P1388 LA and LV strains are closely linked in patients with diastolic dysfunction and preserved ejection fraction

Introduction

Left atrial (LA) strain has been proposed as an independent parameter for the assessment left ventricular (LV) diastolic function. However, there is increasing evidence of impaired LV longitudinal function in patients with diastolic dysfunction(DD) and preserved ejection fraction (EF).

Purpose

To assess the relationship between LA and LV strain parameters with different grades of LV diastolic dysfunction in patients with preserved EF.

Methods

We included 95 patients with EF > 50% and good image quality. Patients with a mobile interatrial septum, more than mild valvular regurgitation and previous heart surgery were excluded. Standard echocardiographic measurements and the assessment of the diastolic function were performed according to current guidelines. LA and LV strains were assed using speckle tracking in 4 and 2 chambers apical views, using R-R gating. Strain values from LA and LV strain curves were derived in every phase of the cardiac cycle (peak systolic, early and late diastole strain).

Results

26 patients had normal diastolic function, 23 had grade 1, 19 grade 2 and 13 grade 3 DD. Fourteen patients with indeterminate DD grade were excluded. Both peak LA and LV strain decreased significant with the degree of DD (Fig.). LA and LV early diastole strain were significantly higher in patients with normal diastolic function than any degree of DD. LA and LV late diastole strain increased in grade 1 DD.

LA and LV strain parameters changes correlated significantly in systole, early and late diastole (r = 0.81,p < 0.0001; r = 0.64, p < 0.0001; r = 0.76, p < 0.0001, respectively). Other standard parameters of DD were not capable to differentiate between grades of DD.

Conclusion

LA and LV strain parameters show similar changes with increasing diastolic dysfunction. Diastolic dysfunction was regularly associated with reduced longitudinal strain in both LA and LV despite preserved EF. This suggest that both LA or LV strain could be used for the assessment of diastolic function.

Abstract P1388 Figure. LA and LV strain parameters by DD

557 Left ventricular diastolic function is a predictor of volumetric response to cardiac resynchronization therapy

Background

Conflicting data exist about the effects of cardiac resynchronization therapy (CRT) on diastolic function (DF). Aims of the study are: 1) to assess diastolic patterns in patients undergoing CRT; 2) to evaluate the role of DF in predicting CRT-response.

Methods

193 patients (age: 67 ± 11 ms, QRS width: 167 ± 21 ms, LVEF 28 ± 8%) were prospectively included in this multicentric study. 2D-standard echocardiography was performed before CRT and at 6-month follow-up (FU). DF was assessed according to recommendations from grade I to III. In case of data in the "grey zone", DF was defined as "indeterminate". A reduction of left ventricular (LV) end-systolic volume >15% at FU identified CRT-responders (CRT-R).

Results

At 6-month FU, 132 patients (68%) were CRT-R. Figure 1 shows DF parameters in the overall population, CRT-R, and CRT-non responders (CRT-NR) before and after CRT. At multivariable analysis, grade I diastolic dysfunction at baseline was a significant independent predictor of CRT response (OR 3.02, p = 0.001) (Table 1). The addition of grade I diastolic dysfunction to a model including clinical (sex, NYHA class, ischemic cardiomyopathy) and echocardiographic parameters (LV size), significantly increase the model power for the prediction of CRT-response (χ2: 29 vs 44, p = 0.001).

Conclusions

Before CRT, DF parameters are significantly altered in CRT-NR with respect to CRT-R. Moreover, CRT-NR experience a significant deterioration of DF after CRT. In our population, grade I diastolic function at baseline was a significant independent predictor of positive response to CRT.

Table 1 Univariable analysis Multivariable analysis Age 1.01 (0.99-1.05) 0.25 Males 0.36 (0.17-0.76) 0.008 0.57 (0.22-1.47) 0.25 CAD 0.21 (0.11-0.40) <0.001 0.31 (0.15-0.65) 0.002 NYHA 0.52 (0.31-0.88) 0.01 0.57 (0.22-1.47) 0.25 QRS 1.01 (0.99-1.02) 0.44 LVEDV 0.99 (0.99-1.00) 0.003 0.98 (0.97-1.01) 0.18 LVESV 0.99 (0.98-0.99) 0.005 1.01 (0.99-1.03) 0.28 LVEF 1.00 (0.97-1.05) 0.63 Grade I DD 4.13 (2.16-7.91) <0.0001 3.02 (1.26-7.23) 0.001 Grade II DD 0.57 (0.40-0.80) 0.001 0.87 (0.35-2.19) 0.79 Grade III DD 0.76 (0.58-1.02) 0.06

Abstract 557 Figure.

417 Can myocardial stiffness measurements distinguish the underlying pathology in hearts with thick walls? A shear wave imaging study using ultra-high frame rate echocardiography

Background

Different pathophysiologic pathways in the development of left ventricular (LV) hypertrophy may alter passive myocardial stiffness differently. Recently, cardiac shear wave (SW) elastography has been proposed as new non-invasive technique for assessing myocardial stiffness.

