Left Ventricular Mechanical Dyssynchrony Research Articles

Association of cardiac mechanical dyssynchrony indices with data of dynamic single-photon emission computed tomography of the myocardium: the role of the time interval between the stress test and recording

Introduction. According to ECG-synchronized myocardial perfusion imaging (MPI) mechanical dyssynchrony (MD) is a sensitive marker of impaired myocardial perfusion. However, its direct comparison with indicators of myocardial blood flow reserve (MFR) according to single-photon emission computed tomography (SPECT) was not carried out. Traditional MPI protocols imply a long gap between stress test and image acquisition, during which stress-induced changes may pass. It is potentially possible to reduce the time interval down to 5 minutes.Aim: To investigate the relationship between early and delayed MD indices and the data of MFR by means of SPECT.Material and Methods. The study included 20 patients with suspected coronary heart disease, preserved left ventricular ejection fraction (> 55%) and without obstructive coronary artery lesions (< 50%) according to multislice computed coronary angiography. All patients underwent dynamic SPECT (dSPECT) according to a two-day rest/stress protocol. Gated MPI was performed 60 minutes after radiopharmaceutical administration. Myocardial blood flow and reserve, as well as phase histogram standard deviation (PSD, degree) and phase histogram bandwidth (HBW, degree) from 5 minutes after radiopharmaceutical administration were obtained from the dSPECT data by postprocessing. Perfusion data as well as MD indices (PSD, HBW) were obtained from delayed images. Based on dSPECT data, patients were divided into 2 groups: with preserved (MFR ≥ 2.0) and reduced (MFR < 2.0) myocardial blood flow reserve.Results. Correlation analysis showed that MD indices on stress test in early scan had a stronger association with MFR (PSD ρ = –0.68, p < 0.001; HBW ρ = –0.68, p = 0.001) compared to those in delayed scan (PSD ρ = –0.38, p = 0.019; HBW ρ = –0.44, p = 0.005). According to multivariate regression analysis, PSD on stress test at early scan was the only independent predictor of reduced MFR (OR 1.29 (1.1; 1.53)). Stress PSD > 22° obtained at early scanning had a sensitivity of 81% and specificity of 87% (AUC = 0.86, p < 0.001) in predicting of reduced MFR.Conclusion. Left ventricular mechanical dyssynchrony indices obtained by early post-stress gated MPI have a stronger association with myocardial blood flow reserve indices.

Prognostic value of left ventricular mechanical dyssynchrony indices derived from gated myocardial perfusion SPECT in coronary artery disease: a systematic review and meta-analysis.

Left ventricular mechanical dyssynchrony (LVMD) is an important prognostic factor in coronary artery disease. A growing body of evidence indicates that LVMD parameters derived from phase analysis of gated myocardial SPECT may allow risk stratification for future cardiac events. We performed a systematic review and meta-analysis on the prognostic value of LVMD on gated SPECT in patients with coronary artery disease. PubMed, Embase, and the Cochrane library were searched until August 25, 2022, for studies reporting the prognostic value of LVMD on gated SPECT for outcomes of all-cause death, cardiac death, or major adverse cardiovascular event (MACE) in patients with coronary artery disease. Hazard ratios (HRs) and their 95% confidence intervals (CIs) were meta-analytically pooled using a random-effects model. Nine studies (26,750 patients) were included in a qualitative synthesis. Among the SPECT LVMD parameters used in various studies, high phase standard deviation, phase bandwidth, and phase entropy were widely evaluated and reported to be associated with high rates of all-cause death, cardiac death, or MACE. For five studies (23,973 patients) in the quantitative synthesis, the pooled HR of LVMD for predicting MACE was 2.81 (95% CI 2.03-3.88). Studies using combined phase parameters to define LVMD showed higher HRs than a study using phase entropy (p = 0.0180). LVMD from gated myocardial SPECT is a significant prognostic factor for coronary artery disease. Phase analysis of gated SPECT may be useful for accurate risk stratification and could be applied for clinical decision-making in such patients.

Effect of His Bundle Pacing on Abnormal Myocardial Fatty Acid and Glucose Metabolism Induced by Right Ventricular Pacing.

