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PubMed1999

The implantable cardioverter defibrillator and primary prevention of sudden death: the Multicenter Automatic Defibrillator Implantation Trial and the Coronary Artery Bypass Graft (CABG)-Patch Trial.

The Multicenter Automatic Defibrillator Implantation Trial (MADIT) and the Coronary Artery Bypass Graft (CABG)-Patch study were the first 2 randomized trials investigating the usefulness of the implanted cardioverter defibrillator (ICD) for primary prevention of sudden death. Patients enrolled in MADIT and CABG-Patch had never experienced a sustained ventricular tachycardia (VT) but were thought to be at high risk of sudden death. All patients had coronary artery disease and severely suppressed left ventricular ejection fraction. CABG-Patch patients received their ICD during CABG surgery. Most MADIT patients already had received CABG or percutaneous transluminal coronary angiography and had no indication for revascularization procedures at study entry. MADIT patients had nonsustained spontaneous VT and inducible, nonsuppressible VT; CABG-Patch patients had only an abnormal signal-averaged electrocardiogram as an indicator of their arrhythmic risk. CABG-Patch patients did not benefit from ICD implantation, presumably due to the influence of revascularization on ischemia and left ventricular function. In contrast, MADIT patients showed an improved survival by the ICD. MADIT patients had no need for revascularization and, presumably, their risk indicator for arrhythmic events was stronger than the one used in CABG-Patch. MADIT criteria have become a class I indication for ICD implantation and, in the absence of testing for suppressibility of induced VTs, a class IIb criterion for ICD implantation. Screening for MADIT patients is expensive, as only relatively few patients after myocardial infarction fulfill the criteria. Nevertheless, in comparison with amiodarone, treatment of MADIT patients with ICDs seems to be cost-effective, especially if ICDs are implanted transvenously and have the improved battery longevity of the current devices.

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PubMed2003

Comparison of medical therapy, pacing and defibrillation in heart failure (COMPANION) trial terminated early; combined biventricular pacemaker-defibrillators reduce all-cause mortality and hospitalization.

The COMPANION trial was terminated prematurely after recruiting 1600 patients, as initial results clearly and for the first time demonstrated survival benefit of resynchronisation and combined device (biventricular pacemaker with defibrillator capacity) therapy in heart failure. The combined primary end-points of all-cause mortality and all-cause hospitalisation in patients with dilated cardiomyopathy and heart failure of poor functional class was reduced by 20% with cardiac resynchronisation therapy (CRT) with or without defibrillator capacity. More importantly, mortality was reduced by 40% (from 19% to 11%) in patients implanted with combined devices, while CRT alone gave an intermediate mortality of 15%.

Cardiac Pacing, Artificial↗
PubMed1998

When an AED meets an ICD... Automated external defibrillator. Implantable cardioverter defibrillator.

The chances of prehospital care providers being confronted with a patient with an implantable cardioverter defibrillator (ICD) are increasing and so care providers must receive proper training. Based on observations made during the resuscitation of a patient with an ICD using an automated external defibrillator (AED) some technical features and possible interactions of ICDs and AEDs are highlighted. Furthermore, we discuss the key points of basic knowledge, safety, and treatment protocols for cardiac arrest and other situations required for practical training in the ICD for prehospital care providers.

Adult↗
PubMed1999

Relative effectiveness of the implantable cardioverter-defibrillator and antiarrhythmic drugs in patients with varying degrees of left ventricular dysfunction who have survived malignant ventricular arrhythmias. AVID Investigators. Antiarrhythmics Versus Implantable Defibrillators.

