[CRT-FORUM] 13E. Right bundle branch block and CRT. Dr. Perez Riera

[CRT-INFO]

Dear colleague Marcos Souza From Belo Horizonte Minas Gerais  Brazil: It 
is unclear whether benefits of CRT extend to patients with right branch 
bundle block (RBBB) or a paced QRS at baseline despite QRS>120 ms. Very 
recently, O'Connor et al (1) in a preliminary report suggests that 
similar reverse remodeling can be observed in Complete RBBB (CRBBB) 
patients as patients with LBBB after CRT. The authors studied 4 
consecutive patients with CRBBB advanced ischemic HF, EF ≤35%) and 
intraventricular asynchrony ≥50 ms scheduled for CRT. Dobutamine stress 
echocardiography  was performed within the week before CRT. Viability 
was defined as increased wall thickening during dobutamine stress 
echocardiography. Viability in the region of LV pacing lead was defined 
as the presence of viability in 2 contiguous segments. Response was 
defined by LV reverse remodeling (i.e. ≥15% reduction in LV end-systolic 
volume) 3-6 months after CRT.
Three patients demonstrated LV reverse remodeling at follow-up. 
Responders showed LV end-systolic volume decrease of -31+/-16% from 
baseline to follow-up whereas no change was observed in the non 
responder patient. Similar LV asynchronism was found in all patients. 
All responders had viability in ≥2 segments in the region of LV pacing. 
Intraventricular asynchrony and CRBBB, viability in the region of pacing 
lead may help to predict response to CRT in patients with HF.

In patients with CRBBB (N= 62 patients: 10% of all universe) undergoing 
CRT had low rates of symptomatic and echocardiographic response, and 
their survival free from orthotopic heart transplantation or ventricular 
assist device placement was significantly worse than in patients with 
LBBB (N=412; 65%),. Patients with conventionally paced QRS (N=412; 65%), 
experienced an intermediate response(2).
 From 29 patients (mean age 61.5) with predominant  chagasic 
cardiomyopathy cardiac resynchronization therapy was effective for 
patients with conventional pacemakers and advanced HF as it yields a 
high rate of response (86.2%), significantly improves LVEF and reduces 
QRS duration(3).
 Finally, Studies have demonstrated a beneficial effect of right 
ventricular  bifocal pacing, using two leads at different positions, in 
Chagas disease patients who developed both severe dilated cardiomiopathy 
and chronic AF.

References

1)    O'Connor K, Sénéchal M, Lancellotti P, Dubois M, Magne J, 
Champagne J, Philippon F, Pierard L, O'Hara G. Usefulness of cardiac 
resynchronisation therapy in patients with right bundle branch block: Is 
viability an important piece of the puzzle? Int J Cardiol. 2009 Jan 23. 
[Epub ahead of print]
2)    Adelstein EC, Saba S. Usefulness of baseline electrocardiographic 
QRS complex pattern to predict response to cardiac resynchronization. Am 
J Cardiol. 2009 Jan 15;103(2):238-42.
3)    Silva RT, Martinelli Filho M, Lima CE, Martins DG, Nishióka SA, 
Pedrosa AA, Crevelari ES, Costa R, Sosa EA, Ramires JA. Functional 
behavior of patients with conventional pacemakers undergoing cardiac 
resynchronization. Arq Bras Cardiol. 2008 Feb;90:138-143.

All the best
Andrés Ricardo Pérez Riera MD, chief of electrovectorcardiology sector
ABC Faculty of Medicine (FMABC), Discipline of Cardiology, Foundation of 
ABC (FUABC), Santo André, São Paulo, Brazil.

> Dear colleagues,
>
> congratulations to all participants and specially to organizers!
>
> I would like a review or a discussion about ressyncronization therapy 
> in patients with right bundle branch block, specially in Chagas disease,
>
> thank you,
>
> Marcos Sousa - Mater Dei hospital and Federal University of Minas Gerais
>
> Belo Horizonte, Minas Gerais,  Brazil
>


-- 
Dr. Sergio Dubner
President of Scientific Committee

Dr. Edgardo Schapachnik
President of Steering Committee