Left Ventricular Dyssynchrony Parameters Research Articles

ECG as a screening tool for detection of significant functional mitral regurgitation in patients with left bundle branch block

Abstract Background Functional mitral regurgitation (FMR) may occur in the left bundle branch block (LBBB) due to mechanical left ventricular (LV) dyssynchrony, by the imbalance between the tethering and the closing forces exerted on the mitral apparatus1-3. Progressive FMR and LV remodeling result in a reciprocal worsening downward spiral and worse clinical outcomes1-3. Therefore, timely screening and follow-up of these patients to prevent the irreversible progression of FMR is required. To date, only LBBB morphology and QRS duration have been proven predictors of FMR4. Purpose This study aimed to assess the relationship between ECG parameters of LV dyssynchrony and the severity of FMR in patients with LBBB. Methods We retrospectively included 154 consecutive patients with LBBB, in sinus rhythm, who had an echocardiogram, with no more than mild organic valvular heart disease. We measured the following intraventricular dyssynchrony markers: LV activation times (LVAT), intrinsicoid deflection (ID) in lateral and aVF leads and a newly defined marker – the difference (Diff) between aVL and aVF ID’s (Diff_IDaVL_aVF). These two leads record the electrical activation of the two opposing myocardial segments adjacent to the posteromedial and anterolateral papillary muscles, respectively5 (Figure 1). Based on the severity of FMR, the patients were divided into two groups: no/mild FMR (grade II or less) (61%), and significant FMR (grade III and IV) (39%). Results In patients with significant FMR, the LVAT measured in lateral leads, the IDaVL and Diff_IDaVL_aVF were significantly longer, but IDaVF was significantly shorter compared to patients with no/mild FMR (p<0.001). Of all studied ECG parameters, the Diff_IDaVL_ aVF was the parameter that had the strongest correlation with significant FMR (r correlation coefficient 0.82, p < 0.001). In multivariable analysis the Diff_IDaVL_aVF (p = 0.010) was the only parameter independently correlated with significant FMR. On ROC analysis the best cut-off for significant FMR prediction was 55 ms (AUC of 0.99, sensitivity 90% and specificity 97%) (Figure 2). Conclusions In LBBB, a simple intraventricular dyssynchrony ECG parameter can provide insights into FMR severity. A 55 msec Diff_IDaVL_aVF identifies significant FMR that may benefit from early medical or CRT treatment to avoid progression and worse prognosis.

Comparison of the left ventricular dyssynchrony between stylet-driven and lumen-less lead technique in left bundle branch area pacing using myocardial perfusion scintigraphy.

Left bundle branch area pacing (LBBAP) has emerged as a novel physiological pacing method to reduce left ventricular (LV) dyssynchrony due to ventricular pacing. Only lumen-less pacing leads (LLLs) with fixed helixes could achieve LBBAP previously, but recently, LBBAP has been performed using stylet-driven leads (SDLs). This study aimed to evaluate the LV dyssynchrony between SDLs and LLLs techniques in LBBAP. We retrospectively evaluated patients who underwent LBBAP with either SDLs or LLLs. We compared both groups' electrocardiogram (ECG) findings and LV dyssynchrony parameters derived from myocardial perfusion scintigraphy. LV dyssynchrony parameters consisted of phase analysis and regional wall motion analysis. We evaluated bandwidth, phase standard deviation (PSD), and entropy in the phase analysis. The time to the end-systolic frame (TES) was calculated in regional wall motion analysis using single-photon emission computed tomography (SPECT). We also evaluated the maximum differences between segmental TES (MDTES), the standard deviation of TES (SDTES), and the difference in the TES between the lateral wall and septum (DTES-LS). In total, 97 patients were enrolled. The success rate of LBBAP did not differ between the groups [SDLs: 47/48 patients (98%) vs. LLLs: 47/51 patients (92%), P=0.36]. The paced QRS duration and the stimulus to the peak LV activation time (stim-LVAT) also did not differ between SDL and LLL groups (122±10 vs. 119±12 ms, P=0.206; 69±12 vs. 66±13 ms, P=0.31, respectively). There were no differences in bandwidth, PSD, and entropy between SDL and LLL groups (73°±37° vs. 86°±47°, P=0.18; 19°±8.5° vs. 21°±9.7°, P=0.19; 0.57±0.08 vs. 0.59±0.08, P=0.17, respectively). The regional wall motion analysis parameters MDTES, SDTES, and DTES-LS also did not differ between SDL and LLL groups (19%±10% vs. 20%±10%, P=0.885; 5.0%±2.5% vs. 5.0%±2.5%, P=0.995; 5.0%±3.7% vs. 4.8%±4.2%, P=0.78, respectively). LBBAP using SDLs was comparable to LV electrical and mechanical synchrony with LLLs.