Purpose

To explore the relationship between myocardial stiffness and the underlying pathological substrates for cardiac hypertrophy.

Methods

We included 17 patients with cardiac amyloidosis (AML) (69 ± 10 years, 41% male), 17 patients with hypertrophic cardiomyopathy (HCM) (59 ± 16 years, 65% male) matched for interventricular septum (IVS) thickness and 17 hypertensive patients (HT) with prominent myocardial remodelling (56 ± 15 years, 71% male). LV parasternal long axis views were acquired with an experimental ultrasound scanner at 1255 ± 354 frames per seconds. Myocardial acceleration maps were created from the HFR-datasets and an anatomical M-mode line was drawn along the midline of the IVS (Figure A). The propagation velocity of natural SWs occurring at mitral valve closure (MVC) was measured on these M-modes in order to assess operating myocardial stiffness. To compare myocardial stiffness among hearts with differing loading conditions and chamber geometry, SW velocities were normalized to operating end-diastolic wall stress. The end-diastolic wall stress was estimated at the IVS from regional wall thickness, longitudinal and circumferential regional radii of curvature, and noninvasively estimated left ventricular end-diastolic pressure (EDP).

Results

IVS thickness was significant different among groups (AML: 1.63 ± 0.33 cm, HCM: 1.69 ± 0.21 cm, HT: 1.48 ± 0.14 cm; p = 0.037). HT patients had significant higher septal radius of curvature compared to other two groups (p < 0.05), while the AML patients had the highest estimated EDP (p < 0.05). All groups had comparable, elevated SW velocities at MVC (AML: 6.49 ± 1.00 m/s, HCM: 6.46 ± 1.45 m/s, HT: 6.22 ± 0.96 m/s; p = 0.752). Considering end-diastolic wall stress, HT patients had the same SW velocity at higher wall stress compared to AML and HCM (Figure B), indicating lower myocardial stiffness in the HT group. SW velocities normalized for wall stress indicated significantly different myocardial stiffness among groups (p = 0.003) (Figure C). The HT group had the lowest normalized myocardial stiffness, whereas values of the AML group overlapped with the HCM group (p = 1.00).

Conclusions

Our study demonstrated that shear wave elastography can detect differences in myocardial stiffness in hearts with thick walls. Considering the effect of wall stress, our results suggest that factors other than chamber geometry and loading condition mediate myocardial stiffness in hearts with thick walls. We hypothesize that differential changes in cardiomyocytes and/or the extracellular matrix contribute to the differential myocardial stiffening in different pathologic entities of LV hypertrophy.

Abstract 417 Figure.

P1585 Cardiac magnetic resonance estimated extracellular volume fraction, but not native T1 mapping, detects scar in patients referred for cardiac resynchronization therapy

Funding Acknowledgements

The study was supported by Center for Cardiological Innovation

Background

Myocardial scar burden (focal fibrosis) is associated with poor response to cardiac resynchronization therapy (CRT), and should preferably be detected prior to device implantation. Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) is considered reference standard for scar detection, but is not available in renal failure. Diffuse fibrosis is assessed by T1 mapping CMR with or without calculation of extracellular volume fraction (ECV). The method is vulnerable to partial volume effects, thus subendocardial tissue is most often not included in mapping analyses. Whether the contrast-free native T1mapping could replace LGE in the preoperative evaluation of patients referred for CRT is unknown.

Purpose

To investigate if native T1 mapping and calculation of ECV can adequately detect scar in patients referred for CRT.

Methods

Scar was quantified as percentage segmental LGE in 45 patients (age 65 ± 10 years, 71% male, QRS-width 165 ± 17ms) referred for CRT. In total 720 segments were analyzed, and LGE≥50% was considered transmural scar. T1-mapping before and after contrast agent injection was performed in all patients. ECV was calculated based on the ratio between tissue T1 relaxation change and blood T1 relaxation change after contrast agent injection, corrected for the haematocrit level. The agreement between native T1/ECV and scar was evaluated with receiver operating characteristic (ROC) curves with calculation of area under the curve (AUC) and 95% confidence interval (CI).

Results

LGE was present in 255 segments, 465 segments were without LGE. Average native T1 in segments with LGE was 1028 ± 88 ms, and 1040 ± 60 ms in segments without LGE (p = 0.16). The corresponding numbers for ECV were 38.7 ± 10.9% and 30.0 ± 4.7%, p < 0.001. Native T1 showed poor agreement to scar independent of scar size (AUC = 0.532, 95% CI 0.485-0.578 for scars of all sizes, and AUC = 0.572, 95% CI 0.495-0.650 for transmural scars). ECV, on the other hand, showed reasonable agreement with scar of all sizes (AUC = 0.777, 95% CI 0.739-0.815), and good agreement with transmural scars (AUC = 0.856, 95% CI 0.811-0.902). (Figure)

Conclusion

The contrast-free CMR technique T1 mapping does not adequately detect scars in patients referred for CRT. Adding post contrast T1 measurements and calculating ECV improves accuracy, especially for transmural scars. Future studies should investigate if diffuse fibrosis could be predictive of CRT response.

