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

Emergent role of dynamic optimization in cardiac resynchronization therapy: Systematic review and network meta-analysis

AIMS

Suboptimal device programming is frequent in non-responders to cardiac resynchronization therapy (CRT). However, the role of device optimization and the most appropriate technique are still unknown. The aim of our study was to analyse the effect of different CRT optimization techniques within a network meta-analysis.

METHODS

A systematic search was conducted on MEDLINE, Embase and CENTRAL for studies comparing outcomes with empirical device settings or optimization using echocardiography, static algorithms or dynamic algorithms. Studies investigating the effect of optimization in non-responders were also analysed.

RESULTS

A total of 17 studies with 4346 patients were included in the quantitative analysis. Of the treatments and outcomes examined, a significant difference was found only between dynamic algorithms and echocardiography, with the former leading to a higher echocardiographic response rate [odds ratio (OR): 2.02, 95% confidence interval (CI) 1.21-3.35], lower heart failure hospitalization rate (OR: 0.75, 95% CI 0.57-0.99) and greater improvement in 6-minute walk test [mean difference (MD): 45.52 m, 95% credible interval (CrI) 3.91-82.44 m]. We found no significant difference between empirical settings, static algorithms and dynamic algorithms. Seven studies with 228 patients reported response rates after optimization in non-responders. Altogether, 34.3%-66.7% of initial non-responders showed improvement after optimization, depending on response criteria.

CONCLUSIONS

At the time of CRT implantation, dynamic algorithms may serve as a resource-friendly alternative to echocardiographic optimization, with similar or better mid-term outcomes. However, their superiority over empirical device settings needs to be investigated in further trials. For non-responders, CRT optimization should be considered, as the majority of patients experience improvement.

Minute Stroke Distance Is a More Reproducible Measurement Than Cardiac Output in the Assessment of Fetal Ventricular Systolic Function

BACKGROUND

Echocardiographic quantification of fetal cardiac output (CO) aids clinical decision-making in the management of various cardiac and extracardiac diseases. Small variability in measuring semilunar valve dimension significantly reduces the reproducibility of the calculated CO. The authors propose minute stroke distance or velocity-time integral (VTI) as a more reproducible measure reflecting fetal ventricular systolic function. The aim of this study was to test the hypothesis that right and left ventricular minute VTI increase predictably with estimated fetal weight and are more reproducible than CO.

METHODS

Five hundred seventy-one singleton fetuses without cardiovascular pathology between 16 and 36 weeks' gestation were reviewed retrospectively. Twenty-two fetuses with pathology resulting in low- or high-CO states were also assessed for comparison. VTI was measured in both ventricular outflow tracts at the level of the semilunar valve, excluding a Doppler insonation angle of >30°. Heart rate, semilunar valve dimension, and VTI determined minute VTI and CO. Inter- and intrarater variability were evaluated in a random 10% subset.

RESULTS

Minute VTI and CO measurements were feasible in 67% to 89% of fetuses in this retrospective study. Minute VTI and CO increased with estimated fetal weight nonlinearly (R = 0.61-0.94). The mean inter- and intrarater variability for VTI, 6% and 5.7%, were significantly less than for CO, 25% and 23.7% (P < .001 for all).

CONCLUSIONS

Minute VTI is an easily measured, highly reproducible method of quantifying fetal ventricular systolic function. Variability in calculated CO from valve measurement differences is minimized by solely using VTI. Nomograms of minute VTI provide an efficient and precise assessment of fetal systolic function and may be used to track fetuses in disease states with low or high CO.

Basic Principles of Hemodynamics in Pacing

Pacing therapy aims to improve overall cardiac function by normalizing cardiac electrical activation. Although hemodynamic measurements allow the impact of cardiac pacing on cardiac function to be quantified, the protocol is crucial to minimize the effect of noise and achieve greater precision. Multiple steps can be undertaken to optimize accuracy of hemodynamic measurements. These include comparing with a reference state, using an average of a set number of beats, making repeated measurements, ensuring all beats are included, and pacing at faster heart rates. These measurements can aid comparison between different pacing modalities and guide optimal programming.

Optimizing atrio-ventricular delay in pacemakers using potentially implantable physiological biomarkers

BACKGROUND

Hemodynamically optimal atrioventricular (AV) delay can be derived by echocardiography or beat-by-beat blood pressure (BP) measurements, but analysis is labor intensive. Laser Doppler perfusion monitoring measures blood flow and can be incorporated into future implantable cardiac devices. We assess whether laser Doppler can be used instead of BP to optimize AV delay.

