Comparison of strain parameters in dyssynchronous heart failure between speckle tracking echocardiography vendor systems.
ABSTRACT: Although mechanical dyssynchrony parameters derived by speckle tracking echocardiography (STE) may predict response to cardiac resynchronization therapy (CRT), comparability of parameters derived with different STE vendors is unknown.In the MARC study, echocardiographic images of heart failure patients obtained before CRT implantation were prospectively analysed with vendor specific STE software (GE EchoPac and Philips QLAB) and vendor-independent software (TomTec 2DCPA). Response was defined as change in left ventricular (LV) end-systolic volume between examination before and six-months after CRT implantation. Basic longitudinal strain and mechanical dyssynchrony parameters (septal to lateral wall delay (SL-delay), septal systolic rebound stretch (SRSsept), and systolic stretch index (SSI)) were obtained from either separate septal and lateral walls, or total LV apical four chamber. Septal strain patterns were categorized in three types. The coefficient of variation and intra-class correlation coefficient (ICC) were analysed. Dyssynchrony parameters were associated with CRT response using univariate regression analysis and C-statistics.Two-hundred eleven patients were analysed. GE-cohort (n = 123): age 68 years (interquartile range (IQR): 61-73), 67% male, QRS-duration 177 ms (IQR: 160-192), LV ejection fraction: 26 ± 7%. Philips-cohort (n = 88): age 67 years (IQR: 59-74), 60% male, QRS-duration: 179 ms (IQR: 166-193), LV ejection fraction: 27 ± 8. LV derived peak strain was comparable in the GE- (GE: -7.3 ± 3.1%, TomTec: -6.4 ± 2.8%, ICC: 0.723) and Philips-cohort (Philips: -7.7 ± 2.7%, TomTec: -7.7 ± 3.3%, ICC: 0.749). SL-delay showed low ICC values (GE vs. TomTec: 0.078 and Philips vs. TomTec: 0.025). ICC's of SRSsept and SSI were higher but only weak (GE vs. TomTec: SRSsept: 0.470, SSI: 0.467) (Philips vs. QLAB: SRSsept: 0.419, SSI: 0.421). Comparability of septal strain patterns was low (Cohen's kappa, GE vs. TomTec: 0.221 and Philips vs. TomTec: 0.279). Septal strain patterns, SRSsept and SSI were associated with changes in LV end-systolic volume for all vendors. SRSsept and SSI had relative varying C-statistic values (range: 0.530-0.705) and different cut-off values between vendors.Although global longitudinal strain analysis showed fair comparability, assessment of dyssynchrony parameters was vendor specific and not applicable outside the context of the implemented platform. While the standardization taskforce took an important step for global peak strain, further standardization of STE is still warranted.
Project description:Parameters using myocardial strain analysis may predict response to cardiac resynchronization therapy (CRT). As the agreement between currently available strain imaging modalities is unknown, three different modalities were compared. Twenty-seven CRT-candidates, prospectively included in the MARC study, underwent cardiac magnetic resonance (CMR) imaging and echocardiographic examination. Left ventricular (LV) circumferential strain was analysed with CMR tagging (CMR-TAG), CMR feature tracking (CMR-FT), and speckle tracking echocardiography (STE). Basic strain values and parameters of dyssynchrony and discoordination obtained with CMR-FT and STE were compared to CMR-TAG. Agreement of CMR-FT and CMR-TAG was overall fair, while agreement between STE and CMR-TAG was often poor. For both comparisons, agreement on discoordination parameters was highest, followed by dyssynchrony and basic strain parameters. For discoordination parameters, agreement on systolic stretch index was highest, with fair intra-class correlation coefficients (ICC) (CMR-FT: 0.58, STE: 0.55). ICC of septal systolic rebound stretch (SRSsept) was poor (CMR-FT: 0.41, STE: 0.30). Internal stretch factor of septal and lateral wall (ISFsep-lat) showed fair ICC values (CMR-FT: 0.53, STE: 0.46), while the ICC of the total LV (ISFLV) was fair for CMR-FT (0.55) and poor for STE (ICC: 0.32). The CURE index had a fair ICC for both comparisons (CMR-FT: 0.49, STE 0.41). Although comparison of STE to CMR-TAG was limited by methodological differences, agreement between CMR-FT and CMR-TAG was overall higher compared to STE and CMR-TAG. CMR-FT is a potential clinical alternative for CMR-TAG and STE, especially in the detection of discoordination in CRT-candidates.