Predictive value of left ventricular dyssynchrony for short-term outcomes in three-vessel disease patients undergoing coronary artery bypass grafting with preserved or mildly reduced left ventricular ejection fraction.

Coronary artery bypass grafting (CABG) is the reference standard intervention in coronary artery disease (CAD) patients with three-vessel disease (3VD). We aimed to evaluate the predictive value of left ventricular (LV) dyssynchrony for short-term adverse outcomes in patients with 3VD undergoing CABG with preserved or mildly reduced LV ejection fraction (LVEF). This study involved ninety-five 3VD patients with preserved or mildly reduced LVEF undergoing scheduled on-pump CABG. The pre-operative diameters and volumes of LV and LVEF were obtained by two-dimensional echocardiography. LV dyssynchrony parameters were acquired by real-time three-dimensional echocardiography (RT-3DE) and analyzed by HeartModel quantification software. And the perfusion index of LV was obtained by contrast echocardiography. The clinical endpoints of short-term adverse outcomes comprised 30-day mortality and/or composite outcomes of postoperative complications. Univariate and multivariate logistic regression analyses were used to identify risk factors for the occurrence of post-CABG short-term adverse outcomes. Short-term adverse outcomes occurred in 12 (12.6%) patients. These patients had higher LV dyssynchrony parameters obtained through RT-3DE. The standard deviation (SD) of the time to minimum systolic volume (Tmsv) corrected by heart rate over 16 segments (Tmsv16-SD%) [odds ratio (OR), 1.362; 95% confidence interval (CI) (1.090-1.702); P = 0.006], one of the LV dyssynchrony parameters, was independently associated with short-term adverse outcomes. Patients with poor synchronization tended to spend more time in the intensive care unit (ICU) and hospital after surgery. Pre-operative LV dyssynchrony parameter Tmsv16-SD% obtained through RT-3DE could be a useful additional predictor of postoperative short-term adverse outcomes in 3VD patients with preserved or mildly reduced LVEF undergoing CABG.

Reproducibility of global LV function and dyssynchrony parameters derived from phase analysis of gated myocardial perfusion SPECT: A multicenter comparison with core laboratory setting

BackgroundGated myocardial perfusion scintigraphy (GMPS) phase analysis is an important tool to investigate the physiology of left ventricular (LV) dyssynchrony. We aimed to test the performance of GMPS LV function and phase analysis in different clinical settings and on a diverse population. MethodsThis is a post hoc analysis of a prospective, non-randomized, multinational, multicenter cohort study. Clinical evaluation and GMPS prior to cardiac resynchronization therapy (CRT)(baseline) and 6-month post CRT (follow-up) were done. LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV), LV ejection fraction (LVEF), LV phase standard deviation (LVPSD), and percentage of left ventricle non-viable (PLVNV) were obtained by 10 centers and compared to the core lab. Results276 GMPS studies had all data available from individual sites and from core lab. There were no statistically significant differences between all variables except for LVPSD. When subjects with no mechanical dyssynchrony were excluded, LVPSD difference became non-significant. LVESV, LVEF, LVPSD and PLVNV had strong correlation in site against core lab comparison. Bland–Altman plots demonstrated good agreement. ConclusionsThe presented correlation and agreement of LV function and dyssynchrony analysis over different sites with a diverse sample corroborate the strength of GMPS in the management of heart failure in clinical practice.

