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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 6  |  Issue : 2  |  Page : 101-103

A case report of tachycardia-dependent right bundle branch block during cardiac resynchronization therapy: A factor for nonresponse


1 Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
2 Department of Cardiology, Northern Jiangsu People's Hospital, Clinical Medical College, Yangzhou University, Yangzhou, Jiangsu Province, China

Date of Submission27-Oct-2021
Date of Decision29-Nov-2021
Date of Acceptance06-Dec-2021
Date of Web Publication28-Dec-2021

Correspondence Address:
Prof. Lei Sun
Department of Cardiology, Northern Jiangsu People's Hospital, Clinical Medical College, Yangzhou University, Yangzhou 225001, Jiangsu Province
China
Xiang Gu
Department of Cardiology, Northern Jiangsu People's Hospital, Clinical Medical College, Yangzhou University, Yangzhou 225001, Jiangsu Province
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijhr.ijhr_13_21

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  Abstract 


Cardiac resynchronization therapy (CRT) has been shown to improve symptoms and mortality in a suitably selected population with systolic heart failure and prolonged QRS duration. Various factors have been reported to be associated with poor response to CRT. A 67-year-old man with CRT implantation experienced response, nonresponse, and response in turn. The new-onset right tachycardia-dependent bundle branch block was considered to be an exclusive cause. More attention should be paid to the possible changes of paced-QRS morphology, resulting from tachycardia-dependent aberrancy during CRT, ensuring a high percentage of effective biventricular pacing.

Keywords: Cardiac resynchronization therapy, heart failure, nonresponse, tachycardia-dependent right bundle branch block


How to cite this article:
Cheng C, Sun L, Gu X. A case report of tachycardia-dependent right bundle branch block during cardiac resynchronization therapy: A factor for nonresponse. Int J Heart Rhythm 2021;6:101-3

How to cite this URL:
Cheng C, Sun L, Gu X. A case report of tachycardia-dependent right bundle branch block during cardiac resynchronization therapy: A factor for nonresponse. Int J Heart Rhythm [serial online] 2021 [cited 2022 May 19];6:101-3. Available from: https://www.ijhronline.org/text.asp?2021/6/2/101/334128




  Introduction Top


Cardiac resynchronization therapy (CRT) is effective in reducing heart failure (HF) symptoms and mortality and improving quality of life. A favorable response to CRT, however, is not achieved in approximately one-third of patients.[1] Various factors such as suboptimal left ventricular lead positioning, suboptimal device programming, or inadequacy of effective synchronous pacing have been reported that they were associated with poor responses to CRT.[2] Rate-related conduction abnormality is commonly seen in clinical practice. However, its effects on CRT responses have been less reported. We described a unique case with CRT implantation experienced the process from response to nonresponse to response again due to the tachycardia-dependent right bundle branch block (RBBB).


