Left ventricular systolic torsion correlates global cardiac performance during dyssynchrony and cardiac resynchronization therapy

Left ventricular (LV) systolic torsion is a primary mechanism contributing to stroke volume (SV). We hypothesized that change in LV torsion parallels changes in global systolic performance during dyssynchrony and cardiac resynchronization therapy (CRT). Seven anesthetized open chest dogs had LV pressure-volume relationship. Apical, basal, and mid-LV cross-sectional echocardiographic images were studied by speckle tracking analysis. Right atrial (RA) pacing served as control. Right ventricular (RV) pacing simulated left bundle branch block. Simultaneous RV-LV free wall and RV-LV apex pacing (CRTfw and CRTa, respectively) modeled CRT. Dyssynchrony was defined as the time difference in peak strain between earliest and latest segments. Torsion was calculated as the maximum difference between the apical and basal rotation. RA pacing had minimal dyssynchrony (52 ± 36 ms). RV pacing induced dyssynchrony (189 ± 61 ms, P < 0.05). CRTa decreased dyssynchrony (46 ± 36 ms, P < 0.05 vs. RV pacing), whereas CRTfw did not (110 ± 96 ms). Torsion during baseline RA was 6.6 ± 3.7°. RV pacing decreased torsion (5.1 ± 3.6°, P < 0.05 vs. control), and reduced SV, stroke work (SW), and dP/d tmax compared with RA (21 ± 5 vs. 17 ± 5 ml, 252 ± 61 vs. 151 ± 64 mJ, and 2,063 ± 456 vs. 1,603 ± 424 mmHg/s, respectively, P < 0.05). CRTa improved torsion, SV, SW, and dP/d tmax compared with RV pacing (7.7 ± 4.7°, 23 ± 3 ml, 240 ± 50 mJ, and 1,947 ± 647 mmHg/s, respectively, P < 0.05), whereas CRTfw did not (5.1 ± 3.6°, 18 ± 5 ml, 175 ± 48 mJ, and 1,699 ± 432 mmHg/s, respectively, P < 0.05). LV torsion changes covaried across conditions with SW ( y = 0.94 x+12.27, r = 0.81, P < 0.0001) and SV ( y = 0.66 x+0.91, r = 0.81, P < 0.0001). LV dyssynchrony changes did not correlate with SW or SV ( r = −0.12, P = 0.61 and r = 0.08, P = 0.73, respectively). Thus, we conclude that LV torsion is primarily altered by dyssynchrony, and CRT that restores LV performance also restores torsion.

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Heart rhythm model for the simulation of electric fields in transesophageal atrial pacing and cardiac resynchronization therapy

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2018-0105 ◽

2018 ◽

Vol 4 (1) ◽

pp. 443-445

Author(s):

Kerem Göküs ◽

Matthias Heinke ◽

Johannes Hörth

Keyword(s):