Metabolic disorder is noted for pacing-induced cardiomyopathy. The benefits of His bundle pacing over right ventricular (RV) pacing in preventing pacing-induced cardiomyopathy from a metabolic perspective are yet to be fully understood. Three pig groups were established for this study: sham control, RV pacing (RV pacing for 6 months), and His pacing (RV pacing for 6 months, followed by His bundle pacing for 3 months). Complete atrioventricular block was created in the last 2 groups. Left ventricular function and dyssynchrony were assessed via echocardiography, while proteins linked to metabolism, endoplasmic reticulum stress, and inflammation in left ventricular myocardium were examined. The RV pacing group had significantly more left ventricular mechanical dyssynchrony compared with the other groups. The RV pacing group exhibited triglyceride and diacylglycerol accumulation in cardiomyocytes and higher expression of binding immunoglobulin protein and tumor necrosis factor-α than the other groups. Additionally, the expression of CD36 was activated, while the expression of hormone-sensitive lipase was downregulated in the RV pacing group compared with the His pacing and sham control groups. Furthermore, the expressions of GLUT4 and pyruvate dehydrogenase were higher in the RV pacing group than the sham control and His pacing groups. Notably, the abnormal fatty acid and glucose metabolic pathways in the left ventricular myocardium during RV pacing could be corrected by His bundle pacing. His bundle pacing can mitigate the abnormal metabolism disorders, endoplasmic reticulum stress, and inflammation induced during RV pacing and may contribute to the superiority of conduction system pacing over RV pacing in reducing heart failure hospitalization.

Left ventricular mechanical dyssynchrony after chemotherapy in breast cancer patients with normal rest gated SPECT-MPI.

Early diagnosis of chemotherapy-induced cardiotoxicity plays an important role in preventing heart failure. The main aim of our study was to assess left ventricular (LV) dyssynchrony measured by phase analysis of gated single-photon emission computed tomography (SPECT) as an early sign of cardiotoxicity after breast cancer chemotherapy. This cross-sectional study was conducted on patients with stage ≤ 3 breast cancer and no history of cardiovascular disease or diabetes. After mastectomy, the patients underwent rest gated SPECT myocardial perfusion imaging (MPI). Sixty patients with normal gated SPECT-MPI were selected and the imaging was performed after chemotherapy with doxorubicin, cyclophosphamide and paclitaxel. LV function and contractility parameters were extracted by QGS software and the results were compared with the t test method. The abnormality of at least one of the three phase analysis indices was considered as left ventricular dyssynchrony (LVD). The average LV end-systolic volume and ejection fraction (LVEF) before and after chemotherapy were (16.2 ± 8.0ml and 21.6 ± 11.6ml) and (73.4 ± 7.9% and 67.5 ± 9.2%) respectively, which showed a significant decrease (P < 0.05). In 2 patients (3.3%), the LVEF decreased to less than 50% after chemotherapy. The average parameters of left ventricular contractility before and after chemotherapy were, respectively, as follows: PHB (24.1 ± 7.5 and 33.8 ± 16.4), PSD (9.4 ± 6.1 and 5.7 ± 1.9) and entropy (28.9 ± 7.1 and 35.6 ± 9.7), which showed a significant increase (P < 0.05). LVD was observed in 14 patients (23.4%) after chemotherapy and prevalence of LVD was significantly higher in patients who had received a cumulative dose of doxorubicin of more than 400mg/m2 (P = 0.005). There was no relationship between age and body mass index with the incidence of LVD after chemotherapy (P > 0.05). Using phase analysis of gated SPECT-MPI, chemotherapy-induced LVD was seen in a significant number of patients with breast cancer, especially with a high cumulative dose of doxorubicin. LVD might indicate chemotherapy-induced cardiotoxicity before LVEF becomes abnormal.

Potential Underestimation of Left Ventricular Mechanical Dyssynchrony in Dyssynchrony and Outcomes Assessment.

Left ventricular (LV) mechanical dyssynchrony (LVMD) is fundamental to the progression of heart failure and ventricular remodeling. The status of LVMD in different patterns of bundle branch blocks (BBB) is unclear. In this study, we analyzed the relationship between LVMD and left ventricular systolic dysfunction using real-time three-dimensional echocardiography (RT-3DE). RT-3DE and conventional two-dimensional echocardiography were performed on 68 patients with left bundle branch block (LBBB group), 106 patients with right bundle branch block (RBBB group), and 103 patients without BBB (Normal group). The RT-3DE data sets provided time-volume analysis for global and segmental LV volumes. The LV systolic dyssynchrony index (LVSDI) was calculated using the standard deviation (SD) and maximal difference (Dif) of time to minimum segmental volume (tmsv) for LV segments adjusted by the R-R interval. LVMD was considered if the LVSDI (Tmsv-16-SD) was greater than or equal to 5%. LVSDI is negatively and significantly correlated with left ventricular ejection fraction (LVEF), but not with BBB or QRS duration. The proportion of LVMD in the LBBB, RBBB, and Normal group was 30.88%, 28.30%, and 25.24%, respectively, and there was no significant difference. In dilated cardiomyopathy, LVMD is more closely related to LVEF reduction than QRS morphology and duration.

