ECG Based Algorithms for CRT Optimization

James H. Baker II, MD
St. Thomas Heart
Nashville, TN

Overview
Non-responder rate with CRT remains 30-35%
despite mature technology
MIRACLE study (ACC 2001): 67% improved HF CCS

Overview
Non-responder rate with CRT remains 30-35%
despite mature technology
MIRACLE study (ACC 2001): 67% improved HF CCS
FREEDOM study (HRS 2010): 67.5%

Overview
Non-responder rate with CRT remains 30-35%
despite mature technology
MIRACLE study (ACC 2001): 67% improved HF CCS
FREEDOM study (HRS 2010): 67.5%
Primary options for improving response rate include
better patient selection, improved LV lead
positioning, and optimization of timing intervals

Optimization of CRT
Programming
Timing interval optimization part of most multicenter
CRT trials, although techniques used were varied
Echocardiographic method
Supported by American Society of Echocardiography

Optimization of CRT
Programming
Timing interval optimization part of most multicenter
CRT trials, although techniques used were varied
Echocardiographic method
Supported by American Society of Echocardiography
Acute hemodynamic and short-term clinical improvement
documented in numerous small studies

Optimization of CRT
Programming
Timing interval optimization part of most multicenter
CRT trials, although techniques used were varied
Echocardiographic method
Supported by American Society of Echocardiography
Acute hemodynamic and short-term clinical improvement
documented in numerous small studies
Limited by cost, complexity, time demands

Optimization of CRT
Programming
Timing interval optimization part of most multicenter
CRT trials, although techniques used were varied
Echocardiographic method
Supported by American Society of Echocardiography
Acute hemodynamic and short-term clinical improvement
documented in numerous small studies
Limited by cost, complexity, time demands
Nominal settings standard of care
ACT Registry of >1000 CRT-D patients found < 10%
received optimization of timing intervals (2006)

Intracardiac Electrogram (IEGM)
Methods for CRT Optimization
Review available techniques
AV optimization
VV optimization
Discuss clinical studies
Future applications

AV Optimization
Goal – maximize LV preload by allowing for the
completion of the atrial contribution to diastolic filling
before mitral valve closure
Barold S S et al. Europace 2008;10:iii88-iii95

QuickOpt TM Method of AV Optimization
Empirical method based on clinical observations and
validated by echocardiographic studies
Algorithm makes optimized AV delay calculations
based on the duration of the intrinsic atrial IEGM
Aims to ensure that ventricular pacing occurs after
atrial depolarization and mechanical contraction are
complete

AV Optimization - QuickOpt TM
Offset factor: 30 ms if AV > 100
60 ms if AV < 100

AV Optimization - SmartDelay TM
Developed through intraoperative measurements
and validated with invasively measured LV dP/dT
Uses intrinsic AV intervals and the duration of native
VV conduction time to calculate the optimal delay
Adjusted for LV lead location
Separate calculations for sensed and paced AV delays
Truncates the AV delay to between 50 ms and 70% of
the intrinsic AV interval

Optimal Balance of Intrinsic and Paced Wavefronts
Better with more
prolonged QRS
interval

VV Optimization - QuickOpt TM
Aims to ensure the paced LV and RV conduction
wave fronts meet in the septum and coordinate LV
and RV contraction to maximize resynchronization
Measures both sensed and paced conduction delays
between the LV and RV leads to calculate the
optimal VV interval
Correlates well with aortic VTI and 3D echo
techniques

Long-term Clinical Studies of
IEGM-Based Optimization
FREEDOM study - investigated effect of frequent
optimization of AV and VV intervals using QuickOpt
on outcome of CRT in comparison to usual care
SMART-AV trial – compared the results of CRT
using 3 different techniques for programming AV
delays: fixed delay of 120 ms, echo-optimized delay
and AV delay optimized with SmartDelay
Adaptive CRT study – Medtronic, results pending

Baseline Evaluation
To document inclusion / exclusion criteria and establish baseline
heart status*
Randomization (1:1:1 SmartDelay: Echo: Fixed)
1 – 14 days post implant
Clinic Follow-up Visits
3 month and 6 months post implant
SMART-AV Trial
Compared the effects of 3 techniques for AV delay programming for CRT
AV Delay Optimized
Quarterly Using
SmartDelay
AV Delay Optimized
Using Echo
(Iterative Method)
AV Delay Fixed at
120ms with 0 Offset

SMART-AV Results – 6 month data*
Ellenbogen et al Circulation 2010; 122:2260-2668
The change in LVESV for
the SmartDelay arm was
no different than echodetermined
AV delay or
fixed delay of 120 mg

SMART-AV Results – 6 month data*
Ellenbogen et al Circulation 2010; 122:2260-2668
The change in LVESV for
the SmartDelay arm was
no different than echodetermined
AV delay or
fixed delay of 120 mg
“The routine use of AV
optimization techniques
assessed in this trial is
not warranted”

Future of EGM-Based Algorithms
Potential role in non-responders
RESPONSE-HF trial (HRS 2010)
Non-responders after 3 months of simultaneous VV
pacing randomized to sequential vs. simultaneous
pacing (primarily using QuickOpt)
Higher percentage converted to responders with VV
optimization: 76.9% vs. 48.4%

Future of EGM-Based Algorithms
Potential role in non-responders
RESPONSE-HF trial (HRS 2010)
Non-responders after 3 months of simultaneous VV
pacing randomized to sequential vs. simultaneous
pacing (primarily using QuickOpt)
Higher percentage converted to responders with VV
optimization: 76.9% vs. 48.4%
SMART-AV substudy – QLV
Subset of CRT patients may benefit from SmartDelay

LVESV Response: SmartDelay vs. Fixed
Multivariate Logistic Regression Results
The LVESV response rate for SD vs. fixed increased as QLV prolonged. In the highest quartile of
QLV, SD had a greater than 6 fold increase in odds ratio for a LVESV response vs. fixed.
Gold MR et al. HRS 2012
Adjusted for baseline EF, LVESV, Etiology of HF, LBBB, Gender, NYHA, QRS and age