Cardiac Resynchronization Therapy ◽

Heart Rhythm ◽

Left Ventricular ◽

Right Atrial ◽

Cardiac Resynchronization ◽

Electrode Position ◽

Atrial Pacing ◽

Far Field ◽

Resynchronization Therapy ◽

Rv Pacing

AbstractElectric field of biventricular (BV) pacing, left ventricular (LV) electrode position and electrical interventricular desynchronization are important parameters for successful cardiac resynchronization therapy (CRT) in patients with heart failure, sinus rhythm and reduced LV ejection fraction. The aim of the study was to evaluate electric pacing field of transesophageal left atrial (LA) pacing and BV pacing with 3D heart rhythm simulation. Bipolar right atrial (RA), right ventricular (RV), LV electrodes and multipolar hemispherical esophageal LA electrodes were modeled with CST (Computer Simulation Technology, Darmstadt). Electric pacing field were simulated with bipolar RA and RV pacing with Solid S (Biotronik) electrode, bipolar LV pacing with Attain 4194 (Medtronic) electrode and bipolar LA pacing with TO8 (Osypka) esophageal electrode. 3D heart rhythm model with esophagus allowed electric pacing field simulation of 4-chamber pacing with bipolar intracardiac RA, RV, LV pacing and bipolar transesophageal LA pacing. The pacing amplitudes were 3V RA pacing amplitude, 50V LA pacing amplitude, 1.5V RV pacing amplitude and 3V LV pacing amplitude with 0.5ms pacing pulse duration. The atrioventricular delay between RA pacing and BV pacing was 140ms atrioventricular pacing delay and simultaneous RV and LV pacing. Electric pacing fields were simulated during the different pacing modes AAI, VVI, DDD and DDD0V. The intracardiac far-field pacing potentials were evaluated with intracardiac electrodes and a distance of 1mm from the electrodes with RA electrode 1.104V, RV electrode 0.703V and LV electrode 1.32V. The transesophageal far-field pacing potential was evaluated with transesophageal electrode and a distance of 10mm from the elelctrode with LA electrode 6.076V. Heart rhythm model simulation with esophagus allows evaluation of electric pacing fields in AAI, VVI, DDD, DDD0V and DDD0D pacing modes. Electric pacing field of RA, RV and LV pacing in combination with LA pacing may additional useful pacing mode in CRT non-responders.

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Mechanical Synchrony and Myocardial Work in Heart Failure Patients With Left Bundle Branch Area Pacing and Comparison With Biventricular Pacing

Frontiers in Cardiovascular Medicine ◽

10.3389/fcvm.2021.727611 ◽

2021 ◽

Vol 8 ◽

Author(s):

Wen Liu ◽

Chunqiang Hu ◽

Yanan Wang ◽

Yufei Cheng ◽

Yingjie Zhao ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Resynchronization Therapy ◽

Biventricular Pacing ◽

Mechanical Efficiency ◽

Left Ventricular ◽

Cardiac Resynchronization ◽

Peak Strain ◽

Resynchronization Therapy ◽

Promising Alternative ◽

Reduced Ejection Fraction

Background: Little is known about the efficacy of permanent left bundle branch area pacing (LBBAP) in delivering cardiac resynchronization therapy (CRT). This study aimed to evaluate the effect of LBBAP on mechanical synchronization and myocardial work (MW) in heart failure (HF) patients and to compare LBBAP with biventricular pacing (BVP).Methods: This is a multicenter, prospective cohort study. From February 2018 to January 2021, 62 consecutive HF patients with reduced ejection fraction (LVEF ≤ 35%) and complete left bundle branch block (CLBBB) who underwent LBBAP or BVP were enrolled in this study. Echocardiograms and electrocardiograms and were conducted before and 3–6 months after implantation. Intra- and interventricular synchronization were assessed using two-dimensional speckle tracking imaging (2D-STI). The left ventricular pressure-strain loop was obtained by combining left ventricular strain with non-invasive blood pressure to evaluate mechanical efficiency.Results: The echocardiographic response rates were 68.6 and 88.9% in the BVP and LBBAP groups, respectively. Left bundle branch area pacing resulted in significant QRS narrowing (from 177.1 ± 16.7 to 113.0 ± 18.4 ms, P < 0.001) and improvement in LVEF (from 29.9 ± 4.8 to 47.1 ± 8.3%, P < 0.001). The global wasted work (GWW) (410.3 ± 166.6 vs. 283.0 ± 129.6 mmHg%, P = 0.001) and global work efficiency (GWE) (64.6 ± 7.8 vs. 80.5 ± 5.7%, P < 0.001) were significantly improved along with shorter peak strain dispersion (PSD) (143.4 ± 45.2 vs. 92.6 ± 35.1 ms, P < 0.001) and interventricular mechanical delay (IVMD) (56.4 ± 28.5 vs. 28.9 ± 19.0 ms, P < 0.001), indicating its efficiency in improving mechanical synchronization. In comparison with BVP, LBBAP delivered greater improvement of QRS narrowing (−64.1 ± 18.9 vs. −32.5 ± 22.3 ms, P < 0.001) and better mechanical synchronization and efficiency.Conclusions: Left bundle branch area pacing was effective in improving cardiac function, mechanical synchronization, and mechanical efficiency and may be a promising alternative cardiac resynchronization therapy.