Blood volume contributes to the mechanical synchrony of the myocardium during moderate and high intensity exercise in women.

Whether blood volume (BV) primarily determines the synchronous nature of the myocardium remains unknown. This study determined the impact of standard blood withdrawal on left ventricular mechanical dyssynchrony (LVMD) in women. Transthoracic speckle-tracking echocardiography and central hemodynamic measurements were performed at rest and during moderate- to high-intensity exercise in healthy women (n = 24, age = 53.6 ± 16.3year). LVMD was determined via the time to peak standard deviation (TPSD) of longitudinal and transverse strain and strain rates (LSR, TSR). Measurements were repeated within a week period immediately after a 10% reduction of BV. With intact BV, all individuals presented cardiac structure and function variables within normative values of the study population. Blood withdrawal decreased BV (5.3 ± 0.7 L) by 0.5 ± 0.1L. Resting left ventricular (LV) end-diastolic volume (-8%, P = 0.040) and passive filling (-16%, P = 0.001) were reduced after blood withdrawal. No effect of blood withdrawal was observed for any measure of LVMD at rest (P ≥ 0.225). During exercise at a fixed submaximal workload (100W), LVMD of myocardial longitudinal strain (LS TPSD) was increased after blood withdrawal (36%, P = 0.047). At peak effort, blood withdrawal led to increased LVMD of myocardial transverse strain rate (TSR TPSD) (31%, P = 0.002). The effect of blood withdrawal on TSR TPSD at peak effort was associated with LV concentric remodeling (r = 0.59, P = 0.003). Marked impairments in the mechanical synchrony of the myocardium are elicited by moderate blood withdrawal in healthy women during moderate and high intensity exercise.

A preliminary study on the standard value of left ventricular mechanic dyssynchrony by speckle tracking

Abstract Background Speckle tracking imaging automatic functional imaging (AFI) is a new method to measure left ventricular mechanical dyssynchrony. Parameter peak strain dispersion (PSD) is the standard deviation when the long axial strain of 17 segments of the left ventricle (LV) reach there’s peak. There is no unified standard value at present. Li C[1] included 59 healthy women aged 43.08 ± 8.22 years old, whose PSD was 31.44±3.83ms. Ji X[2] included 57 healthy volunteers aged 43.30 ±6.03 years old whose PSD value was 23.8±2.2ms. Some studies referred to the standard range of Yu index and used PSD&amp;gt;32.6ms as an indicator of left ventricular mechanic dyssynchrony. Purpose To investigate the standard value range of PSD and PSD/R-R interval. Methods Healthy volunteers who came to our hospital for physical examination from March 2020 to September 2021 were included, excluding hypertension, diabetes, hyperlipidemia, coronary heart disease and other diseases. According to the 20∼29 years old, 30∼39 years old, 40∼49 years old, 50∼59 years old, 60∼69 years old and 70∼79 years old, 10 males and 10 females were included, respectively. GE Vivid E95 was used to collect echocardiographic images, and the following parameters were measured: ①The general parameters of the heart, such as the diameter of the atrium(LA) and the left ventricle (LV) and the thickness of the left ventricular wall .; ②the values of PSD and PSD/ R-R interval. The normal distribution parameters were represented by mean plus or minus the standard deviation. Analysis of variance and post hoc test (LSDt-test) were used to analyse measured values statistically. Results Values of general echocardiographic data such as BSA, atrial and ventricular diameter, interventricular septal thickness, left ventricular posterior wall thickness, and LV ejection fraction were consistent with the guideline of Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging published in 2015. The range of PSD values for subjects in this study was 43±9ms, and the maximum was 65ms. The range of PSD/R-R was 5±1%, and the maximum was 7%. The values of PSD and PSD/R-R were 36±5ms(27∼45ms) and 4.4±0.76%(3∼6.4%) for 20∼39 years old, 42±5ms(34.9-54ms), 5.0±0.8%(3.5-6.7%) in 40∼59 years; 51±8ms(34∼65ms), 5.8±0.9%(3.9∼7%) in age 60∼79. Conclusions The preliminary study has shown that left ventricular mechanical dyssynchrony is associated with age. The standard value range of PSD is inconsistent in different age groups, and PSD and PSD/R-R values increase with age.PSD values at different agesBar chart of PSD values at different age