Correlation of newer indices of dyssynchrony with clinical response in patients undergoing cardiac resynchronisation therapy

–The benefits of CRT in select subsets of systolic heart failure patients with LBBB are proven. We prospectively evaluated conventional and newer echocardiographic parameters of left ventricular dyssynchrony in 35 patients who underwent CRT and were followed up after 6 months. Of the 33 surviving patients, 21 were echocardiographic responders and 24 were clinical responders. The parameters in clinical responders and non-responders were compared. The anatomic M Mode parameters of delays improved, while the radial strain and the mitral valve velocity time integral (MVVTI) did not show any significant change after CRT.

Prediction of response to cardiac resynchronization therapy using a multi-feature learning method.

We hypothesized that a multiparametric evaluation, based on the combination of electrocardiographic and echocardiographic parameters, could enhance the appraisal of the likelihood of reverse remodeling and prognosis of favorable clinical evolution to improve the response of cardiac resynchronization therapy (CRT). Three hundred and twenty-three heart failure patients were retrospectively included in this multicenter study. 221 patients (68%) were responders, defined by a decrease in left ventricle end-systolic volume ≥15% at the 6-month follow-up. In addition, strain data coming from echocardiography were analyzed with custom-made signal processing methods. Integrals of regional longitudinal strain signals from the beginning of the cardiac cycle to strain peak and to the instant of aortic valve closure were analyzed. QRS duration, septal flash and different other features manually extracted were also included in the analysis. The random forest (RF) method was applied to analyze the relative feature importance, to select the most significant features and to build an ensemble classifier with the objective of predicting response to CRT. The set of most significant features was composed of Septal Flash, E, E/A, E/EA, QRS, left ventricular end-diastolic volume and eight features extracted from strain curves. A Monte Carlo cross-validation method with 100 runs was applied, using, in each run, different random sets of 80% of patients for training and 20% for testing. Results show a mean area under the curve (AUC) of 0.809 with a standard deviation of 0.05. A multiparametric approach using a combination of echo-based parameters of left ventricular dyssynchrony and QRS duration helped to improve the prediction of the response to cardiac resynchronization therapy.

Correlation of left ventricular dyssynchrony on gated myocardial perfusion SPECT analysis with extent of late gadolinium enhancement on cardiac magnetic resonance imaging in hypertrophic cardiomyopathy.

Myocardial perfusion-single-photon emission computed tomography (MP-SPECT) is used to evaluate microvascular dysfunction and coexisting coronary artery disease in patients with hypertrophic cardiomyopathy (HCM). Phase analysis in gated MP-SPECT can provide additional information on left ventricular (LV) dyssynchrony, while the extent of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging is an important prognostic factor in patients with HCM. We, therefore, sought to investigate the relationship of dyssynchrony by phase analysis on gated MP-SPECT and LGE on CMR imaging in 22 patients with HCM who underwent both stress/rest-gated MP-SPECT and contrast-enhanced CMR imaging. LV dyssynchrony parameters [phase standard deviation (SD) and histogram bandwidth] from gated MP-SPECT were compared with LGE parameters from CMR imaging [L/C contrast and %LGE calculated, respectively, as LGE intensity/LV cavity intensity and (LGE volume/myocardial volume)×100]. Phase SD and histogram bandwidth showed strong correlation with %LGE (r=0.73, p<0.0001 and r=0.73, p<0.0001, respectively), although they did not significantly correlate with L/C contrast (r=0.30, p=0.17 and r=0.26, p<0.25, respectively). The LV dyssynchrony derived from gated MP-SPECT strongly correlated with the extent of LGE on CMR imaging. In conclusion, our investigation suggests that gated MP-SPECT may be useful not only for the assessment of myocardial ischemia but also the extent of myocardial replacement fibrosis.