OBJECTIVES: We sought to assess the effect of baseline ejection fraction on survival difference between patients with life-threatening ventricular arrhythmias who were treated with an antiarrhythmic drug (AAD) or implantable cardioverter-defibrillator (ICD). BACKGROUND: The Antiarrhythmics Versus Implantable Defibrillators (AVID) study demonstrated improved survival in patients with ventricular fibrillation or ventricular tachycardia with a left ventricular ejection fraction (LVEF) < or =0.40 or hemodynamic compromise. METHODS: Survival differences between AAD-treated and ICD-treated patients entered into the AVID study (patients presenting with sustained ventricular arrhythmia associated with an LVEF < or =0.40 or hemodynamic compromise) were compared at different levels of ejection fraction. RESULTS: In patients with an LVEF > or =0.35, there was no difference in survival between AAD-treated and ICD-treated patients. A test for interaction was not significant, but had low power to detect an interaction. For patients with an LVEF 0.20 to 0.34, there was a significantly improved survival with ICD as compared with AAD therapy. In the smaller subgroup with an LVEF <0.20, the same magnitude of survival difference was seen as that in the 0.20 to 0.34 LVEF subgroup, but the difference did not reach statistical significance. CONCLUSIONS: These data suggest that patients with relatively well-preserved LVEF (> or =0.35) may not have better survival when treated with the ICD as compared with AADs. At a lower LVEF, the ICD appears to offer improved survival as compared with AADs. Prospective studies with larger patient numbers are needed to assess the effect of relatively well-preserved ejection fraction (> or =0.35) on the relative treatment effect of AADs and the ICDs.

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PubMed2001

Do current dual chamber cardioverter defibrillators have advantages over conventional single chamber cardioverter defibrillators in reducing inappropriate therapies? A randomized, prospective study.

INTRODUCTION: Supraventricular tachyarrhythmias are the main cause of inappropriate therapies in patients with conventional single chamber implantable cardioverter defibrillators (VVI-ICD). It was anticipated that dual chamber cardioverter defibrillators (DDD-ICD), with their capacity to analyze atrial and ventricular rhythm, could substantially reduce inappropriate therapies. METHODS AND RESULTS: Our prospective study included 92 patients (87 men; mean age 61 +/- 12.7 years) who were randomly assigned to a VVI-ICD (45 patients) or a DDD-ICD (47 patients). Both groups were followed for 7.5 +/- 3.5 and 7.6 +/- 4.1 months, respectively. During the follow-up period, overall 725 ventricular tachycardia (VT)/ventricular fibrillation (VF) episodes were recorded in 45 (49%) of 92 patients. Of these episodes, 404 (56%) occurred in the VVI-ICD group and 321 (44%) episodes occurred in the DDD-ICD group. Twenty-three (51%) patients in the VVI-ICD group and 22 (47%) patients in the DDD-ICD group (P = 0.8) developed VT/VF. Overall, 73 (10%) of 725 treated episodes were inappropriate in 6 (13%) patients in the VVI group and in 10 (21%) patients in the DDD-ICD group (P = 0.2). There were 22 (31%) inappropriately treated episodes in the VVI-ICD group and 51 (69%) in the DDD-ICD group. Thirty-two of the 51 inappropriate episodes in the DDD-ICD patients resulted from intermittent atrial sensing problems that led to failure of the respective dual chamber algorithms. Nonfatal complications occurred in 6 (13%) patients in the VVI-ICD group and in 3 (6%) patients in the DDD-ICD group (P = 0.7). CONCLUSION: We conclude that the implanted DDD-ICD and conventional VVI-ICD are equally safe and effective for therapy of life-threatening ventricular tachyarrhythmias. Although DDD-ICDs allow better rhythm classification, the applied detection algorithms do not offer benefits in avoiding inappropriate therapies during supraventricular tachyarrhythmias.

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PubMed2003

Analysis of implantable cardioverter defibrillator therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial.

INTRODUCTION: The implantable cardioverter defibrillator (ICD) is commonly used to treat patients with documented sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia recurrence rates in these patients are high, but which patients will receive a therapy and the forms of arrhythmia recurrence (VT or VF) are poorly understood. METHODS AND RESULTS: The therapy delivered by the ICD was examined in 449 patients randomized to ICD therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. Events triggering ICD shocks or antitachycardia pacing (ATP) were reviewed for arrhythmia diagnosis, clinical symptoms, activity at the onset of the arrhythmia, and appropriateness and results of therapy. Both shock and ATP therapies were frequent by 2 years, with 68% of patients receiving some therapy or having an arrhythmic death. An appropriate shock was delivered in 53% of patients, and ATP was delivered in 68% of patients who had ATP activated. The first arrhythmia treated in follow-up was diagnosed as VT (63%), VF (13%), supraventricular tachycardia (18%), unknown arrhythmia (3%), or due to ICD malfunction or inappropriate sensing (3%). Acceleration of an arrhythmia by the ICD occurred in 8% of patients who received any therapy. No physical activity consistently preceded arrhythmias, nor did any single clinical factor predict the symptoms of the arrhythmia. CONCLUSION: Delivery of ICD therapy in AVID patients was common, primarily due to VT. Inappropriate ICD therapy occurred frequently. Use of ICD therapy as a surrogate endpoint for death in clinical trials should be avoided.