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Abstract 12722: Cardiac Resynchronization Therapy in Pacing Induced Cardiomyopathy: A Higher Right Ventricle Pacing Percentage Predicts Greater Improvement in Left Ventricle Ejection Fraction

Circulation ◽

10.1161/circ.142.suppl_3.12722 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Sean Lacy ◽

Jonathan Chandler ◽

NACHIKET MADHAV APTE ◽

Seth Sheldon ◽

Madhu Reddy ◽

...

Keyword(s):

Left Ventricle ◽

Ejection Fraction ◽

Cardiac Resynchronization Therapy ◽

Left Ventricular ◽

Left Ventricle Ejection Fraction ◽

Cardiac Resynchronization ◽

Resynchronization Therapy ◽

Qrs Duration ◽

Rv Pacing ◽

The Impact

Introduction: Cardiac resynchronization therapy (CRT) upgrade is indicated for improvement of cardiac function in patients with chronic right ventricular (RV) pacing burden >40% and heart failure with reduced ejection fraction. It is uncertain whether the CRT response is different among patients with high (≥90%) versus intermediate (<90%) burden of baseline RV pacing. Hypothesis: To assess the impact of baseline RV pacing percent on ECG and echocardiographic response after CRT upgrade for pacing induced cardiomyopathy. Methods: We conducted a retrospective study of all CRT upgrades for pacing induced cardiomyopathy at our hospital from January 2017 to December 2018. Cohorts were grouped by RV pacing burden ≥90% or <90%. QRS duration, left ventricle ejection fraction (LVEF), and left ventricular internal dimension systolic (LVIDs) were assessed at baseline and 3-12 months post CRT upgrade. Results: We included 82 patients (age 74 ± 12 yr., 71% male) who underwent CRT upgrade for pacing induced cardiomyopathy. The RV pacing burden was ≥90% [median 99% (IQR 98-99%)] in 61 patients, and <90% [median 79% (IQR 69-88%)] in 21 patients. There was a trend towards greater reduction in QRS duration in the ≥90% RV pacing group (28 ± 29 ms vs. 22 ± 38 ms, p=0.5). Improvement in LVEF was greater in ≥90% vs. <90% RV pacing group (14.3 ± 10.1% vs. 6.3 ± 10.1%, p=0.003). The association persisted on multivariable adjustment for age, sex and baseline LVEF (p=0.004). There was a trend towards greater % reduction in LVIDs in the ≥90% vs. <90% RV pacing group (6.4 ± 15.5 % vs. 3.9 ± 14.3 %, p=0.5) [Figure]. Conclusions: A higher baseline RV pacing burden predicts a greater improvement in LVEF after CRT upgrade for pacing induced cardiomyopathy.

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P1488Autonomic nervous system optimized cardiac resynchronization therapy

EP Europace ◽

10.1093/europace/euaa162.315 ◽

2020 ◽

Vol 22 (Supplement_1) ◽

Author(s):

T Thong ◽

D Tran-Tat ◽

T Nguyen-Duy

Keyword(s):