Abstract P1585 Figure. Detection of transmural scars

160 Echocardiographic assessment of CRT candidates. Does additional scar evaluation by MRI improve prediction of response?

Background

Myocardial scar presence and extent, has a considerable influence on response to cardiac resynchronization therapy (CRT). Apical rocking (ApRock) and septal flash (SF) are associated with favourable outcome after CRT. Little is known however to which extent visual assessment of mechanical dyssynchrony by ApRock, SF and scar predicts CRT response. We therefore investigated, if additional scar assessment by cardiac magnetic resonance imaging (MRI) adds to the predictive value of the visual evaluation of echocardiographic images in CRT candidates.

Methods

A total of 201 unselected patients referred for CRT, who fulfil the contemporary guidelines for CRT implantation, were enrolled in this prospective multicentre study. Two experienced observers visually assessed echocardiographic images before CRT implantation, focussing on the presence of ApRock, SF and location and extent of scar segments of the left ventricle (LV), resulting in a CRT response prediction (i.e. Integrative Prediction). A third observer provided a consensus reading in case of disagreement. All observers were blinded to all patient information other than the ischaemic aetiology of heart failure. Independent from that, segmental myocardial scar burden was objectified by late gadolinium enhancement (LGE) cardiac MRI (LGE > 50%). CRT response was defined as ≥15% reduction in LV end-systolic volume on echocardiography, one year after device implantation.

Results

Overall, 69 (34%) patients had an ischaemic aetiology of heart failure. Before CRT, ApRock and SF were present in 129 (64%) and 136 (68%) patients, respectively. ApRock and SF alone predicted CRT response with an area under the curve (AUC) of 0.85 (95% CI: 0.79-0.91) and 0.84 (95% CI: 0.77-0.91) (Figure A), while the echocardiographic Integrative Prediction had an AUC of 0.90 (95% CI: 0.84-0.95), with a sensitivity of 93% and a specificity of 87% for the prediction of CRT response (Figure B) (p < 0.05 vs. ApRock and SF alone). When combining information on ApRock, SF and the number of scarred segments on MRI in a statistical model, the AUC was comparable to the echocardiographic Integrative Prediction [0.90 (95% CI: 0.84-0.96)] as was sensitivity and specificity (91% and 83%, respectively, p = N.S. vs. Integrative Prediction) (Figure C).

Conclusions

An integrative visual assessment of LV function has an excellent predictive value for CRT response. Our data show, that the echocardiographic estimation of scar burden is sufficiently accurate and cannot be further improved by an additional MRI scar assessment.

Abstract 160 Figure.

P1281 Are left atrial and left ventricular strains independent from each other?

Introduction

Left atrium (LA) and ventricle (LV) share the mitral annular plane so that the motion and deformation of both chambers are coupled.

Purpose

To investigate the interdependence between LA and LV strain curves using strain-strain loops.

Methods

We included 101 patients with a wide range of pathology and selected for having sufficient image quality for both LA and LV analysis. Patients with a mobile interatrial septum and more than mild valvular regurgitation were excluded. LA and LV strains were assessed using speckle tracking in 4 and 2 chambers apical views, using the same cardiac cycle and R-R gating. Strain-strain-loops were reconstructed using LV strain data on the x-axis and corresponding, synchronized LA strain data on the y-axis (Fig .A). Linear regressions were calculated for the entire strain-strain-loop as well as for the three phases of the cardiac cycle (systole, early and late diastole) seperately. LA and LV volumes were also measured on the same images and their ratio was calculated and correlated with the slope of the regression line of the strain-strain loop (Fig. B).

Results

Our study population comprised normal volunteers (27), amyloidosis (8), hypertrophic cardiomyopathy (6), ischemic disease (19), non-ischemic cardiomyopathy (22), aortic stenosis (13) atrial fibrillation (6).

On average, LA and LV strain curves correlated with an R2= 0.92 ± 0.04 for the entire loop, R2= 0.97 ±0.01 in systole, R2= 0.98 ± 0.02 in early diastole and R2= 0.97 ±0.03 late diastole. Further, in the individual patients, the ratio of LV/LA volumes correlated with the LA/LV strain ratio with a slope of ∼1.0 (R2 = 0.8).

Conclusions

LA and LV deformation are closely coupled. Strain curves have a similar shape throughout the cardiac cycle leading to a tight correlation of strain values from both chambers. The relation of LA and LV strain is dominated by the two chambers" dimensions.

Abstract P1281 Figure.

561 Targeting septal work and viability identifies responders to cardiac resynchronization therapy

Funding Acknowledgements

The study was supported by Center for Cardiological Innovation.

Introduction

Septal dysfunction is the dominant mechanism of left ventricular (LV) failure in left bundle branch block (LBBB). We hypothesize that, provided septum is viable, septal function can recover and hence LV function improve after cardiac resynchronization therapy (CRT).

Purpose

To determine if combined assessment of septal function and viability identifies responders to CRT.

