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Major Guideline Changes for CRT in the 2012 ACCF/AHA/HRS Focused Update

Disclosure: Dr. Page reported a modest NIH relationship
Pub Date: Monday, Sept. 10, 2012
Author: Richard L. Page, MD
Affiliation: Department of Medicine University of Wisconsin School of Medicine and Public Health


Tracy CM, Epstein AE, Darbar D, DiMarco JP, Dunbar SB, Estes NAM 3rd, Ferguson TB Jr, Hammill SC, Karasik PE, Link MS, Marine JE, Schoenfeld MH, Shanker AJ, Silka MJ, Stevenson LW, Stevenson WG, Varosy PD. 2012 ACCF/AHA/HRS focused update of the 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation /American Heart Association Task Force on Practice Guidelines. Circulation. 2012: published online before print September 10, 2012, 10.1161/CIR.0b013e3182618569.

Article Text

The release of any guidelines from the ACCF/AHA Task Force on Practice Guidelines1   represents the culmination of a tremendous effort on the part of a number of experts in our field.  Having served in the past on this Task Force, and having contributed as a member of the writing committee for the 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities (“2008 Guidelines” in this paper),2 I recognize the substantial effort that is undertaken to synthesize the available data and to get the guideline “right” at the time of publication.  Even before the manuscript is published, a guideline starts to become out of date because new data are published during production.  The 2012 ACC/AHA/HRS Focused Update of the 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities builds on the 2008 Guidelines and represents an important contribution to our field in that it brings together the latest data that allow both refinement and expansion of the indications for device-based therapy.

The document begins by pointing out that much of the 2008 Guideline remains unchanged, since the solid data in support of the recommendations have not been refuted.  Likewise, the authors identified other areas, such as genetic arrhythmia syndromes and congenital heart disease, where there remains a relative dearth of data and, as such, no changes could be recommended.  In contrast to the areas where no change is indicated, over the last 4 years several major studies have been published that provide insight related to treatment of ventricular electromechanical delay with multi-side ventricular pacing (also called “bi-ventricular pacing” or “cardiac resynchronization therapy” [CRT in this paper].  As a result of these large randomized studies, and other analyses, reexamination of the 2008 recommendations was not just warranted—it was imperative.

In addition to new data being published that relate to CRT, since 2008 there have been significant changes in the technology available for pacemaker follow-up, specifically in the area of remote follow-up and monitoring.  These new technologies, and the data now available to support their use, allow for refined recommendations for the minimum frequency of cardiovascular implantable electronic device (CIED) follow-up.  While certain visits for pacemakers/ICDs/CRT still mandate in-person evaluation (such as at 72 hours, 2-12 weeks, and annually), others may be performed either in-person or remotely.

Recommendations for CRT in Patients with Systolic Heart Failure

Changes in the recommendations:

All recommendations for the 2008 Guidelines and 2012 Update are predicated on the expectation that appropriate medical therapy already is being provided.  The 2012 Update defines this as “guideline-directed medical therapy” (GDMT) and the discussion below assumes that GDMT is being provided.

As mentioned above, the 2012 Update provides both expansion and limitation of the indications for CRT.  Previously, the only Class I recommendation for CRT was in patients with relatively severe symptoms (NYHA Functional Class III or IV heart failure) accompanied by sinus rhythm, left ventricular ejection fraction (LVEF) ≤ 35%, a QRS duration ≥0.12 second.  For the 2012 update, this Class I indication is expanded to patients with NYHA Class II, extending the clear message that CRT “is indicated” for a population with milder symptoms. At the same time, the 2012 Update limits, or refines, this single Class I recommendation by confining it only to patients with left bundle branch block (LBBB) and QRS ≥150 msec.  The patients with left bundle branch block but QRS duration only 120 to 149 msec and those with non-LBBB pattern and QRS ≥150 msec, included in Class I in 2008, now receive a Class IIa recommendation.  Of note, the former group (LBBB with QRS 120 to 149 msec) is now extended to patients with NHYA Class II (in addition to Class III/ambulatory Class IV). In contrast, for the latter group (non-LBBB and QRS 120-149) the indication is not expanded beyond patients with NYHA Class III/ ambulatory Class IV; to the contrary, CRT for patients in this group with NYHA Class II symptoms is “not recommended” (with a Class III Recommendation).

Further Class IIa recommendations, specifically pertinent for patients with requirement for ventricular pacing, have been modified.  Patients with atrial fibrillation and LVEF ≤35% now are indicated for CRT if rate control allows near 100% ventricular pacing; this recommendation no longer specifies functional symptom class.  In addition, there is now a IIa recommendation (as opposed to IIb) for patients with LVEF ≤35% who are anticipated to require ventricular pacing greater than 40% of the time.

A further major expansion of the indication for CRT, for the first time ever in patients with NYHA Class I symptoms, is provided with a recommendation Class IIb (“may be considered”). This is limited to patients with relatively severe cardiomyopathy (LVEF ≤30%) due to ischemia, LBBB, and QRS duration ≥150 msec, but expands the option of CRT to patients who previously would not have been considered candidates.  There are also two other new IIb recommendations:  for patients with LVEF ≤35%, a non-LBBB pattern with QRS duration 120-149 msec and NYHA Class III/ functional Class IV; and, for patients with LVEF ≤35%, in sinus rhythm with non-LBBB pattern but QRS ≥150 msec and NYHA Class II symptoms (again expanding the option of guideline-based CRT in patients with relatively modest symptoms). 

