(Circulation. 1996;94:1491-1493.)
© 1996 American Heart Association, Inc.
Articles |
Quality of Life in Patients With Supraventricular Arrhythmia
the Departments of Health Research and Policy and of Medicine (M.A.H.), Stanford University School of Medicine, Stanford, Calif; and the Texas Heart Institute (W.K.V.), Houston, Tex.
Correspondence to Mark Hlatky, MD, Stanford University School of Medicine, HRP Redwood Building, Room 150, Stanford, CA 94305-5092. E-mail mr.mah@forsythe.stanford.edu.
Key Words: catheter ablation • tachyarrhythmia • Wolff-Parkinson-White syndrome • Editorials
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Introduction |
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 Top Introduction Supraventricular ArrhythmiasThe Present StudyConclusionsReferences |
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Physicians have always sought to relieve the suffering of patients and, if possible, to extend their lives. These goals may be expressed in modern terminology as improving the quality of life and reducing mortality. Although death is a definitive end point that is relatively simple to assess, quality of life is much more difficult to define and measure. Consequently, quality of life has less often been included as an outcome in clinical research, and clinicians have had little solid information about the effect of treatment on quality of life. Fortunately, more studies now include quality of life assessments, so clinicians will soon have a more complete picture of the outcomes of care.
Quality of life measurement is a relatively new field in medicine1 2 3 4 that is derived from two broad schools of thought in the social sciences, which have led to two distinct approaches to measurement. Researchers grounded in the discipline of psychology have emphasized the multiple dimensions of quality of life and developed instruments that assess each dimension separately.3 5 The scales originally developed at the RAND Corporation for use in the Medical Outcomes Study exemplify this approach.6 An abbreviated version of this instrument, known as the Short Form-36 (SF-36), contains 36 items that are scored in scales assessing physical limitations, emotional health, role functioning, pain, and general health. In contrast, researchers grounded in the disciplines of economics and decision analysis have emphasized the synthesis of quality of life assessment into a single summary measure corresponding to the concept of "utility," which incorporates both the patient's rating of his or her state of health and how the patient values that state of health.7 Health utility has been measured with a variety of techniques, including the standard gamble, time-tradeoff methods, and rating scales. With these methods, a single number that summarizes the quality of life can be combined with data about length of life to calculate quality-adjusted life-years, the outcome measure used in decision and cost-effectiveness analyses. Multidimensional scales (eg, the SF-36) and utility measures have each been used in cardiovascular disease investigations.
Another choice to be made in the measurement of quality of life is whether to use a generic instrument or a disease-specific instrument. Generic instruments (eg, the SF-36, Sickness Impact Profile, Nottingham Health Profile, Psychological General Well-Being Scale, or McMaster Health Index) attempt to assess aspects of health that are relevant regardless of the underlying condition and therefore can be applied to a broad array of patient populations, as well as to the general public. The use of generic instruments would allow the quality of life effects of, for example, congestive heart failure and arrhythmias to be compared.8 Generic instruments provide a larger context in which to assess quality of life effects but, being broadly based, may be insensitive to specific impairments imposed by particular illnesses. Disease-specific scales are used to measure the particular effects of conditions, such as angina, congestive heart failure, rheumatoid arthritis, and cataracts. These scales are useful in studies of particular conditions but have the disadvantage of not providing a broader context for interpretation. As a result, recent clinical studies have used a battery of quality of life instruments that includes both generic and disease-specific measures.
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Supraventricular Arrhythmias |
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With rare exceptions, supraventricular arrhythmias are generally not life threatening, but they can have considerable effects on quality of life.9 Paroxysmal arrhythmias may cause disabling symptoms at unpredictable times, disrupting the lives of patients. The effect on quality of life is greater as the paroxysms occur more frequently, as the severity of the symptoms during an attack increases, and as the length of the paroxysms increases. Apart from the actual disability of the attacks, paroxysmal arrhythmias may impair quality of life through restriction of activities or adverse effects of medications prescribed to prevent recurrences.10 Fear of arrhythmia recurrence may also diminish quality of life. Therefore, "benign" supraventricular arrhythmias can cause considerable distress for patients.