Methods

In a prospective multicenter study of 200 unselected patients referred for CRT, we measured myocardial strain by speckle-tracking echocardiography and regional work by pressure-strain analysis before and 7 ± 1 months after CRT. Viability was assessed by late gadolinium enhancement cardiac magnetic resonance imaging (n = 123). CRT response was defined as ≥15% reduction in LV end-systolic volume.

Results

Before CRT, septal work was 258 ± 463 and LV lateral wall work 1469 ± 674 mmHg·% (p < 0.0001). In CRT responders, septal work was restored to 1243 ± 495 mmHg·%, whereas non-responders showed less marked improvement (p < 0.0001). The figure illustrates a typical CRT responder with negative septal work and a large difference between work in the LV lateral wall and septum (panel A). There was no septal scar (panel B) and, after 6 months with CRT, septal work was recovered (panel C). Pressure-strain loops illustrate that CRT converted inefficient septal contractions with substantial negative (wasted) work to positive work throughout systole. For the entire study population, the difference between work in the LV lateral wall and septum predicted CRT response with area under the curve (AUC) 0.75 (95% CI: 0.68-0.83) and was feasible in 98% of patients. Furthermore, septal scar predicted non-response to CRT with AUC 0.76 (95% CI: 0.65-0.86). Combining work difference and septal viability improved AUC for CRT response to 0.85 (95% CI: 0.76-0.94) (figure panel D). The AUC was similar for QRS 120-150 and >150 ms.

Conclusions

The proposed combined approach with assessment of septal work and viability identified CRT responders with high precision.

Abstract 561 Figure.

553 Acute re-distribution of regional left ventricular work by cardiac resynchronization therapy determines long-term remodelling

Background

In patients with dilated cardiomyopathy and left bundle branch block (LBBB), different regions of the left ventricle (LV) have been shown to perform different amounts of work. In this study, we investigate the acute impact of cardiac resynchronization therapy (CRT) on regional LV work distribution and its relation to long-term reverse-remodelling.

Methods

We recruited 140 heart failure patients, referred for CRT. Regional myocardial work was calculated from non-invasive echocardiographic segmental stress-strain-loop-area before and immediately after CRT. The magnitude of volumetric reverse-remodelling was determined from the change in LV end-systolic volume (ESV), 11 ± 3 months after implantation. Characteristics of patients with the lowest and highest quartile of LV ESV reverse remodelling (LV ESV reduction of less than 10% and LV ESV reduction of more than -48%) were compared.

Results

Before CRT, myocardial work showed significant differences among the walls of the LV (Figure A). CRT caused an acute re-distribution of myocardial work, on average with most increase in the septum and most decrease laterally (all walls p < 0.05) and lead to a homogeneous work distribution (Figure B). The acute change in the difference between lateral and septal wall work (Δ Lateral-to-septal work) correlated significantly with LV ESV reverse-remodelling (r = 0.63, p < 0.0001). The smallest changes in work were seen in the patients with the least LV ESV reverse remodelling (Figure C, red markers), while patients with the most LV ESV reverse remodelling showed the largest changes in work (Figure C, green markers). In multivariate linear regression analysis, including conventional parameters such as pre-implant QRS duration, LV ejection fraction, LV end-diastolic volume and global longitudinal strain, the re-distribution of work across the septal and lateral walls appeared as the strongest determinant of volumetric reverse-remodelling after CRT (R²=0.393, p < 0.0001).

Conclusions

The acute re-distribution of regional myocardial work between the septal and lateral wall of the left ventricle is an important determinant of long term reverse-remodelling after CRT-implantation. Our data suggest that modification of regional loading is the mode of action of CRT treatment.

Abstract 553 Figure.

Partial volume and motion correction in cardiac PET: First results from an in vs ex vivo comparison using animal datasets

BACKGROUND

In a previous study on ex vivo, static cardiac datasets, we investigated the benefits of performing partial volume correction (PVC) in cardiac 18F-Fluorodeoxyglucose(FDG) PET datasets. In the present study, we extend the analysis to in vivo cardiac datasets, with the aim of defining which reconstruction technique maximizes quantitative accuracy and, ultimately, makes PET a better diagnostic tool for cardiac pathologies.

METHODS

In vivo sheep datasets were acquired and reconstructed with/without motion correction and using several reconstruction algorithms (with/without resolution modeling, with/without non-anatomical priors). Corresponding ex vivo scans of the excised sheep hearts were performed on a small-animal PET scanner (Siemens Focus 220, microPET) to provide high-resolution reference data unaffected by respiratory and cardiac motion. A comparison between the in vivo cardiac reconstructions and the corresponding ex vivo ground truth was performed.

RESULTS

The use of an edge-preserving prior (Total Variation (TV) prior in this work) in combination with motion correction reduces the bias in absolute quantification when compared to the standard clinical reconstructions (- 0.83 vs - 3.74 SUV units), when the end-systolic gate is considered. At end-diastole, motion correction improves absolute quantification but the PVC with priors does not improve the similarity to the ground truth more than a regular iterative reconstruction with motion correction and without priors. Relative quantification was not influenced much by the chosen reconstruction algorithm.

