Echocardiographic parameters of mechanical synchrony in healthy individuals

Early myocardial changes in patients undergoing rheumatic mitral valve repair versus replacement

BACKGROUND

Rheumatic mitral valve repair and replacement techniques are frequently used with excellent outcomes in experienced centers. This study aims to evaluate the impact of procedural types on left ventricular function in quinquagenarians.

METHODS

Between January 2018 and September 2019, patients with severe rheumatic mitral stenosis were prospectively recruited. Propensity score matching was performed to reduce the selection bias. We compared the strain, twist and synchrony parameters of left ventricle in 70 quinquagenarian patients who underwent rheumatic mitral valve repair and replacement 12 hours before surgery, at 7 days and 6 months postoperatively.

RESULTS

The overall group displayed significant improvement of left ventricular deformation after rheumatic mitral valve surgery. Compared with patients undergoing posterior chordal-sparing mitral valve replacement, patients undergoing rheumatic mitral valve repair showed more significant amelioration in global longitudinal strain (-18.6% versus -16.2%, P<0.001), twist (18.2° versus 15.9°, P<0.001), torsion (1.8°/cm versus 1.3°/cm, P<0.001), apical rotation (10.5° versus 8.8°, P<0.001), basal rotation (-7.7° versus -7.1°, P=0.049), systolic dyssynchrony index (4.7% versus 5.1%, P=0.021), standard deviation of time to peak longitudinal (46.9 ms versus 49.3 ms, P=0.024) and radial strain (15.8 ms versus 17.1 ms, P=0.037) at 6-month follow-up.

CONCLUSIONS

Rheumatic mitral valve repair might provide patients with better postoperative left ventricular performance than posterior chordal-sparing mitral valve replacement. Longer follow-up is required to compare long-term outcomes.

Prognostic value of three-dimensional echocardiographic right ventricular ejection fraction in patients with pulmonary arterial hypertension

Background

Right ventricular (RV) function is an independent predictor of clinical outcomes in patients with pulmonary arterial hypertension (PAH). However, it remains controversial which RV parameter should be measured as an appropriate index for the treatment of PAH. The aim of this study was to identify the most useful parameter that correlates with hemodynamics and predicts clinical outcomes in PAH.

Results

Most of the clinical and echocardiographic RV parameters were significantly correlated with pulmonary vascular resistance (PVR) as well as mean pulmonary arterial pressure (mPAP). Among these, three dimensional right ventricular ejection fraction (3DRVEF) showed the strongest hemodynamic correlation, followed by 6-minute walk distance. Receiver operating characteristic analysis of association with cardiac events including death, hospitalization, and intervention revealed a greater area under the curve for 3DRVEF than for mPAP (0.78 vs. 0.74). Kaplan-Meier analysis showed that patients with 3DRVEF less than 38% had significantly shorter event-free survival than those with greater than 38% (P = 0.0007). Finally, the Cox proportional hazards analysis revealed that 3DRVEF, but not mPAP, was an independent predictor of clinical events in PAH.

Materials and Methods

Eighty-six consecutive patients were enrolled in this study. RV hemodynamic parameters were measured by right heart catheterization (RHC). RV function was assessed using two-dimensional speckle-tracking echocardiography and three-dimensional transthoracic echocardiography (3DTTE) to evaluate RV free wall global strain (RVFS) and RVEF.

Conclusions

RVEF measured by 3DTTE could be a useful parameter for noninvasively assessing RV hemodynamics and predicting the clinical outcomes in PAH patients.

Changes in Right Ventricular Dysfunction After Balloon Pulmonary Angioplasty in Patients With Chronic Thromboembolic Pulmonary Hypertension

The aim was to investigate the effect of balloon pulmonary angioplasty (BPA) on right ventricular (RV) function in chronic thromboembolic pulmonary hypertension. Twenty-six patients with chronic thromboembolic pulmonary hypertension were enrolled and were divided into 2 groups, group H with high (>30 mm Hg) mean pulmonary arterial pressure and group L with low (25 to 30 mm Hg) mean pulmonary arterial pressure. RV function was assessed using 2-dimensional speckle-tracking echocardiography as well as 3-dimensional echocardiography, and RV dyssynchrony was assessed by the RV strain curves. Exercise capacity was evaluated by the 6-minute walk distance. RV dilatation was significantly reduced after BPA. In group H, RV ejection fraction, RV free wall longitudinal strain and RV dyssynchrony were all impaired before BPA and were ameliorated after BPA. In group L, RV ejection fraction as well as RV dyssynchrony were impaired without the reduction of RV free wall longitudinal strain and were improved after BPA, indicating that RV dysfunction may be attributable to the RV dyssynchrony in group L. Furthermore, RV dyssynchrony at baseline was the only parameter that was correlated with improvement in the 6-minute walk distance after BPA. RV dyssynchrony may affect RV function and could be the useful parameter for clinical outcome after BPA.

