ClinicalDeviceUpgrade and de novo cardiac resynchronization therapy: Impact of paced or intrinsic QRS morphology on outcomes and survival
Introduction
Cardiac resynchronization therapy (CRT) has been shown to improve outcomes in trials in which most patients with drug-refractory heart failure (HF) had intrinsic left bundle branch block (LBBB).1, 2, 3, 4 However, the benefits of CRT have not been conclusively demonstrated in patients with other native QRS morphologies or those who have undergone right ventricular (RV) pacing in the setting of a preexisting pacemaker or defibrillator due to limited representation within randomized controlled trials and variable outcomes.
The impact of QRS morphology on HF outcomes has been examined in four randomized trials of CRT.1, 2, 4, 5 In a substudy of CRT-D recipients from the MIRACLE (Multicenter InSync Randomized Clinical Evaluation) ICD study, RBBB was associated with less improvement in peak oxygen consumption than other QRS morphologies in univariate, but not multivariate, analysis.6 In a retrospective, pooled analysis from MIRACLE and CONTAK-CD that compared outcomes in 34 patients with RBBB who received CRT and 27 who received medical management, New York Heart Association (NYHA) functional class was the only clinical outcome that improved significantly more after active CRT. Improvements in other HF parameters, such as 6-minute walk, peak oxygen consumption, and ejection fraction, did not differ significantly between the groups.7 In the Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure (COMPANION) trial, a survival benefit of CRT over pharmacologic therapy was observed in patients with LBBB but not in those with other QRS morphologies.4 Together, these data raise the concern that patients with non-LBBB morphologies somehow fare worse than their LBBB counterparts after CRT, possibly contributing to a significant nonresponse rate. The few retrospective studies that have attempted to clarify the prognostic impact of QRS morphology on survival after CRT have yielded mixed results.8, 9
In a subset of potential CRT recipients who have previously undergone pacemaker or defibrillator placement, the underlying QRS morphology is a paced LBBB. In such patients, particularly those with AV nodal disease, chronic RV pacing can result in interventricular and intraventricular dyssynchrony in the short term and in adverse biventricular remodeling that predisposes to HF or atrial fibrillation in the long term.10, 11, 12, 13 Although upgrade to CRT has been recommended as a class IIa indication in these patients who otherwise meet CRT criteria, this recommendation is based largely on consensus and only on limited clinical data.14, 15
The aim of this single-center, retrospective study was to assess the impact of native QRS morphologies or previous RV pacing on clinical and survival outcomes of de novo or upgrade CRT recipients.
Section snippets
Study design
This cohort consists of 505 consecutive patients who underwent de novo (n = 338; 39 CRT and 299 CRT-D) or upgrade CRT (n = 167; 10 CRT and 157 CRT-D) at Mayo Clinic from January 1, 2002, to December 31, 2006. Indications for CRT were HF symptoms despite optimal medical therapy (NYHA class II or greater), left ventricular ejection fraction (LVEF) ≤35%, and QRS duration ≥120 ms with the exception of select patients with QRS <120 ms. Patients with QRS <120 ms were included based on the combined
Patient characteristics
Baseline characteristics in the de novo (n = 338) and upgrade groups (n = 167) are summarized in Table 1. The de novo group was younger, had less chronic atrial fibrillation, had less prolonged QRS duration, and had lower creatinine levels than the upgrade group. NYHA class, echocardiographic parameters, and pharmacologic HF regimens were similar (>80% on beta blockers, >60% digoxin), except for the more frequent use of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in
Discussion
There were two main findings in this study of CRT in a clinical practice population. First, no evidence of a difference in outcomes between the upgrade and de novo implantation groups was observed. Second, native QRS morphology had clinical and prognostic value in recipients of de novo CRT. Patients with RBBB or nonspecific IVCD experienced less clinical improvement and less LV functional improvement. In addition, patients with RBBB experienced less survival benefit than did those with
Conclusion
Despite these limitations, our data identify the relative prognostic values of device upgrade and intrinsic QRS morphology in CRT in a clinical practice population. We established that CRT upgrade is comparable to, but not better than, de novo implantation in clinical and survival outcomes. We further identified less clinical and/or survival benefit for patients with RBBB and IVCD. Patients with widened QRS without LBBB appear less likely to respond to CRT and, therefore, may be better served
References (25)
- et al.