Project description:AIMS:Various strain parameters and multiple imaging techniques are presently available including cardiovascular magnetic resonance (CMR) tagging (CMR-TAG), CMR feature tracking (CMR-FT), and speckle tracking echocardiography (STE). This study aims to compare predictive performance of different strain parameters and evaluate results per imaging technique to predict cardiac resynchronization therapy (CRT) response. METHODS AND RESULTS:Twenty-seven patients were prospectively enrolled and underwent CMR and echocardiographic examination before CRT implantation. Strain analysis was performed in circumferential (CMR-TAG, CMR-FT, and STE-circ) and longitudinal (STE-long) orientations. Regional strain values, parameters of dyssynchrony, and discoordination were calculated. After 12 months, CRT response was measured by the echocardiographic change in left ventricular (LV) end-systolic volume (LVESV). Twenty-six patients completed follow-up; mean LVESV change was -29 ± 27% with 17 (65%) patients showing ?15% LVESV reduction. Measures of dyssynchrony (SD-TTPLV ) and discoordination (ISFLV ) were strongly related to CRT response when using CMR-TAG (R2 0.61 and R2 0.57, respectively), but showed poor correlations for CMR-FT and STE (all R2 ? 0.32). In contrast, the end-systolic septal strain (ESSsep ) parameter showed a consistent high correlation with LVESV change for all techniques (CMR-TAG R2 0.60; CMR-FT R2 0.50; STE-circ R2 0.43; and STE-long R2 0.43). After adjustment for QRS duration and QRS morphology, ESSsep remained an independent predictor of response per technique. CONCLUSIONS:End-systolic septal strain was the only parameter with a consistent good relation to reverse remodelling after CRT, irrespective of assessment technique. In clinical practice, this measure can be obtained by any available strain imaging technique and provides predictive value on top of current guideline criteria.
Project description:Patients with non-ischemic heart failure etiology and left bundle branch block (LBBB) show better response to cardiac resynchronization therapy (CRT). While these patients have the most pronounced left ventricular (LV) dyssynchrony, LV dyssynchrony assessment often fails to predict outcome. We hypothesized that patients with favorable outcome from CRT can be identified by a characteristic strain distribution pattern.From 313 patients who underwent CRT between 2003 and 2006, we identified 10 patients who were CRT non-responders (no LV end-systolic volume [LVESV] reduction) with non-ischemic cardiomyopathy and LBBB and compared with randomly selected CRT responders (n = 10; LVESV reduction ≥15%). Longitudinal strain (εlong) data were obtained by speckle tracking echocardiography before and after (9 ± 5 months) CRT implantation and standardized segmental εlong-time curves were obtained by averaging individual patients.In responders, ejection fraction (EF) increased from 25 ± 9 to 40 ± 11% (p = 0.002), while in non-responders, EF was unchanged (20 ± 8 to 21 ± 5%, p = 0.57). Global εlong was significantly lower in non-responders at pre CRT (p = 0.02) and only improved in responders (p = 0.04) after CRT. Pre CRT septal εlong -time curves in both groups showed early septal contraction with mid-systolic decrease, while lateral εlong showed early stretch followed by vigorous mid to late contraction. Restoration of contraction synchrony was observed in both groups, though non-responder remained low amplitude of εlong.CRT non-responders with LBBB and non-ischemic etiology showed a similar improvement of εlong pattern with responders after CRT implantation, while amplitude of εlong remained unchanged. Lower εlong in the non-responders may account for their poor response to CRT.