Mechanical dyssynchrony and deformation imaging in patients with functional mitral regurgitation

Chronic functional mitral regurgitation (FMR) is a frequent finding of ischemic heart disease and dilated cardiomyopathy (DCM), associated with unfavourable prognosis. Several pathophysiologic mechanisms are involved in FMR, such as annular dilatation and dysfunction, left ventricle (LV) remodeling, dysfunction and dyssynchrony, papillary muscles displacement and dyssynchrony. The best therapeutic choice for FMR is still debated. When optimal medical treatment has already been set, a further option for cardiac resynchronization therapy (CRT) and/or surgical correction should be considered. CRT is able to contrast most of the pathophysiologic determinants of FMR by minimizing LV dyssynchrony through different mechanisms: Increasing closing forces, reducing tethering forces, reshaping annular geometry and function, correcting diastolic MR. Deformation imaging in terms of two-dimensional speckle tracking has been validated for LV dyssynchrony assessment. Radial speckle tracking and three-dimensional strain analysis appear to be the best methods to quantify intraventricular delay and to predict CRT-responders. Speckle-tracking echocardiography in patients with mitral valve regurgitation has been usually proposed for the assessment of LV and left atrial function. However it has also revealed a fundamental role of intraventricular dyssynchrony in determining FMR especially in DCM, rather than in ischemic cardiomyopathy in which MR severity seems to be more related to mitral valve deformation indexes. Furthermore speckle tracking allows the assessment of papillary muscle dyssynchrony. Therefore this technique can help to identify optimal candidates to CRT that will probably demonstrate a reduction in FMR degree and thus will experience a better outcome.

Recoordination of opposing walls drives the response to cardiac resynchronization therapy: a longitudinal study using a strain discoordination index

BACKGROUND AND AIMS

Intraventricular dyssynchrony has traditionally been studied by means of contraction delays between different myocardial segments. Recently, the discoordination of opposing wall contraction throughout the cardiac cycle has been proposed as a more faithful predictor of response. Aim of the current study was to evaluate which parameters - mechanical dyssynchrony or discoordination - normalize with left ventricular response to cardiac resynchronization therapy (CRT).

METHODS

Cardiac mechanics were analysed before and after 6 months of CRT in 53 patients with left bundle branch block and advanced heart failure. Discoordination was quantified by means of the transverse strain discoordination index (TSDI) at basal and mid-ventricular segments; this index takes into account the percentage of time in the cardiac cycle in which cardiac deformation (transverse strain) of the two opposing walls occurs in noncoordinated directions. Dyssynchrony indices included septal to lateral peak-to-peak transverse strain delay and the standard deviation of time to peak tissue velocity in 12 mid-basal segments (Yu index).

RESULTS

Around 63% of patients met the response criteria. Several baseline indices were predictive of reverse remodelling; TSDI at the mid-ventricular level demonstrated the best accuracy. Time from Q to peak velocity and strain tended to increase in all explored myocardial segments; despite a trend towards a decrease in septal-to-lateral strain delay, the latter decreased equally in responders and in nonresponding patients. Yu index decreased in responders more than in nonresponders, with borderline significance. Basal and medium TSDI remained unchanged in nonresponders and consistently normalized in patients who responded to CRT. The changes in TSDI were significantly correlated with improvements in left ventricular end-systolic volume and ejection fraction; the strongest correlation was observed for changes in TSDI measured at the mid-ventricular level.

CONCLUSION

Left ventricular reverse remodelling after CRT is accompanied by the recoordination of opposite-wall contraction, as testified by changes in mid-ventricular TSDI, which also reveals as a very good predictor of response. On the contrary, changes of segmental peak-to-peak delays (dyssynchrony indices) fail to capture the complex nature of left ventricular response to CRT.