  Case Report Top


A 67-year-old man with a history of nonischemic dilated cardiomyopathy, left ventricular ejection fraction (LVEF) of 22%, and an electrocardiogram (ECG) showing sinus rhythm with intraventricular conduction block (IVCB) [Figure 1]a underwent CRT implantation. A left ventricular lead was successfully implanted into the lateral branch of coronary sinus veins. The postoperative ECG showed a significant narrowing of QRS duration from 158 ms at baseline to 128 ms at biventricular pacing [Figure 1]b. During the 6-month follow-up, his clinical symptoms improved significantly with the New York Heart Association (NYHA) function classification decreasing from IV to II and a corresponding rise in LVEF to 35%. However, 12 months after implantation, he was admitted to our hospital again because of the aggravated HF symptoms (NYHA IV). Echocardiography showed that LVEF decreased to 22%. Moreover, ECG showed that the paced-QRS duration was prolonged to 185 ms, and the morphology [Figure 1]c was significantly different from that immediately after CRT implantation [Figure 1]b. Chest X-ray revealed that all pacing leads were in position. CRT device interrogation showed that all pacing lead parameters were within the normal range and the ventricular pacing percentage was 95%. However, when the CRT device was programed to AAI pacing mode, the intrinsic QRS morphology was variable and heart rate (HR) was dependent. The intrinsic ECG QRS morphology was IVCB morphology [Figure 1]d with atrial pacing rate ≤60 beats/min (the resting sinus rate was 52 beats/min) but a new-onset RBBB morphology [Figure 1]e and [Figure 1]f with atrial pacing rate >60 beats/min. Further, the RBBB morphology could convert to IVCB morphology after a premature ventricular contraction [Figure 2]. Therefore, the basic atrial pacing rate was adjusted to 50 beats/min, with the rate response function turning off. A narrow paced-QRS was reacquired [Figure 1]g. Ivabradine (10 mg/day) was also used to control sinus HR. Holter monitor then showed an average HR of 55 beats/min, with narrow paced-QRS accounting for 95% of the total QRS complex. Three months later, ECG revealed that intrinsic QRS morphology was IVCB morphology while atrial pacing rate ≤55 beats/min, and Holter monitor showed that narrow paced-QRS accounted for 88% of the total QRS complex. The patient had a favorable response to CRT again with the NYHA function classification decreasing from IV to II and LVEF increasing from 22% to 33%.
Figure 1: Twelve-lead electrocardiogram recordings with different pacing mode at baseline and follow-up. Horizontal-axis scale: 10 mm/mV; vertical-axis scale: 25 mm/s. (a) Preoperative ECG shows IVCB morphology with a QRS duration of 158 ms. (b) Postoperative BiVP ECG showng a shortened QRS duration of 128 ms. (c) BiVP ECG at 12-month follow-up showing a wide QRS of 185 ms, which is significantly different from that immediately after CRT implantation. (d) AAI pacing mode with atrial pacing rate 60 bpm showing the intrinsic QRS is IVCB morphology, which is similar to that before operation. (e and f) AAI pacing mode with pacing rate 70 and 90 bpm showing the intrinsic QRS is RBBB morphology with wider QRS. (g) A narrow BiVP QRS is reacquired after adjusting the basic atrial pacing rate to 50 bpm and turning off the rate response function. BiVP=Biventricular pacing, bpm=Beats/min, ECG=Electrocardiogram, IVCB=Intraventricular conduction block, RBBB=Right bundle branch block

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Figure 2: Electrocardiogram showing that the intrinsic QRS RBBB morphology could convert to IVCB morphology after a premature ventricular beat. IVCB=Intraventricular conduction block, PVC=Premature ventricular contraction, RBBB=Right bundle branch block

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  Discussion Top


A previous study has demonstrated that HF patients with left bundle branch block (LBBB) can derive substantial clinical benefits from CRT, while patients with non-LBBB QRS morphology derive less benefits.[3] A recent study further showed that among non-LBBB CRT-eligible patients, CRT implantation was associated with better outcomes, specifically in IVCB patients rather than RBBB patients.[4] In the present case, the patient with reduced LVEF and IVCB got a favorable response to CRT at 6-month follow-up. However, despite all parameters of the device remaining stable with a high (95%) percentage of ventricular pacing, the response status still converted to nonresponse. The tachycardia-dependent RBBB may account for the change. Since a high percentage of narrow paced-QRS is reacquired, a favorable response[5] to CRT is observed again. In other words, a proportion of ventricular pacing based on tachycardia-dependent RBBB is invalid and even aggravates dyssynchrony.

Rate-related conduction abnormality is not uncommon in clinical practice. However, the adverse effect of tachycardia-dependent RBBB on CRT response has been less studied, although rate-dependent LBBB could benefit from CRT.[6],[7] We presented a case of tachycardia-dependent RBBB, which is evidenced by ECG of AAI pacing at different pacing rates and resolution of RBBB following a longer cycle length. This observation supports the concept that the underlying RBBB mechanism may be due to a functional block. This can be further explained by the linking phenomenon, which means that there is repetitive trans-septal concealed retrograde penetration of the right bundle by impulses propagating along the left bundle, resulting in a functional block in the right bundle branch.[8] Otherwise, we speculate that the presence of tachycardia-induced RBBB may be consequential to his underlying dilated cardiomyopathy and contribute to HF progression.

