New Guidelines for Implantation of Pacemakers and ICDs Highlighted at ACC

April 28, 2003

April 28, 2003 — In September 2002, a joint committee of the American College of Cardiology (ACC), American Heart Association (AHA), and North American Society for Pacing and Electrophysiology (NASPE) released revised practice guidelines for the implantation of cardiac pacemakers and antiarrhythmia devices.[1] The new guidelines, which update those published in 1998, include several significant changes in the areas of device-based therapy for heart failure, pacing in children and adolescents, and the use of implantable cardioverter defibrillators (ICDs) for primary and secondary prevention of sudden cardiac death. In general, the guidelines expand the indications for pacemaker and ICD use and are the first to endorse the use of biventricular pacing (BVP) technology for patients with medically refractory moderate to severe heart failure.

At the American College of Cardiology 52nd Annual Scientific Session held recently in Chicago, Illinois, the new guidelines were the subject of an extended panel discussion that provided physicians with an overview of the most important changes and their implications for clinical practice. According to panelist Andrew E. Epstein, MD, University of Alabama School of Medicine (Birmingham), the new revised recommendations reflect the explosive growth in device therapy that has occurred since 1998. New applications are being reported regularly that will necessitate updates every 1-2 years in the future and that will require the joint committee to consider the enormous logistic, financial, and societal implications of these new device-based therapies, he said.

Dr. Epstein told Medscape CRM that physicians need to be responsible in their use of these technologies and employ a common sense approach that is evidence-based, because the consequences in terms of cost are substantial. "The new guidelines reflect the knowledge gained from clinical research and clinical trials," he said, "and the results apply to patients similar to those in the trials and can't be extrapolated beyond that."

(A summary of the guideline classifications is provided in the table below).

Pacing for AV Block "Beefed Up"

The major changes in the 2002 guidelines for the treatment of acquired atrioventricular (AV) block involved amendments that emphasize the importance of heart failure due to bradycardia as a reason for pacing. According to panelist Roger A. Freedman, MD, University of Utah School of Medicine (Salt Lake City), the change in this area reflects a general recognition, based on recent clinical studies, of the importance of pacing device selection and indication in heart failure patients. The revised guidelines continue the Class IIa indication for pacemaker implantation in patients with asymptomatic third-degree AV block and average awake ventricular rates of 40 bpm or faster; however, the panel added the wording "especially if cardiomegaly or left ventricular (LV) dysfunction is present."

Pacemaker indications for AV block in patients with neuromuscular diseases were also beefed up a bit, according to Dr. Freedman. Although pacemaker implantation in neuromuscular disease patients with third-degree and advanced second-degree AV block has always been a Class I indication, the new guidelines add the wording "with or without symptoms." Moreover, the Class IIb indication for neuromuscular disease patients with first-degree AV block has been changed to "with any degree of AV block (including first-degree AV block) with or without symptoms..." In addition to these changes, the new guidelines were the first to list alternating bundle-branch block as a Class I pacing indication.

Pediatric Guidelines Enhanced

Several changes were also made to the guidelines with regard to pacing in pediatric patients. A new Class IIa recommendation for pacing was added for children with congenital heart disease and impaired hemodynamics caused by sinus bradycardia or loss of AV synchrony. According to the guidelines, clinical experience to date indicates that children with these characteristics have an unfavorable prognosis if they are not paced. In addition, a new Class IIb recommendation was added for pacing in children and adolescents with neuromuscular diseases with any degree of AV block, with or without symptoms, because of the potential for the unpredictable progression of AV conduction disease. This recommendation is similar to the pacing recommendations for adults with neuromuscular disease and AV block.

Changes in AF Guidelines

The 2002 guidelines provide a minor update to indications for pacing to prevent atrial fibrillation (AF). As in the previous guidelines, pacing is given a Class IIb recommendation for the prevention of symptomatic drug-refractory recurrent AF; however, the new guidelines add the words "in patients with coexisting sinus node dysfunction." Moreover, the Level of Evidence was upgraded from "C" to "B" in the new guidelines. These changes were made to reflect several new studies suggesting that in some patients with recurrent AF and coexisting sinus node dysfunction, atrial-based pacing reduces the arrhythmia recurrence rate.