Feature-tracking cardiovascular magnetic resonance as a novel technique for the assessment of mechanical dyssynchrony

BACKGROUND

Myocardial tagging using cardiovascular magnetic resonance (CMR) is the gold-standard for the assessment of myocardial mechanics. Feature-tracking cardiovascular magnetic resonance (FT-CMR) has been validated against myocardial tagging. We explore the potential of FT-CMR in the assessment of mechanical dyssynchrony, with reference to patients with cardiomyopathy and healthy controls.

METHODS

Healthy controls (n=55, age: 42.9 ± 13 yrs, LVEF: 70 ± 5%, QRS: 88 ± 9 ms) and patients with cardiomyopathy (n=108, age: 64.7 ± 12 yrs, LVEF: 29 ± 6%, QRS: 147 ± 29 ms) underwent FT-CMR for the assessment of the circumferential (CURE) and radial (RURE) uniformity ratio estimate based on myocardial strain (both CURE and RURE: 0 to 1; 1=perfect synchrony)

RESULTS

CURE (0.79 ± 0.14 vs. 0.97 ± 0.02) and RURE (0.71 ± 0.14 vs. 0.91 ± 0.04) were lower in patients with cardiomyopathy than in healthy controls (both p<0.0001). CURE (area under the receiver-operator characteristic curve [AUC]: 0.96), RURE (AUC: 0.96) and an average of these (CURE:RUREAVG, AUC: 0.98) had an excellent ability to discriminate between patients with cardiomyopathy and controls (sensitivity 90%; specificity 98% at a cut-off of 0.89). The time taken for semi-automatically tracking myocardial borders was 5.9 ± 1.4 min.

CONCLUSION

Dyssynchrony measures derived from FT-CMR, such as CURE and RURE, provide almost absolute discrimination between patients with cardiomyopathy and healthy controls. The rapid acquisition of these measures, which does not require specialized CMR sequences, has potential for the assessment of mechanical dyssynchrony in clinical practice.

Right ventricular mechanics using a novel comprehensive three-view echocardiographic strain analysis in a normal population

BACKGROUND

Although quantitative right ventricular (RV) strain analysis may be useful in congenital and acquired heart disease populations with RV failure, a comprehensive, standardized approach is lacking. An 18-segment RV strain analysis obtained from three standardized RV apical echocardiographic images was used to determine the feasibility, normal values, and reproducibility of the method in normal adults.

METHODS

Forty healthy, prospectively enrolled volunteers with no cardiac histories and normal QRS durations underwent echocardiography optimized for strain analysis including three RV apical views. Two-dimensional speckle-tracking longitudinal strain analysis was performed using EchoPAC software. Eleven retrospectively identified subjects with RV disease were included as a pilot population. All had been imaged using the same protocol including the three RV apical views.

RESULTS

All control subjects had normal anatomic morphology and function by echocardiography. Feasibility of the RV strain analysis was good (adequate tracking in 696 of 720 segments [97%]). RV global peak systolic strain was -23 ± 2%. Peak strain was highest in the RV free wall and lowest in the septum. Dyssynchrony indices demonstrated no dyssynchrony using left ventricular criteria. Reproducibility of most strain measures was acceptable. This methodology identified important disease not seen in the four-chamber apical view alone in the pilot population of 11 patients with RV disease. Strain patterns and values were different from those in the control population, indicating that differences do exist from normal.

CONCLUSIONS

Eighteen-segment RV strain analysis is feasible, with strain measures falling into discrete ranges in this normal population. Those with RV disease illustrate the potential utility of this approach. These data indicate that this model can be used for more detailed studies evaluating abnormal RV populations, in which its full potential can be assessed.

Influence of percutaneous atrial septal defect closure on inter- and intra-ventricular mechanical dyssynchrony in adults: evaluation of strain pattern

Previous studies using speckle-tracking echocardiography (STE) for quantifying the functions of the right and left ventricles (RV and LV, respectively) in the presence of percutaneous atrial septal defect (ASD) closure have focused on the peak systolic strain (PSS). This study investigated changes in the mechanical dyssynchrony of ventricular contraction before and after ASD closure, issues that have been little addressed in the literature. Thirty-one adults with ASD were studied using two-dimensional STE before and 24 h after ASD closure. Thirty-one healthy age- and sex-matched subjects were recruited as controls. Global and segmental PSS values from the longitudinal, circumferential, and radial directions were analyzed. The time to peak systolic strain (PSST) and the standard deviation of the time to peak strain (SDT) among segments in each direction were calculated, to investigate the inter- and intra-ventricular mechanical dyssynchrony in these patients and improvements after closure. Compared to the control group, patients with ASD had higher RV free-wall longitudinal systolic strain, with increased PSST and SDT. The SDT values of the LV longitudinal and circumferential strains were also increased. By 24 h after ASD closure, the RV free-wall longitudinal strain and its PSST and SDT had reverted to normal levels. The LV circumferential strain was increased, and its SDT was decreased. The contraction period of the RV and myocardial contraction dyssynchrony in the RV and LV were increased in ASD patients. The inter- and intra-ventricular mechanical utilities were improved after percutaneous closure of the ASD.