Cardiac resynchronization therapy in patients with right bundle branch block: analysis of pooled data from the MIRACLE and CONTAK-CD trials
Heart Rhythm
(2005) - et al.
Prognostic value of electrocardiographic measurements before and after cardiac resynchronization device implantation in patients with heart failure due to ischemic or nonischemic cardiomyopathy
Am J Cardiol
(2008) - et al.
Usefulness of baseline electrocardiographic QRS complex pattern to predict response to cardiac resynchronization
Am J Cardiol
(2009) - et al.
The benefit of upgrading chronically right ventricle-paced heart failure patients to resynchronization therapy demonstrated by strain rate imaging
Heart Rhythm
(2006) - et al.
Diminished left ventricular dyssynchrony and impact of resynchronization in failing hearts with right versus left bundle branch block
J Am Coll Cardiol
(2007) - et al.
ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities
J Am Coll Cardiol
(2008) - et al.
Usefulness of tissue Doppler velocity and strain dyssynchrony for predicting left ventricular reverse remodeling response after cardiac resynchronization therapy
Am J Cardiol
(2007) - et al.
Biventricular pacemaker upgrade in previously paced heart failure patients—improvements in ventricular dyssynchrony
J Card Fail
(2006) - et al.
Usefulness of baseline electrocardiographic QRS complex pattern to predict response to cardiac resynchronization
Am J Cardiol
(2009) - et al.
Effect of bundle branch block patterns on mortality in hospitalized patients with heart failure
Am J Cardiol
(2008)
Usefulness of biventricular pacing in patients with congestive heart failure and right bundle branch block
Am J Cardiol
Cardiac resynchronization in chronic heart failure
N Engl J Med
Cited by (63)
2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: Developed by the Task Force on Cardiac Pacing and Cardiac Resynchronization Therapy of the European Society of Cardiology (ESC), with the special contribution of the European Heart Rhythm Association (EHRA)
2022, Revista Espanola de CardiologiaMortality and Heart Failure After Upgrade to Cardiac Resynchronization Therapy
2019, CJC OpenCitation Excerpt :There are few studies that have examined long-term outcomes of mortality and HF hospitalization for patients who receive upgrades to CRT-D vs patients with de novo CRT-D implants. Several analyses have been conducted to date, but thus far, the available evidence has yielded conflicting results.19-30 Bogale et al.19 investigated 692 patients with upgrades to CRT/CRT-D and 1675 patients with de novo CRT/CRT-D, with follow-up of approximately 1 year, and did not find significant differences in survival (P = 0.57) between the 2 groups.
Outcomes With Left Bundle Branch Block and Mildly to Moderately Reduced Left Ventricular Function
2016, JACC: Heart FailureCitation Excerpt :As was alluded to in the introduction, however, it is not imperative to show that patients with LBBB have a worse outcome than their counterparts do. It seems to be true that cardiac resynchronization is most effective in patients with LBBB (20,21). Therefore, the fact that these patients have this ECG finding suggests that they may potentially benefit from CRT, a proven effective treatment for severe HF.
Cardiac Resynchronization Therapy
2016, Clinical Cardiac Pacing, Defibrillation and Resynchronization TherapyCardiac Magnetic Resonance, Electromechanical Activation, Kidney Function, and Natriuretic Peptides in Cardiac Resynchronization Therapy Upgrades
2023, Journal of Cardiovascular Development and DiseaseUseful Electrocardiographic Signs to Support the Prediction of Favorable Response to Cardiac Resynchronization Therapy
2023, Journal of Cardiovascular Development and Disease
Dr. Wokhlu has received travel support from Medtronic, Boston Scientific, and St. Jude Medical to attend educational seminars. Dr. Hayes is an educational speaker and serves on the advisory boards for Medtronic, Boston Scientific, Sorin Medical Group, and St. Jude Medical, and he is a member of the steering committee for St. Jude Medical. Dr. Asirvatham receives honoraria and is on the speaker's board for St. Jude Medical, Boston Scientific, and Medtronic. In addition, he is a co-patent holder for an alternative resynchronization therapy technique. Ms. Webster is on an advisory board for Boston Scientific.