment.
- Ejection Fraction – a measurement of how well the heart pumps out blood.
Sometimes an AF episode occurs only once, sometimes due to stress or substance abuse. This is diagnosed as Lone atrial fibrillation (LAF) because no other clinically relevant symptoms can be found. Secondary AF is diagnosed when atrial fibrillation is caused by another primary condition like hypothyroidism. Other times, an individual may have a combination of diagnoses. One classification may dominate at times or events may worsen or get better over time. The main classifications used for general purposes and simplicity are:
- Only one diagnosed episode – First detected.
- Recurrent episodes that self-terminate in less than 7 days – Paroxysmal.
- Recurrent episodes that last more than 7 days – Persistent.
- Ongoing and long-term episodes – Permanent.
Atrial Fibrillation Treatment
Physicians attempt to improve AF with synergistic methods and a comprehensive approach. Better detection, screening and management of risk factors, anti-stroke medications, and more aggressive rhythm control therapies in early stages improve outcomes for AF patients. Preventing stroke with anticoagulation drugs is the cornerstone of AF treatment. However, these drugs do not produce a cure and a significant percentage of AF patients on medication can still have a stroke and die.
Physicians attempt to help the patient take control of some of the factors that influence AF. Instructions for lifestyle improvement can be given, treatment attempted and modified as necessary. Follow up appointments are often necessary and recommendations are given for what to do in the case of worsening symptoms.
Common treatment options include:
- Blood pressure and cholesterol level managed.
- Medications like blood thinners or anticoagulation drugs, enzyme inhibitors, and beta blockers may be prescribed.
- Implantable cardioverter defibrillators (ICDs) correct abnormal heartbeats.
- Smoking cessation counseling.
- Weight monitoring.
- Nutritional advice.
- Mental Health.
Rate and Rhythm
Rate control is more likely to be used in chronic phase AF. The heartbeat is brought to a more normal beats per minute, usually 60-100 bpm. Medication is used to disrupt the pathways that influence AF, without trying to force the heart into a regular rhythm.
Rhythm control is a more complicated method with equal effectiveness in outcomes and mortality rate, to the rate control method. However, patients with a high degree of anxiety had improved response to the rhythm control method. Newly diagnosed AF patients often use rhythm as well. This method uses medication and cardioversion, an electric shock device, to restore a regular heartbeat.
Warfarin – one of a few anticoagulation drugs used to thin the blood and prevent blood clots. Aspirin therapy is the simplest blood thinner. The mainstay of AF treatment is Warfarin, brand name Coumadin, introduced in 1954. Warfarin is very effective in preventing stroke. About one half to two thirds of patients receiving Warfarin can avoid a stroke. Warfarin acts by blocking Vitamin K-dependent molecules and is called a Vitamin K agonist. Vitamin K molecules get blood to thicken and clot. Clotting of blood is critical to stop bleeding and heal wounds. Warfarin treatment has some serious downsides including uncontrolled bleeding and requirements for the patient to have regular monitoring, testing and dosage adjustments.
Warfarin use is compromised, however, with other drug use, diet and supplement use. Researchers have discovered that patients often use Warfarin with supplements and 50% of the time, they are unaware of potential negative interactions. 69 percent of the top 100 supplements used, have actions that interfere with Warfarin. Patients often use fish oil, glucosamine and vitamins as supplements to their diets. These supplements can either intensify Warfarin, potentially increasing the risk of bleeding, or reduce its effectiveness, inviting a greater chance of a stroke. Patients are often inconsistent with their Warfarin use and fail to tell their physicians about supplement use. Patients who took supplements often skipped their Warfarin dose or took extra doses unnecessarily.
Diet choices can also affect Warfarin’s effectiveness. Vitamin K intake must be monitored and regulated. Green leafy vegetables like collard and kale are high in Vitamin K. However, the same green leafy vegetables are also high in anti-inflammatory properties and promote a healthy immune system. Eating small amounts of foods rich in Vitamin K is generally seen as harmless so long as it is within limits. The average daily allowance of vitamin K for adult men is 120 micrograms (mcg). Adult women can have up to 90 mcg. Talking to a physician about diet and supplement use is the best course of action when taking Warfarin or any other medication.
Dabigatran – marketed as Pradaxa, was approved by the U.S. Food and Drug Administration on Oct. 19, 2010 for the prevention of stroke in patients with atrial fibrillation. Dabigatran is the first new drug in 20 years to be approved in the U.S. for stroke prevention. It has been sold in Canada and Europe since 2008. This is a new drug and may mean a new era for AF patients. Dabigatran is a safer anticoagulant and works by inhibiting the enzyme thrombin.
This new drug does not require blood testing. It is more like aspirin and simple to use. Effectiveness is equal to Warfarin, with a lower risk of bleeding. Because of its molecular action, it does not react negatively with food. However, some studies report a slightly increased risk of heart attack.
Other drugs under investigation and in clinical use in some areas include:
- Eplerenone – brand name, Inspira, an aldosterone antagonist. Aldosterone is a hormone made in the adrenal gland and helps regulate blood pressure, fluids and electrolytes. Aldesterone in high levels can lead to AF. Eplerenone is available generically in the US.
- Rivaroxaban – as effective as Warfarin in reducing the risk of stroke. This drug does not need to be as closely monitored as Warfarin nor have the dose adjusted.
- Clopidogrel– a combination with aspirin recommended for patients who are poor candidates for Warfarin.
Cardiac Ablation Technique
When medications don’t work, or stop working, a technique called catheter ablation is recommended. In use since 1997 and growing in use, ablation is when a long, thin tube is threaded through the vein in the groin area and up into the heart. Typically the tip of the tube, the catheter is heated or radiofrequency energy is used and ablation or burning of the heart’s inner surface is performed. Scar tissue forms around the burns to isolate the irregular heartbeats. Erratic electrical signals are blocked from spreading and so cancel out atrial fibrillation. Ablation is successful for about 70 percent of patients.