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PubMed1999

Prevention of implantable-defibrillator shocks by treatment with sotalol. d,l-Sotalol Implantable Cardioverter-Defibrillator Study Group.

BACKGROUND: Patients with implantable cardioverter-defibrillators often receive adjunctive antiarrhythmic therapy to prevent frequent shocks. We tested the efficacy and safety of sotalol, a beta-blocker with class III antiarrhythmic effects, for this purpose. METHODS: In a multicenter trial, patients were stratified according to left ventricular ejection fraction (< or =0.30 or >0.30), randomly assigned to double-blind treatment with 160 to 320 mg of sotalol per day (151 patients) or matching placebo (151 patients), and followed for 12 months. Kaplan-Meier analyses of the time to an event were performed. Three end points were used: the delivery of a first shock for any reason or death from any cause, the first appropriate shock for a ventricular arrhythmia or death from any cause, and the first inappropriate shock for a supraventricular arrhythmia or death from any cause. RESULTS: Compliance with double-blind treatment was similar in the two groups. There were seven deaths in the placebo group and four in the sotalol group. As compared with placebo, treatment with sotalol was associated with a lower risk of death from any cause or the delivery of a first shock for any reason (reduction in risk, 48 percent; P<0.001 by the log-rank test), death from any cause or the delivery of a first appropriate shock (reduction in risk, 44 percent; P=0.007), or death from any cause or the delivery of a first inappropriate shock (reduction in risk, 64 percent; P=0.004). Sotalol also reduced the mean (+/-SD) frequency of shocks due to any cause (1.43+/-3.53 shocks per year, as compared with 3.89+/-10.65 in the placebo group; P=0.008). In the sotalol group, the reduction in the risk of death from any cause or the delivery of a first shock for any reason did not differ significantly between patients with ejection fractions of more than 0.30 and those with ejection fractions of 0.30 or less. CONCLUSIONS: Oral sotalol was safe and efficacious in reducing the risk of death or the delivery of a first defibrillator shock whether or not ventricular function was depressed.

Adrenergic beta-Antagonists↗
PubMed2001

Antiarrhythmic drug use in the implantable defibrillator arm of the Antiarrhythmics Versus Implantable Defibrillators (AVID) Study.

BACKGROUND: Previous retrospective or observational series suggest that many patients with an implantable cardioverter-defibrillator (ICD) will be treated with antiarrhythmic drugs (AADs) to modify the frequency or manifestation of recurrent ventricular arrhythmias. The relative clinical benefit, however, is uncertain, and deleterious interactions can occur. The objective of this clinical investigation was to study the need for, and effects of, concomitant AAD use with the ICD in a prospectively defined cohort. METHODS: All patients randomly assigned to the ICD arm of the Antiarrhythmics Versus Implantable Defibrillators (AVID) study were followed for the addition of class I or III AADs ("crossover") after hospital discharge. Addition of AADs was strictly regulated by AVID protocol. The timing and reasons for crossover and the effects on ventricular arrhythmia recurrence were analyzed. Patients were excluded if they required AADs before hospital discharge after index arrhythmias or if they had no ventricular arrhythmia before initiation of AADs. RESULTS: After a median follow-up of 135 days, 81 (18%) of the 461 eligible patients required AADs and formed the crossover group. The primary reason for crossover was frequent ICD shocks in 64% of patients. The most common AAD selected was amiodarone (in 42%). Independent predictors of crossover were lower ejection fraction, absence of ventricular fibrillation, or presence of nonsyncopal ventricular tachycardia at presentation, prior unexplained syncope, female sex, and history of cigarette smoking. Before AAD use, the 1-year arrhythmia event rate was 90%; after AAD, the event rate was only 64% (P =.0001). The time to first event was extended from 3.9 +/- 0.7 months to 11.2 +/- 1.8 months. There were 1.4 +/- 3.7 fewer ICD therapy events (P =.005) after crossover, predominantly accounted for by reduction in shocks rather than antitachycardia pacing therapies. CONCLUSIONS: The majority of patients who receive ICDs for sustained ventricular tachycardia or ventricular fibrillation can be treated without AADs. Most commonly, AADs are added to combat frequent ICD shocks, which are successfully reduced by AAD therapy.