Usefulness of real-time 3-dimensional echocardiography to identify and quantify left ventricular dyssynchrony in patients with Kawasaki disease

OBJECTIVES

The role of left ventricular (LV) dyssynchrony in Kawasaki disease is unknown. This study sought to establish values for real-time 3-dimensional (3D) echocardiographically derived LV dyssynchrony parameters and identify and quantify LV dyssynchrony in patients with Kawasaki disease.

METHODS

Forty patients hospitalized for Kawasaki disease were analyzed retrospectively, and 40 sex- and age-matched healthy control volunteers were also enrolled. The systolic dyssynchrony index (percentage of the cardiac cycle) from 16 and 12 LV segments on real-time 3D echocardiography was analyzed to calculate LV dyssynchrony (defined as the standard deviation of the time to reach the minimum systolic volume for 16 LV segments) according to a 17-segment model. We analyzed the 3D LV ejection fraction (LVEF), end-diastolic volume, and end-systolic volume in the patients with Kawasaki disease compared to the controls.

RESULTS

The 16-segment systolic dyssynchrony index ± SD was significantly higher in the patients with Kawasaki disease: 2.73% ± 0.96% compared to 2.01% ± 0.85% in the controls (P < .05). The 12-segment systolic dyssynchrony index in the patients with Kawasaki disease was 2.65% ± 0.93% compared to 1.98% ± 0.81% in the controls (P< .05). Patients with Kawasaki disease and an LVEF of less than 50% had a significantly higher systolic dyssynchrony index compared to patients with an LVEF of 50% or greater (2.89% ± 0.79% versus 2.26% ± 0.73%; P < .05). The LVEF measured by echocardiography was decreased in the patients with Kawasaki disease, and global systolic function was impaired. The LVEF measured by a biplane method was sufficiently related to the LVEF measured by echocardiography.

CONCLUSIONS

Real-time 3D echocardiography is a noninvasive and feasible method for identifying and evaluating LV dyssynchrony in children with Kawasaki disease. Left ventricular dyssynchrony is significantly impaired and related to LV systolic function in patients with Kawasaki disease.

Equilibrium radionuclide angiocardiography: Its usefulness in current practice and potential future applications

The routine and potential future applications of equilibrium radionuclide angiocardiography/multigated acquisition (MUGA) in clinical decision making are explored in this review. The non-invasive nature of the test, less operator dependence, lower radiation dose and ease of performing, even in ill patients, are important considerations in clinical cardiology practice. Two important routine uses of this modality in day-to-day clinical practice include the following: serial assessment of left ventricular ejection fraction (LVEF) in patients receiving cardiotoxic chemotherapy, and determination of accurate LVEF in patients with intractable heart failure. Other potential utilities of MUGA that could be translated into clinical practice include determination of regional LVEF, obtaining information about both right and left ventricle in suitable patients as a part of first pass angiocardiography, identification of diastolic dysfunction in patients with heart failure with preserved LVEF, and demonstration of dyssynchrony prior to cardiac resynchronisation, specifically by MUGA single photon emission tomography.The last two indications are particularly important and evolving at this point.

How to improve outcomes: should we put more emphasis on programming and medical care and less on patient selection?

Many factors contribute to the pathophysiology and progression of heart failure (HF), offering the potential for many synergistic therapeutic approaches to its management. For patients, who have systolic HF, prolonged QRS and receiving guideline-indicated pharmacological therapy, cardiac resynchronization therapy (CRT) may provide additional benefits in terms of symptom improvement and mortality reduction. Nevertheless, in many patients, moderate or severe symptoms may persist or recur after CRT implantation due to either the severity or progression of the underlying disease, the presence of important co-morbidities or suboptimal device programming. Identifying and, where possible, treating the reasons for persistent or recurrent symptoms in patients who have received CRT is an important aspect of patient care. The present review summarizes the available evidence on this topic.

