Clinical Practice Guideline
Developed for the
Aerospace Medical Association
by their constituent organization
Overview: The aeromedical disposition of atrial fibrillation (AF) associated with underlying disease should be guided by policies for the underlying disease [e.g., hypertension, hyperthyroidism, congestive heart failure, valvular heart disease, cardiomyopathy], with the AF considered a complication or endpoint. This guideline addresses lone AF, a misleading term in the cardiac literature which would be better termed idiopathic AF. Lone (or idiopathic) AF is defined as AF without structural heart disease, hyperthyroidism or hypertension in patients under age 60 at presentation. Lone AF may occur as a single isolated episode, recurrent paroxysmal events or chronically persistent AF. AF encountered in the younger aviation population will usually be lone AF that is converted spontaneously or by medical intervention within 1-2 days. Single idiopathic episode often has an identifiable precipitating cause, such as acute abuse of alcohol and /or stimulants (holiday heart syndrome).
Atrial flutter rarely occurs as an isolated rhythm; it is usually associated with atrial fibrillation. This guideline addresses idiopathic atrial flutter, not associated with an underlying disease. The atrial rate of atrial flutter is about 300 beats per minute. Typically there is physiologic AV block of 4:1, 3:1 or 2:1, yielding a ventricular rate of about 75, 100 or 150 beats per minute, respectively. However, 1:1 conduction with a ventricular rate of about 300 beats per minute is possible, especially in young, healthy subjects. With expected resting ventricular rates up to 150 beats per minute, persistent or frequent atrial flutter requires AV node blocking medication for ventricular rate control.
Initial treatment of AF or atrial flutter depends on individual’s clinical status with the objectives being to slow the ventricular rate and/or restore sinus rhythm. Mediations and/or cardioversion may be used. In cases of lone AF, after sinus rhythm is restored, one month of prophylactic therapy with a beta blocker, calcium channel blocker or digitalis preparation maybe used to suppress short-term recurrence of AF, without delaying the waiver process. A history of cardioversion or short-term use of antiarrhythmic medications does not preclude waiver.
Medications and/or radiofrequency ablation are used for long term management of paroxysmal and chronic AF and atrial flutter. Paroxysmal and chronic AF often require chronic treatment with an atrioventricular (AV) node blocking medication, such as a beta blocker, calcium channel blocker or digitalis for ventricular rate control. Nifedipine used to treat hypertension in aircrew (Procardia XL® and Adalat CC®) is not effective for AV node blockade. The beta blocker, atenolol, is the only AV node blocking agent currently approved for military aircrew. Atrial flutter can also be treated with AV node blocking medication, but control is often difficult to achieve. Both AF and atrial flutter may also be treated by radiofrequency ablation. Ablation of atrial flutter is very low risk, technically simple and essentially 100% curative. Radiofrequency ablation for AF is 70 to 85% effective in individuals with paroxysmal AF and 50 to 70% in individuals with chronic AF.3
Aeromedical Concerns: Clinical and aeromedical concerns for lone AF and atrial flutter include hemodynamic instability and exercise tolerance, thromboembolic risk and requirement for chronic medication to maintain sinus rhythm or to control ventricular rate. Loss of atrial contribution to cardiac output, loss of atrioventricular synchrony, and rapid ventricular rate response may impair cardiac performance, especially during exertion, resulting in hemodynamic symptoms or reduced exercise capacity. This reduced exercise capacity has operational implications, especially for pilots in high performance aircraft. AV blocking medication may be required – without such the ventricular rate response of AF during exertion may quickly increase to the range of 220-250 beats per minute. AV blockade with a beta blocker, by suppressing heart rate and blood pressure response, adds to the concern regarding +Gz tolerance. Published guidelines regarding the management of AF advise that beta blockers are safe and effective for long-term control of ventricular rate response at rest and during exercise. This effect was felt to be drug specific, with atenolol and nadolol being most efficacious.
Clinical literature typically reports cardiac event rates less than 1% per year for lone AF, whether a single event, paroxysmal or chronic. Previously, waivers for AF were limited to an isolated episode without hemodynamic symptoms. In order to better define the natural history of lone AF in a young and otherwise healthy population and refine waiver policy, the USAF Aeromedical Consultation Service (ACS) reviewed its experience with AF in aircrew. From 1957 to 1993, 300 male aircrew were evaluated for AF approximately 6 months after the initial AF episode. Two hundred thirty-four of the 300 (78%) were found to have lone AF. Events considered were hemodynamic symptoms, cerebral ischemic events, and sudden cardiac death. The arrhythmic event rate prior to age 60 was low (0.4% per year) and the likelihood of a cerebral ischemic event before age 60 without chronic AF was minimal (none in this review). Of those initially presenting with an isolated episode of AF, 63% had no recurrence, 36% developed paroxysmal AF and 1% developed chronic AF. Of those presenting initially with paroxysmal AF, 15% subsequently developed chronic AF.
Medical Work-up: Before waiver can be considered for a history of afib or aflutter, an internal medicine or cardiology consult will be needed to rule out underlying organic heart disease or thyroid disease. This will include a complete history and physical exam to include description of any symptoms, blood pressure, medications, and activity level. Local evaluation would also include thyroid function tests, repeat ECG (if possible, a tracing prior to treatment and after treatment), echocardiogram, exercise treadmill, and three 24 hour Holters (may be accomplished in 72 hours). If thyrotoxicosis is determined to be the cause of the afib, waiver can be considered after the correction of the thyrotoxicosis. If the aviator had treatment more extensive than medication, a complete history of this treatment along with any accompanying tracings and reports will be required.