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PubMed1999

Defibrillation thresholds are increased by right-sided implantation of totally transvenous implantable cardioverter defibrillators.

Whether an ICD is placed via a left- or right-sided approach depends on venous access, the presence of a preexisting pacemaker, and other factors. Since the DFT is affected by lead position, which in turn is determined in part by the side of access, right-sided venous access could adversely affect DFTs. Furthermore, right-sided active can placement directs electric current toward the right hemithorax, which could further increase DFTs. This study sought to determine whether DFTs were increased by right-sided vascular access, and whether active can technology was beneficial or detrimental with right-sided ICD placement. Stepdown to failure DFTs were found in 290 patients receiving transvenous systems at the time of initial ICD implantation. Of these, 271 (93%) received left-sided systems and 19 (7%) received right-sided systems. The mean DFT in systems placed via left-sided vascular access was 11.3 +/- 5.3 J versus 17.0 +/- 4.9 J for right-sided implantation (P < 0.0001); right-sided DFTs were elevated for both active can and cold can systems. Right-sided active can devices had a lower DFT than right-sided cold can systems (15 +/- 4.1 J vs 19 +/- 4.8 J, P = 0.05). The right-sided implantation of implantable defibrillators results in significantly higher DFTs than the left-sided approach. This may be due to the less favorable distribution of the defibrillating field relative to the myocardium with the devices on the right. When right-sided implantation is clinically mandated, active can devices result in lower thresholds and should be used.

Adult↗
PubMed2006

Predictors of appropriate defibrillator therapy among patients with an implantable defibrillator that delivers cardiac resynchronization therapy.

INTRODUCTION: The purpose of this study was to determine predictors of appropriate implantable defibrillator (ICD) therapy among patients with heart failure who are treated with a cardiac resynchronization therapy-defibrillator (CRT-D). METHODS AND RESULTS: Patients enrolled in the Ventak CHF/Contak CD study were treated with a CRT-D device and were required to have NYHA class II-IV CHF, QRS duration > or = 120 msec, and a class I or II indication for an ICD. The study database was retrospectively analyzed during the 6-month postimplant period to identify predictors of appropriate ICD therapy. Five hundred and one of the 581 patients enrolled in the trial had successful device implantation and were included in this analysis. Patients were mostly male (83%), 66 +/- 11 years old, and had coronary artery disease (69%), a mean left ventricular ejection fraction (EF) = 0.22 +/- 0.07, and NYHA class II (33%), III (58%), or IV (9%) CHF symptoms. During 6 months of follow-up, 73 of 501 (14%) patients received an appropriate ICD therapy. Two independent predictors of appropriate therapy were identified: a history of a spontaneous, sustained ventricular arrhythmia (HR = 2.05; 95% CI = 1.31-3.20; P = 0.002) and NYHA class IV CHF (HR = 1.81; 95% CI = 1.10-2.96; P = 0.019). When patients with NYHA class II were excluded from analysis, a history of a sustained ventricular arrhythmia and the presence of NYHA class IV CHF symptoms remained as independent predictors of appropriate ICD therapy. CONCLUSIONS: In a select population of advanced heart failure patients receiving a CRT-D, NYHA class IV CHF was a powerful independent predictor of appropriate ICD therapy. Approximately one-quarter of the patients with NYHA class IV CHF who received a CRT-D device received an appropriate ICD therapy within 3 months after implant. Additional studies are needed to confirm an association between class IV CHF symptoms and an increased frequency of ICD shocks.