CONCLUSIONS

The relative ranking of the algorithms suggests superiority of the PVC reconstructions with dual gating in terms of overall absolute quantification and noise properties. A well-tuned edge-preserving prior, such as TV, enhances the noise properties of the resulting images of the heart. The end-systolic gate yields the most accurate quantification of cardiac datasets.

P2459Do left atrial strain measurements provide information independent from left ventricular function parameters?

Introduction

LA strain has been proposed to be a reliable and independent prognostic marker, as well as a useful surrogate of LA function.

Purpose

To assess if LA deformation measurements add independent information to standard echocardiographic measurements.

Methods

We included 66 normals and patients with a wide range of pathology and diastolic dysfunction grade from the echo data base of our hospital if image quality was sufficient for both LA and LV strain analysis. Patients with a mobile interatrial septum, arrhythmias and more than mild valvular regurgitation were not considered. Standard echocardiographic measurements including LA and LV volumes were performed according to current guidelines. LA and LV longitudinal strains were assessed by 2D speckle tracking in the same cardiac cycle in apical 4 and 2 chambers views using peak R as time reference. Peak LA and LV strain as well as LA and LV strain at onset of LA contraction were measured to calculate the strain components of all three phases of the cardiac cycle (systolic, early diastolic and late diastolic).

Results

In our cohort, the ratio of LA and LV systolic strain was directly and strongly related to the volume ratio of the two chambers (R2=0,894, slope=-1.001, p<0.0001, see Figure 1). This was confirmed by a multivariate regression analysis, where systolic LA strain proved to be strongly dependent on systolic LV strain, LA volume and LV volume (R2=0.872, p<0.0001 for the final model).

For early diastolic strain, confounders were LV early diastolic strain, LA volume, LV volume and lateral wall E' tissue velocity (R2=0.784, p<0.0001); while LA late diastolic strain was dependent on LV late diastolic strain, LA volume, LV volume and lateral wall A' tissue velocity (R2=0.823, p<0.0001).

Strain ratio vs volume ratio

Conclusions

Our data suggest that systolic LA strain (reservoir strain) is strictly dependent on systolic LV strain and the volume ratio of both chambers and, therefore, its measurement cannot provide additional information beyond classical measurements. Diastolic LA strain components show a less strict dependence on LV function and may therefore provide additional information.

P4364A direct comparison between 2D and 4D deformation imaging in hypertrophic hearts. An agreement of disagreement

Background

Previous studies have directly compared 2-dimensional (2D) and 4-dimensional (4D) deformation imaging in normal and ischemic hearts suggesting a moderate agreement prone to technical considerations. However, the level of agreement between 2D and 4D-strain imaging has never been adequately addressed in hypertrophic hearts, nor has it been validated against a “ground truth”.

Purpose

We aimed at directly comparing 4D and 2D global and regional deformation parameters and depict which may best reflect underlying segmental fibrosis in hypertrophic cardiomyopathy (HCM), as defined by late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR).

Methods

We included 40 HCM patients (54.1±14.3 years, 82.5% male, maximum wall thickness 19.3±4.8mm) who have consecutively undergone 2D-,4D-speckle tracking echocardiography and CMR. Global and segmental circumferential (CS) and longitudinal (LS) strain have been calculated from 2D acquisitions and 4D full volume data, where additionally radial (RS) and area (AS) strain have been extracted using an 18 segment left ventricle model. Accordingly, segmental fibrosis was defined by LGE in corresponding CMR slices.

Results

Deformation parameters (2D and 4D, global and regional) presented overall poor to moderate agreement (Figure A+B) with regional 4D_LS and 4D_CS values being constantly less negative compared to 2D derivatives (−7.29±6.94% and −8.53±8.8% accordingly). In regional analysis, 720 segments were evaluated of which 134 (19.7%) were enhanced and 95 of them thickened (68.8%) (thickness>12 mm), with segments presenting both characteristics showing the greatest impairment both in 2D and 4D strain values. Among segmental deformation indices, 2D_SLS showed the best area under the curve [(AUC)=0.78, 95% CI (0.75–0.81), p<0.0005] to detect segmental fibrosis, with 2D_SCS and all 4D deformation indices presenting significantly lower AUC (Figure C).

Conclusions

In HCM, 2D and 4D deformation parameters are not interchangeable, showing modest agreement. Thickness and tracking algorithm calculating assumptions seem to induce this variability. Nevertheless, among HCM patients 2D_SLS remains the best strain parameter for tissue characterization and fibrosis detection.

Acknowledgement/Funding

Supported with a scholarship by the Greek State Scholarship Foundation (IKY).

P5429Mechanical dyssynchrony has a higher predictive value for CRT response than different ECG-based definitions of LBBB

Background/Aim

To investigate the value of baseline assessment of mechanical dyssynchrony (Dyss) in predicting response to cardiac resynchronization therapy (CRT) in comparison to the classic ECG definition of left bundle branch block (LBBB) (Classic-def) as well as the recently proposed Sex- based definition (Sex-def.).