Acute deterioration in dyssynchrony and systolic function from Lot-CRT to LBBB pacing

Abstract Background Better electrical synchronization and left ventricular (LV) systolic function was recently reported in left bundle branch–optimized cardiac resynchronization therapy ( Lot-CRT ) when compared with conventional CRT. The implantation of left bundle branch pacing (LBBP) is less expensive, easier to operate and has shorter exposure time to X-ray than Lot-CRT. Purpose To observe whether there are negative changes in dyssynchrony and LV systolic function when switched from Lot-CRT to LBBP. determine whether LBBP pacing alone can replace CRT therapy. Methods 30 patients (21 males, 64.4±9.5 years, 43% with persistent atrial fibrillation) who fulfilled the criteria of CRT implantation received Lot-CRT. The right atrial electrode of the patients with atrial fibrillation or the right ventricular electrode of those with sinus rhythm was implanted into the left bundle branch area. After six months, 20 patients whose LV ejection fraction (LVEF) increased by more than 5% and New York Heart Association functional class increased by at least 1 grade were selected for further investigation. Right and left ventricular pacemaker electrodes were programmed to shut off, leaving only the left bundle branch area pacing for one month. The LV size, systolic function, interventricular mechanical delay (IVMD), and LV mechanical dyssynchrony (LVMD) were compared by using two-dimensional speckle tracking echocardiography. Results It was found that QRS duration slightly widened, the LA size increased, the LV size slightly increased and LVEF decreased, p&amp;lt;0.05. There was no statistical significance in the IVMD (p=0.064). The LV mechanical dyssynchrony increased significantly, p&amp;lt;0.001. Conclusions Deteriotation of LV dyssynchrony and systolic function was recorded when Lot-CRT to LBBP for a short period in recovering patients with systolic dysfunction. It indicates that LBBP may not yet maintain the benefits of Lot-CRT in this group of patients.The comparison between Lot-CRT and LBBP

Left bundle branch pacing better preserves ventricular mechanical synchrony than right ventricular pacing: a two-centre study.

Left bundle branch pacing (LBBP) has been shown to better maintain electrical synchrony compared with right ventricular pacing (RVP), but little is known about its impact on mechanical synchrony. This study investigates whether LBBP better preserves left ventricular (LV) mechanical synchronicity and function compared with RVP. Sixty patients with pacing indication for bradycardia were included: LBBP (n = 31) and RVP (n = 29). Echocardiography was performed before and shortly after pacemaker implantation and at 1-year follow-up. The lateral wall-septal wall (LW-SW) work difference was used as a measure of mechanical dyssynchrony. Septal flash, apical rocking, and septal strain patterns were also assessed. At baseline, LW-SW work difference was small and similar in two groups. SW was markedly decreased, while LW work remained mostly unchanged in RVP, resulting in a larger LW-SW work difference compared with LBBP (1253 ± 687 mmHg·% vs. 439 ± 408 mmHg·%, P < 0.01) at last follow-up. In addition, RVP more often induced septal flash or apical rocking and resulted in more advanced strain patterns compared with LBBP. At 1 year follow-up, LV ejection fraction (EF) and global longitudinal strain (GLS) were more decreased in RVP compared with LBBP (ΔLVEF: -7.4 ± 7.0% vs. 0.3 ± 4.1%; ΔLVGLS: -4.8 ± 4.0% vs. -1.4 ± 2.5%, both P < 0.01). In addition, ΔLW-SW work difference was independently correlated with LV adverse remodelling (r = 0.42, P < 0.01) and LV dysfunction (ΔLVEF: r = -0.61, P < 0.01 and ΔLVGLS: r = -0.38, P = 0.02). LBBP causes less LV mechanical dyssynchrony than RVP as it preserves a more physiologic electrical conduction. As a consequence, LBBP appears to preserve LV function better than RVP.