METHODS

Fifty eight patients underwent 94 AV delay optimizations with biventricular or His-bundle pacing using laser Doppler and simultaneous noninvasive beat-by-beat BP. Optimal AV delay was defined using a curve of hemodynamic response to switching from AAI (reference state) to DDD (test state) at several AV delays (40-320 ms), with automatic quality control checking precision of the optimum. Five subsequent patients underwent an extended protocol to test the impact of greater numbers of alternations on optimization quality.

RESULTS

55/94 optimizations passed quality control resulting in an optimal AV delay on laser Doppler similar to that derived by BP (median absolute deviation 12 ms). An extended protocol with increasing number of replicates consistently improved quality and reduced disagreement between laser Doppler and BP optima. With only five replicates, no optimization passed quality control, and the median absolute deviation would be 29 ms. These improved progressively until at 50 replicates, all optimizations passed quality control and the median absolute deviation was only 13 ms.

CONCLUSIONS

Laser Doppler perfusion produces hemodynamic optima equivalent to BP. Quality control can be automatic. Adding more replicates, consistently improves quality. Future implantable devices could use such methods to dynamically and reliably optimize AV delays.

Improvement of LV Reverse Remodeling Using Dynamic Programming of Fusion-Optimized Atrioventricular Intervals in Cardiac Resynchronization Therapy

Background: The patient-tailored SyncAV algorithm shortens the QRS duration (QRSd) beyond what conventional biventricular (BiV) pacing can. However, evidence of the ability of SyncAV to improve the cardiac resynchronization therapy (CRT) response is lacking. The aim of this study was to evaluate the impact of CRT enhanced by SyncAV on echocardiographic and clinical responses.

Methods and Results: Consecutive heart failure (HF) patients from three centers treated with a quadripolar CRT system (Abbott) were enrolled. The total of 122 patients were divided into BiV+SyncAV (n = 68) and BiV groups (n = 54) according to whether they underwent CRT with or without SyncAV. Electrocardiographic, echocardiographic, and clinical data were assessed at baseline and during follow-up. Echocardiographic response to CRT was defined as a ≥15% decrease in left ventricular end-systolic volume (LVESV), and clinical response was defined as a NYHA class reduction of ≥1. At the 6-month follow-up, the baseline QRSd and LVESV decreased more significantly in the BiV+SyncAV than in the BiV group (QRSd −36.25 ± 16.33 vs. −22.72 ± 18.75 ms, P < 0.001; LVESV −54.19 ± 38.87 vs. −25.37 ± 36.48 ml, P < 0.001). Compared to the BiV group, more patients in the BiV+SyncAV group were classified as echocardiographic (82.35 vs. 64.81%; P = 0.036) and clinical responders (83.82 vs. 66.67%; P = 0.033). During follow-up, no deaths due to HF deterioration or severe procedure related complications occurred.

Conclusion: Compared to BiV pacing, BiV combined with SyncAV leads to a more significant reduction in QRSd and improves LV remodeling and long-term outcomes in HF patients treated with CRT.

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.

Comparison of Echocardiographic and Electrocardiographic Mapping for Cardiac Resynchronisation Therapy Optimisation

Study hypothesis

We sought to investigate the association between echocardiographic optimisation and ventricular activation time in cardiac resynchronisation therapy (CRT) patients, obtained through the use of electrocardiographic mapping (ECM). We hypothesised that echocardiographic optimisation of the pacing delay between the atrial and ventricular leads-atrioventricular delay (AVD)-and the delay between ventricular leads-interventricular pacing interval (VVD)-would correlate with reductions in ventricular activation time.

Background

Optimisation of AVD and VVD may improve CRT patient outcome. Optimal delays are currently set based on echocardiographic indices; however, acute studies have found that reductions in bulk ventricular activation time correlate with improvements in acute haemodynamic performance.

Materials and methods

Twenty-one patients with established CRT criteria were recruited. After implantation, patients underwent echo-guided optimisation of the AVD and VVD. During this procedure, the participants also underwent noninvasive ECM. ECM maps were constructed for each AVD and VVD. ECM maps were analysed offline. Total ventricular activation time (TVaT) and a ventricular activation time index (VaT_10-90) were calculated to identify the optimal AVD and VVD timings that gave the minimal TVaT and VaT_10-90 values. We correlated cardiac output with these electrical timings.

Results

Echocardiographic programming optimisation was not associated with the greatest reductions in biventricular activation time (VaT_10-90 and TVaT). Instead, bulk activation times were reduced by a further 20% when optimised with ECM. A significant inverse correlation was identified between reductions in bulk ventricular activation time and improvements in LVOT VTI (p < 0.001), suggesting that improved ventricular haemodynamics are a sequelae of more rapid ventricular activation.

Conclusions

EAM-guided programming optimisation may achieve superior fusion of activation wave fronts leading to improvements in CRT response.