Methods

The baseline ECGs of 194 patients (31% females, 39% with ischemic cardiomyopathy, mean QRS width 159±25 ms and mean LVEF 29±8%) were investigated for identifying the criteria of LBBB before CRT implantation. Classic-def., defined as notched or slurred QRS complex in at least two of the leads I, aVL, V1, V2, V5 and V6 with a total width of at least 120 ms in addition to the absence of Q wave in lead I, V5 and V6 was identified in 74% of the study population. Sex-def. was identified in 69%, which is a QRS duration of at least 140 and 130 ms for men and women respectively with otherwise the same criteria of the Classic definition. Dyss was defined as the presence of either apical rocking and/or septal flash in 2D echocardiography prior to implantation. Volumetric response to CRT was defined as a reduction of at least 15% of the LV-end systolic volume (ESV) at follow up echocardiography (12±6 months after device implantation).

Results

Patient with baseline Dyss showed the highest response rates (76%) with a sensitivity of 88%, a specificity of 63% and an area under the curve (AUC) of 0.76 (P<0.001) compared to 70% (sensitivity 82%, specificity 47%, AUC 0.65, P<0.01) in patients with Sex-def. and 65% (sensitivity 84%, specificity 40%, AUC 0.62, P=0.01) in patients with Classic-def. (Figure A).

Pairwise comparisons showed that the accuracy of the Sex-def. did not differ significantly from the Classic-def. in response prediction (AUC=0.65 vs. 0.62 for Sex-def. vs. Classic-def. respectively, P=0.27). Alternatively, Dyss showed a significantly higher accuracy in predicting response to therapy (AUC=0.76) as compared to Sex-def. and Classic-def. (P=0.02 and <0.01 respectively, Figure B).

Mech. dyssynchrony vs. ECG-based LBBB

Conclusion

The presence of Apical rocking and/or septal flash before CRT is associated with better response to CRT as compared to various ECG definitions of LBBB. Although a Sex-based definition of LBBB showed a trend of better response to CRT as compared to the Classic definition, it was not statistically significant.

P1238Acute re-distribution of myocardial work by cardiac resynchronization therapy determines long-term remodelling of the left ventricle

Background

In patients with dilated cardiomyopathy and left bundle branch block (LBBB), different regions of the left ventricle (LV) have been shown to perform different amounts of work. In this study, we investigate the acute impact of cardiac resynchronization therapy (CRT) on regional LV work distribution and its relation to long-term reverse-remodelling.

Methods

We recruited 130 heart failure patients, referred for CRT. Regional myocardial work was calculated from non-invasive echocardiographic segmental stress-strain-loop-area before and immediately after CRT. The magnitude of volumetric reverse-remodelling was determined from the change in LV end-systolic volume (ESV), 11±2 months after implantation. Characteristics of patients with the lowest and highest quartile of LV ESV reverse remodelling (ΔLV ESV <−9% and ΔLV ESV >−48%) were compared.

Results

Before CRT, myocardial work showed significant differences among the walls of the LV (Figure 1A). CRT caused an acute re-distribution of myocardial work, on average with most increase in the septum and most decrease laterally (all walls p<0.05) and lead to a homogeneous work distribution (Figure 1B). The acute change in the difference between lateral and septal wall work (Δlateral − septal work) correlated best and significantly with LV ESV reverse-remodelling (r=0.62, p<0.0001). The smallest changes in work were seen in the patients with the least LV ESV reverse remodelling (Figure 1C, red markers), while patients with the most LV ESV reverse remodelling showed the largest changes in work (Figure 1C, green markers). In a multivariate-linear-regression-analysis, including pre-implant QRS duration, LVEF, LV EDV and GLS, the re-distribution of work remained as the strongest determinant of volumetric reverse-remodelling after CRT (r=0.63, p<0.0001).

Figure 1

Conclusions

The acute re-distribution of regional myocardial work between the septal and lateral wall of the left ventricle is the main determinant of long term reverse-remodelling after CRT-implantation. Our data suggest that modification of regional loading is the mode of action of CRT treatment.

P619Stress-strain loop area better represents regional myocardial work than pressure-strain loop area in the dyssynchronous and remodelled left ventricle

Background

Pressure-strain-loops (PSL) have been suggested as surrogate parameter of regional myocardial work. However, in left ventricles (LV) with inhomogeneous remodelling, e.g. due to left bundle branch block (LBBB), wall stress may be unevenly distributed. Stress-strain loops (SSL) include information on both regional wall thickness and curvature, and may therefore provide a better surrogate.

Study plan

We therefore compared the correlation of segmental myocardial work estimated through both PSL and SSL to segmental myocardial glucose metabolism as a gold standard, in an animal model of pacing-induced LV remodelling.