Nervous System ◽

Cardiac Resynchronization Therapy ◽

Index Patient ◽

Left Ventricular ◽

Cardiac Resynchronization ◽

Mode Switching ◽

Resynchronization Therapy ◽

Bundle Branch Block ◽

Rv Pacing ◽

Ventricular Conduction

Abstract Introduction. Traditional Cardiac Resynchronization Therapy, CRT, relies on bi-ventricular, bi-V, pacing. For left bundle branch block, LBBB, patients with good atrial-right ventricular conduction, A-RVc, alternatives have been proposed that use left-ventricular only pacing, LVoP, with adaptive atrio-ventricular delay, AVD, that is updated every minute from A-RVc measurements. The key advantage is extended device longevity since the RV pacing pulse is not emitted. Purpose. In this paper we present a CRT alternative using fixed AVD LVoP + RV sense trigger (an LV pulse is triggered when an RV depolarization is sensed), RVsT, that can be used with LBBB patients with good A-RVc. Intrinsic RV depolarization is used. The longevity of the device is expected to approach that of a dual chamber device since AVD adaption is not needed. Method. 5 CRT patients with LBBB and good A-RVc, previously programmed to bi-V pacing, were reprogrammed to fixed AVD LVoP + RVsT. The devices are standard CRT pacemakers, CRT-P, with RVsT. They are normally operated in LVoP mode. In response to atrial tachycardia, mode switching to bi-V will be required. So, 3 chamber devices are still required. Results. Nightly at about 02:00 the CRT-P collects Ax-Vs (Ax = As & Ap) statistics for 35 consecutive heart cycles with AVD of 300 ms, while the patient is asleep. A typical plot of these timing statistics at the time of reprogramming to LVoP is shown in Fig. 1. After a self-training period of 2 weeks to 9 months, these statistics coalesce in a narrow range of values, 20 ms wide, as illustrated in Fig. 2 for our super responder (2 weeks). This 20 ms wide pattern persisted for the next 9 months. In the case of the index patient this lasted 3+ years. This persistent A-RVc pattern across all 5 patient can only be explained by a tight dromotropic control by the Autonomic Nervous System, ANS. Fig. 3 illustrates RVsT. As the RVs arrives earlier than the LVp, there is no longer synchronicity improvement since the LVp now follows the RVs immediately. In Fig. 4, we see long periods with high %RVs associated with high heart rates. Increased hemodynamic demand can only be met by increased contractility. Thus inotropic modulation by the ANS is now active and effective. The patients were put on remote monitoring with nightly follow-ups. Over a period of 6.5 months RVs (pre LVp) statistics were collected. A daily median of 11% was reported for this patient. On a particular day, it can be as high as 50%. Dromotropic action to pull in the RVs cannot be explained without concurrent inotropic modulation. Conclusions. Traditional CRT leads to ineffective ANS modulation due to bi-V pacing for >95-98% of the cycles. In our 5 patients the fixed AVD LVoP + RVsT program has allowed nervous system remodeling and the ANS is back in control of hemodynamics. Thus we have ANS optimized CRT! It is an attractive CRT alternative for LBBB patients with good A-RVc since device longevity is also improved. Abstract Figure. Fixed delay LV-only + RVs trigger

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Deleterious effect of right ventricular pacing in patients with cardiac transthyretin amyloidosis: potential clinical benefit of cardiac resynchronization therapy

European Heart Journal - Case Reports ◽

10.1093/ehjcr/ytaa088 ◽

2020 ◽

Vol 4 (3) ◽

pp. 1-5

Author(s):

David Aouate ◽

Aymeric Menet ◽

Dimitri Bellevre ◽

Thibaud Damy ◽

Sylvestre Marechaux

Keyword(s):

Heart Failure ◽

Cardiac Resynchronization Therapy ◽

Right Ventricular ◽

Cardiac Amyloidosis ◽

Left Ventricular ◽

Cardiac Resynchronization ◽

Ventricular Pacing ◽

Resynchronization Therapy ◽

Transthyretin Amyloidosis ◽

Rv Pacing

Abstract Background Cardiac amyloidosis involvement is associated with a detrimental outcome including frequent arrhythmias, heart failure, and conduction disturbances which may need permanent pacing. Cases summary We report two cases of patients with transthyretin amyloidosis (ATTR) who developed heart failure and depressed left ventricular ejection fraction (LVEF) following permanent right ventricular (RV) pacing but highly responded to cardiac resynchronization therapy (CRT). Discussion The impact of RV pacing and CRT in cardiac amyloidosis is not known. In our cases, the detrimental effect of permanent RV pacing on left ventricular (LV) systolic function and heart failure symptoms was suggested by both permanent RV pacing mediated functional and LV function decline and LV systolic dysfunction reversal following CRT along with QRS width reduction. Whether cardiac resynchronization should be readily recommended in ATTR patients who need ventricular pacing whatever the LVEF deserves further investigation.