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PubMed2005

Differences in outcomes between patients treated with single- versus dual-chamber implantable cardioverter defibrillators: a substudy of the Multicenter Automatic Defibrillator Implantation Trial II.

OBJECTIVES: We sought to evaluate the influence of single- versus dual-chamber implantable cardioverter defibrillators (ICDs) on the occurrence of heart failure and mortality as well as appropriate and inappropriate ICD therapy in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II). BACKGROUND: In MADIT-II, ICD therapy in patients with a prior myocardial infarction and ejection fraction < or =0.30 was associated with a 31% reduction in risk of mortality when compared to conventionally treated patients. An unexpected finding was an increased occurrence of hospitalization for heart failure in the ICD group. METHODS: Data from 717 patients randomized to ICD therapy with single- or dual-chamber pacing devices in MADIT-II were retrospectively analyzed. Endpoints selected for analysis included death from any cause, new or worsening heart failure requiring hospitalization, death or heart failure, appropriate therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF), and inappropriate ICD therapy for atrial fibrillation or supraventricular tachycardia. RESULTS: A total of 404 single-chamber ICDs (S-ICDs) and 313 dual-chamber ICDs (D-ICDs) were implanted. Patients receiving D-ICDs were at a higher risk at baseline than those receiving S-ICDs, with older age, higher NYHA class, more frequent prior CABG, wider QRS complex, more LBBB, higher BUN level, a history of more atrial arrhythmias requiring treatment, and a longer time interval from their index myocardial infarction to enrollment. While there was a trend toward an increase in adverse outcomes in the D-ICD group, no statistically significant differences in heart failure or mortality were observed between S-ICD versus D-ICD groups. CONCLUSIONS: Patients with D-ICDs had a nonsignificant trend toward higher mortality and heart failure rates than patients with S-ICDs.

Arrhythmias, Cardiac↗
PubMed2002

Cost-effectiveness of the implantable cardioverter-defibrillator versus antiarrhythmic drugs in survivors of serious ventricular tachyarrhythmias: results of the Antiarrhythmics Versus Implantable Defibrillators (AVID) economic analysis substudy.

BACKGROUND: The implantable cardioverter-defibrillator (ICD) is an effective but expensive device. We used prospectively collected data from a large randomized clinical trial of secondary prevention of life-threatening ventricular arrhythmias to determine the cost-effectiveness of the ICD compared with antiarrhythmic drug (AAD) therapy, largely with amiodarone. METHODS AND RESULTS: Charges for initial and repeat hospitalizations, emergency room, and day surgery stays and the costs of antiarrhythmic drugs were collected on 1008 patients. Detailed records of all other medical encounters and expenses were collected on a subgroup of 237 patients. Regression models were then created to attribute these expenses to the rest of the patients. Charges were converted to 1997 costs using standard methods. Costs and life years were discounted at 3% per year. Three-year survival data from the Antiarrhythmics Versus Implantable Defibrillators trail were used to calculate the base-case cost-effectiveness (C/E) ratio. Six-year, twenty-year, and lifetime C/E ratios were also estimated. At 3 years, total costs were $71 421 for a patient taking AADs and $85 522 for a patient using an ICD, and the ICD provided a 0.21-year survival benefit over AAD treatment. The base-case C/E ratio was thus $66 677 per year of life saved by the ICD compared with AAD therapy (95% CI, $30 761 to $154 768). Six- and 20-year C/E ratios remained stable between $68 000 and $80 000 per year of life saved. CONCLUSIONS: The ICD is moderately cost-effective for secondary prevention of life-threatening ventricular arrhythmias, as judged from prospectively collected data in a randomized clinical trial.

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PubMed2004

Long-term comparison of the implantable cardioverter defibrillator versus amiodarone: eleven-year follow-up of a subset of patients in the Canadian Implantable Defibrillator Study (CIDS).