Air Force: The airman’s evaluation will include a flight medicine and internal medicine evaluation. Procedures include routine labs, ECG, TFTs, chest X-Ray, cardiac fluoroscopy, echocardiogram, PFT’s, 24 hour Holter, thallium (for evaluees over the age of 35), and treadmill. Chronic or recurrent-sustained afib will most likely not be considered for a waiver. The majority of these cases will require a visit to the Aeromedical Consultation Service for a complete work-up.
Army: Atrial fibrillation and flutter are disqualifying for aviation service according to AR 40-501 and thus require waiver. These conditions each have their individual Aeromedical Policy Letters which outline waiver guidelines. The range of acceptable therapeutic interventions and concerns are the same as those in the US Air Force. Waivers are possible for non-recurrent atrial fibrillation and flutter when precipitating factors are clearly identified and corrected. Waiver may be applied for six months after successful radiofrequency ablation treatment if that modality is selected. Exceptions to policy are usually not granted to applicants with recurrent atrial fibrillation and flutter.
Navy: The condition is CD. No waivers are recommended in recurrent cases or in candidates, but a return to full flight status is possible 6 months following a single episode of atrial fibrillation/flutter with a documented precipitating factor (e.g. Holiday Heart). No medications are waiverable. Waivers are not recommended for candidates.
Civilian: The FAA requires sometime after the diagnosis of the arrhythmia is made TFTs, 2 D echocardiogram, a maximal Bruce protocol stress test (maximal nuclear stress in the case of a first-or second-class airman), and a 24 hour Holter Monitor. The FAA allows all medications that are utilized for the prevention of the dysrhythmia as well as those medications that are used to slow the ventricular response. More specifically in the case of flecainide, the airman cannot have had a myocardial infarction. Amiodarone is only acceptable in low doses less than or equal to 200 mg twice daily. Radiofrequency ablation is acceptable but a 90 day observation period is required. If the airman is cardioverted, this too requires a three-month period of observation.
The FAA is also very concerned over the prevention of thromboembolism. High risk individuals are those with chronic or paroxysmal AFIB who also have had a cerebrovascular event (stroke or transient ischemic attack), moderate to severe left ventricular dysfunction (LVEF < 40%), coronary disease, mitral valve disease, prosthetic heart valve or age over 75 and those with lesser risk are those individuals with hypertension, diabetes mellitus, thyrotoxicosis, and age 65-74. In individuals age less than 65 y/o and absent risk factors aspirin is acceptable and if risk factors are present, then warfarin is required. In ages between 65-75 with absent risk factors, aspirin or warfarin are acceptable and if the risk factors are present warfarin is required. The FAA requires that 80 % of the monthly International Normalized Ratio values be between 2.0 and 3.0. If the airman does not follow these guidelines, they are not granted medical certification.
Airmen who have 3.0 second or greater sinus pauses during the waking hours will have their authorization for special issuance withdrawn. If the resting heart rate is 100 or there are episodes where the heart rate is greater than 130-140 with minimal exertion the FAA will withdraw the authorization. Airmen with valvular heart disease and chronic AFIB are also generally not granted medical certification.
Air Force: Review of AIMWTS showed 138 cases of atrial fibrillation/flutter; one FC I, 98 FC II and 43 FC III. The aeromedical summaries were reviewed for all the disqualified individuals (18) and in 33 others selected randomly. Of the 18 disqualified, 14 were disqualified due to the atrial fibrillation/flutter requiring non-approved medications for control (radiofrequency ablation failed in three cases); four were disqualified for other medical conditions (e.g., stroke, ankle arthritis requiring narcotics, coronary artery disease, and bilateral vestibular hypofunction). Of the 33 cases randomly selected, all were approved for lone fibrillation without hemodynamic symptoms.
Army: Since 1990 there have been 123,259 aviators of all types, including applicants enrolled in the Aeromedical Epidemiological Data Repository. Among the rated aviators, there have been 82 cases of atrial fibrillation and flutter. The majority of these were fibrillation (78). Of note there were also 29 applicants with these rhythms. Fifty-three of the rated aviators were waivered and 25 suspended. Of the applicants, 18 with fibrillation were waivered and two with flutter were not, the others were lost to study.
Navy: Precise statistics are not available at this time.
Civilian: As of January 2010 there were 32 first-class, 92 second-class, and 722 third-class airmen currently issued with this medical condition.
ICD 9 Codes for atrial fibrillation and flutter
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Olgin JE, Zipes DP. Chapter 35 – Specific arrhythmias: diagnosis and treatment. In: Libby P, Bonow RO, Mann DL, et al eds, Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed. Philadelphia: Saunders Elsevier, 2008.
Strader JR, Jr, Gray GW, Kruyer WB. Clinical aerospace cardiovascular medicine. In: Davis JR, et al eds. Fundamentals of Aerospace Medicine, 4th ed. Philadelphia: Lippincott Williams & Wilkins, 2008; 344-345.
Prepared by Drs. William Kruyer and Karen Fox