Cardiac Resynchronization Therapy:
Should Non-LBBB or Patients With
Atrial Fibrillation Receive CRT?
Michael R Gold, MD, PhD
Medical University of South Carolina
Charleston, SC
Disclosures: Consultant, Speaker Fees and Clinical Trials –
Boston Scientific, Medtronic, St Jude
Cardiac Resynchronization Therapy: Weight of Evidence
9,000 patients evaluated in randomized controlled trials of heart failure
Consistent improvement in quality of life, functional status, and exercise capacity
Strong evidence of changes in LV structure – ↓ LV volumes and dimensions
– LVEF
– ↓ Mitral regurgitation
Reduction in HF and all-cause morbidity and mortality
Pivotal RCTs of CRT
• NYHA II-IV
• LVEF < 35%
• QRS > 120-130 msec
• NRS (except RAFT)
• No study was restricted to LBBB or
even stratified randomization by BBB
or QRS duration
Subgroups Discouraged or
Prohibited from CRT by Updated
Guidelines
1. Non-LBBB
2. QRS < 150 msec
3. AF
RBBB in CRT Trials
Advanced HF
– MIRACLE
– CONTAK CD
– COMPANION
– CARE HF
Mild HF
– REVERSE
– MADIT-CRT
– RAFT
(28)
(33)
(162)
(35)
(82)
(228)
(161)
Fantoni C, Kawabata M, Massaro R et al. J Cardiovasc Electrophysiol. 2005 Feb;16(2):112-9
Electrical Activation in RBBB and LBBB
12
REVERSE: Clinical Composite Subgroup Analysis
0.01 0.1 1 10
All Patients
Ischemic
Non-ischemic
CRT-P
CRT-D
NYHA Class I
NYHA Class II
Male
Female
0.26
0.90
0.46
0.52
Interaction
P-value
0.01 0.1 1 10
LBBB
RBBB
IVCD
Non-white
White
> 65 yrs
< 65 yrs0.75
0.60
0.01
Odds Ratio with 95% CI Odds Ratio with 95% CI
CRT ON
Better
CRT OFF
Better
CRT ON
Better
CRT OFF
Better
What is the QRS Morphology Hiding?
Can we identify patients or pacing sites with late mechanical or
electrical LV activation?
Q-LV Interval to Predict Acute Response
R = 0.74
-5
0
5
10
15
20
25
30
35
40
0 50 100 150 200
Q-LV (ms)
%L
V+
dP
/dT
max
R
NR
Mean F.U. :
25.2 + 18 months
673 pts 162 Permanent AF
114 pts
AF-abl
48 pts
Drugs + VRR
BVP % at 2 months
> 85% 85%
1. AVJ ablation and reverse remodelling
J Am Coll Cardiol 2006; 48 (4): 734-743
1) Significant EF increase both in SR and AF-abl No change for AF drugs
3) Similar LVESV reductions in SR and AF-abl
2) Functional capacity score increase both in SR and AF-abl
Summary
CRT response rates are best in the presence
of sinus rhythm, LBBB and QRS > 150 msec
However, RCT included or studied other
groups of patients who show benefit, albeit
more variable
Late electrical mechanical activation helps
identify subjects with non-LBBB who respond
AV node ablation improves CRT response in
AFib