Effectiveness Of Implantable Cardioverter-defibrillator Therapy Research Articles

RR interval variability in the evaluation of ventricular tachycardia and effects of implantable cardioverter defibrillator therapy.

BackgroundAn implantable cardioverter defibrillator (ICD) is the most reliable therapeutic device for preventing sudden cardiac death in patients with sustained ventricular tachycardia (VT). Regarding its effectiveness, targeted VT is defined based on the tachyarrhythmia cycle length. However, variations in RR interval variability of VTs may occur. Few studies have reported on VT characteristics and effects of ICD therapy according to the RR interval variability. We aimed to identify the clinical characteristics of VTs and ICD therapy effects according to the RR interval variability.MethodsWe analyzed 821 VT episodes in 69 patients with ICDs or cardiac resynchronization therapy defibrillators. VTs were classified as irregular when the difference between two successive beats was >20 ms in at least one of 10 RR intervals; otherwise, they were classified as regular. We evaluated successful termination using anti‐tachycardia pacing (ATP)/shock therapy, spontaneous termination, and acceleration between regular and irregular VTs. The RR interval variability reproducibility rates were evaluated.ResultsRegular VT was significantly more successfully terminated than irregular VT by ATP. No significant difference was found in shock therapy or VT acceleration between the regular and irregular VTs. Spontaneous termination occurred significantly more often in irregular than in regular VT cases. The reproducibility rates of RR interval variability in each episode and in all episodes were 89% and 73%, respectively.ConclusionsATP therapy showed greater effectiveness for regular than for irregular VT. Spontaneous termination was more common in irregular than in regular VT. RR interval variability of VTs seems to be reproducible.

Effect of Implantable Cardioverter-defibrillator Therapy for Ventricular Fibrillation Patients with Out-of-hospital Cardiac Arrest

Effect of Implantable Cardioverter-defibrillator Therapy for Ventricular Fibrillation Patients with Out-of-hospital Cardiac Arrest

Efficacy of an implantable cardioverter-defibrillator in patients with diabetes and heart failure and reduced ejection fraction

BackgroundThe effect of implantable cardioverter-defibrillator (ICD) therapy in patients with heart failure with reduced ejection fraction (HFrEF) and diabetes is not fully elucidated.MethodsWe examined the effect of ICD therapy on sudden cardiac death, cardiovascular death and all-cause mortality, according to diabetes status at baseline in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). The outcomes were analyzed by use of cumulative incidence curves and Cox regressions models.ResultsOf the 1676 patients randomized to an ICD or placebo, 540 (32%) had diabetes at baseline. Patients with diabetes were slightly older (61 vs 58 years) and were more often in NYHA class III (37% vs 28%). ICD therapy did not reduce the risk of sudden cardiac death in HFrEF patients with diabetes (HR = 0.85; 95% CI 0.52–1.40); even though these patients had a higher risk of sudden cardiac death compared to patients without diabetes (HR = 1.73 95% CI 1.22–2.47). By contrast, ICD therapy did reduce sudden cardiac death in HFrEF patients without diabetes (HR = 0.26; 95% CI 0.15–0.46); Pinteraction=0.002. The findings for cardiovascular and all-cause death were similar.ConclusionICD therapy did not reduce the risk of sudden cardiac death (or, as a consequence, all-cause death) in HFrEF patients with diabetes. Conversely, an ICD reduced the risk of sudden death in patients without diabetes, irrespective of etiology.

Controversy surrounding the best time for ICD implantation after myocardial infarction

Controversy surrounding the best time for ICD implantation after myocardial infarction

Rhetorical Strategies Used in the Reporting of Implantable Defibrillator Primary Prevention Trials

Previous studies have suggest that the authors of randomized trial reports frequently use rhetorical strategies, such as framing, the use of ratios rather than absolute values to report results, and underreporting of complications, to convince readers of treatment efficacy. The objective of this study was to determine if such rhetorical strategies were used in the publication of implantable-cardioverter defibrillator (ICD) primary prevention trials. Medline and the Cochrane Central Register of Controlled Trials were searched for all publications that described ICD primary prevention trials and that involved >100 subjects. Each publication was analyzed for evidence of message framing, the exclusive use of ratios to report outcomes, underreporting of ICD complications, and interpretation bias favoring ICD therapy. Ten publications were identified. Introductory remarks in 8 of the 10 publications cited the evaluation of ICD benefits as the sole objective and mentioned only background studies that supported ICD efficacy, suggesting message framing in support of ICD efficacy. Five publications provided no specific information about the frequency of unsuccessful ICD implantations, and 8 publications provided incomplete or no information about implantation and postimplantation complications. ICD complications were not mentioned in the discussion sections of 9 publications, and none of the publications included a comprehensive comparison of ICD benefits versus risks, consistent with interpretation bias. Ratios and statistically insignificant data were not used to emphasize ICD benefits. In conclusion, message framing, underreporting of ICD complications, and interpretation bias were used to emphasize ICD efficacy in the reporting of ICD primary prevention trials.