Association of left ventricular diastolic function with systolic dyssynchrony: a population study

AIMS

Left ventricular (LV) (dys)synchrony has an important impact on LV function and structure. Our study aimed to describe the distribution and determinants of LV mechanical delay indexes in the general population and to assess an association of different Doppler indexes reflecting LV diastolic function with LV mechanical delay indexes.

METHODS AND RESULTS

In 200 subjects enrolled in a family-based population study (46.5% women; mean age, 57.9; 48% hypertensive), we performed echocardiography with tissue synchronization imaging (TSI) and two-dimensional speckle tracking. We measured the maximum difference in time to peak systolic velocity between any 2 of 12 LV segments (Ts-max); the standard deviation of time to peak systolic velocity of 12 segments (Ts-sd); the difference in time to peak systolic velocity and strain between septal and lateral LV walls and the strain delay index in septal and lateral walls [septal and lateral (SDI)]. In univariable and multivariable regression analyses, TSI indexes and lateral SDI independently increased with age (P ≤ 0.027) and body mass index (P ≤ 0.010). Ts-max and Ts-sd also increased with female sex (P ≤ 0.0002) and decreased with heart rate (P ≤ 0.0004). Septal SDI only increased with female sex (P < 0.0001). Among the Doppler indexes of LV diastolic function, only E/e' was significantly and positively associated with TSI indexes (P ≤ 0.037) and lateral SDI (P = 0.0026), but not with septal SDI (P = 0.69). In participants with advanced stage of LV diastolic dysfunction, TSI indexes were prolonged compare with subjects with normal LV diastolic function (P ≤ 0.002).

CONCLUSION

We demonstrated that in unselected subjects LV diastolic dysfunction was associated with mechanical LV dyssynchrony as assessed by echocardiography.

Phase space analysis of myocardial coordination related to left ventricular ejection fraction by echocardiographic speckle-tracking radial strain

Phase space reconstruction, which is performed by converting echocardiogram-derived strain data from different ventricular regions into phase space trajectories, is applied in this study to describe nonlinear behaviour of myocardial coordination. A new method was developed to quantify patterns of phase space trajectories. Echocardiograms of 31 healthy individuals and 63 patients with left bundle branch block (LBBB) and different left ventricular ejection fractions (LVEFs) were used to evaluate this method. The LBBB patients were separated into two groups: LBBB with a LVEF≥50% and LBBB with a LVEF<50%. LVEF is used to represent levels of systolic function and disease severity. A classifying map was constructed to separate the reconstructed phase space into three zones and to acquire the parameters Pz1, Pz2 and Pz3 as percentiles of phase points related to the zones. The criteria used to define the zones were cross-tested. Based on these parameters, significant group-related differences in myocardial coordination were observed. Significantly smaller Pz1 and significantly larger Pz2 values were observed in the healthy group, as compared to the patient group, and similar, significant results were obtained for the patients with LVEF≥50%, as compared to the patients with LVEF<50% (p<.05). A significantly larger Pz3 was observed in patients with LVEF<50%, as compared to the other patients (p<.05). In addition, different inter-regional relationships among strain pairs (all, near-side, middle-side and opposite-wall) were examined to create phase space trajectories. Consistent group-related differences were observed when different inter-regional relationships were applied. Expanding the use of the proposed method to assess various pathological factors and therapeutic impacts is promising.

Dyssynchrony contributes to false-positive myocardial perfusion SPECT results in patients with stable angina

AIM

We designed this study to evaluate the possibility that dyssynchrony might lead to false-positive myocardial perfusion single photon emission computed tomography myocardial perfusion image (MPS) results in stable angina patients.

METHODS AND RESULTS

This study included 61 patients with both clinically diagnosed stable angina and quantitative MPS results who underwent coronary angiography. The patients were divided into two groups: those who had positive MPS results and normal coronary angiography (Group I, n = 28, 64.05 ± 10.14 years, 11 males and 17 females) and those who had positive MPS results and significant coronary lesions as determined by coronary angiography (Group II, n = 33, 69.2 ± 10.4 years, 14 males and 19 females). The maximal difference in time-to-peak myocardial sustained systolic velocity among all 12 left ventricular (LV) segments (maximal difference in TS) was significantly delayed in Group I as compared with Group II (125.00 ± 46.10 vs. 87.33 ± 40.53 ms, P=0.001). The standard deviation of the time-to-peak myocardial sustained systolic velocity of all 12 LV segments (TS-SD) was also significantly different in the two groups (45.12 ± 19.25 vs. 30.10 ± 15.80 , P=0.002).

