Blacks With Atrial Fibrillation Have Much Higher Risk Of Stroke Than Whites

by NCN Health And Science Team Posted on September 16th, 2018

Houston, Texas, USA : Blacks with atrial fibrillation (AF or AFib) have significantly higher risk of stroke than whites. Compared with whites, blacks have a higher risk of developing an ischemic stroke whether the stroke occurred before or after an initial AF diagnosis, report scientists in a new population-based study published in HeartRhythm.

Blacks have a higher incidence of stroke and stroke-associated disability than whites. However, few studies have evaluated racial differences in stroke before a diagnosis of atrial fibrillation (AF or AFib). A new report published in HeartRhythm examined stroke risk in the short term prior to a diagnosis of AF. Investigators determined that, although blacks have a lower risk of developing AF, blacks with AF have a significantly higher risk of stroke during this period compared with whites with AF.

Investigators assessed racial differences in ischemic and hemorrhagic strokes using data on more than 3,500 patients from the Penn Atrial Fibrillation Free (PAFF) study with incident AF and without any history of stroke. This enabled them to evaluate strokes that occurred in a short window of time prior to the clinical diagnosis of AF, as well as ischemic and hemorrhagic stroke risk after the diagnosis of AF. PAFF consists of nearly 57,000 patients from the University of Pennsylvania Health System who were free of AF or atrial flutter at the beginning of the study.

“Our study design was unique because we have a time point that represents the initial diagnosis of AF,” explained senior author Rajat Deo, MD, MTR, Associate Professor of Medicine, Section of Electrophysiology, Division of Cardiovascular Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA. “A better understanding of the burden of AF before and after an ischemic stroke is important. Anticoagulation with newer agents such as novel oral anticoagulant (NOAC) medications could help mitigate the risk of a first stoke and recurrent events.”

The study showed that nearly half of the ischemic strokes in this population (254/538) occurred within six months before the diagnosis of AF. In many cases stroke was the presenting symptom of AF. Analysis demonstrated that blacks with a new diagnosis of AF were 62 percent more likely to have had an ischemic stroke prior to AF diagnosis than whites who developed AF. In strokes that occurred after the diagnosis of AF, blacks had 67 percent higher and independent risk of developing an ischemic stroke compared with whites with AF.

“The clinical implications of these findings indicate that a more rigorous effort to identify individuals from the community with AF, for example by using mobile and wearable technologies, may result in a reduction in overall stroke burden. Further, any effort to enhance AF management across diverse populations is a critical area of public health importance. A widespread screening effort to diagnose subclinical AF may help to reduce the racial disparities observed in the incidence of stroke,” commented Dr Deo.

In an accompanying editorial, Sumeet S. Chugh, MD, FHRS, from the Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, observed that an earlier study into reasons for geographic and racial differences in stroke reported a significantly lower awareness of AF and anticoagulation in blacks. The same study also showed that self-reported AF is a strong predictor of stroke that can be used interchangeably or in combination with electrocardiogram-detected AF in stroke risk prediction models.

“Dr. Deo and colleagues are to be congratulated for successfully bringing together the electronic data repositories of several hospitals to study their PAFF cohort,” stated Dr. Chugh. “Their findings provide a strong impetus for implementing community-based efforts that address racial disparities in AF and stroke. Given what we already know, it is time to act on these disparities, while continuing to investigate other factors such as differential access to preventive healthcare and compliance with prescribed medications.”

What is Atrial Fibrillation? (AFib)

Atrial fibrillation (AFib) is the most common type of arrhythmia (abnormal heart rate or rhythm). During AFib, the heart’s upper chambers (atria) beat in an irregular pattern (fibrillate).

Normally, the electrical signals that control the heartbeat begin in an area of the right atrium called the sinoatrial node. The signals travel from the atria to the heart’s lower chambers (ventricles). This electrical pattern causes the heart’s chambers to contract in a coordinated rhythm that pumps blood from the atria to the ventricles.

In AFib, the electrical signals originate in other parts of the atria or in the pulmonary veins, which bring blood from the lungs into the right atrium. The signals spread through the atria in a disorganized way, causing fibrillation.

As these erratic electrical signals spread through the heart, the ventricles also begin to beat rapidly, but out of sync with the atria. As a result, the atria cannot properly pump blood to the ventricles, which in turn cannot pump enough blood to the body.