Methods

Twelve sheep developed LV dilatation, thinned septum and thickened lateral wall, due to eight weeks of rapid right-atrial and right-ventricular free wall (DDD) pacing (at 180 bpm), causing a LBBB-like dyssynchrony. Invasive LV pressure and echocardiographic speckle tracking based circumferential strain were used to construct PSL. SSL were calculated by considering in addition dynamic changes in segmental myocardial wall thickness and curvature using the formula of Laplace. 18F-fluorodeoxyglucose (FDG)-uptake was measured by positron emission tomography (PET) in absolute values as standardised uptake ratio (SUR). Spatial resolution of PET was improved by ECG- and breathing-gating and using anatomical priors. All imaging was performed during dyssynchronous DDD-pacing and synchronous AAI-pacing (right-atrial pacing only), at baseline (n=3 animals), and after eight weeks of pacing induced remodelling (n=12 animals).

Results

Both at baseline (Fig. A+B) and after 8 weeks (Fig. D+E), switching between AAI and DDD-pacing caused an acute re-distribution of regional myocardial work as measured by both PSL and SSL. In contrast to PSL, however, SSL identified more regional differences among walls in remodelled hearts and showed clearer regional changes when switching between AAI and DDD-pacing. The correlation between regional work, assessed by PSL and SSL, and metabolism by PET, was comparable at baseline (r=0.65 and r=0.64, respectively) (Fig. C). In remodelled hearts after 8 weeks, however, the correlation of regional work assessed by SSL and glucose uptake by PET was significantly higher compared to PSL (r=0.73 vs. r=0.59, respectively; p<0.05) (Fig. F).

Conclusions

Regional myocardial work assessed by stress-strain loops correlates significantly better to regional metabolism as measured by PET glucose uptake, particularly after remodelling. Our findings therefore suggest that integrating information on wall thickness and curvature is essential for the reliable assessment of regional myocardial work, especially in dyssynchronous and remodelled left ventricles.

P602Septal function and viability determine response to cardiac resynchronization therapy

Introduction

Cardiac resynchronization therapy (CRT) has evolved as an important treatment in patients with symptomatic heart failure, reduced left ventricular (LV) ejection fraction and wide QRS. However, as one third of patients do not benefit from the therapy, there is need for better selection criteria. Previous studies have shown an association between recovery of septal function and response to CRT.

Purpose

To test the hypothesis that septal dysfunction in the absence of scar predicts response to CRT.

Methods

In 121 patients undergoing CRT implantation according to current European Society of Cardiology guidelines, we performed speckle-tracking echocardiography and estimated LV pressure non-invasively based on a method recently innovated in our lab. Pressure-strain analysis was used to calculate myocardial work. Septal dysfunction with asymmetric LV workload was calculated as the difference between LV lateral wall and septal work. Late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR) was performed to assess septal scar. CRT response was defined as ≥15% reduction of LV end systolic volume by echocardiography at 6 months follow-up.

Results

Eighty-eight patients (73%) responded to CRT at 6 months follow-up. Multivariate logistic regression analysis including lateral-to-septal work difference, septal scar, QRS duration and QRS morphology found that only lateral-to-septal work difference and septal scar were significant predictors of CRT response (both p<0.005). Using logistic regression and receiver operating characteristic (ROC) curve analysis, we found that the combined approach of these two parameters identified CRT responders with a sensitivity of 86% and a specificity of 82%. The area under the curve (AUC) for CRT response prediction was 0.85 (95% CI: 0.76–0.94) (Figure). In comparison, the AUC value for QRS duration was 0.63 (95% CI: 0.52–0.75). Furthermore, for the subgroup of patients with QRS duration 120–150 ms (n=27), the AUC value for lateral-to-septal work difference in combination with septal scar was 0.90 (95% CI: 0.78–1.00).

Conclusions

A multimodality approach with strain echocardiography and LGE-CMR was able to detect CRT responders with high accuracy, also in the subset of patients with intermediate QRS duration. A dysfunctional but viable septum appears to be an ideal target for CRT.

P6180Septal negative work correlates inversely with septal scar in patients referred for cardiac resynchronization therapy

Background

Myocardial scar is frequently present in patients with heart failure and left bundle branch block (LBBB), and associated with reduced response to cardiac resynchronization therapy (CRT). Furthermore, LBBB may be associated with markedly reduced strain, work, metabolism and perfusion in septum, even without septal ischemia. Therefore, it may be challenging to identify scar by functional imaging methods.

Purpose

To investigate the ability of advanced echocardiographic and nuclear imaging techniques to detect septal and left ventricular (LV) lateral wall scar in patients referred for CRT, compared to late gadolinium enhancement (LGE) cardiac magnetic resonance.

Methods

Scar was quantified as percentage LGE in five septal and five LV lateral wall segments of 131 patients (age 66±10, 66% male, QRS-width 164±17ms) referred for CRT, 92% with LBBB. Longitudinal strain was assessed by speckle tracking echocardiography in 130 patients (652 septal and 631 LV lateral wall segments). Myocardial work was calculated by LV pressure-strain analysis. Systolic shortening defined positive work, while systolic lengthening defined negative work. Glucose metabolism was assessed by 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) in 52 patients (260 septal and 260 LV lateral wall segments). Perfusion was assessed in 46 patients (230 septal and 230 LV lateral wall segments) by either 13N-ammonia PET (n=32) or Single Photon Emission Computed Tomography (SPECT) (n=14). Metabolism and perfusion were reported as percentages of the segment with maximum tracer uptake. We evaluated parameter relationship to scar with Spearman correlation (rs) and regression analysis.