Although multiple AF pacing options are currently available, the United States Food and Drug Administration (FDA) has endorsed only one pacing option for the prevention of AF -- dynamic atrial overdrive pacing, according to Dr. Freedman, who said that the joint committee based its decision on AF suppression in part on the Atrial Dynamic Overdrive Pacing Trial (ADOPT-A). This randomized trial demonstrated that AF suppression with this pacing mode results in a modest decline in symptomatic AF burden, but in no statistically significant difference in quality of life.

Pacing Indications for Syncope

There were no changes in the Class I indications for pacing in syncope; however, under the Class IIa indications, the new guidelines added a category for "significantly symptomatic and recurrent neurocardiogenic syncope associated with bradycardia documented spontaneously or at the time of tilt-table testing." This indication was given a "B" Level of Evidence rating. According to Gerald V. Naccarelli, MD, Milton S. Hershey Medical Center (Hershey, Pennsylvania), who also spoke at the ACC panel discussion, this recommendation was based on several studies supporting the benefit of pacemakers for syncope reduction in patients with episodes of spontaneous or provoked bradycardia. However, the "B" rating was adopted because of concern about the lack of a control arm in most of these studies and the question of a possible placebo effect.

BVP for Dilated Cardiomyopathy Given Class IIa Recommendation

In terms of pacing indications for dilated cardiomyopathy, the big change in 2002 was the addition of a new Class IIa recommendation (Level of Evidence: A) for the use of BVP therapy in patients with advanced heart failure and prolonged QRS duration. Specifically, the recommendations endorse BVP in medically refractory symptomatic New York Heart Association (NYHA) class III/IV patients with idiopathic, dilated, or ischemic cardiomyopathy with a QRS ≥ 130 ms, LV end-diastolic diameter ≥ 55 mm, and ejection fraction ≤ 35%. This recommendation was supported by multiple trials, including the Multicenter InSync Randomized Clinical Evaluation (MIRACLE)[2] trial and the Multisite Stimulation in Cardiomyopathies (MUSTIC)[3] trial, demonstrating clinical and structural cardiac improvement with BVP therapy in this patient population.

MADIT II Criteria Endorsed, but Questions Remain

Dr. Epstein presented a summary of the 2002 guidelines for the use of ICDs in primary prevention. The big change was the addition of a Class IIa (Level of Evidence: B) recommendation for patients meeting the criteria set forth inthe Multicenter Automatic Defibrillator Implantation (MADIT II)[4] trial: LV ejection fraction ≤ 30%, post myocardial infarction ≥ 1 month, and post coronary artery revascularization surgery ≥ 3 months.

There were several reasons that this indication was not given a Class I recommendation, Dr. Epstein said. Specifically, there are several questions that still need to be addressed, including the reason for the higher rate of heart failure hospitalization seen in MADIT II patients who received ICDs; whether QRS interval makes a difference in who should receive ICD therapy; whether the benefit of ICDs is confined largely to patients with inducible ventricular tachycardia (VT); and issues regarding the cost effectiveness of the therapy in this patient population. The data thus far has demonstrated that patients with a longer QRS interval achieve a beneficial effect from ICD therapy, but there is no specific data for the converse, Dr. Epstein said.