Project description:Background: 3D speckle-tracking echocardiography (3D-STE) is a novel method to quantify left ventricular (LV) mechanical dyssynchrony. 3D-STE is influenced by image quality, but studies on the magnitude of its effect on 3D-STE derived LV systolic dyssynchrony indices (SDIs) and their test-retest reproducibility are limited. Methods: 3D-STE was performed in two groups, each comprising 18 healthy volunteers with good echocardiographic windows. In study 1, optimal and inferior-quality images, by intentionally poor echocardiographic technique, were acquired. In study 2, sub-optimal quality images were acquired by impairing ultrasound propagation using neoprene rubber sheets (thickness 2, 3, and 4 mm) mimicking mildly, moderately, and severely impaired images, respectively. Measures (normalized to cardiac cycle duration) were volume- and strain-based SDIs defined as the standard deviation of time to minimum segmental values, and volume- and strain-derived dispersion indices. For both studies test-retest reproducibility was assessed. Results: Test-retest reproducibility was better for most indices when restricting the analysis to good quality images; nevertheless, only volume-, circumferential strain-, and principal tangential strain-derived LV dyssynchrony indices achieved fair to good reliability. There was no evidence of systematic bias due to sub-optimal quality image. Volume-, circumferential strain-, and principal tangential strain-derived SDIs correlated closely. Radial strain- and longitudinal strain-SDI correlated moderately or weakly with volume-SDI, respectively. Conclusions: Sub-optimal image quality compromised the reliability of 3D-STE derived dyssynchrony indices but did not introduce systematic bias in healthy individuals. Even with optimal quality images, only 3D-STE indices based on volume, circumferential strain and principal tangential strain showed acceptable test-retest reliability.
Project description:To evaluate the effects of cardiac resynchronization therapy (CRT) on long-term survival of patients without baseline left ventricular (LV) mechanical dyssynchrony.A total of 290 heart failure patients (age 67 ± 10 years, 77% males) without significant baseline LV dyssynchrony (<60 ms as assessed with tissue Doppler imaging) were treated with CRT. Patients were divided according to the median LV dyssynchrony measured after 48 h of CRT into two groups. All-cause mortality was compared between the subgroups. In addition, the all-cause mortality rates of these subgroups were compared with the all-cause mortality of 290 heart failure patients treated with CRT who showed significant LV dyssynchrony (?60 ms) at baseline. In the group of patients without significant LV dyssynchrony, median LV dyssynchrony increased from 22 ms (inter-quartile range 16-34 ms) at baseline to 40 ms (24-56 ms) 48 h after CRT. The cumulative mortality rates at 1-, 2-, and 3-year follow-up of patients with LV dyssynchrony ?40 ms 48 h after CRT implantation were significantly higher when compared with patients with LV dyssynchrony <40 ms (10, 17, and 23 vs. 3, 8, and 10%, respectively; log-rank P< 0.001). Finally, the cumulative mortality rates at 1-, 2-, and 3-year follow-up of patients with baseline LV dyssynchrony were 3, 8, and 11%, respectively (log-rank P= 0.375 vs. patients with LV dyssynchrony <40 ms). Induction of LV dyssynchrony after CRT was an independent predictor of mortality (hazard ratio: 1.247; P= 0.009).In patients without significant LV dyssynchrony, the induction of LV dyssynchrony after CRT may be related to a less favourable long-term outcome.
Project description:BACKGROUND: Parameters of myocardial deformation have been suggested to be superior to conventional measures of ventricular function in patients with tetralogy of Fallot (ToF), but have required non-routine, tagged cardiovascular magnetic resonance (CMR) techniques. We assessed biventricular myocardial function using CMR cine-based feature tracking (FT) and compared it to speckle tracking echocardiography (STE) and to simple endocardial border delineation (EBD). In addition, the relation between parameters of myocardial deformation and clinical parameters was assessed. METHODS: Overall, 28 consecutive adult patients with repaired ToF (age 40.4?±?13.3?years) underwent standard steady-state-free precession sequence CMR, echocardiography, and cardiopulmonary exercise testing. In addition, 25 healthy subjects served as controls. Myocardial deformation was assessed by CMR based FT (TomTec Diogenes software), CMR based EBD (using custom written software) and STE (TomTec Cardiac Performance Analysis software). RESULTS: Feature tracking was feasible in all subjects. A close agreement was found between measures of global left (LV) and right ventricular (RV) global strain. Interobserver agreement for FT and STE was similar for longitudinal LV global strain, but FT showed better inter-observer reproducibility than STE for circumferential or radial LV and longitudinal RV global strain. Reproducibility of regional strain on FT was, however, poor. The relative systolic length change of the endocardial border measured by EBD yielded similar results to FT global strain. Clinically, biventricular longitudinal strain on FT was reduced compared to controls (P?<?0.0001) and was related to the number of previous cardiac operations. In addition, FT derived RV strain was related to exercise capacity and VE/VCO2-slope. CONCLUSIONS: Although neither the inter-study reproducibility nor accuracy of FT software were investigated, and its inter-observer reproducibility for regional strain calculation was poor, its calculations of global systolic strain showed similar or better inter-oberver reproducibility than those by STE, and could be applied across RV image regions inaccessible to echo. 'Global strain' calculated by EBD gave similar results to FT. Measurements made using FT related to exercise tolerance in ToF patients suggesting that the approach could have clinical relevance and deserves further study.