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Atrial and ventricular signal averaging electrocardiography in pacemaker and cardiac resynchronization therapy

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2015-0015 ◽

2015 ◽

Vol 1 (1) ◽

pp. 58-60

Author(s):

C. Haschemi ◽

M. Heinke

Keyword(s):

Heart Failure ◽

Cardiac Resynchronization Therapy ◽

Left Ventricular ◽

Right Atrial ◽

Cardiac Resynchronization ◽

Left Ventricular Ejection ◽

Conduction Delay ◽

Signal Averaging ◽

Resynchronization Therapy ◽

Heart Failure Patients

AbstractCardiac resynchronization therapy with atrioventricular and interventricular delay optimized biventricular pacing is an established therapy for symptomatic heart failure patients with prolongation of QRS duration, left bundle branch block and reduced left ventricular ejection fraction. The aim of the investigation was to evaluate right atrial, right ventricular and left ventricular electrical signals of implantable electronic cardiac devices with and without signal averaging technique with novel LabVIEW software. Electrical interatrial conduction delay and inter-ventricular conduction delay may be useful parameters to evaluate electrical atrial and ventricular desynchronization in heart failure patients.

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Impact of chronic sequential LV-RV pacing with cardiac resynchronization therapy for patients with narrower (<130 ms) QRS complexes following evaluation of acute myocardial strain characteristics

European Heart Journal ◽

10.1093/ehjci/ehaa946.0813 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

B Kantharia ◽

A Singh ◽

R Karnik ◽

A Shah ◽

L Wu ◽

...

Keyword(s):

Cardiac Resynchronization Therapy ◽

Speckle Tracking ◽

Myocardial Strain ◽

Left Ventricular ◽

Cardiac Resynchronization ◽

Left Ventricular Ejection ◽

Resynchronization Therapy ◽

Ventricular Ejection Fraction ◽

Writing Group ◽

Rv Pacing

Abstract Background Prior studies have shown acute improvement in myocardial strain patterns (SP) and strain rates (SR), left ventricular ejection fraction (LVEF), and long-term clinical improvement by Cardiac Resynchronization Therapy (CRT) preferential LV pacing. This relationship has not been studied in patients (pts) with narrower QRS. Objectives We aimed to evaluate myocardial speckle tracking SP and SR at different VV intervals in pts with narrow (<130 ms) and wide (>130 ms) QRS. Methods We assessed LVEF and speckle tracking myocardial SP and SR as per the American Society of Echocardiography (ASE) Dyssynchrony Writing Group methods in pts with CRT in acute settings at VV0, VV60 and LV-only pacing. For SP assessment, we used Bull's eye format display of the LV segments, and scores for SR, 2 = early stretch, late peak, 1= early stretch, early peak, and 0 = single peak at aortic closure. Results Total cohort of 271 pts; age 69.2±10.3 yrs (mean ± SD), male - 60%, divided into 2 groups; Gp A (QRS <130 ms, n=69) and Gp B (QRS >130 ms, n=202). QRS width and LVEF in Gp A and B were 120.1±12.3 ms and 152.1±12.9 ms, and 22.3±9.4% and 23.3±10.2% respectively. With VV0 increase in LVEF, 67±6.0% from baseline 22.3±9.4% was seen in Gp A compared to 43±6.5% from 23.3±10.2% in Gp B (p<0.01). With VV60 and LV-only pacing further rise in LVEF to 100.0±7.1% and 112.0±7.2% in Gp A and 80.2±8.0% and 93±8.1% in Gp B was seen. (Figure 1). Strain scores at different VV timings in both groups are shown in Table 1. Conclusions In pts with CRT, different VV timings show differences in acute myocardial speckle tracking SP and SR, and LVEF. These changes are markedly favorable with LV-only and sequential LV-RV pacing even in pts with narrower QRS. Our findings support chronic sequential LV-RV pacing programming in CRT pts with narrow QRS. Figure 1 Funding Acknowledgement Type of funding source: None

