Atrial Fibrillation and Flutter in Endurance Athletes
Monday September 28, 2009
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AF Risk Factors
• Myocardial infarction
• Abnormal heart valves
• Congenital heart defects
• Sick sinus syndrome
• Viral infections
• Previous heart surgery
• Sleep apnea
• Hyperthyroidism or other metabolic imbalances
• Exposure to stimulants such as medications, caffeine, tobacco, or alcohol
• Emphysema and other lung diseases
• Stress from pneumonia, surgery, or other illnesses
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“When the heart beats normally, its natural pacemaker - the sinoatrial node - in the top right chamber (atrium) of the heart sends out electrical impulses at regular intervals signaling the ventricles to pump,” says Frederick Ehlert, MD, an associate clinical professor of medicine and the director of the Cardiac Electrophysiology Fellowship Program at Columbia University’s College of Physicians and Surgeons in New York. “Atrial fibrillation is the result of electrical chaos in the atria that causes the heart to beat rapidly and erratically.”
In contrast to AF, atrial flutter refers to a heartbeat that is extremely fast but still regular. It can, however, progress to AF.
Compared with ventricular fibrillation, the instigator of cardiac arrest, AF is usually not life threatening on its own, but coupled with other conditions, it can lead down a risky road.
“A continually elevated heart rate has the propensity to weaken the heart sufficiently to allow congestive heart failure to develop,” Ehlert says. “In addition, AF is associated with stroke, so it is important that other stroke risk factors be considered in patients presenting with AF symptoms so that they can be prescribed anticoagulants if indicated.”
Cardiologists concur that the most significant risk factor in AF is age: 0.1% in the 30-year-old population, increasing to 2.4% by age 80. Aging is accompanied by muscle loss, fibrosis, and a greater likelihood of other factors predisposing to AF, such as leaky heart valves and hypertension. Although additional risk factors abound, “lone atrial fibrillation” can occur in the absence of any.
“Statistics show that more and more people are getting involved in endurance sports,” says Stephen Black, DSc, PT, ATC/L, NSCA-CPT, an Ironman triathlete as well as an athletic trainer and strength and conditioning coach at Rocky Mountain Human Performance Center in Boulder, Colo. “However, the typical endurance athlete exercises too long, too often, and at too high a heart rate, which significantly elevates their odds of sudden-onset exercise-induced AF.”
The most prevalent explanation for this correlation is that sustained physical training enlarges the diameter and volume of the atria. Such substrate alterations force changes in the generation and dispersion of electrical impulses, thus predisposing athletes to an uneven and/or rapid heartbeat. Sometimes, that’s all it takes to trip the wire. “Exercise is proven to be good for the heart because it enhances its structure, increases vagal tone, and lowers its resting rate,” Ehlert says. “However, all those things also can cause extra beats, and the more of those you have the higher the likelihood of triggering AF.”
“Anyone with AF should seek medical attention, [because] it can be persistent or self-resolve but recur without notice,” Insel says. “Athletes with new-onset AF should not train until it has been addressed and they are cleared to resume.” Once AF is diagnosed, the first line of defense is to re-establish a regular rhythm, either with anti-arrhythmic medication or cardioversion (shocking the heart into a normal rhythm), after which patients should rest a few days before being re-evaluated. Often this process is sufficient, but some patients require long-term treatment, including medication, cardiac ablation (electronic destruction of short-circuiting tissue), modified training programs, and routine follow-ups.
“While our approach is to find a workaround that returns athletes to their former training levels, it’s not always possible,” Black says. “I’ve treated a few whose extenuating circumstances — valve issues, previous lifestyle and/or genetic predisposition — required us to reduce their activity to just a daily walk or a downhill ski at a conservative level,” he says. “It’s often such a dramatic lifestyle change that I strongly encourage psychological counseling through the transition.”
AF is a serious but not necessarily permanent condition. Experts agree there are actions that can be taken to alleviate or at least accommodate the condition and continue training. It also offers an ideal opportunity for PT involvement. “PTs have a lot to offer in the realm of physical and cardiac health, and it’s a two-way street,” Black says. “From a revenue perspective, the increasing popularity of endurance sports together with an aging population makes a cardiology specialty well worth considering.”
Ceri Usmar is a medial writer for TodayinPT. To comment, e-mail pteditor@gannetthg.com.