Project description:BACKGROUND: Quantification of left ventricular (LV) dyssynchrony allows for objective measures of resynchronization therapy (CRT) effectiveness. We tested the hypothesis that site of LV pacing, fusion beats and baseline contractility alter contraction synchrony as quantified by regional and global measures of LV performance. METHODS AND RESULTS: In 8 open-chested pentobarbital-anesthetized canine preparations we compared the effects of right atrial (RA), RA-high right ventricular (RV) free wall, as a model of left bundle branch block contraction pattern, RA-LV apex (LVa), RA-LV free wall (LVfw), and RA-RV-apical LV (CRTa) and RA-RV-free wall LV (CRTfw), as CRT. LV pressure-volume loops recorded using high-fidelity pressure and conductance catheters and echocardiographic angle-corrected color-coded strain imaging of mid-LV short axis views analyzed radial strain from six segments. To control for contractile state esmolol-induced beta blockage was studied, and in 5 dogs to control for RA and ventricular pacing fusion beat artifacts, repeat studies were done following AV node ablation. RA-RV pacing reduced stroke work (SW) (57±18 to 33±13* mmHg·mL,*p<0.05 vs RA pacing), decreased LV end-diastolic volume and induced marked radial dyssynchrony (maximal time difference between peak segmental strain) from 31±15 to 234±60* ms. Changes in radial dyssynchrony correlated significantly with changes in SW (r=-0.53, p<0.01). Dyssynchrony improved with both CRTa and CRTfw (69*±31 and 98*±63 ms, respectively) while SW only improved with CRTa (62±22* and 37±13 mmHg·mL, respectively * p<0.05 vs RV pacing). CRTa also tended to increased LV end-diastolic volume over RA-RV. Esmolol slowed HR from 118±10 to 108±10 beats/min* and tended to decrease contractility (end-systolic elastance (Ees) from 12.1±7.9 to 8.9±3.9 mmHg/ml, p=0.167) but did not alter the degree of RV-pacing induced dyssynchrony. AV ablation had no effect on the observed apical and free wall contraction differences seen during baseline conditions. CONCLUSION: Although both CRTa and CRTfw reduced contraction dyssynchrony, CRTa tended to improve global LV performance more by increasing end-diastolic volume. Thus, CRT may improve global LV performance differently, depending on the LV pacing site.
Project description:BACKGROUND: Right ventricular (RV) pacing generates regional disparities in electrical activation and mechanical function (ventricular dyssynchrony). In contrast, left ventricular (LV) or biventricular (BIV) pacing can improve cardiac efficiency in the setting of ventricular dyssynchrony, constituting the rationale for cardiac resynchronization therapy (CRT). Animal models of ventricular dyssynchrony and CRT currently relay on large mammals which are expensive and not readily available to most researchers. We developed a methodology for double-site epicardial pacing in conscious rats. Here, following post-operative recovery, we compared the effects of various pacing modes on LV dyssynchrony in normal rats and in rats with ischemic cardiomyopathy. METHODS: Two bipolar electrodes were implanted in rats as follows: Group A (n = 6) right atrial (RA) and RV sites; Group B (n = 7) RV and LV sites; Group C (n = 8) as in group B in combination with left coronary artery ligation. Electrodes were exteriorized through the back. Following post-operative recovery, two-dimensional transthoracic echocardiography was performed during pacing through the different electrodes. Segmental systolic circumferential strain (Ecc) was used to evaluate LV dyssynchrony. RESULTS: In normal rats, RV pacing induced marked LV dyssynchrony compared to RA pacing or sinus rhythm, as measured by the standard deviation (SD) of segmental time to peak Ecc, SD of peak Ecc, and the average delay between opposing ventricular segments. LV pacing and, to a greater extend BIV pacing diminished the LV dyssynchrony compared to RV pacing. In rats with extensive MI, the effects of LV and BIV pacing were markedly attenuated, and the response of individual animals was variable. CONCLUSIONS: Rodent cardiac pacing mimics important features seen in humans. This model may be developed as a simple new tool to study the pathophysiology of ventricular dyssynchrony and CRT.