Simultaneous assessment of left ventricular mechanical dyssynchrony using integrated 13N-ammonia PETMR system: direct comparison of PET phase analysis and MR feature tracking

BackgroundTo compare phase analysis with positron emission tomography (PA) and magnetic resonance feature tracking derived myocardial strain (FT) for left ventricular (LV) mechanical dyssynchrony using PETMR system in patients with ischemic heart disease. Methods and resultsPatients who underwent rest-pharmacological stress 13N ammonia PETMR were enrolled. Histogram bandwidth (BW) and phase standard deviation (PSD) were compared to global longitudinal, long axis radial, short axis circumferential, and radial strain (GLS, GRS, SA Circ, and SA Rad) obtained from FT. LV dyssynchrony index (SDI) derived from PA and FT were compared. BW and PSD showed significant correlations with FT (a Pearson’s coefficient r = 0.64, P < .0001, and r = 0.51, P < .0001 for SA Circ; r = 0.67, P < .0001, and r = 0.74, P < .0001 for GLS; r = − 0.60, P < .0001, r = − 0.61, P < .0001 for SA Rad; r = − 0.62, P < .0001, and r = − 0.68, P < .0001 for GRS, respectively). Bland-Altman plots for SDI showed a preferable agreement (95% limit of agreement − 0.12 to 0.075, − 0.20 to 0.098, − 0.38 to 0.077, and − 0.37 to 0.032; bias 0.0068 ± 0.056, 0.026 ± 0.068, 0.11 ± 0.088, and 0.13 ± 0.079 for SA Circ, SA Rad, GLS, and GRS, respectively). ConclusionIn simultaneous acquisition using PETMR, comparison of PET phase analysis and MR strain showed a good correlation.

Perspectives on Secondary Mitral Regurgitation in Heart Failure.

This review focuses on broader perspectives of mitral regurgitation (MR) in patients with heart failure. The ratio of regurgitant volume to end-diastolic volume appears to help identify patients who may benefit from valve interventions. Secondary MR is not only attributed to geometric changes of the LV but also related to the structural changes in the mitral valve that include fibrosis of the mitral leaflets and changes in the extracellular matrix. The transition from mild to severe secondary MR can occur at different rates, from a slow LV remodeling process to a more abrupt process precipitated by an inciting event such as atrial fibrillation. Septal flash and apical rocking, two new visual markers of LV mechanical dyssynchrony, appear to be predictive of MR reduction following cardiac resynchronization therapy. Optimal guideline-directed medical therapy has been shown to decrease the severity of secondary MR effectively. A theoretical framework to characterize secondary MR as it relates to the onset of MR is proposed. Type A: Early onset of MR contemporaneous with myocardial injury. The maladaptive LV remodeling occurs in parallel with MR. Type B: LV remodeling proceeds without significant MR until the LV is moderately dilated, which coincides with or without inciting factors such as atrial fibrillation. Type C: LV remodeling proceeds after myocardial injury without significant MR until the LV is severely dilated. MR is a late manifestation of LV remodeling.

Relationship between left ventricular mechanical dyssynchrony with cardiac resynchronization therapy response in chronic heart failure patients with left bundle branch block

Aim. To investigate the relationship between left ventricular (LV) mechanical dyssynchrony with cardiac resynchronization therapy (CRT) response in chronic heart failure (CHF) pts with left bundle branch block.Methods. Forty-nine pts (male - 34 [69.4%], average age 58.3±11.4 years) with sinus rhythm, permanent left bundle branch block with QRS duration ≥150 ms and New York Heart Association (NYHA) II-III functional class of CHF were included in the study. In addition to full examination, myocardial perfusion scintigraphy (MPS) and gated blood pool single-photon emission computed tomography (gBPS) were performed before and 6 months after CRT devices with cardioverter-defibrillator function implantation. Pts were considered as responders to CRT if they fulfilled after 6-month follow-up the following combined criteria: NYHA FC improvement ≥1 class + LV end systolic volume decrease &gt;15% or NYHA FC improvement ≥1 class + LV ejection fraction improvement &gt;5%.Results. The 1st and 2nd groups included 35 (71.4%) and 14 (28.6%) pts with and without response to CRT respectively. Groups were comparable in terms of pre-CRT implantation clinical and instrumental parameters, except for MPS and gBPS parameters. The multivariate logistic regression had shown that only ∆interventricular dyssynchrony (adjusted odds ratio [OR] 1,0349; 95% confidence interval [CI] 1.0075-1,0631; р=0.01) and phase standard deviation of the anterior LV wall (OR 1.0669; 95% CI 1.0118-1.1251; p=0.01) were independently related with CRT response. An increase in the prognostic coefficient, calculated using the ∆interventricular dyssynchrony and phase standard deviation of the anterior LV wall, more than 0.67 was a predictor of CRT response (area under the curve 0.918; sensitivity 85.71; specificity 85.71; p &lt;0.001).Conclusion. The mechanical dyssynchrony assessed by MPS and gBPS is associated with CRT response. According to our predictive model, an increase in prognostic coefficient more than 0.67 is a predictor of CRT response.

