Cost-Effectiveness of Catheter Ablation for Ventricular Tachycardia
abstract & commentary
Synopsis: Catheter ablation is a reasonable alternative for VT patients who have ICDs yet have a need for frequent therapy.
Source: Calkins H, et al. Circulation 2000;101: 280-288.
This study was designed to evaluate the cost- effectiveness of catheter ablation compared to amiodarone therapy in patients with implantable cardioverter defibrillators (ICDs) and sustained monomorphic ventricular tachycardia (VT) who experience frequent VT episodes or shocks. Most of the data were collected during a multicenter prospective, randomized clinical trial of a new catheter ablation system (Chilli Cooled Ablation System, Cardiac Pathways Corporation, Sunnyvale, Calif.). This system irrigates the catheter tip to prevent local heat build-up, thus permitting larger lesions. Patients with previously implanted ICDs were eligible to participate in the trial if they had documented sustained monomorphic VT with two or more episodes during the two months before enrollment. In the study, catheter ablation demonstrated that 72% of patients who underwent the procedure experienced a greater than 75% reduction in VT episodes or ICD shocks at two months. Fifty-five percent of the patients who underwent ablation had no recurrent VT at six months. The study collected data concerning ablation-related major adverse events, and clinical and adverse events during follow-up and quality-of-life data.
Cost utility analysis was performed to adjust for quality of life during follow-up. Calkins and colleagues developed a decision-analytic Markov model to simulate the five-year clinical, economic, and quality-of-life outcomes associated with catheter ablation vs. medical therapy in a hypothetical cohort of ICD patients with recurrent VT. In a Markov model, patients move at one-month intervals between one of 24 health states that reflect the two treatment alternatives and associated outcomes. The probabilities for moving from one health state to another were derived from data from the trial combined with the opinion panel based on a comprehensive literature review. Quality-of-life data were obtained from the Medical Outcome Study 36-item Short Form Health Survey (SF-36) obtained as part of the catheter trial. Actual medical costs were obtained using standard techniques and adjusted for 1998 values. Finally, sensitivity analyses were performed to determine the consequences of changes in any of the variables included in the models.
Catheter ablation was more expensive than amiodarone therapy, with a mean total cost of $21,795 vs. $19,000 ± $75. However, since there was less late VT, the mean total quality-adjusted life-years saved were 2.78 with catheter ablation vs. 2.65 with amiodarone. This yields an incremental cost with catheter ablation of $2720 for an incremental quality-adjusted life-year of 0.13 years and an incremental cost per quality-adjusted life-year gained of $20,923.
Calkins et al conclude that catheter ablation is a reasonable alternative for VT patients who have ICDs yet have a need for frequent therapy.
Comment by John P. DiMarco, MD, PhD
One of the requirements for developing or gaining FDA approval of a new catheter ablation system is to prove its effectiveness in both an absolute sense and in relationship to other available therapies. One of the potential benefits of catheter ablation is to reduce long-term costs as well as to decrease morbidity due to recurrent VT. This study shows that catheter ablation offers some advantages over drug therapy in ICD patients with frequent episodes of VT. Although this study deals with a relatively narrow population, it is one that is becoming more frequently encountered as ICD use increases.
The study deals with an artificial situation, however. The major cost associated with amiodarone relates to its lack of efficacy and its potential for toxicity. However, in real practice, there is nothing to prevent patients from being started on amiodarone. If they are effectively treated without side effects, they can just continue on that drug. Catheter ablation would then be withheld as a second option in those patients, with little loss in terms of patient morbidity or cost. The major cost for these patients would be related to the ICD implant itself. Since both groups of patients in the study had ICDs, the cost advantage of catheter ablation presented here seems relatively minor.
More interesting is the brief analysis Calkins et al present about a theoretical group of patients with good ejection fractions and well-tolerated VT. These patients would not have ICDs. The problem here is that in patients with structural heart disease, it is hard to guarantee that only a single ventricular tachycardia will be encountered over the life span of the patient. Thus, the nonspecific protection offered by the ICD may be important in case of the development of new and more dangerous arrhythmias.
Despite its limitations, this paper is an interesting example of the use of cost-effectiveness analysis to assess competing medical strategies. If new technology allows higher success rates with ablation, we can expect to see even greater advantages with the catheter approach.
Catheter ablation for frequent VT episodes in patients with implanted defibrillators:
a. reduces recurrent VT by 90%.
b. abolishes recurrent VT for six months.
c. is cost effective.
d. is ineffective.