Atrial fibrillation prevents your heart from pumping blood normally. It increases your risk of stroke and can lead to heart failure.

Symptoms Of Atrial Fibrillation

You may not notice any symptoms at first. Symptoms may occur only occasionally or constantly, depending on the type of AFib you have. Common symptoms include:

  • Chest pain or discomfort
  • Difficulty exercising because you tire easily
  • Fatigue or low energy
  • Heart palpitations (feeling that your heart is beating too hard or too fast, fluttering, or skipping a beat)
  • Lightheadedness, dizziness, or fainting (syncope)
  • Shortness of breath\
  • Weakness

Causes Of Atrial Fibrillation

In some people with AFib, the cause is unknown. This condition is known as lone AFib. Usually, AFib results from damage to the heart’s electrical system from other health conditions, such as:

  • Blockage of a lung artery (pulmonary embolism)
  • Congenital heart disease (heart birth defects)
  • Heart conditions, including a heart attack, heart failure, cardiomyopathy, coronary artery disease, or valvular heart disease
  • Heart surgery, such as bypass surgery
  • Inflammation of the membrane that surrounds the heart (pericarditis)
  • Stress from pneumonia or other infections
  • Thyroid problems, especially an overactive thyroid (hyperthyroidism)
  • Use of some medications, including certain decongestants and diet pills
  • Use of stimulants such as caffeine, tobacco, excessive alcohol use, and some illegal drugs

These factors may increase your risk of AFib:

  • Chronic health conditions such as chronic lung or kidney disease, diabetes, high blood pressure, or sleep apnea
  • Family medical history
  • Increased age
  • Obesity

Types of Atrial Fibrillation (AFib)

There are three types of AFib, determined by how frequently they occur. The symptoms and causes of all three types are the same. AFib may occur more frequently over time and can become permanent.

Paroxysmal Atrial Fibrillation

This type of AFib occurs occasionally, starting and stopping on its own. Paroxysmal AFib can last for just a few seconds or minutes, or it can last hours or days before your heart returns to its normal rhythm. As the AFib comes and goes, your pulse rate may go from slow to fast and back to slow in a short time.

Persistent Atrial Fibrillation

This AFib continues for more than a week. It may resolve on its own, or it may require treatment.

Permanent Atrial Fibrillation

The permanent type does not go away, either by itself or with treatment. Medications and other treatments can control your symptoms and manage the condition. These treatments can help maintain a regular heart rate and rhythm or thin your blood to help prevent stroke.

No matter what type of AFib you have, the arrhythmia experts at Stanford can help. Our doctors participate in groundbreaking research to develop improved therapies for AFib and other types of arrhythmias.

Aadvanced treatments for AFib include:

  • Several types of cardiac ablation
  • Implantable cardioverter-defibrillator (ICD)
  • Pacemaker
  • MAZE procedure

Diagnostic Tests for Atrial Fibrillation (AFib)

Diagnostic Tests for Atrial Fibrillation by an arrhythmia team starts with a comprehensive diagnostic evaluation, taking extra time and care to thoroughly understand your symptoms. reputation for our deep Advanced diagnostic testing for atrial fibrillation includes:

  • Blood tests: We check for levels of thyroid hormone, electrolytes, and other substances that can cause AFib.
  • Chest X-ray: This imaging study uses radiation to produce images of your heart.
  • Echocardiogram (echo): This test uses sound waves (ultrasound) to create detailed images of your heart. The type used most often is a transthoracic echocardiogram (TTE), which captures the images from several locations on your chest.
  • Electrocardiogram (EKG): This painless, noninvasive test uses a monitor with electrodes attached to your body to measure your heart’s electrical activity.
  • Holter and event monitors: These portable EKG monitors record your heart’s electrical activity over a longer time. Holter monitors record your heart continuously for 24 to 48 hours. Event monitors record abnormal activity only when it occurs, over several weeks.
  • Stress test: This test measures your heart’s electrical activity using an EKG while you exercise on a treadmill or stationary bicycle.
  • Transesophageal echocardiogram (TEE): This type of echocardiogram (echo, or heart ultrasound) is an imaging test that uses sound waves to produce images of the heart’s structures. A TEE involves an ultrasound probe inserted into the mouth and down the esophagus to provide more detailed images than an external echo.

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