Rational and design of EuroCRT: an international observational study on multi-modality imaging and cardiac resynchronization therapy.

Assessment of left ventricular (LV) volumes and ejection fraction (LVEF) with cardiac imaging is important in the selection of patients for cardiac resynchronization therapy (CRT). Several observational studies have explored the role of imaging-derived LV dyssynchrony parameters to predict the response to CRT, but have yielded inconsistent results, precluding the inclusion of imaging-derived LV dyssynchrony parameters in current guidelines for selection of patients for CRT. The EuroCRT is a large European multicentre prospective observational study led by the European Association of Cardiovascular Imaging. We aim to explore if combing the value of cardiac magnetic resonance (CMR) and echocardiography could be beneficial for selecting heart failure patients for CRT in terms of improvement in long-term survival, clinical symptoms, LV function, and volumes. Speckle tracking echocardiography will be used to assess LV dyssynchrony and wasted cardiac work whereas myocardial scar will be assessed with late gadolinium contrast enhanced CMR. All data will be measured in core laboratories. The study will be conducted in European centres with known expertise in both CRT and multimodality cardiac imaging.

Influence of acquisition orbit on phase analysis of gated single photon emission computed tomography myocardial perfusion imaging for assessment of left ventricular mechanical dyssynchrony.

The association between left ventricular (LV) dyssynchrony parameters, given by phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), and acquisition orbits is unclear. The aim of this study was to assess the dependence of LV dyssynchrony parameters on acquisition orbits. Ninety-nine patients who underwent 201Tl-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. Forty-four patients who underwent 99mTc-tetrofosmin-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. The major hypoperfusion group with 201Tl was divided into inferior or non-inferior wall hypoperfusion subgroups, and anteroseptal or non-anteroseptal wall hypoperfusion subgroups. Gated SPECT MPI data over a 360° acquisition orbit (360° images) and a 180° acquisition orbit (180° images) were reconstructed, and histogram bandwidth (HBW) and phase standard deviation (PSD) were compared. Between 360° and 180° images with 201Tl, there were significant differences in HBW and PSD both globally (HBW 34.8 ± 16.6 vs. 29.1 ± 10.2; PSD 8.8 ± 4.9 vs. 7.0 ± 2.3, p < 0.05 for both) and in the inferior wall (HBW 29.5 ± 15.5 vs. 23.3 ± 9.0; PSD 7.6 ± 4.6 vs. 5.6 ± 2.4, p < 0.001 for both) in the major hypoperfusion group, and also in the inferior wall in all subgroups of the major hypoperfusion group. In contrast, no segment had any significant differences in HBW or PSD between 360° and 180° images with 99mTc. Differences in acquisition orbit had a significant influence on HBW and PSD with 201Tl-gated SPECT MPI in the inferior wall in patients with major hypoperfusion myocardium.

Abstract 13059: Diagnostic Performance of Left Ventricular Contractile Entropy in Patients With Heart Failure: Analysis by Quantitative Gated Semiconductor-SPECT

Background: Left ventricular (LV) dyssynchrony is considered as an important cause of congestive heart failure (CHF) admission. However, among the parameters of dyssynchrony, the prognostic value of LV contractile entropy is not elucidated. Hypothesis: Left ventricular contractile entropy can predict early re-hospitalization of heart failure patients. Method: Ninety-eight consecutive patients with first onset CHF who underwent quantitative gated demiconductor SPECT (QGS) before discharge were investigated retrospectively. Patients with re-hospitalization after discharge within 30-days were assigned to Group A, and patients without re-hospitalization were assigned to Group B. Data regarding electrocardiogram, and parameters of QGS including LV remodeling, systolic function, diastolic function and phase analysis (Phase SD, bandwidth, entropy) were collected automatically, and compared between Group A and B. Kaplan-Meier survival curves were used to compare variables between the patients, as appropriate. Multivariate analysis was performed on variables with a value of P &lt; 0.05 using the stepwise regression approach. Result (See figure and table): Of 98 patients, 92 patients did not readmit and other 6 patients readmitted within 30-days. ROC analysis showed that the cut-off value 0.785 predicted Group A (95% CI: 0.563-0.894) with 0.652 specificity and 0.833 sensitivity. Multivariate analysis showed that ‘entropy &gt; 0.785’ was a significant and independent predictor with a high odds ratio (OR:9.375, 95%CI :1.050-83.724). The Kaplan-Meier survival curve revealed a significant difference between the patients of ‘entropy ≧ 0.785’ and ‘entropy &lt; 0.785’ in 30-days re-hospitalization rate (Log-rank test, p=0.016). Conclusion: The LV contractile entropy was a powerful indicator of early phase re-hospitalization in patients with CHF, rather than ejection fraction or other parameters of LV dyssynchrony.

