15 Jun 08

ACC/AHA/HRS 2008 Guidelines for device-based therapy of cardiac rhythm abnormalities

Posted in Arrhythmia, Pacemaker - ICD at 10:13 by Laci

By R A Freedman, L S Gettes, A. Marc Gillinov, G Gregoratos, A E Epstein, J P DiMarco et al.

J. Am. Coll. Cardiol. 2008;51:1-62

It is important that the medical profession play a significant role in critically evaluating the use of diagnostic procedures and therapies as they are introduced and tested in the detection, management, or prevention of disease states. Rigorous and expert analysis of the available data documenting absolute and relative benefits and risks of those procedures and therapies can produce helpful guidelines that improve the effectiveness of care, optimize patient outcomes, and favorably affect the overall cost of care by focusing resources on the most effective strategies.

The American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA) have jointly engaged in the production of such guidelines in the area of cardiovascular disease since 1980. The American College of Cardiology (ACC)/AHA Task Force on Practice Guidelines, whose charge is to develop, update, or revise practice guidelines for important cardiovascular diseases and procedures, directs this effort. Writing committees are charged with the task of performing an assessment of the evidence and acting as an independent group of authors to develop, update, or revise written recommendations for clinical practice.

Experts in the subject under consideration have been selected from both organizations to examine subject-specific data and write guidelines. The process includes additional representatives from other medical practitioner and specialty groups when appropriate. Writing committees are specifically charged to perform a formal literature review, weigh the strength of evidence for or against a particular treatment or procedure, and include estimates of expected health outcomes where data exist. Patient-specific modifiers and comorbidities and issues of patient preference that may influence the choice of particular tests or therapies are considered, as well as frequency of follow-up and cost-effectiveness. When available, information from studies on cost will be considered; however, review of data on efficacy and clinical outcomes will constitute the primary basis for preparing recommendations in these guidelines.

The ACC/AHA Task Force on Practice Guidelines makes every effort to avoid any actual, potential, or perceived conflicts of interest that may arise as a result of an industry relationship or personal interest of the writing committee. Specifically, all members of the writing committee, as well as peer reviewers of the document, were asked to provide disclosure statements of all such relationships that may be perceived as real or potential conflicts of interest. Writing committee members are also strongly encouraged to declare a previous relationship with industry that may be perceived as relevant to guideline development. If a writing committee member develops a new relationship with industry during his or her tenure, he or she is required to notify guideline staff in writing. The continued participation of the writing committee member will be reviewed. These statements are reviewed by the parent task force, reported orally to all members of the writing committee at each meeting, and updated and reviewed by the writing committee as changes occur. Please refer to the methodology manual for ACC/AHA guideline writing committees for further description of the relationships with industry policy. See Appendix 1 for author relationships with industry and Appendix 2 for peer reviewer relationships with industry that are pertinent to this guideline.

These practice guidelines are intended to assist health care providers in clinical decision making by describing a range of generally acceptable approaches for the diagnosis, management, and prevention of specific diseases or conditions. Clinical decision making should consider the quality and availability of expertise in the area where care is provided. These guidelines attempt to define practices that meet the needs of most patients in most circumstances. These guideline recommendations reflect a consensus of expert opinion after a thorough review of the available current scientific evidence and are intended to improve patient care.

Patient adherence to prescribed and agreed upon medical regimens and lifestyles is an important aspect of treatment. Prescribed courses of treatment in accordance with these recommendations will only be effective if they are followed. Because lack of patient understanding and adherence may adversely affect treatment outcomes, physicians and other health care providers should make every effort to engage the patient in active participation with prescribed medical regimens and lifestyles.

If these guidelines are used as the basis for regulatory or payer decisions, the ultimate goal is quality of care and serving the patient’s best interests. The ultimate judgment regarding care of a particular patient must be made by the health care provider and the patient in light of all of the circumstances presented by that patient. There are circumstances in which deviations from these guidelines are appropriate.

26 Sep 07

Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy

Posted in Pacemaker - ICD at 18:31 by Laci

By B J Maron, P Spirito, W-K Shen, T S Haas, F Formisano, M S Link, A E Epstein, A K Almquist et al

JAMA. 2007;298:405-412

Recently, the implantable cardioverter-defibrillator (ICD) has been promoted for prevention of sudden death in hypertrophic cardiomyopathy (HCM). However, the effectiveness and appropriate selection of patients for this therapy is incompletely resolved.