Prognostic impact of cardiac resynchronization therapy guided by phase analysis: a CZT study

Abstract Aims To evaluate whether phase analysis imaging may predict treatment response and long-term prognosis after cardiac resynchronization therapy (CRT). Methods and results Sixty-nine patients underwent myocardial perfusion imaging followed by CRT. Patients with ischaemic heart disease and non-ischaemic cardiomyopathy (NICM) were identified. Left ventricular (LV) mechanical dyssynchrony (LVMD) was assessed at phase analysis and the region of the latest mechanical activation was identified. LV pacing lead position was considered ‘concordant’ when located in the region of the latest mechanical activation, and ‘discordant’ otherwise. The ‘6 months post-CRT’/‘baseline’ ratio of LV ejection fraction was computed as a measure of CRT response. LVMD was revealed in 47/69 patients, 27 of whom (57%) had a concordant LV lead implantation. Only concordant pacing was associated with LV functional improvement (ejection fraction ratio: 1.28 ± 0.25 vs. 1.11 ± 0.32 in discordant stimulation, P = 0.028). However, this relationship persisted only in patients with NICM (P &amp;lt; 0.001), while it disappeared in those with ischaemic heart disease (P = NS). Twenty-eight events occurred during 30 ± 21 months follow-up. While discordant LV lead location was the major predictor of unfavourable prognosis (hazard ratio 3.29, 95% confidence interval 1.25–8.72; P = 0.016), this relationship was confirmed only in patients with NICM. Conclusions Phase analysis of myocardial perfusion imaging may guide CRT implantation, identifying patients who would most likely benefit from this procedure.

Prognostic Role of Diastolic Left Ventricular Mechanical Dyssynchrony by Gated Single Photon Emission Computed Tomography Myocardial Perfusion Imaging in Post-Myocardial Infarction.

Objective This study is aimed to assess the prognostic value of diastolic left ventricular mechanical dyssynchrony (LVMD) measured by gated-single photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI) in post-myocardial infarction (MI). Subjects and Methods The study was conducted on 106 post-MI from January 2015 to January 2019. First, the indices of diastolic LVMD phase standard deviation (PSD) and histogram bandwidth (HBW) of post-MI were measured using the Cardiac Emory Toolbox. Subsequently, the post-MI patients were followed up, and the primary endpoint was major adverse cardiac events (MACEs). Finally, the prognostic value of dyssynchrony parameters for MACE was analyzed by the receiver-operating characteristics curve and survival analyses. Results With the cut-off values of 55.5 degrees of PSD, the sensitivity and specificity in prediction of MACE were 75% and 80.8%, with the cut-off values of 174.5 degrees of HBW, the sensitivity and specificity were 75% and 83.3% respectively. There was a significant difference of time to MACE between groups of PSD less than 55.5 degrees and more than 55.5 degrees. PSD, HBW, and left ventricle ejection fraction (LVEF) assessed on GSPECT were significant factors in the prediction of MACE. Conclusion Diastolic LVMD parameters of PSD and HBW derived from GSPECT are significant prognostic factors in predicting MACE in post-MI patients.

Quantitative left ventricular mechanical dyssynchrony by magnetic resonance imaging predicts the prognosis of dilated cardiomyopathy

PurposeLeft ventricular (LV) dyssynchrony is believed to be associated with the prognosis of dilated cardiomyopathy (DCM) mainly assessed by echocardiography. This study sought to explore whether quantitative LV mechanical dyssynchrony by cardiovascular magnetic resonance imaging (CMR) tissue feature tracking could predict the prognosis of DCM. MethodPatients undergoing CMR between January 2016 and December 2017 were reviewed to identify DCM patients. Quantitative LV mechanical dyssynchrony was assessed by CMR strain analysis. The outcomes of these DCM patients were followed up. The association between LV mechanical dyssynchrony and outcomes was analyzed by Cox proportional regression analysis. ResultsA total of 417 patients with DCM were enrolled. At a median follow-up of 57 months, 109 patients reached endpoints: 19, sudden cardiac death; 34, heart failure death; 41, heart transplantation; 9, malignant ventricular arrhythmias; 2, LV assist devices; and 4, appropriate shocks of defibrillators. After adjustment for confounding variables, the 16-segment standard deviation of the time-to-peak radial strain (16SDTTPRS) (HR, 1.932 [95% CI: 1.079, 3.461]; P = 0.027), LV end-diastolic diameter index (HR, 1.049 [95% CI: 1.020, 1.080]; P = 0.001), NYHA classes (HR, 2.131 [95% CI: 1.597–2.844]; P < 0.001) and late gadolinium enhancement (HR, 3.219 [95% CI: 2.164, 4.787]; P < 0.001) were independently associated with composite endpoints. ConclusionsThe quantitative LV mechanical dyssynchrony parameter 16SDTTPRS derived from CMR was independently associated with adverse outcomes in patients with DCM.