Clinical Course and Implantable Cardioverter Defibrillator Therapy in Postinfarction Women with Severe Left Ventricular Dysfunction

There are limited data regarding implantable cardioverter defibrillator (ICD) therapy in postinfarction women with severe left ventricular dysfunction. The aim of this study was to evaluate the risk of cardiac events and effects of ICD therapy in women as compared to men enrolled in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II). Among 1,232 patients enrolled in MADIT II, there were 192 (16%) women and 1,040 (84%) men. When compared to men, women had an increased frequency of NYHA class > or =II (70 vs 63%; P = 0.067), hypertension (60% vs 52%; P = 0.047), diabetes (42% vs 34%; P = 0.027), and LBBB (25% vs 17%; P = 0.011), and less frequent CABG surgery (42% vs 60%; P < 0.001). The 2-year cumulative mortality in patients randomized to conventional therapy was not significantly different in women and men (30% and 20%, respectively; P = 0.19). Adjusting for relevant clinical covariates, the hazard ratios for ICD effectiveness were similar in women (0.57; 95% CI = 0.28-1.18; P = 0.132) and men (0.66; 95% CI = 0.48-0.91; P = 0.011). The risk of appropriate ICD therapy for VT/VF was lower in women than in men (hazard ratio = 0.60 for female vs male gender; 95% CI = 0.37-0.98; P = 0.039). MADIT II women had similar mortality and similar ICD effectiveness when compared to men. MADIT II women with ICDs had a lower risk of arrhythmic events with fewer episodes of ventricular tachycardia than men.

Survival benefit of the implantable cardioverter-defibrillator in patients on the waiting list for cardiac transplantation.

The implantable cardioverter-defibrillator (ICD) effectively reduces sudden cardiac death in patients with severe LV dysfunction. Effect of ICD therapy on total mortality in patients on the waiting list for cardiac transplantation is still uncertain. We retrospectively analyzed 854 unselected consecutive patients (ICD therapy, n=102; 11.9%) on the waiting list for cardiac transplantation between January 1992 and March 2000. Actuarial 12-month total mortality rate on the waiting list was 24.2%; sudden cardiac death was the predominant mode of death (66.7% of total deaths). Kaplan-Meier analysis revealed improved survival for ICD (total mortality, 13.2%) compared with non-ICD (total mortality, 25.8%) patients (log rank, P=0.03). No event of sudden death occurred in ICD patients, whereas in non-ICD patients, 12-month sudden death rate was 20.1% (P=0.0001). Nonsudden death rates did not differ between ICD and non-ICD patients (P=0.16). A Cox proportional hazards model demonstrated that absence of an ICD was a powerful independent predictor of total mortality (P=0.02; relative risk, 2.22; 95% confidence interval, 1.16 to 4.17) and sudden cardiac death (P<0.0001; infinite relative risk) on the waiting list. ICD therapy, because it prevents sudden cardiac death, significantly improves survival on the waiting list for cardiac transplantation. The present study supports the use of ICDs as a bridge to transplantation in patients who are at risk of sudden cardiac death. Prospective randomized trials are needed to evaluate the potential benefit of prophylactic ICD therapy as a bridge to transplantation in all patients on cardiac transplant waiting lists.