Project description:<h4>Background</h4>Cardiovascular magnetic resonance (CMR) feature tracking is increasingly used to quantify cardiac mechanics from cine CMR imaging, although validation against reference standard techniques has been limited. Furthermore, studies have suggested that commonly-derived metrics, such as peak global strain (reported in 63% of feature tracking studies), can be quantified using contours from just two frames - end-diastole (ED) and end-systole (ES) - without requiring tracking software. We hypothesized that mechanics derived from feature tracking would not agree with those derived from a reference standard (displacement-encoding with stimulated echoes (DENSE) imaging), and that peak strain from feature tracking would agree with that derived using simple processing of only ED and ES contours.<h4>Methods</h4>We retrospectively identified 88 participants with 186 pairs of DENSE and balanced steady state free precession (bSSFP) image slices acquired at the same locations across two institutions. Left ventricular (LV) strains, torsion, and dyssynchrony were quantified from both feature tracking (TomTec Imaging Systems, Circle Cardiovascular Imaging) and DENSE. Contour-based strains from bSSFP images were derived from ED and ES contours. Agreement was assessed with Bland-Altman analyses and coefficients of variation (CoV). All biases are reported in absolute percentage.<h4>Results</h4>Comparison results were similar for both vendor packages (TomTec and Circle), and thus only TomTec Imaging System data are reported in the abstract for simplicity. Compared to DENSE, mid-ventricular circumferential strain (Ecc) from feature tracking had acceptable agreement (bias: -?0.4%, p =?0.36, CoV: 11%). However, feature tracking significantly overestimated the magnitude of Ecc at the base (bias: -?4.0% absolute, p <?0.001, CoV: 18%) and apex (bias: -?2.4% absolute, p =?0.01, CoV: 15%), underestimated torsion (bias: -?1.4 deg/cm, p <?0.001, CoV: 41%), and overestimated dyssynchrony (bias: 26 ms, p <?0.001, CoV: 76%). Longitudinal strain (Ell) had borderline-acceptable agreement (bias: -?0.2%, p =?0.77, CoV: 19%). Contour-based strains had excellent agreement with feature tracking (biases: -?1.3-0.2%, CoVs: 3-7%).<h4>Conclusion</h4>Compared to DENSE as a reference standard, feature tracking was inaccurate for quantification of apical and basal LV circumferential strains, longitudinal strain, torsion, and dyssynchrony. Feature tracking was only accurate for quantification of mid LV circumferential strain. Moreover, feature tracking is unnecessary for quantification of whole-slice strains (e.g. base, apex), since simplified processing of only ED and ES contours yields very similar results to those derived from feature tracking. Current feature tracking technology therefore has limited utility for quantification of cardiac mechanics.
Project description:Previous methods to quantify dyssynchrony could not determine regional 3-dimensional (3-D) strain. We hypothesized that a novel 3-D speckle tracking strain imaging system can quantify left ventricular (LV) dyssynchrony and site of latest mechanical activation. We studied 64 subjects; 54 patients with heart failure were referred for cardiac resynchronization therapy (CRT) with an ejection fraction 25 +/- 6% and QRS interval 165 +/- 29 ms and 10 healthy volunteer controls. The 3-D speckle tracking system determined radial strain using a 16-segment model from a pyramidal 3-D dataset. Dyssynchrony was quantified as maximal opposing wall delay and SD in time to peak strain. The 3-D analysis was compared to standard 2-dimensional (2-D) strain datasets and site of 3-D latest mechanical activation, not possible by 2D was quantified. As expected, dyssynchrony in patients on CRT was significantly greater than in controls (maximal opposing wall delay 316 +/- 112 vs 59 +/- 12 ms and SD 124 +/- 48 vs 28 +/- 11 ms, p <0.001 vs normal). The 3-D opposing wall delay was closely correlated with 3-D 16-segment SD (r = 0.95) and 2-D mid-LV strain (r = 0.83) and SD (r = 0.85, all p values <0.001). The 3-D site of the latest mechanical activation was most commonly midposterior (26%), basal posterior (22%), midlateral (20%), and basal lateral (17%). Eleven patients studied after CRT demonstrated improvements in 3-D synchrony (300 +/- 124 to 94 +/- 37 ms) and ejection fraction (24 +/- 6% to 31 +/- 7%, p <0.05). In conclusion, 3-D speckle tracking can successfully quantify 3-D dyssynchrony and site the latest mechanical activation. This approach may play a clinical role in management of patients on CRT.