BACKGROUND: The implantable cardioverter defibrillator (ICD) is superior to amiodarone for secondary prophylaxis of sudden cardiac death. However, the magnitude of this benefit over long-term follow-up is not known. Thus, our objective was to evaluate the long-term consequences of using amiodarone versus an ICD as first-line monotherapy in patients with a prior history of sustained ventricular tachycardia/ventricular fibrillation or cardiac arrest. METHODS AND RESULTS: A total of 120 patients were enrolled at St Michael's Hospital in the Canadian Implantable Defibrillator Study (CIDS) and were randomly assigned to receive either amiodarone (n=60) or an ICD (n=60). The treatment strategy was not altered after the end of CIDS unless the initial assigned therapy was not effective or was associated with serious side effects. After a mean follow-up of 5.6+/-2.6 years, there were 28 deaths (47%) in the amiodarone group, compared with 16 deaths (27%) in the ICD group (P=0.0213). Total mortality was 5.5% per year in the amiodarone group versus 2.8% per year in the ICD group (hazard ratio of amiodarone: ICD, 2.011; 95% confidence interval, 1.087 to 3.721; P=0.0261). In the amiodarone group, 49 patients (82% of all patients) had side effects related to amiodarone, of which 30 patients (50% of all patients) required discontinuation or dose reduction; 19 patients crossed over to ICD because of amiodarone failure (n=7) or side effects (n=12). CONCLUSIONS: In a subset of CIDS, the benefit of the ICD over amiodarone increases with time; most amiodarone-treated patients eventually develop side effects, have arrhythmia recurrences, or die.

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PubMed2000

Identification of patients most likely to benefit from implantable cardioverter-defibrillator therapy: the Canadian Implantable Defibrillator Study.

BACKGROUND: Patients with resuscitated ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation) benefit from implantable cardioverter-defibrillators (ICDs) compared with medical therapy. We hypothesized that the patients who benefit most from an ICD are those at greatest risk of death. METHODS AND RESULTS: In the Canadian Implantable Defibrillator Study (CIDS), 659 patients with resuscitated ventricular tachyarrhythmias were randomly assigned to receive an ICD or amiodarone and were then followed for a mean of 3 years. There were 98 and 83 deaths in the amiodarone and ICD groups, respectively. We used multivariate Cox analysis to assess the impact of baseline parameters on the mortality in the amiodarone group. Reduced left ventricular ejection fraction, advanced age, and poor NYHA status identified high-risk patients (P=0.0001 to 0.0009). Quartiles of risk were constructed, and the mortality reduction associated with ICD treatment in each quartile was assessed. There was a significant interaction between risk quartile and the ICD treatment effect (P=0.011). In the highest risk quartile, there was a 50% relative risk reduction (95% CI 21% to 68%) of death in the ICD group, whereas in the 3 lower quartiles, there was no benefit. Patients who are most likely to benefit from an ICD can be identified with a simple risk score (>/=2 of the following factors: age >/=70 years, left ventricular ejection fraction </=35%, and NYHA class III or IV). Thirteen of 15 deaths that were prevented by the ICD occurred in patients with >/=2 risk factors. CONCLUSIONS: In CIDS, patients at highest risk of death benefited most from ICD therapy. These can be identified easily on the basis of age, poor ventricular function, and poor functional status.

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PubMed2001

Cost-effectiveness of the implantable cardioverter-defibrillator: results from the Canadian Implantable Defibrillator Study (CIDS).

BACKGROUND: In the Canadian Implantable Defibrillator Study (CIDS), we assessed the cost-effectiveness of the implantable cardioverter-defibrillator (ICD) in reducing the risk of death in survivors of previous ventricular tachycardia (VT) or fibrillation (VF). METHODS AND RESULTS: Healthcare resource use was collected prospectively on the first 430 patients enrolled in CIDS (n=212 ICD, n=218 amiodarone). Mean cost per patient, adjusted for censoring, was computed for each group based on initial therapy assignment. Incremental cost-effectiveness of ICD therapy was computed as the ratio of the difference in cost (ICD minus amiodarone) to the difference in life expectancy (both discounted at 3% per year). All costs are in 1999 Canadian dollars (C$1 approximately US$0.65). Over 6.3 years, mean cost per patient in the ICD group was C$87 715 versus C$38 600 in the amiodarone group (difference C$49 115; 95% CI C$25 502 to C$69 508). Life expectancy for the ICD group was 4.58 years versus 4.35 years for amiodarone (difference 0.23, 95% CI -0.09 to 0.55), for incremental cost-effectiveness of ICD therapy of C$213 543 per life-year gained. ICD benefit was greater in patients with low left ventricular ejection fraction (<35%), and cost-effectiveness in this group was more attractive (C$108 484). Alternative extrapolations of survival benefit and costs to 12 years indicated cost-effectiveness in the range of C$100 000 to C$150 000 per life-year gained. CONCLUSIONS: At C$213 543, the value for the money offered by ICD therapy is not attractive by currently accepted standards. Further research is warranted to identify the indications and patient subgroups for whom ICDs are a cost-effective use of resources.