Results

LGE was present in 198 septal (30%) and 136 LV lateral wall (21%) segments. In a multivariate regression model with negative work, metabolism, perfusion and peak strain, only the first three parameters showed a significant association with LGE percent in septum (p<0.001, p=0.022 and p<0.001, respectively), while peak strain did not (p=0.270). Negative work in septum correlated inversely with percentage septal LGE-uptake (rs=-0.33): increasing amount of scar was associated with less negative work (Figure).

In the LV lateral wall, however, negative work did not shown a significant association with percentage LGE in univariate regression analysis (p=0.109). In a multivariate regression model positive work, metabolism and perfusion correlated with percentage LGE (p=0.049, p=0.008 and p<0.001), while peak strain did not (p=0.607).

Two representative patients

Conclusions

Septal negative work correlates inversely with septal scar in patients referred for CRT. This finding is probably linked to LBBB, and may be explained by increased stiffness of scar tissue. Myocardial work, but not peak strain, reflects scar in the LV lateral wall. Future studies should explore the assessment of scar in the complete LV and how this relates to CRT response.

P1501Can we measure the stiffening of hypertensive hearts non-invasively? A shear wave imaging study using ultra-high frame rate echocardiography

Background

Cardiac shear wave (SW) elastography is a novel technique based on high-frame-rate (HFR) echocardiography which has been shown to be related to myocardial stiffness. In this study we explore the relation between myocardial SW velocity and myocardial remodelling in remodelled hearts of patients with arterial hypertension (AH).

Methods

We prospectively included 33 treated AH patients with hypertrophic left ventricular (LV) remodelling (59±14 years, 55% male) and 26 aged matched healthy controls (55±15 years, 77% male). AH patients were further divided according to their LV geometric pattern into a concentric remodelling (CR) group (13 patients) and a concentric hypertrophy (CH) group (20 patients). LV parasternal long axis views were acquired with an experimental HFR ultrasound scanner (HD-PULSE) at 1266±317 frames per seconds. Myocardial acceleration maps were created from the HFR-datasets and an anatomical M-mode line was drawn along the midline of the interventricular septum (IVS). The propagation velocity of natural SWs occurring at mitral valve closure (MVC) was measured on these M-modes (Figure A) in order to assess passive myocardial stiffness. Standard echocardiography using a commercial scanner was performed to evaluate LV remodelling.

Results

SW velocities at MVC differed significantly between AH patients and controls (5.83±1.20 m/s vs. 4.04±0.96 m/s; p<0.001). Within the patient group, patients with CH had highest SW velocities at MVC (p<0.001), whereas values between controls and patients with CR were comparable (p=0.075) (Figure B). In AH patients, significant positive correlations were found between SW velocity at MVC and parameters of LV remodelling (IVS thickness: r=0.728, p<0.001; LV mass index: r=0.780, p<0.001, LV end-diastolic volume: r=0.604, p=0.008) (Figure C) and also parameters of diastolic function (E/e': r=0.495, p=0.005, left atrium diameter: r=0.866, p<0.001, left atrium volume index: r=0.661, p<0.001).

Figure A, B, C

Conclusions

SW velocity – and therefore myocardial stiffness – is higher in AH patients compared to healthy controls and increases with increasing severity of hypertensive heart disease. Patients with concentric remodelling have still close-to-normal passive myocardial properties while patients with concentric hypertrophy show significant stiffening. Echocardiographic shear wave elastography is a promising new technique for the non-invasive assessment of myocardial stiffness and might provide valuable new insights into myocardial function and the pathophysiology of myocardial disease.

Deuxième niveau de compétence pour l’échographie clinique en médecine d’urgence. Recommandations de la Société française de médecine d’urgence par consensus formalisé

La Société française de médecine d’urgence a élaboré en 2016 des recommandations formalisées d’experts définissant le premier niveau de compétence en échographie clinique en médecine d’urgence. Ce niveau est maintenant complété par un deuxième niveau correspondant à une pratique plus avancée utilisant des techniques non envisagées dans le premier niveau comme l’utilisation du Doppler et nécessitant aussi une pratique et une formation plus poussées. Des champs déjà présents dans le premier référentiel sont complétés, et de nouveaux champs sont envisagés. La méthodologie utilisée est issue de la méthode « Recommandations par consensus formalisé » publiée par la Haute Autorité de santé et de la méthode Delphi pour quantifier l’accord professionnel. Ce choix a été fait devant l’insuffisance de littérature de fort niveau de preuve dans certaines thématiques et de l’existence de controverses. Ce document présente les items jugés appropriés et inappropriés par les cotateurs. Ces recommandations définissent un deuxième niveau de compétence en ECMU.