Left ventricular scar impact on left ventricular synchronization parameters and outcomes of cardiac resynchronization therapy

BackgroundLeft ventricular scar, including global scar and lateral wall, plays an important role in predicting response to cardiac resynchronization therapy (CRT). Materials and methodsThirty patients underwent CRT implantation. Assessment of left ventricular (LV) dyssynchrony was done through Gated SPECT LV phase analysis. Pre-implantation cardiac magnetic resonance (CMR) with late gadolinium enhancement technique to examine LV scar burden. Echocardiographic examination of LV end-systolic volume (LVES) prior to CRT and 6 months later. ResultsThirty patients received CRT (mean age 58.7±9.0, 24 males). Reverse LV remodeling (decline ≥15% from baseline VES) was documented in 19 patients. Temporal changes in LV dyssynchrony parameters were correlated to LV reverse remodeling. Applying ROC for predicting CRT non-response showed a cutoff 36.5% of global LV scar burden had a sensitivity of 81.8% and specificity of 68.4%. A cutoff for lateral wall scar burden 40.5% of whole lateral wall had a sensitivity of 72.7% and specificity of 68.4%. ConclusionReverse LV remodeling is associated with temporal improvements in LV dyssynchrony parameters. LV scar had an unfavorable impact on CRT response. Both global and lateral wall scar burden could predict CRT nonresponse status.

Reference values for left ventricular systolic synchrony according to phase analysis of ECG-gated myocardial perfusion SPECT.

The aim of this study was to define reference values for left ventricular systolic synchrony and for the volume parameters of the left ventricle using myocardial perfusion SPECT-derived phase analysis method. We evaluated data of 433 patients who underwent myocardial perfusion SPECT/CT during January 2012-February 2013 in Kuopio University Hospital. The final study population consisted of 52 patients (aged 42-84years) who met the criteria: (1) no previously diagnosed cardiac disease, (2) normal ECG at rest, (3) no advanced coronary artery disease in CT and 4) normal myocardial perfusion in stress/rest myocardial perfusion SPECT/CT. The severity of mechanical dyssynchrony was assessed by phase analysis of gated myocardial SPECT at stress stage after pharmacological exercise and at rest using Quantitative Gated SPECT (QGS) software. Volume parameters of the left ventricle were also assessed. The phase histogram bandwidth at rest was 28.0 [63.7] degrees (median [95th percentile]). The standard deviation of phase histogram at rest was 7.8 [26.5] degrees. Entropy at the rest study was 54.0 [63.7] %. All left ventricular dyssynchrony parameters were statistically significantly higher at stress compared to rest. There were no statistically significant differences in dyssynchrony values between men and women. In volume parameters, reference values in male were expectedly higher than in female. Cardiac output did not differ significantly between genders. In subjects without signs of cardiac diseases, the left ventricular systolic function is well synchronized. Phase analysis measurement does not depend on gender, age, BMI or blood pressure, but the values of dyssynchrony parameters increase during pharmacological stress.