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P6016His bundle pacing versus biventricular pacing in cardiac resynchronization therapy: acute hemodynamic and electrophysiological effects

European Heart Journal ◽

10.1093/eurheartj/ehz746.0736 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

F Salden ◽

J G Luermans ◽

S W Westra ◽

R Cornelussen ◽

S Ghosh ◽

...

Keyword(s):

Cardiac Resynchronization Therapy ◽

Biventricular Pacing ◽

Left Ventricular ◽

Cardiac Resynchronization ◽

Resynchronization Therapy ◽

Surface Mapping ◽

Hemodynamic Improvement ◽

Rv Pacing ◽

Activation Times ◽

Electrophysiological Effects

Abstract Background Cardiac resynchronization therapy (CRT) is usually performed with a right (RV) and left ventricular (LV) lead. Previous observational studies showed promising results with His bundle pacing (HBP) in patients with left bundle branch block (LBBB) by capturing and recruiting the native His-Purkinje system as an alternative to provide ventricular resynchronization. Objective To investigate the effects of HBP as compared to conventional biventricular (BiV) pacing with respect to acute hemodynamic and electrophysiological effects in heart failure patients with LBBB. Methods RV apical and BiV pacing, using the implanted leads, and temporary HBP, using an electrophysiology catheter, was performed in 13 patients (QRS duration 168±16 ms) undergoing CRT implantation. Hemodynamic response (relative to baseline AAI pacing) was assessed as change in LVdP/dtmax. Multi-electrode body-surface mapping, what has been used previously to characterize electrical dyssynchrony in CRT patients, was evaluated using the standard deviation of activation times (SDAT) (figure, right panel). Results HBP resulted in a significant LV dP/dtmax increase, that was comparable to the increase during BiV pacing and significantly larger than RV pacing (figure, left panel). HBP resulted in a more homogenized electrical activation and larger reduction in SDAT than both conventional BiV pacing and RV pacing (figure, middle panel). Conclusions Acute HBP results in hemodynamic improvement and electrical resynchronization that is as good as conventional BiV pacing. These results suggest that HBP may serve as an alternative for conventional BiV pacing in LBBB patients, however prospective studies are needed to prove chronic clinical outcomes. Acknowledgement/Funding Medtronic is a subsidising party.

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Abstract 822: Change in Regional Strain after Cardiac Resynchronization Therapy

Circulation ◽

10.1161/circ.118.suppl_18.s_618-b ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Chinami Miyazaki ◽

Grace Lin ◽

Margaret M Redfield ◽

Raul E Espinosa ◽

Charles J Bruce ◽

...

Keyword(s):