CONCLUSION

Dyssynchrony may be a cause of false-positive quantitative MPS results, even if patients have narrow QRS complexes on ECG. Dyssynchrony index can increase the specificity of quantitative MPS in stable angina patients.

Speckle-tracking echocardiography: a new technique for assessing myocardial function

Speckle-tracking echocardiography has recently emerged as a quantitative ultrasound technique for accurately evaluating myocardial function by analyzing the motion of speckles identified on routine 2-dimensional sonograms. It provides non-Doppler, angle-independent, and objective quantification of myocardial deformation and left ventricular systolic and diastolic dynamics. By tracking the displacement of the speckles during the cardiac cycle, strain and the strain rate can be rapidly measured offline after adequate image acquisition. Data regarding the feasibility, accuracy, and clinical applications of speckle-tracking echocardiography are rapidly accumulating. This review describes the fundamental concepts of speckle-tracking echocardiography, illustrates how to obtain strain measurements using this technique, and discusses their recognized and developing clinical applications.

Cardiac resynchronization therapy guided by cardiovascular magnetic resonance

Cardiac resynchronization therapy (CRT) is an established treatment for patients with symptomatic heart failure, severely impaired left ventricular (LV) systolic dysfunction and a wide (> 120 ms) complex. As with any other treatment, the response to CRT is variable. The degree of pre-implant mechanical dyssynchrony, scar burden and scar localization to the vicinity of the LV pacing stimulus are known to influence response and outcome. In addition to its recognized role in the assessment of LV structure and function as well as myocardial scar, cardiovascular magnetic resonance (CMR) can be used to quantify global and regional LV dyssynchrony. This review focuses on the role of CMR in the assessment of patients undergoing CRT, with emphasis on risk stratification and LV lead deployment.

Relation of right ventricular pacing site to left ventricular mechanical synchrony

Transvenous pacing leads are regularly placed in the right ventricular (RV) apex. Pediatric patients can develop myopathic changes after long-term RV apical pacing. Left ventricular (LV) mechanical dyssynchrony, estimated with echocardiography, may explain the acute decrease in LV function and long-term histopathologic changes. Ts-4w is an established echocardiographic measurement of LV synchrony, using tissue Doppler imaging (TDI). The purpose of this study was to determine whether TDI could identify acute changes in LV synchrony during pacing from different RV sites. We prospectively measured Ts-4w and Doppler-derived cardiac output after 5 minutes of pacing in 19 subjects undergoing catheter ablation. Each subject underwent pacing at 4 sites in random order: high right atrium, high RV septum (septal), RV outflow tract, and RV apex. Ts-4w was measured during sinus rhythm and each pacing protocol, with a value >65 ms defining mechanical dyssynchrony. Ts-4w during high right atrial (32.6 +/- 17.6 ms) and septal (28.9 +/- 10.9 ms) pacing were not different from sinus rhythm (39.5 +/- 15.5 ms). RV apex (85.7 +/- 18.4 ms) and RV outflow tract (84.2 +/- 20.4 ms) pacing induced mechanical dyssynchrony (p <0.0001). In conclusion, TDI demonstrated significant differences in LV synchrony related to pacing site. Ts-4w may be useful to determine ideal lead placement because it correlates with acutely improved hemodynamics.

Ventricular asynchrony of time-to-peak systolic velocity in structurally normal heart by tissue Doppler imaging

BACKGROUND

Echocardiographic measurements of time-to-peak systolic velocities (Ts) are helpful for assessing the degree of cardiac asynchrony. We assessed the degree of ventricular asynchrony in structurally normal heart according to Ts by tissue Doppler imaging.

METHODS

We performed conventional echocardiography and tissue velocity imaging for 65 healthy adult volunteers to measure the Ts of 12 left ventricular segments in the mid and basal levels delay of Ts and standard deviation (SD) of Ts in all and basal segments. Six frequently used markers of dyssynchrony were measured and were also compared between men and women. Data are presented as median (25th and 75th percentile).

RESULTS

Septal-lateral and anteroseptal-posterior delays were 50 (20, 90) and 20 (0, 55) ms. The delay between the longest and the shortest Ts in basal and all segments were 100 (80, 120) and 110 (83, 128) ms, respectively. SD of Ts was 39 (24, 52) ms for basal and 41 (28, 51) ms for all segments. Overall, 76.9% of cases had at least one marker of dyssynchrony. Frequencies of dyssynchrony markers were almost significantly higher in women compared to men. The most frequently observed dyssynchrony marker was SD of Ts of all segments (70.8%) and the lowest was anteroseptal-posterior delay (21.5%).

