Quality of Life in the Antiarrhythmics vs. Implantable Defibrillators Trial
Abstract & Commentary
Synopsis: Both ICD and antiarrhythmic drug therapy are associated with similar disturbances in quality of life.
Source: Schron EB. Circulation. 2002;105:589-594.
The antiarrhythmics versus implantable defibrillators (AVID) trial compared antiarrhythmic drug therapy, amiodarone or sotalol, and implantable cardioverter defibrillator (ICD) therapy in patients who had survived either a cardiac arrest or ventricular tachycardia with syncope or hypotension. A total of 1016 patients were enrolled in the trial. Of these, 800 participants survived 1 year and participated in a quality-of-life substudy, the results of which are reported here. Quality of life measurements were obtained at baseline before randomization and at 3, 6, and 12 months after randomization. Several measures of quality of life were used. The Medical Outcomes Short Form 36 item questionnaire (SF-36) was used to measure generic health status. This instrument has 4 subscales that measure physical health and 4 that measure mental health. These were summarized as a physical component summary score and a mental component summary score. Higher scores indicate superior quality of life. The Patients Concern Checklist evaluated disease-specific aspects of quality of life relevant to patients with ventricular arrhythmias. Higher scores indicated increased concern and poorer quality of life. The cardiac version of the Quality of Life Index assesses issues relevant to all patients with heart disease. Higher scores indicate superior quality of life. In addition, symptoms were assessed and recorded at baseline and at a follow-up visit by the AVID study coordinator at each site. Local investigators characterized symptoms as mild to severe on the basis of prespecified descriptions. Defibrillator shocks were analyzed at follow-up visits. Shocks were characterized as appropriate or inappropriate based on clinical presentation, RR intervals and stored electrograms.
Eight hundred patients participated in the quality of life substudy. The 800 patients who provided data for this report were more likely to live with a spouse or partner, to have graduated from high school, and to have a higher ejection fraction than those who did not participate or who died during the first year after enrollment. The quality-of-life substudy group included 416 patients who were randomized to an ICD and 384 patients who were randomized to antiarrhythmic drug therapy. Baseline characteristics between these 2 groups were similar except that more patients in the ICD group were discharged on beta blockers. Self perceived physical functioning and mental well being scores were significantly impaired compared to a normal population in both treatment groups at baseline. At baseline, both groups also had high Patient Concern Checklist scores and low scores on the Quality of Life Index. There were no differences between the ICD and antiarrhythmic drug therapy groups in these measures. Physical component scores and mental component scores on the SF-36 improved over time in both groups. Similar improvements were also noted in both groups in the Patient Concern Checklist scores and the Quality of Life Index scores. Adverse symptoms were reported in a high proportion of patients in both groups. Most adverse symptoms were cardiovascular or related to heart failure. The occurrence of adverse symptoms was associated with significant reduction in the physical and mental component scores on the SF-36 in the ICD group, but only in the physical component score in patients randomized to antiarrhythmic drug therapy. The development of adverse symptoms also lowered quality-of-life scores and increased patient concerns independent of the randomized therapy group. Among the ICD recipients, 39% experienced greater than or equal to one shock during the initial year follow-up. Of these, half had more than or equal to 3 shocks. The occurrence of a shock was associated with significant reductions in mental well being and physical functioning and an increase in patient concerns. Those with more frequent shocks had a decrease in their self-perceived quality of life.
Schron and colleagues conclude that both ICD and antiarrhythmic drug therapy are associated with similar disturbances in quality of life. The changes over time are largely dictated by the development of adverse symptoms and the occurrence of sporadic ICD shocks. They hypothesize that studies to assess the ability of antiarrhythmic drugs to decrease the frequency of ICD shocks may lead to further improvements in quality of life in this patient population.
Comment by John P. DiMarco, MD, PhD
The AVID Trial was a landmark study which showed the superiority of ICD therapy to antiarrhythmic drug therapy in patients who had survived a cardiac arrest or an episode of sustained ventricular tachycardia. Although improved survival with ICD therapy was demonstrated in this trial, questions have been raised concerning the effects of the ICD on quality of life as well as the cost effectiveness of ICD therapy. This paper points out that quality of life in patients with cardiac arrest are largely determined by a patient’s cardiac condition, not by their therapy. At baseline, their quality-of-life measures are lower than would be expected in a normal healthy population and changes over time are largely determined by the complications of the original disease. In patients with ICDs, the frequency of ICD shocks is also associated with quality of life in disease. Since it has been reported that antiarrhythmic drug therapy may decrease the frequency of shocks, selective use of antiarrhythmic drugs, particularly in patients with a high probability of recurrence, may well be indicated.
One of the trends in antiarrhythmic therapy now is the use of hybrid therapy. Devices are used because of their reliability, and antiarrhythmic drugs are used in well-tolerated doses to decrease patient’s symptoms. This paper would support the strategy of initial use of an ICD only in patients who are stable between arrhythmia episodes. Once the pattern of recurrence has been determined, an antiarrhythmic drug may prevent further deterioration in the patient’s quality of life even though it will probably not affect overall mortality.
Dr. DiMarco is Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville.
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