Temporal changes of left ventricular synchronization parameters and outcomes of cardiac resynchronization therapy

BackgroundLeft ventricular dyssynchrony plays an important role in predicting response to cardiac resynchronization therapy (CRT). MethodsThirty patients underwent CRT implantation. Assessment of left ventricular (LV) dyssynchrony was done through Gated SPECT LV phase analysis. ResultsThirty patients received CRT (mean age 58.7±9.0, 24 males). CRT implantation had a favorable prognosis on cardiac functions (LVEF preimplantation: 26.8±4.7% versus 29.1±6.4% post-implantation; P=0.002). Reverse LV remodeling (⩾15%) was documented in 19 patients. Temporal changes in LV dyssynchrony parameters were correlated to LV reverse remodeling. Applying ROC curve for LV phase analysis showed that a cutoff value of 152° for histogram bandwidth had a sensitivity of 72.7% and specificity of 63.2% for predicting CRT non-response status. Also, a cutoff value of 54° for histogram standard deviation had a sensitivity of 81.8% and specificity of 63.2%. ConclusionResponders of CRT showed improved LV dyssynchrony profiles. Utilizing Gated SPECT LV analysis could provide predictors for CRT non-response. Reverse LV remodeling is associated with temporal improvements in LV dyssynchrony parameters.

Association of subclinical atherosclerosis using carotid intima-media thickness, carotid plaque, and coronary calcium score with left ventricular dyssynchrony: The multi-ethnic Study of Atherosclerosis

BackgroundThe role of atherosclerosis in the progression of global left ventricular dysfunction and cardiovascular events has been well recognized. Left ventricular (LV) dyssynchrony is a measure of regional myocardial dysfunction. Our objective was to investigate the relationship of subclinical atherosclerosis with mechanical LV dyssynchrony in a population-based asymptomatic multi-ethnic cohort. Methods and ResultsParticipants of the Multi-Ethnic Study of Atherosclerosis (MESA) at exam 5 were evaluated using 1.5T cardiac magnetic resonance (CMR) imaging, carotid ultrasound (n = 2062) for common carotid artery (CCA) and internal carotid artery (ICA) intima-media thickness (IMT), and cardiac computed tomography (n = 2039) for coronary artery calcium (CAC) assessment (Agatston method). Dyssynchrony indices were defined as the standard deviation of time to peak systolic circumferential strain (SD-TPS) and the difference between maximum and minimum (max-min) time to peak strain using harmonic phase imaging in 12 segments (3-slices × 4 segments). Multivariable regression analyses were performed to assess associations after adjusting for participant demographics, cardiovascular risk factors, LV mass, and ejection fraction. In multivariable analyses, SD-TPS was significantly related to measures of atherosclerosis, including CCA-IMT (8.7 ms/mm change in IMT, p = 0.020), ICA-IMT (19.2 ms/mm change in IMT, p < 0.001), carotid plaque score (1.2 ms/unit change in score, p < 0.001), and log transformed CAC+1 (0.66 ms/unit log-CAC+1, p = 0.018). These findings were consistent with other parameter of LV dyssynchrony i.e. max–min. ConclusionIn the MESA cohort, measures of atherosclerosis are associated with parameters of subclinical LV dyssynchrony in the absence of clinical coronary event and left-bundle-branch block.

Diagnostic Value of Vasodilator-Induced Left Ventricular Dyssynchrony as Assessed by Phase Analysis to Detect Multivessel Coronary Artery Disease