CONCLUSIONS

Normal population almost had dyssynchrony by previously described markers and many of these markers were more frequent in women. Conducting more studies on normal population by other tissue Doppler modalities may give better description of cardiac synchronicity.

Imaging synchrony

Cardiac resynchronization therapy (CRT) is a relatively new therapy for patients with symptomatic heart failure resulting from systolic dysfunction. CRT is achieved by simultaneously pacing both the left and right ventricles. Biventricular pacing resynchronizes the timing of global left ventricular depolarization and improves mechanical contractility and mitral regurgitation. Published clinical trials have demonstrated that CRT results in improved clinical status and lower mortality rate when selected patients with systolic ventricular dysfunction and heart failure are treated with CRT. This advisory identifies appropriate candidates for CRT on the basis of the inclusion criteria and results from the published clinical trials.

Impact of left ventricular dyssynchrony early on left ventricular function after first acute myocardial infarction

The impact of left ventricular (LV) dyssynchrony after acute myocardial infarction (AMI) on LV ejection fraction (EF) is unknown. One hundred twenty-nine patients with a first ST-elevation AMI (58 + or - 11 years, 78% men) and QRS duration <120 ms were included. All patients underwent primary percutaneous coronary intervention. Real-time 3-dimensional echocardiography and myocardial contrast echocardiography were performed to assess LV function, LV dyssynchrony, and infarct size. LV dyssynchrony was defined as the SD of the time to reach the minimum systolic volume for 16 LV segments, expressed in percent cardiac cycle (systolic dyssynchrony index [SDI]). Myocardial perfusion at myocardial contrast echocardiography was scored (1 = normal/homogenous; 2 = decreased/patchy; 3 = minimal/absent) using a 16-segment model; a myocardial perfusion index, expressing infarct size, was derived by summing segmental contrast scores and dividing by the number of segments. SDI in patients with AMI was 5.24 + or - 2.23% compared to 2.02 + or - 0.70% of controls (p <0.001). Patients with AMI and LVEF <45% had significantly higher SDI compared to patients with LVEF > or = 45% (4.29 + or - 1.44 vs 6.95 + or - 2.40, p <0.001). At multivariate analysis, SDI was independently related to LVEF; in addition, the impact of SDI on LV systolic function was incremental to infarct size and anterior location of AMI (F change 16.9, p <0.001). In conclusion, LV synchronicity is significantly impaired soon after AMI. LV dyssynchrony is related to LVEF and has an additional detrimental effect on LV function, beyond infarct size and the anterior location of AMI.

New method for evaluation of left ventricular dyssynchrony and success of cardiac resynchronization therapy: real-time 3-dimensional echocardiography

A klinikai tapasztalat azt mutatja, hogy a jelenleg elérhető kritériumok alapján kiválasztott szívelégtelen betegek közel egyharmada a kardiális reszinkronizációs terápia (CRT) ellenére nonreszpondernek bizonyul, vagyis az optimális kezelés ellenére klinikai állapotukban javulás nem észlelhető. Ez a tény vezetett ahhoz a kutatási irányhoz, hogy találjunk olyan, noninvazív képalkotó diagnosztika (például echokardiográfia) során mérhető és/vagy számítható értéket, amely alkalmas a diszszinkrónia megítélésére és jobban segíti kiválasztani a CRT-re alkalmas betegeket. Ennek az áttekintő közleménynek a célja a legújabb noninvazív echokardiográfiás módszer, a real-time háromdimenziós echokardiográfia lehetséges szerepének bemutatása lenne az elérhető irodalom alapján.

Development and validation of a clinical index to predict survival after cardiac resynchronisation therapy

Objective:

To develop and validate a prognostic risk index of cardiovascular mortality after cardiac resynchronisation therapy (CRT).

Design:

Prospective cohort study.

Setting:

District general hospital.

Patients:

148 patients with heart failure (mean age 66.7 (SD 10.4) years), New York Heart Association class III or IV, LVEF <35%) who underwent CRT.

Interventions:

CRT device implantation.

Main outcome measures:

Value of a composite index in predicting cardiovascular mortality, validated internally by bootstrapping. The predictive value of the index was compared to factors that are known to predict mortality in patients with heart failure.