Ablation does not always work and patients must return a second or third time. The heart may be so strong that blocking its signals may not work the first time. The patient and physicians are exposed to radiation with this procedure as X-rays are used to guide the catheter through the vein. Patients who qualify for ablation:
- Those who have not had success with drug treatment.
- Those who have a normal or mildly dilated left atrium.
- Those with symptomatic paroxysmal atrial fibrillation.
- Those who do not have severe lung disease.
- Those who have normal or mildly reduced function of the left ventricle.
- Those with symptomatic persistent atrial fibrillation.
Currently, patients with chronic AF must use a defibrillating device which shocks the heart into a normal rhythm. Patients feel a shock, often painful. The shock can damage the tissue around the heart. The strong electric pulse may be unnecessary according to researchers. A new low-energy device called LEAP (Low-Energy Anti-fibrillation Pacing) reduces the shock by 80 percent. This low energy pulse may be painless for the patient and cause less damage to the heart. A cardiac catheter delivers 5 signals much weaker than conventional devices. The low energy stimulation forces the heart to resume beating normally. It only takes a few seconds for the heart to beat regularly again.
The new procedure recruits blood vessels, fatty tissues and fibrotic tissues to initiate a cascade of electrical activity, step by step. These helper tissues synchronize electrical activity and terminate erratic pulses. The low energy pulses act to set off waves within the helper tissues. The whole heart is reprogrammed when the helper tissues coordinate themselves to stop AF electric activity. The malfunctioning heart is stimulated to act normally when tiny doses of electricity recruit smaller control tissues.
Get With The Guidelines®-Heart Failure program
The American Heart Association runs a “Get With The Guidelines®-Heart Failure” program. This program attempts to offer quality improvement information to health care providers. A database with 3.5 million patient records is currently being mined for quality improvement points. Identifying strengths and weaknesses in health care delivery can improve patient outcomes. This program identified weaknesses in the gender gap for atrial fibrillation. The data showed that women with AF were less likely than men to receive blood thinners and cardioversion therapy. Providers can use the data to find racial discrepancies, overall care issues and a multitude of issues of concern to patients.
Ablation procedures currently use X-rays to guide the catheter through the vein in the groin up into the heart. Operating times may be reduced now with a new computerized catheter. Maneuverability and control improvements for catheter threading can reduce the time patient and physicians have to endure X-rays or radiation. Less time in the surgical room also means less expensive treatment. The new device is computerized and made of smart materials which can bend and maneuver in all directions. A special joystick controls the catheter and computer software can help locate precise positions where ablation burns should be placed. Efficiency is improved and patients may not have to return for second and third procedures.
A hybrid procedure has been developed to improve the highly effective ablation procedure with a minimally invasive surgical technique. AF patients can reduce their risk of stroke with a single procedure. Physicians at a few medical centers can perform this procedure. A two pronged approach applies burns to the heart’s inner and outer surface. Scar tissue forms on both the inner and outer heart and more effectively blocks signals which cause the heart to behave erratically. Traditional ablation performed through the vein can only access the inside of the heart. However, the hybrid procedure is minimally invasive surgery and can access the outside of the heart as well.
Surgeons make three tiny incisions near the patient’s armpit. One incision is used for a small camera and the other two incisions are for surgical instruments. Once the surgery is complete on the outside of the heart, the ablation procedure is performed on the inside of the heart. The ablation points are tested until surgeons determine that signals are blocked that induce AF. The goal is to make a complete scar across the full thickness of the heart to permanently cure AF. The final step is to close the left atrial appendage or the site where most blood clots begin.
The Arctic Front Device
Patients who received cardiac ablation with cryotherapy became free of AF within one year. Using cold instead of heat or radiofrequency at the tip of the catheter can reduce the time necessary for surgery. The outcome for patients was similar to heat ablation with limited negative effects. The device is called The Arctic Front device, was developed in Montreal and is manufactured by Medtronic.
Cysteine is an amino acid and antioxidant found in blood, and is easily measured. Patients with high levels of cysteine were 2 times more likely to develop AF. Cysteine is a biomarker for oxidative stress. When oxidative stress is present, the heart remodels its structure and action in the cellular metabolism pathways. Researchers hope that measuring oxidative stress biomarkers like cysteine can help them detect AF earlier and with better precision.
Fatty acid intake with food such as salmon or with supplements from fish oil have been studied and thought to improve AF. One study did not find this to be true. Patients were given high doses of prescription omega-3 and studied for six months. Researchers found that omega-3 did not reduce the recurrence of AF. However, scientists did point out some inconsistencies in their studies. Fish oil may not have fast acting effects, as half of the AF events in the study group, occurred in the first two weeks of the study. Product formulations and dosing schedules may have also played a part in the weak results. Another long term study conducted over a period of 3 years had more positive results. Deaths were reduced by 20% with one gram of prescription fish oil per day.
In Italy, it is considered malpractice for a physician to send a patient home without a prescription for fish oil, after a heart event. Researchers say that since fish oil is not licensed in many countries to heal heart disease, pharmaceutical companies do not promote it. Physicians often prescribe what big pharmaceutical companies recommend. Therefore, patients do not receive recommendations or prescriptions for fish oil in many parts of the world. One study found that only17 percent of family doctors prescribe fish oil for any reason, including for heart problems. Many people including physicians seem to view omega 3 as a dietary supplement and not as a powerful agent with curative abilities. More studies are being conducted, however, there is very little evidence that shows omega 3 has any negative effects. Fish oil does have proven benefits for general health and disease conditions and may still be a source of hope for AF patients.