Purpose: Phase analysis was recently developed to allow left ventricular(LV)mechanical dyssynchrony to be assessed by gated single-photon emission computed tomography(SPECT) . However, few studies have analyzed LV dyssynchrony during pharmacological stress and at rest by applying phase analysis to detect multivessel coronary artery disease(CAD)using the SyncTool TM . Methods: Adenosine triphosphate(ATP)loading electrocardiogram-gated 99m Tc-sestamibi SPECT was performed on 180 patients with suspected or known CAD. LV dyssynchrony was evaluated using the SyncTool TM ; the phase standard deviation(SD)and histogram bandwidth were derived. Results: The summed stress score(SSS) , summed difference score(SDS) , post-stress increase in phase SD, and histogram bandwidth were greater in 78 patients with multivessel CAD than in 102 patients with insignificant or single-vessel CAD. In the detection of multivessel CAD, SSS of >9 and SDS of >5 showed sensitivities of 74% and 74%,and specificities of 71% and 78% respectively, whereas an increase in phase SD>8.3°and in histogram bandwidth >16°after ATP loading had sensitivities of 62% and 74% and specificities of 77% and 68%, respectively. A multivariate logistic analysis revealed that the identification of multivessel CAD was superior with the combination of a post-ATP increase in phase SD, increase in histogram bandwidth, and SDS(sensitivity 82%, specificity 76%, chi-square=80.0)than with SDS alone (sensitivity 74%, specificity 78%, chi-square=58.9) . Conclusion: The addition of ATP-induced LV dyssynchrony parameters to conventional perfusion analysis enabled the superior identification of patients with multivessel CAD.

The acute and chronic effects of different right ventricular site pacing on left ventricular mechanical synchrony as assessed by phase analysis of SPECT myocardial perfusion imaging

BackgroundThis study aimed to assess acute and chronic effects of right ventricular mid-septum (RVS) versus right ventricular apex (RVA) pacing on left ventricular (LV) mechanical dyssynchrony using phase analysis of gated single photon emission computed tomography myocardial perfusion imaging (MPI). MethodsThirty-nine patients with complete atrioventricular (AV) block, who were indicated for permanent pacing, were recruited and randomized to receive RVA (n = 20) or RVS (n = 19) pacing. All patients underwent MPI at 1 week and 6 months after pacemaker implantation. LV dyssynchrony and cardiac function were assessed by MPI and compared between the two groups. ResultsThere were no significant differences in baseline characteristics between the RVS and RVA groups. The paced QRS duration was significantly longer in the RVA group than in the RVS group. LV dyssynchrony parameters were not significantly different between the groups at the 1-week follow-up, but they were significantly smaller in the RVS group than in the RVA group at the 6-month follow-up. LV dyssynchrony parameters significantly decreased in the RVS group from the 1-week follow-up to the 6-month follow-up, but were unchanged in the RVA group. No differences in LV function parameters were observed between the groups at the 1-week and 6-month follow-ups. ConclusionsRVS pacing produces better electrical and mechanical synchrony than RVA pacing for patients with complete AV block.

Impact of right-ventricular apical pacing on the optimal left-ventricular lead positions measured by phase analysis of SPECT myocardial perfusion imaging

The use of SPECT phase analysis to optimize left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT) was performed at baseline, but CRT works as simultaneous right ventricular (RV) and LV pacing. The aim of this study was to assess the impact of RV apical (RVA) pacing on optimal LV lead positions measured by SPECT phase analysis. This study prospectively enrolled 46 patients. Two SPECT myocardial perfusion scans were acquired under sinus rhythm with complete left bundle branch block and RVA pacing, respectively, following a single injection of (99m)Tc-sestamibi. LV dyssynchrony parameters and optimal LV lead positions were measured by the phase analysis technique and then compared between the two scans. The LV dyssynchrony parameters were significantly larger with RVA pacing than with sinus rhythm (p ~0.01). In 39 of the 46 patients, the optimal LV lead positions were the same between RVA pacing and sinus rhythm (kappa = 0.861). In 6 of the remaining 7 patients, the optimal LV lead positions were along the same radial direction, but RVA pacing shifted the optimal LV lead positions toward the base. The optimal LV lead positions measured by SPECT phase analysis were consistent, no matter whether the SPECT images were acquired under sinus rhythm or RVA pacing. In some patients, RVA pacing shifted the optimal LV lead positions toward the base. This study supports the use of baseline SPECT myocardial perfusion imaging to optimize LV lead positions to increase CRT efficacy.

