(Editor’s note: Health Care Ethics is a new column featuring Catholic health care experts from St. Thomas Aquinas Guild of the Quad Cities sharing their thoughts on timely issues.)
Atrial fibrillation (AF) is the most common heart rhythm abnormality. In AF, the top chambers of the heart — the atria — no longer pump blood into the lower chambers — the ventricles — at normal rates of 60 to 100 beats per minute, but simply quiver (fibrillate) with electrical rates of 350 to 400 per minute. In AF, the ventricles beat irregularly and inefficiently. Cardiac output decreases at least 15-20 percent.
Symptoms of AF vary from none to fatigue, shortness of breath and exercise intolerance, chest pains, palpitations, dizziness and even loss of consciousness.
AF accounts for greater than 30 percent of all arrhythmia-related hospitalizations. AF is more common in men than in women, and increases with age. The lifetime risk of developing AF is approximately 25 percent. The incidence of AF has been increasing, attributed to the prevalence of obesity. Heart failure, hyperthyroidism, hypertension, obstructive sleep apnea, valvular heart disease and left atrial enlargement have been reported as independent risk factors. Other risk factors include Caucasian race, being tall in stature, cigarette smoking and coronary artery disease.
AF that stops on its own or with medications within seven days is termed paroxysmal AF. If AF continues more than seven days, it is termed persistent AF. Physicians have three main concerns in AF patients: symptoms, stroke and long-term injury to the heart.
Symptoms may be subtle or dramatic, persistent or intermittent. Many seemingly asymptomatic patients may admit that their exercise tolerance has declined or that they are napping more frequently, etc. Many patients think they are asymptomatic and function normally, but after treatment to restore a normal rhythm, they notice a significant improvement and are aware of a decline in function the second time they go into AF.
Concern for stroke is a major issue. Studies vary in the duration of an AF episode considered at risk for blood clots and stroke. In general, if episodes of AF are less than 24 hours, risk should be low and anticoagulation often isn’t necessary. If patients have other risk factors such as a previous history of stroke, pulmonary embolism or a hypercoagulable state, the benefit of anticoagulation may exceed the risk. Episodes that last days or weeks require anticoagulant therapy.
Long-term damage to the heart can be due to a rapid heart rate that depletes the heart muscle cells of energy or simply due to the irregular rhythm. This is usually reversible if the rate is slowed and the heart is regulated with therapies. Patients unaware of the irregular rhythm often present when they have heart failure symptoms.
Options for treating AF include:
• Rate control and appropriate anticoagulation. This is used in persons who either function normally in AF or are not candidates for other therapy. In most patients the goal is to restore a regular rhythm. The medicines used are usually beta-blockers or calcium channel blockers rather than potent antiarrhythmic agents.
• Rhythm medicines and possible electrical cardioversion. Some patients need daily medicine to control their arrhythmia; others who have AF occasionally can use a “pill-in-the-pocket” approach where they take medicine at the onset of an episode to restore a normal rhythm.
• Atrial fibrillation ablation. AF ablation is an excellent option in patients who either fail medical therapy or opt for a potential curative therapy rather than long-term medical treatment. AF ablation has progressed over the last few years. Various pacing, ultrasound and ablation catheters are advanced to the heart through the veins to study the atria to look for areas that could be causing arrhythmias. The tissue is deadened with either radiofrequency energy (heat), cryo (cold) or laser energy. The success for AF ablation ranges from 70 to over 90 percent, depending on the health of the atrial tissue. Some patients go home the same day and others are discharged the next morning.
• Pacemaker placement — For patients who fail medical therapy and are not candidates for AF ablation, pacemaker placement is an excellent option for restoring a reliable regular rhythm and peace of mind to the patient. Studies have shown a dramatic improvement in quality of life and improvement in cardiac output. Patients who undergo this therapy will need to remain on anticoagulation, if appropriate, but are able to discontinue both rate and rhythm control medications.
• Surgical Options. Various open chest and thoracoscopic surgical techniques are available for AF. Surgery is usually an open procedure done along with valve surgery or bypass grafting. Like AF ablation, there are radiofrequency and cryo procedures and surgical procedures like the MAZE, which usually includes removal of the left atrial appendage, a common location of stroke-producing blood clots.
In summary, AF is quite common and very treatable. The goals of therapy are elimination of the irregular rhythm, improvement in cardiac performance and prevention of stroke.
(Dr. Michael Giudici is director of Arrhythmia Services at University of Iowa Hospitals, Iowa City.)