Antiarrhythmic drugs have been the mainstay of treatment for supraventricular arrhythmias, including those that block conduction through the atrioventricular node and those that reduce atrial ectopic activity.9 Drugs have been used for decades and have well-recognized limitations, including lack of complete efficacy, adverse effects, and cost. More recently, safety concerns have emerged about potential proarrhythmic effects of type I agents used in the treatment of supraventricular arrhythmias.11 The development of radiofrequency catheter ablation offers the opportunity to treat supraventricular arrhythmias with potentially greater efficacy and reduced morbidity.12 13 14 15 16
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The Present Study |
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TopIntroductionSupraventricular ArrhythmiasThe Present StudyConclusionsReferences |
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Improvement of quality of life is the major therapeutic goal of radiofrequency ablation for supraventricular arrhythmias, but few data are available to document the efficacy of the procedure on this outcome.10 17 The study by Bubien and associates from the University of Alabama reported in this issue of Circulation18 helps to fill this gap. A total of 161 patients undergoing radiofrequency ablation were studied, including 59 patients with atrioventricular nodal reentrant tachycardia, 46 with Wolff-Parkinson-White syndrome, 22 with atrial fibrillation, 22 with atrial flutter, and 10 with ventricular tachycardia. These patients were long suffering and severely symptomatic, and the effect of ablation on their quality of life was quite dramatic. Large improvements in both the SF-36 general health measure and in disease-specific symptom frequency and severity were documented at 1 and 6 months of follow-up. These changes were both statistically significant and clinically important and suggest that in properly selected patients, catheter ablation of supraventricular arrhythmias can substantially enhance quality of life.
Although the study by Bubien and associates18 is important and provocative, it cannot be regarded as definitive for several reasons. Most important, it is an observational study and not a randomized clinical trial. Some of the improvements seen may have been due to the referral of these patients to a group of clinicians who were experienced in the management of refractory supraventricular arrhythmias. The referral center may have used a variety of management measures in addition to the ablation itself that improved the quality of life of these patients. Small randomized, unblinded trials of ablation of accessory pathways10 and the atrioventricular node17 show improvements in symptoms and quality of life scores. Second, the patients' quality of life may fluctuate over time due to variations in disease activity or other factors. Because patients may seek care when most severely ill, some "improvement" in quality of life may be expected due to regression to the mean. Finally, the placebo effect of a new procedure provided by an enthusiastic group of experts may nonspecifically improve quality of life.
The patients included in the Alabama series were severely affected by their arrhythmias. The average atrioventricular nodal reentry tachycardia patient in this study had been symptomatic for 16.2 years and was taking 2.4 medications. Patients with supraventricular tachycardia had quality of life scores comparable to those of patients with congestive heart failure or AIDS.19 By selecting highly symptomatic patients who were substantially impaired by their arrhythmias, the Alabama investigators were able to document impressive improvements in quality of life. It is unlikely that less severely ill patients would receive as great an effect on quality of life from catheter ablation.
Radiofrequency catheter ablation was initially used in patients with severe, frequent symptoms due to arrhythmia and in patients with accessory pathways capable of antegrade conduction sufficiently rapid to pose a risk of sudden death. Once the technique had been established for use in the most severely affected patients, it was natural to extend its application to mildly symptomatic individuals. Catheter ablation appears to be cost effective in patients who are at risk of sudden death20 or in patients with frequent, disabling symptoms.21 The cost-effectiveness ratio of catheter ablation in these analyses was, however, very sensitive to the underlying risk of death20 and the frequency of symptoms,21 suggesting that catheter ablation may not be cost effective for all patients with supraventricular arrhythmias. It is likely that patient selection for this procedure can be improved through consideration of the frequency of arrhythmia, severity of symptoms during an attack, cost of medical treatment, and patient attitudes toward the risk of the procedure and the risk of paroxysmal tachycardia.
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Conclusions |
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TopIntroductionSupraventricular ArrhythmiasThe Present StudyConclusionsReferences |
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Quality of life is an important measure in clinical studies and should be incorporated in clinical trials with the more traditional outcomes of mortality, morbidity, and laboratory findings. Documentation of the salutory effects of therapies on quality of life will help to provide the evidence of the value of medical care that is increasingly demanded by skeptical payers and by the public.
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Acknowledgments |
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This work was supported by grant HS-08362 from the Agency for Health Care Policy and Research, Rockville, Md.
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References |
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