Calibration of the normal cutoff values of systolic dyssynchrony of the left ventricular synchronicity in normal subjects using real-time 3-dimensional echocardiography and the effects of age and heart rate.

The normal data of left ventricular (LV) synchronicity by real-time 3-dimensional echocardiography (RT3DE) are lacking. We assessed the normal range/cutoff values of LV dyssynchrony parameters by RT3DE. For this purpose, RT3DE was performed in 130 healthy subjects, aged 53 ± 12 years. Time to the point of minimal regional systolic volume (Tmsv) was measured from time-volume curves in each segment. Standard deviation (SD) and maximal difference (Dif) of Tmsv were calculated from 16 (6 basal/6 mid/4 apical), 12 (6 basal/6 mid), and 6 (basal) LV segments together with the corresponding parameters adjusted by R-R interval. The data show non-significant difference between Tmsv-16-SD (9.24 ± 3.54 ms) and Tmsv-12-SD (8.80 ± 3.82 ms); with a correlation between two by both unadjusted (ms; r = 0.87) and adjusted (%R-R; r = 0.84) methods (P < 0.001). Heart rate correlated negatively with Tmsv (r = -0.13 to -0.34, P < 0.05-0.001) but had no effect on parameters adjusted for %R-R. Age and gender did not affect any of these parameters. Inter-observer variability was 3.3-4.6 % for 16, 4.8-9.1 % for 12, and 14.4-19.7 % for 6 segments. Thus, RT3DE is a reliable technique for detecting LV systolic dyssynchrony whereas the heart rate, but not age and gender, affects Tmsv parameters. Dyssynchrony parameters by 16 or 12 segments are superior to 6 segments in yielding comprehensive information and lower variability.

Left ventricular performance and dyssynchrony in heart failure and normal ejection fraction: assessment by stress echocardiography

Purpose: We evaluated the left ventricular (LV) performance and dyssynchrony in patients with heart failure and normal ejection fraction (HFNEF) during exercise as compared to those with heart failure and reduced ejection fraction (HFREF) and healthy subjects. Methods: All subjects received echocardiographic (Vivid7) examination with symptom-limited (fatigue or dyspnea) exercise testing on a semi-recumbent and tilting bicycle ergometer. The exercise images for two-dimensional (2D) speckle tracking were acquired with submaximal heart rate of 90-100bpm, while M-mode and tissue Doppler Imaging (TDI) exercise images were stored with attainment of >85% of maximal age-predicted heart rate response. Results: Stress echocardiography exams were performed in 40 HFNEF (aged 65±9 years; 53% male), 40 HFREF (aged 62±9 years; 90% male) and 30 normals (aged 56±5 years; 33% male). Trends of progressive decline in 2D global circumferential and radial strains (GCS & GRS), global longitudinal strains (2D GLS & GLS_TDI), pulsed-wave TDI systolic velocity (septal S') and M-mode mitral annular plane systolic excursion (MAPSE) were observed from control, HFNEF to HFREF groups (all p<0.05). LV twist was preserved in HFNEF but reduced in HFREF patients as compared to normals (p<0.001). Diastolic function measured by spetal e' progressively decreased from controls to HFNEF followed by HFREF (all p<0.05). LV filling pressure (septal E/e'), stroke volume and cardiac indices (LVSI & LVCI) were preserved in HFNEF but deteriorated in HFREF than controls. LV dyssynchrony parameters (standard deviation of time to peak systolic velocity, Ts-SD) were similar in all groups. Conclusions: This study provides the reference values of LV performance and dyssynchrony during exercise in HFNEF and knowledge about these changes provide important insights for future clinical studies.

GW24-e0649 Assessment of left ventricular regional systolic function in patients with hypertrophic cardiomyopathy by real-time three-dimensional echocardiography

ObjectivesThe aim of our study is to assess left ventricular regional systolic function in patients with hypertrophic cardiomyopathy (HCM) using real-time three-dimensional echocardiography (RT-3DE).MethodsRT-3DE was performed in 25 HCM patients...