Survival Benefit of the Implantable Cardioverter-Defibrillator in Patients on the Waiting List for Cardiac Transplantation

Background The implantable cardioverter-defibrillator (ICD) effectively reduces sudden cardiac death in patients with severe LV dysfunction. Effect of ICD therapy on total mortality in patients on the waiting list for cardiac transplantation is still uncertain. Methods and Results We retrospectively analyzed 854 unselected consecutive patients (ICD therapy, n=102; 11.9%) on the waiting list for cardiac transplantation between January 1992 and March 2000. Actuarial 12-month total mortality rate on the waiting list was 24.2%; sudden cardiac death was the predominant mode of death (66.7% of total deaths). Kaplan-Meier analysis revealed improved survival for ICD (total mortality, 13.2%) compared with non-ICD (total mortality, 25.8%) patients (log rank, P =0.03). No event of sudden death occurred in ICD patients, whereas in non-ICD patients, 12-month sudden death rate was 20.1% ( P =0.0001). Nonsudden death rates did not differ between ICD and non-ICD patients ( P =0.16). A Cox proportional hazards model demonstrated that absence of an ICD was a powerful independent predictor of total mortality ( P =0.02; relative risk, 2.22; 95% confidence interval, 1.16 to 4.17) and sudden cardiac death ( P &lt;0.0001; infinite relative risk) on the waiting list. Conclusions ICD therapy, because it prevents sudden cardiac death, significantly improves survival on the waiting list for cardiac transplantation. The present study supports the use of ICDs as a bridge to transplantation in patients who are at risk of sudden cardiac death. Prospective randomized trials are needed to evaluate the potential benefit of prophylactic ICD therapy as a bridge to transplantation in all patients on cardiac transplant waiting lists.

Indications for implantable cardioverter defibrillator (ICD) therapy. Study Group on Guidelines on ICDs of the Working Group on Arrhythmias and the Working Group on Cardiac Pacing of the European Society of Cardiology

Last year was the 20th anniversary of the first defibrillator implantation in a human being. Since then, the number of new defibrillator implants has gradually increased following an exponential curve. In 1998, nearly 50 000 new ICD implants were carried out worldwide. This tremendous increase was due to technological improvements in the device and the effectiveness of ICD therapy. Technological improvements in devices and leads included a gradual reduction in the size of the device, the introduction of the endocardial approach in 1988, the biphasic waveform and antitachycardia pacing in 1991, pectoral implantation in 1995, inclusion of DDD pacing in 1996 and finally, inclusion of DDDR and also atrial defibrillation in 1998. Efficacy assessment started with observational studies. In 1985, FDA approval for ICD implantation was obtained. Results of prospective randomized studies, which assessed the effectiveness of ICDs, were obtained in the late 1990s. The first reported trial was essentially an analysis of cost-effectiveness, which compared ICD implantation as first-choice therapy vs conventional strategy starting with antiarrhythmic drugs in postinfarct sudden death survivors. If drugs failed, the patient was treated with endocardial resection or a late defibrillator implant. The cost-effectiveness ratio, defined as costs per day of life, was significantly in favour of early ICD implantation. However, because the number of patients was relatively small, total mortality showed only a trend in favour of early ICD implantation.

Assessing the psychosocial impact of the ICD: a national survey of implantable cardioverter defibrillator health care providers.

The implantable cardioverter defibrillator (ICD) provides a survival advantage over antiarrhythmic medications for patients with life-threatening ventricular arrhythmias. However, the effect of ICD therapy on quality-of-life and psychosocial functioning are not as well understood. Health care providers (e.g., physicians, nurses) can serve as a valuable source of information related to these ICD outcomes. The purpose of this study was to investigate health care provider perceptions regarding: (1) the quality-of-life and psychosocial functioning of their ICD recipients, (2) the concerns or problems reported by ICD recipients, and (3) the degree of provider comfort in managing these concerns. The final sample of health care providers (n = 261) rated ICD recipients' global quality-of-life and psychosocial functioning, and specific concerns about health care, lifestyle, special population adjustment, marital and family adjustment, and emotional well-being. With regard to quality-of-life, health care providers reported that the majority of ICD recipients were functioning better (38%) or about the same (47%) than before implantation. However, health care providers reported that 15% of recipients experienced worse quality-of-life postimplantation. Similarly, health care providers indicated that 10%-20% of ICD recipients experienced worse emotional functioning and strained family relationships. Moreover, issues related to driving, dealing with ICD shocks, and depression were the most common ICD recipient concerns. Significant differences were noted between physicians and nurses/other health care professionals on a wide range of psychosocial issues. Health care providers generally reported the most comfort dealing with traditional medical issues (i.e., patient adherence), and the least comfort in managing emotional well-being issues (e.g., depression and anxiety). These results suggest that routine attention to ICD quality-of-life and psychosocial outcomes is indicated for health care providers who care for ICD recipients.