Cardiac Resynchronization Therapy ◽

Myocardial Function ◽

Left Ventricular ◽

Cardiac Resynchronization ◽

Reverse Remodeling ◽

Entire Group ◽

Peak Strain ◽

Free Wall ◽

Resynchronization Therapy ◽

Regional Myocardial Function

Background: Cardiac resynchronization therapy (CRT) improves global systolic function in left ventricle. However, the impact of CRT on regional myocardial function is less clear. The aim of this study, therefore, is to evaluate regional changes in myocardial strain after CRT. Methods: Speckle tracking echocardiography (STE) was performed in 91 patients before and 6 month after CRT. Peak longitudinal strain was measured in 18 segments at base, mid and apex in three apical views. Left ventricular end-systolic volume (ESV) was measured by biplane Simpson’s method and reverse remodeling was defined as 10 % reduction in ESV at 6 month after CRT. Results: Peak strain improved in basal and mid segments of medial walls (basal inferoseptal, anteroseptal and inferior segments, p<0.05, mid inferoseptal and inferior segments: p<0.01) in entire group after CRT, with a greater degree of improvement in CRT responders than in nonresponders (Figure ). There was no significant improvement in free wall strain, with significant reduction in basal inferolateral segment after CRT (P=0.047) in entire group. Nonresponders had significant reduction in strain at the mid anterolateral segment (P=0.004) (Figure ). Strain of the apical segments also did not improve. Conclusions: CRT induces reverse remodeling by enhancing regional myocardial function in the septum, but suppresses the function in the free wall. Lack of reverse remodeling after CRT was characterized by the reduced function in lateral segments without improvement in septal function..

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Baseline left atrial strain is associated with clinical outcomes following cardiac resynchronization therapy in patients with intermediate electrocardiographic criteria

European Heart Journal ◽

10.1093/ehjci/ehaa946.0080 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

P Huntjens ◽

M Sugahara ◽

Y Soyama ◽

M Faddis ◽

J Gorcsan

Keyword(s):

Clinical Outcome ◽

Cardiac Resynchronization Therapy ◽

Left Atrial ◽

Prognostic Value ◽

Longitudinal Strain ◽

Left Ventricular ◽

Cardiac Resynchronization ◽

Peak Strain ◽

Resynchronization Therapy ◽

Ecg Criteria

Abstract Background Guidelines favor patient selection by left bundle branch block (LBBB) with QRS width ≥150 ms for cardiac resynchronization therapy (CRT). However, predicting response to CRT patients with QRS width 120 to 149 ms or non-LBBB remains difficult. Speckle tracking left atrial (LA) strain is a novel means to assess cardiac function, however its applications to CRT patients remains unclear. Purpose To test the hypothesis that baseline LA strain has prognostic value in CRT patients with intermediate ECG criteria. Methods We studied 195 patients with heart failure (HF) who underwent CRT based on routine indications: ejection fraction ≤35% and QRS width ≥120 ms. GLS was assessed using the 3 standard apical views. LA longitudinal strain was based on 12 segments from the 2 and 4-chamber apical view. Peak LA strain, a measure associated with the reservoir function of the LA, was defined as the average of peak longitudinal strain from all segments. The predefined combined clinical endpoint was death, heart transplant or left ventricular assist device (LVAD) over 4 years after CRT. Results LA strain was feasible in 162 (83%) of the candidates for CRT: age 64±11 years, 72% male, QRS duration 156±26 ms, 39.5% had LBBB with QRS ≥150ms, 60.5% had intermediate ECG criteria. Median LA strain was 11.0% [1.3% - 36.8%]. High LA peak strain was associated with more favorable event-free survival and Low LA Peak strain was associated with worse clinical outcome following CRT (FIGURE, p<0.001). Patients with intermediate ECG criteria for CRT (non-LBBB or QRS width 120 to 149 ms) and high peak LA strain had similar outcome to those with Class I indications for CRT (LBBB and QRS≥150 ms). Multivariable analysis revealed that LA strain had independent prognostic value (hazard ratio 0.98 per LA strain %, p<0.01) even after adjusted for other clinical, electrophysiological and echocardiographic covariates including QRS morphology and duration, ischemic cardiomyopathy, LVEF and global longitudinal strain. Conclusions Baseline peak LA strain had important prognostic value in HF patients who are candidates for CRT. Prognostic value of LA strain was most significant in CRT patients with intermediate ECG criteria (QRS 120 to 149ms or non-LBBB) and has promise for clinical applications. LA strain and clinical outcome after CRT Funding Acknowledgement Type of funding source: None

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