Dr. Epstein also stressed that the reasons for the 5% increased probability of heart failure hospitalization observed in the MADIT II ICD group have not yet been determined; however, he speculated that possibilities could include a potential detrimental effect from right ventricular pacing, as seen in the recent Dual Chamber and VVI Implantable Defibrillator (DAVID)[5] trial; simply a study artifact from retrospective analysis; or the result of longer survival in these patients, a point brought up by the MADIT II study authors. Cost is another major issue that affects the decision of whether to implant an ICD in this patient population. The expanded use of ICDs for this indication could add $1 billion to the $2.2 billion already spent each year for ICD therapy, observed Dr. Epstein. The additional cost must come from somewhere, he said. "There is a fixed amount of money and if we take for Peter, we have to rob Paul." Epstein noted that there is a lot of pressure to place ICD devices in everyone within a few days of infarct, however, the guidelines clearly stipulate that the devices should not be placed until 1 month after infarct or 3 months post revascularization. The reason for this, he said, is that a significant number of infarct patients on good medical therapy achieve salutary left ventricular remodeling and improvement in EF above 30%. Thus physicians do have the luxury of waiting a few months before considering device implantation.

Dr. Epstein noted that the FDA indications for combined CRT/ICDs include patients at high risk of sudden death and those with moderate to severe heart failure, a prolonged QRS interval, and LV dysfunction. These patients are covered under current guidelines, because the ICD indications are the same, he said. Thus, if you have an ICD indication and a wide QRS with class II/III heart failure, you can get a combined CRT/ICD device.

Secondary Prevention Guidelines Stress Underlying Disease

Secondary prevention guidelines were summarized by Cynthia M. Tracy, MD, Georgetown University Hospital (Washington, DC), who noted that some significant changes were made in this category based on new prospective data comparing device therapy with drug therapy. The joint committee relied in part on a pooling of the available data that shows an overall 27% reduction in total mortality in secondary prevention patients given an ICD, Dr. Tracy said. In addition, the new guidelines are the first to relate ICD implantation for secondary prevention to the underlying cardiac disease. This change was based on a number of new studies suggesting that disease states may significantly affect prognosis, and thus the patient's underlying condition should be used when deciding whether to implant an ICD. Again, the data suggest that patients with VT who have a reduced ejection fraction may achieve the greatest benefit from ICD implantation, she said. Alternatively, VT arising in structurally normalhearts can usually be treated with drug therapy or catheter ablation, according to the guidelines. The guidelines also include a new Class I recommendation for ICD implantation in patients with sustained VT and structurally normal hearts who have failed alternative treatments (Level of Evidence: C).

Table. Standard ACC/AHA Classification System
Classification Description
Class I Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective.
Class II Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment.

IIa: Weight of evidence/opinion is in favor of usefulness/efficacy.

IIb: Usefulness/efficacy is less well established by evidence/opinion.
Class III (nonindication) Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and that in some cases it may be harmful.

Note: The weight of the evidence was ranked highest (A) if the data were derived from multiple randomized clinical trials that involved large numbers of patients. The weight of the evidence was ranked intermediate (B) if the data were derived from a limited number of randomized trials that involved small numbers of patients or from careful analyses of nonrandomized studies or observation registries. A lower rank (C) was given when expert consensus was the primary basis for the recommendation.

References
  1. Gregoratos G, Abrams J, Epstein AE, et al. ACC/AHA/NASPE 2002 guidelines update for implantation of cardiac pacemakers and antiarrhythmia devices: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee on Pacemaker Implantation. 2002. Available at: https://www.acc.org/clinical/guidelines/pacemaker/Pacemakerclean.pdf.

  2. Abraham WT, Fisher WG, Smith AL, et al. Cardiac resynchronization in chronic heart failure. N Engl J Med. 2002;346:1845-1853.

  3. Cazeau S, Leclercq C, Lavergne T, et al. Effects of multisite biventricular pacing in patients with heart failure and intraventricular conduction delay. N Engl J Med. 2001;344:873-880.

  4. Moss AJ, Zareba W, Hall WJ, et al., for the Multicenter Automatic Defibrillator Implantation Trial II Investigators. Prophylactic implantation on a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med. 2002;346:877-883.

  5. Wilkoff BL, Cook JR, Epstein AE, et al. Dual-chamber pacing or ventricular backup pacing in patients with an implantable defibrillator: the Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial. JAMA. 2002;288:3115-3123.

By Staff Writer, Medscape CRM
Reviewer: Andrew E. Epstein, MD and Albert A. Del Negro, MD, FACC

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