Cost-Benefit Analysis↗
PubMed2002

Quality of life in the antiarrhythmics versus implantable defibrillators trial: impact of therapy and influence of adverse symptoms and defibrillator shocks.

BACKGROUND: Implantable cardioverter defibrillator (ICD) use reduces mortality in patients with serious ventricular arrhythmias compared with antiarrhythmic drug (AAD) use. However, the relative impact of these therapies on self-perceived quality of life (QoL) is unknown. METHODS AND RESULTS: Three self-administered instruments were used to measure generic and disease-specific QoL in Antiarrhythmics Versus Implantable Defibrillators trial participants. Generalized linear models were used to assess the relationships between self-perceived QoL and treatment (AAD versus ICD) and adverse symptoms and ICD shocks. To minimize the impact of missing data, only patients surviving 1 year were included in the primary analyses. Baseline characteristics among QoL participants (n=905) and nonparticipants (n=111) were similar, but participants who survived 1 year (n=800) were healthier at baseline than nonsurvivors (n=105). Of the 800 patients in the primary analysis, characteristics of those randomized to AAD (n=384) versus ICD (n=416) were similar. Overall, ICD and AAD use were associated with similar alterations in QoL. The development of sporadic shocks and adverse symptoms were each associated with reduced physical functioning and mental well-being and increased concerns among ICD recipients, whereas development of adverse symptoms was associated with reduced physical functioning and increased concerns among AAD recipients. CONCLUSIONS: ICD and AAD therapy are associated with similar alterations in self-perceived QoL over 1-year follow-up. Adverse symptoms were associated with reduced self-perceived QoL in both groups, and sporadic shocks were associated with reduced QoL in ICD recipients.

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PubMed2001

Effect of clinical risk stratification on cost-effectiveness of the implantable cardioverter-defibrillator: the Canadian implantable defibrillator study.

BACKGROUND: Three randomized clinical trials showed that implantable cardioverter-defibrillators (ICDs) reduce the risk of death in survivors of ventricular tachyarrhythmias, but the cost per year of life gained is high. A substudy of the Canadian Implantable Defibrillator Study (CIDS) showed that 3 clinical factors, age >/=70 years, left ventricular ejection fraction </=35%, and New York Heart Association class III, predicted the risk of death and benefit from the ICD. We estimated the extent to which selecting patients for ICD therapy based on these risk factors makes ICD therapy more economically attractive. METHODS AND RESULTS: Patients in CIDS were grouped according to whether they had >/=2 of 3 risk factors. Incremental cost-effectiveness of ICD therapy was computed as the ratio of the difference in mean cost to the difference in life expectancy between the 2 groups. Over 6.3 years, the mean cost per patient in the ICD group was Canadian (C) $87 715 versus $38 600 in the amiodarone group (C$1 approximately US$0.67). Life expectancy for the ICD group was 4.58 years versus 4.35 years for amiodarone, for an incremental cost-effectiveness of ICD therapy of C$213 543 per life-year gained. The cost per life-year gained in patients with >/=2 factors was C$65 195, compared with C$916 659 with <2 risk factors. CONCLUSIONS: The cost-effectiveness of ICD therapy varies by patient risk factor status. The use of ICD therapy in patients who have >/=2 risk factors of age >/=70 years, left ventricular ejection fraction </=35%, and NYHA class III is C$65 195 to gain a year of life.

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