The Value of Left Ventricular Mechanical Dyssynchrony and Scar Burden in the Combined Assessment of Factors Associated with Cardiac Resynchronization Therapy Response in Patients with CRT-D.

Cardiac resynchronization therapy (CRT) improves the outcome in patients with heart failure (HF). However, approximately 30% of patients are nonresponsive to CRT. The aim of this study was to determine the role of the left ventricular (LV) mechanical dyssynchrony (MD) and scar burden as predictors of CRT response. In this study, we included 56 patients with HF and the left bundle-branch block with QRS duration ≥ 150 ms who underwent CRT-D implantation. In addition to a full examination, myocardial perfusion imaging and gated blood-pool single-photon emission computed tomography were performed. Patients were grouped based on the response to CRT assessed via echocardiography (decrease in LV end-systolic volume ≥15% or/and improvement in the LV ejection fraction ≥5%). In total, 45 patients (80.3%) were responders and 11 (19.7%) were nonresponders to CRT. In multivariate logistic regression, LV anterior-wall standard deviation (adjusted odds ratio (OR) 1.5275; 95% confidence interval (CI) 1.1472-2.0340; p = 0.0037), summed rest score (OR 0.7299; 95% CI 0.5627-0.9469; p = 0.0178), and HF nonischemic etiology (OR 20.1425; 95% CI 1.2719-318.9961; p = 0.0331) were the independent predictors of CRT response. Scar burden and MD assessed using cardiac scintigraphy are associated with response to CRT.

Relationship between intraventricular mechanical dyssynchrony and left ventricular systolic and diastolic performance: An in vivo experimental study.

Left ventricular mechanical dyssynchrony (LVMD) refers to the nonuniformity in mechanical contraction and relaxation timing in different ventricular segments. We aimed to determine the relationship between LVMD and LV performance, as assessed by ventriculo-arterial coupling (VAC), LV mechanical efficiency (LVeff ), left ventricular ejection fraction (LVEF), and diastolic function during sequential experimental changes in loading and contractile conditions. Thirteen Yorkshire pigs submitted to three consecutive stages with two opposite interventions each: changes in afterload (phenylephrine/nitroprusside), preload (bleeding/reinfusion and fluid bolus), and contractility (esmolol/dobutamine). LV pressure-volume data were obtained with a conductance catheter. Segmental mechanical dyssynchrony was assessed by global, systolic, and diastolic dyssynchrony (DYS) and internal flow fraction (IFF). Late systolic LVMD was related to an impaired VAC, LVeff , and LVEF, whereas diastolic LVMD was associated with delayed LV relaxation (logistic tau), decreased LV peak filling rate, and increased atrial contribution to LV filling. The hemodynamic factors related to LVMD were contractility, afterload, and heart rate. However, the relationship between these factors differed throughout the cardiac cycle. LVMD plays a significant role in LV systolic and diastolic performance and is associated with hemodynamic factors and intraventricular conduction.

Frequency of Left Ventricular Mechanical Dyssynchrony in Chronic Heart Failure

Objective: To determine the frequency of left ventricular mechanical dyssynchrony in chronic heart failure patients. Material and Methods: After approval from the Hospital ethical committee, the study was conducted in the department of cardiology Hayatabad medical complex Peshawar from 1st September 2021 to 28th February 2022. In this descriptive cross-sectional study, 155 patients in total were examined while 27% of heart failure patients had mechanical dyssynchrony, a 95% confidence interval, and a 7% margin of error were maintained according to WHO sample size computations. Results: This study's participants had an average age of 60, with a standard deviation of ±1.26 years. 62% of the patients were male, compared to 38% of females. 35% of patients had a Broad QRS complex, whereas 65% of patients had a Narrow QRS complex. Mechanical dyssynchrony was identified in 32% of chronic heart failure patients. Conclusion: Patients in chronic heart failure with QRS &gt; 150ms and having mechanical dyssynchrony are benefited with Cardiac Ressynchronisation Therapy (CRT) implantation which reduces morbidity and mortality, while those with a narrow QRS (&lt;150ms) are generally non – responders. Keywords: Mechanical dyssynchrony, chronic heart failure, left ventricular ejection fraction