The Class III recommendations, where CRT is “not recommended,” are reserved for patients with NYHA Class I or II symptoms, non-LBBB pattern and QRS <150 msec; in addition, Class III is now applied to patients in whom cardiac or non-cardiac comorbidity and/or frailty limit survival with good functional capacity to less than 1 year.

Rationale for the changes:

The new recommendations, summarized above, build on data published prior to the 2008 guidelines.3-6   Since publication of the 2008 Guideline, REVERSE,7 MADIT-CRT,8 and RAFT9 have allowed for the refinements described above, based on inclusion criteria of these trials that provide data for CRT in patients with less severe symptoms.  These large randomized studies, along with meta-analyses,10,11 have also tempered enthusiasm for CRT in patients with QRS less than 150 msec based on failure to respond to CRT for all functional NYHA classes. 

Furthermore, studies published in 2009 and 2010,12-14 and a meta-analysis from 2011,11 demonstrated that non-LBBB conduction abnormalities are associated with failure to benefit from CRT.  The jury may still be out on this issue, since there are some data to suggest that patients with non-LBBB can benefit from CRT when the QRS is markedly prolonged8,9; as such, these patients still are included in recommendation Class II.

Where Do We Go From Here?

With the publication of the 2012 focused update, CRT has truly come of age.  Even though CRT is generally appreciated to increase the risk of complications, prolong procedural time and increase cost, in comparison to single or dual chamber ICD therapy, well-conducted randomized trials irrefutably demonstrate benefit in well-defined patient groups.  The cardiovascular and clinical cardiac electrophysiology community should be congratulated for the generation of important data that provide for evidence-based recommendations for CRT.  Of course, as soon as this Focused Update is published, new data will be available, and future Updates or full Guidelines will follow along with further refinement.

Guidelines are exactly as they are named—guidelines.  These documents synthesize the data that are available and provide recommendations to the clinician for consideration in each individual patient.  There will always be groups of patients for whom guidelines are not strictly applicable.  Unfortunately, at times placement of CIEDs in situations not covered by the document or “contrary” to the guidelines, but appropriate for the individual patient, may risk failure of reimbursement or even litigation.  In situations where the guidelines do not apply to “real world” patients, it is hoped that appropriate use criteria (AUC) methodology will further guide therapy.  This methodology, currently being applied to ICD and CRT therapy, with expected publication in 2012, will examine a large number of  “indications” or scenarios where the guidelines might not strictly apply, and provide the practitioner with levels of appropriateness based on the scale of 1 through 9.  The AUC document, in combination with this current focused update, will provide the best guidance to date for application of CIED therapy.


  1. Tracy CM, Epstein AE, Darbar D, DiMarco JP, Dunbar SB, Estes NAM III, Ferguson TB, Hammill SC, Karasik PE, Link MS, Marine JE, Schoenfeld MH, Shanker AJ, Silka MJ, Stevenson LW, Stevenson WG, Varosy PD. 2012 ACCF/AHA/HRS focused update of the 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2012; September 10, 2012, 10.1161/CIR.0b013e3182618569.
  2. Epstein AE, DiMarco JP, Ellenbogen KA, et al. ACC/AHA/HRS 2008 Guidelines for device-based therapy of cardiac rhythm abnormalities. Heart Rhythm. 2008;5:e1-62.
  3. Abraham WT, Fisher WG, Smith AL, et al. Cardiac resynchronization in chronic heart failure. N Engl J Med 2002;346:1845-53
  4. Young JB, Abraham WT, Smith jAL,et al. Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure:; the MIRACLE ICD Trial. JAMA 2003;289:2685-94.
  5. Bristow MR, Saxon LA, Boehmer J, et al. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. N Engl J Med. 2004;350:2140-50.
  6. Cleland JG, Daubert JC, Erdmann E, et al. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med. 2005;352:1539-49.
  7. Linde C, Abraham WT, Gold MR, et al. Randomized trial of cardiac resynchronization in mildly symptomatic heart failure patients and in asymptomatic patients with left ventricular dysfunction and previous heart failure symptoms. J Am Coll Cardiol. 2008;52:1834-43.
  8. Moss AJ, Hall WJ, Cannom DS, et al. Cardiac-resynchronization therapy for the prevention of heart-failure events. N Engl J Med. 2009;361:1329-38.
  9. Tang AS, Wells GA, Talajic M, et al. Cardiac-resynchronization therapy for mild-to-moderate heart failure. N Engl J Med. 2010;363:2385-95.
  10. Stavrakis S., Lazzara R, Thadani U. The benefit of cardiac resynchronization therapy and QRS duration: A Meta-Analysis. J. Cardiovasc Electrophysiol. 2012;23:163-8.
  11. Sipahi I, Carrigan TP, Rowland DY, et al. Impact of QRS duration on clinical event reduction with cardiac resynchronization therapy: meta-analysis of randomized controlled trials. Arch Intern Med. 2011;171:1454-62.
  12. Bilchick KC, Kamath S, DiMarco JP, et al. Bundle-branch block morphology and other predictors of outcome after cardiac resynchronization therapy in Medicare patients. Circulation. 2010;122:2022-30.
  13. Adelstein EC, Saba S. Usefulness of baseline electrocardiographic QRS complex pattern to predict response to cardiac resynchronization. Am J Cardiol. 2009;103:238-42.
  14. Rickard J, Kumbhani DJ, Gorodeski EZ, et al. Cardiac resynchronization therapy in non-left bundle branch block morphologies. Pacing Clin Electrophysiol. 2010;33:590-5.

-- The opinions expressed in this commentary are not necessarily those of the editors or of the American Heart Association --