Results:

All patients underwent assessment of 16 prognostic risk factors, including cardiovascular magnetic resonance (CMR) measures of myocardial scarring (gadolinium-hyperenhancement) and dyssynchrony, before implantation. Clinical events were assessed after a median follow-up of 913 (interquartile range 967) days. At follow-up, 37/148 (25%) of patients died from cardiovascular causes. In Cox proportional hazards analyses, (DSC) Dyssynchrony, posterolateral Scar location (both p<0.0001) and Creatinine (p = 0.0046) emerged as independent predictors of cardiovascular mortality. The DSC index, derived from these variables combined, emerged as a powerful predictor of cardiovascular mortality. Compared to patients with a DSC <3, cardiovascular mortality in patients in the intermediate DSC index (3–5; HR: 11.1 (95% confidence interval (CI) 3.00 to 41.1), p = 0.0003) and high DSC index (⩾5; HR: 30.5 (95% CI 9.15 to 101.8), p<0.0001) were higher. Bootstrap validation confirmed excellent calibration and internal validity of the prediction model.

Conclusion:

The DSC index, derived from a standard CMR scan and plasma creatinine before implantation, is a powerful predictor of cardiovascular mortality after CRT.

A critical comparison of echocardiographic measurements used for optimizing cardiac resynchronization therapy: stroke distance is best

AIMS

Dyssynchrony assessment in cardiac resynchronization therapy (CRT) is controversial, and there are no standard protocols for optimizing treatment. We studied the feasibility and reproducibility of several echocardiographic measures to optimize CRT pacemaker settings. We also assessed the utility of 'stroke distance' [left ventricular outflow tract velocity-time integral (LVOT VTI)] in performing this function.

METHODS AND RESULTS

Thirty patients underwent the following functional assessments; 6 min walk test distance, peak VO(2) consumption on cardiopulmonary exercise testing (VO(2) peak), quality-of-life scoring, and echocardiography; before and at 3 and 6 months after implantation of the CRT device. At 3 months, patients received LVOT VTI-guided optimization of interventricular (VV) and atrioventricular (AV) delays. The feasibility and reproducibility of each optimization measurement was statistically analysed, and the functional benefits of optimization examined. Left ventricular outflow tract VTI, interventricular mechanical delay (IVMD), and tissue Doppler lateral-septal delay showed good feasibility (>90%), whereas LVOT VTI, IVMD, and the 12-segment tissue Doppler dyssynchrony index showed good reproducibility (coefficient of variation <20%). The most feasible and reproducible measure was LVOT VTI. Our optimization protocol necessitated alteration of AV and/or VV delays in 60% of patients at 3 months and was associated with a 50% improvement in functional responder status between 3 and 6 months.

CONCLUSION

Left ventricular outflow tract VTI provides us with a single, direct measure of global LV function which is robust, and easily applicable in routine clinical practice, and which is effective at improving response to CRT.

Comparison of eight echocardiographic methods for determining the prevalence of mechanical dyssynchrony and site of latest mechanical contraction in patients scheduled for cardiac resynchronization therapy

Prevalence of echocardiographically assessed mechanical dyssynchrony and consistency in detection of the latest mechanical left ventricular (LV) contracting region when different echocardiographic methods are used in the same patient remains ill-defined. The objectives of this study were to evaluate (1) the prevalence of intraventricular mechanical dyssynchrony and (2) consistency of latest mechanical LV contraction using a multiparametric approach derived from tissue Doppler imaging (TDI), 3-dimensional (3D) echocardiography, and speckle tracking in patients scheduled for cardiac resynchronization therapy (CRT). In 63 patients with heart failure scheduled for CRT, 2D echocardiography, TDI, 3D echocardiography, and speckle tracking were prospectively collected and analyzed. Prevalence of dyssynchrony was low for some tissue-velocity derived indexes (11%, 13%, and 43%) but was >or=80% for strain derived by TDI, for systolic dyssynchrony index by 3D echocardiography, and for longitudinal and radial strains by speckle tracking. Prevalence of dyssynchrony was 69% for maximum delay between anteroseptal and posterolateral walls by radial strain. Agreement among dyssynchrony indexes was generally low (kappa -0.02). Agreement of each of these echocardiographic indexes in determining, in the same patient with heart failure, the latest LV mechanical contraction site was also low (no site agreement in 77%). In conclusion, in a typical CRT population there is considerable variability among various techniques that assess prevalence of mechanical dyssynchrony and in identification of the latest mechanical LV contracting region.