Various factors have been reported to be associated with poor response to CRT.[2] We present a factor that was not only rarely reported before but also reversible by device reprogramming. For this patient, a narrow paced-QRS was regained after device programming and a favorable response was observed during short-term follow-up. However, the long-term prognosis of this patient deserves further studies and follow-up. Although the right bundle branch conduction could be recovered at a slow HR now, we speculate that it may be a transient phenomenon. As the conduction system disease increasingly worsens, the tachycardia-dependent RBBB may progress to permanent RBBB, which could result in a nonresponse to CRT finally.

In conclusion, we described a unique case that experienced a process of response to nonresponse and response again after CRT implantation. The tachycardia-dependent RBBB was considered as the main cause of nonresponse. Physicians should pay more attention to the possible abnormality of paced-QRS, resulting from tachycardia-dependent aberrancy during CRT, and ensure a high percentage of effective biventricular pacing.

Institutional review board statement

The ethical approval was waived by the Institutional Ethical Committee of our hospital owing to the retrospective nature of the study and routine treatments performed on this patient in clinical practice. The study was conducted in accordance with the Declaration of Helsinki.

Declaration of patient consent

The authors certify that they have obtained all appropriate consent from patients. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity forms.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Randolph TC, Hellkamp AS, Zeitler EP, Fonarow GC, Hernandez AF, Thomas KL, et al. Utilization of cardiac resynchronization therapy in eligible patients hospitalized for heart failure and its association with patient outcomes. Am Heart J 2017;189:48-58.  Back to cited text no. 1
    
2.
European Heart Rhythm Association (EHRA); European Society of Cardiology (ESC); Heart Rhythm Society; Heart Failure Society of America (HFSA); American Society of Echocardiography (ASE); American Heart Association (AHA), et al. 2012 EHRA/HRS expert consensus statement on cardiac resynchronization therapy in heart failure: Implant and follow-up recommendations and management. Europace 2012;14:1236-86.  Back to cited text no. 2
    
3.
Zareba W, Klein H, Cygankiewicz I, Hall WJ, McNitt S, Brown M, et al. Effectiveness of cardiac resynchronization therapy by QRS morphology in the multicenter automatic defibrillator implantation trial-cardiac resynchronization therapy (MADIT-CRT). Circulation 2011;123:1061-72.  Back to cited text no. 3
    
4.
Kawata H, Bao H, Curtis JP, Minges KE, Mitiku T, Birgersdotter-Green U, et al. Cardiac resynchronization defibrillator therapy for nonspecific intraventricular conduction delay versus right bundle branch block. J Am Coll Cardiol 2019;73:3082-99.  Back to cited text no. 4
    
5.
Ellenbogen KA, Huizar JF. Foreseeing super-response to cardiac resynchronization therapy: A perspective for clinicians. J Am Coll Cardiol 2012;59:2374-7.  Back to cited text no. 5
    
6.
Haseeb S, Gul EE. Rate-dependent aberrancy and cardiac resynchronization therapy. Pacing Clin Electrophysiol 2020;43:1210-2.  Back to cited text no. 6
    
7.
Prystowsky EN, Padanilam BJ. Cardiac resynchronization therapy reverses severe dyspnea associated with acceleration-dependent left bundle branch block in a patient with structurally normal heart. J Cardiovasc Electrophysiol 2019;30:517-9.  Back to cited text no. 7
    
8.
Hillyard J, Mankad P, Ellenbogen KA, Padala SK. Resolution of right bundle branch block after a premature ventricular beat: What is the mechanism? HeartRhythm Case Rep 2019;5:597-9.  Back to cited text no. 8
    


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