Objective
To study the relationship between clinical risk profile and incidence and efficacy of ICD intervention in HCM.

Design, Setting, and Patients
Multicenter registry study of ICDs implanted between 1986 and 2003 in 506 unrelated patients with HCM. Patients were judged to be at high risk for sudden death; had received ICDs; underwent evaluation at 42 referral and nonreferral institutions in the United States, Europe, and Australia; and had a mean follow-up of 3.7 (SD, 2.8) years. Measured risk factors for sudden death included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope.

Main Outcome Measure
Appropriate ICD intervention terminating ventricular tachycardia or fibrillation.

Results
The 506 patients were predominately young (mean age, 42 [SD, 17] years) at implantation, and most (439 [87%]) had no or only mildly limiting symptoms. ICD interventions appropriately terminated ventricular tachycardia/fibrillation in 103 patients (20%). Intervention rates were 10.6% per year for secondary prevention after cardiac arrest (5-year cumulative probability, 39% [SD, 5%]), and 3.6% per year for primary prevention (5-year probability, 17% [SD, 2%]). Time to first appropriate discharge was up to 10 years, with a 27% (SD, 7%) probability 5 years or more after implantation. For primary prevention, 18 of the 51 patients with appropriate ICD interventions (35%) had undergone implantation for only a single risk factor; likelihood of appropriate discharge was similar in patients with 1, 2, or 3 or more risk markers (3.83, 2.65, and 4.82 per 100 person-years, respectively; P = .77). The single sudden death due to an arrhythmia (in the absence of advanced heart failure) resulted from ICD malfunction. ICD complications included inappropriate shocks in 136 patients (27%).

Conclusions
In a high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients who had undergone implantation for a single risk factor. Therefore, a single marker of high risk for sudden death may be sufficient to justify consideration for prophylactic defibrillator implantation in selected patients with HCM.

29 Aug 07

Implantable cardioverter defibrillators for adults with left ventricular systolic dysfunction

Posted in Heart failure/Cardiogenic shock, Pacemaker - ICD at 17:12 by Laci

By JA Ezekowitz, BH Rowe, DM Dryden, N Hooton, B Vandermeer, C Spooner and FA McAlister

Ann Intern Med. 2007;147:251-262

Patients with left ventricular (LV) systolic dysfunction have an increased risk for ventricular arrhythmias.

Purpose
To summarize the evidence about benefits and harms of implantable cardioverter defibrillators (ICDs) in adult patients with LV systolic dysfunction.

Data Sources
A search of electronic databases (including MEDLINE, EMBASE, Cochrane Central, and U.S. Food and Drug Administration reports) from 1980 through April 2007, not limited by language of publication, was supplemented by hand searches and contact with study authors and device manufacturers.

Study Selection
Two reviewers independently selected studies on the basis of prespecified criteria. They selected 12 randomized, controlled trials (RCTs) (8516 patients) that reported on mortality and 76 observational studies (96 951 patients) that examined safety or effectiveness.

Data Extraction
Data were extracted in duplicate and independently by 2 reviewers.

Data Synthesis
In adult patients with LV systolic dysfunction, 86% of whom had New York Heart Association class II or III symptoms, ICDs reduced all-cause mortality by 20% (95% CI, 10% to 29%) in the RCTs and by 46% (CI, 32% to 57%) in the observational studies. Death associated with implantation of ICDs occurred during 1.2% (CI, 0.9% to 1.5%) of procedures. The frequency of postimplantation complications per 100 patient-years included 1.4 (CI, 1.2 to 1.6) device malfunctions, 1.5 (CI, 1.3 to 1.8) lead problems, and 0.6 (CI, 0.5 to 0.8) site infection. Rates of inappropriate discharges per 100 patient-years ranged from 19.1 (CI, 16.5 to 22.0) in RCTs to 4.9 (CI, 4.5 to 5.3) in observational studies.

Limitations
Studies were of short duration and infrequently reported nonfatal outcomes. Few studies evaluated dual-chamber ICDs. Lack of individual-patient data prevents identification of subgroup-specific effects.

Conclusions
Implantable cardioverter defibrillators are efficacious in reducing mortality for adult patients with LV systolic dysfunction, and this benefit extends to nontrial populations. Improved risk stratification tools to identify patients who are most likely to benefit from ICD are needed.

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