Impaired cardiac mechanical synchrony revealed with increased myocardial work in women with advanced age

BackgroundWhether the synchronous nature of the myocardium is sex-dependent or affected by the aging process remains unknown. This study aimed to determine the influence of sex and age on cardiac mechanical synchrony during controlled hemodynamic stress. MethodsTransthoracic speckle-tracking echocardiography analyses and central hemodynamics were assessed at rest and during moderate- to high-intensity exercise in healthy young (<45 yr) and older (≥45 yr) women (n = 32) and men (n = 34) matched by age, physical activity and exercise capacity. Left ventricular mechanical dyssynchrony (LVMD) was determined as the time to peak standard deviation (TPSD) of longitudinal and transverse strain and strain rates (LSR, TSR). ResultsPhysical activity, aerobic capacity, heart rate, blood pressure and LVMD at rest were similar between women and men in each age group (P > 0.05). The rate pressure product, an index of myocardial work, did not differ between sex and age groups at rest and during exercise at a given percentage of peak heart rate (P > 0.05). A consistent age effect was observed for transverse LVMD (P-for-age ≤ 0.011). Specifically, older women presented with marked increments (≥42 %) in TSR TPSD at all exercise levels compared with younger women (P ≤ 0.005). Sex per se did not generally affect LVMD. ConclusionA prevailing impairment of cardiac mechanical synchrony in the transverse axis of the left ventricle is revealed during conditions of elevated hemodynamic stress in women with advanced age.

Correlation of left ventricular mechanical dyssynchrony in patients with chronic kidney disease using phase analysis of gated single photon emission computed tomography myocardial perfusion imaging

Abstract Background Left ventricular mechanical dyssynchrony (LVMD) possesses deleterious effects that have been neglected in chronic kidney disease (CKD) as a cause of left ventricular dysfunction and further progression to heart failure, possibly contributing to sudden cardiac death in this population. Thus, cardiovascular risk assessment is essential in early stages of CKD as well as in the pre-transplant screening and this can be performed non-invasively by modalities including phase analysis Gated-SPECT myocardial perfusion imaging (MPI). This modality has emerged as a prognostic tool to predict mortality independent of MPI abnormalities as well as assessment of ventricular synchrony. Purpose The goal of this study is to evaluate the relationship of left ventricular mechanical dyssynchrony using phase analysis G-SPECT and chronic kidney disease severity and its predictors. Methods We included 567 patients who underwent one day rest/stress (dipyridamole) 99mTc-sestamibi myocardial perfusion imaging with G-SPECT for the following indications for testing: detection of CAD among asymptomatic patients, risk assessment during pre-operative evaluation for kidney transplantation and evaluation for noncardiac surgery without active cardiac conditions between January 2017 to January 2021. Data was collected including gender, age, risk factors resting heart rate and baseline blood pressure. Gated SPECT-MPI was performed according to the protocol rest followed by stress images (dipyridamole) 99mTc-sestamibi. The rest and stress phase analysis (histogram bandwidth, standard deviation of phase and entropy) parameters were compared between the five stages of chronic kidney disease. Data of the stress-rest difference in dyssynchrony was analyzed using McNemar's test; crude odds ratios and adjusted odds or multivariate analysis were done. Results Advanced CKD (Stage 4–5) shows statistically significant correlation with the Histogram bandwidth (HBW) both at stress (p=0.008) and rest (p=0.018), and stress entropy (p=0.007). As for the other stages, LVMD is present with similar results seen with the phase parameters HBW and PSD, the entropy values at rest than at stress for Stages I to IV (p&amp;lt;0.05). On further analysis, abnormal perfusion showed to be an independent predictor of left ventricular mechanical dyssynchrony across all arms. Other associated factors includes advanced CKD (stages 4–5), male sex, BMI ≥30 kg/m2, blood pressure and resting heart rate were significantly associated with increased odds of dyssynchrony across stress and rest tests. Overall, the full models were statistically significant, with R-squared ranging from 14.96% to 30.11% (p&amp;lt;0.001). Conclusion This study showed that CKD patients have left ventricular mechanical dyssynchrony on gated-SPECT MPI. Hence, it can be used as an alternative for early assessment and guide decision making for the treatment of patients with CKD to prevent further cardiovascular complication. Funding Acknowledgement Type of funding sources: None.