Haemodynamic changes during propofol induction in dogs: new findings and approach of monitoring

BACKGROUND

Propofol is one of the most widely used injectable anaesthetic agents in veterinary practice. Cardiovascular effects related to propofol use in dogs remain less well defined. The main objective of this study was to evaluate the haemodynamic changes during induction of general anaesthesia with propofol in healthy dogs, by a beat-to-beat continuous monitoring. All dogs were premedicated with intramuscular acepromazine (0.015 mg/kg) and methadone (0.15 mg/kg). Transthoracic echocardiography was used to measure the velocity time integral (VTI) of the left ventricular outflow tract. A syringe driver, programmed to deliver propofol 5 mg/kg over 30 s followed by a continuous infusion of 25 mg/kg/h, was used to induce and maintain anaesthesia. From the initiation of propofol administration, heart rate (HR) and mean invasive arterial blood pressure (MAP) were recorded every 5 s for 300 s, while aortic blood flow was continuously recorded and stored for 300 S. maximum cardiovascular depression was defined the lowest MAP (MAP_Tpeak) recorded during the monitored interval. VTI and VTI*HR were calculated at 0, 30, 90, 120, 150 and 300 s post administration of propofol, and at MAP_Tpeak. Haemodynamic effects of propofol in relation to plasma and biophase concentrations were also evaluated by pharmacokinetics simulation.

RESULTS

The median (range) HR was significantly higher (p = 0.006) at the moment of maximum hemodynamic depression (Tpeak) [105(70-148) bpm] compared with pre-induction values (T0) [65(50-120) bpm]. The median (range) MAP was significantly lower (p < 0.001) at Tpeak [61(51-69) mmHg] compared with T0 [88(72-97) mmHg]. The median (range) VTI and VTI*HR were similar at the two time points [11.9(8.1-17.3) vs 13,3(9,4-16,5) cm, and 1172(806-1554) vs 1002(630-1159) cm*bpm, respectively].

CONCLUSIONS

Induction of anaesthesia with propofol causes a drop of arterial pressure in healthy dogs, however cardiac output is well maintained by compensatory chronotropic response. The magnitude of MAP_Tpeak may be strictly related with propofol plasma concentration.

Relation of Velocity-Time Integral of the Left Ventricular Outflow Tract to that of the Descending Thoracic Aorta and Usefulness of a Fixed Ratio for Internal Validation

Measurement of left ventricular outflow tract velocity-time integral (LVOT VTI) is technician-, instrument-, and reader-dependent; variability is more common for pulsed-wave Doppler than continuous-wave Doppler. We hypothesize that in a population with normal cardiac structure and function, LVOT VTI is higher than VTI of the descending thoracic aorta (DTA) and this relation may be used clinically to validate the former. Furthermore, the DTA VTI could also be used to estimate LVOT. We retrospectively compared the LVOT VTI against VTI measured from DTA, abdominal aorta, and pulmonary artery among 108 healthy subjects. The ratio of LVOT VTI (n = 108) to DTA VTI (n = 108) was 1.27. There was a difference of 19.6% between LVOT VTI and DTA VTI with the former being higher. This percentage decrease in VTI from LVOT VTI to abdominal aortic (AA) VTI was directly proportional to the LVOT VTI. Similarly, there was a difference of 23.4% in the VTI values obtained from DTA and abdominal aorta. Moreover, there was a decrease of 40.4% when LVOT VTI was compared against AA VTI. The ratio of LVOT VTI to pulmonary VTI was 1.19. VTI values decrease in a linear fashion from the LVOT to abdominal aorta likely because of progressive decrease in circulating volume, and this change is not obscured by diminishing aortic diameter. Any deviation from this relation should be treated as abnormal and should prompt further investigation. Our findings support routine measurement of DTA VTI in clinical practice.

Non-invasive electrophysiological assessment of the optimal configuration of quadripolar lead vectors on ventricular activation times

BACKGROUND

Cardiac resynchronization therapy (CRT) is now generally delivered via quadripolar leads. Assessment of the effect of different vector programs from quadripolar leads on ventricular activation can be now done using non-invasive electrocardiographic mapping (ECM).

MATERIAL AND METHODS

In nineteen patients with quadripolar LV leads, activation maps were constructed. The total ventricular activation time (TVaT) and the time for the bulk of ventricular activation (VaT_10-90) were calculated.

RESULTS

CRT delivered via a quadripolar lead significantly reduced TVaT and VaT_10-90 by a mean of 16 ms and 31 ms, respectively, compared to baseline. There was a marked reduction in ventricular activation between the most and least synchronous vectors: 28% difference in baseline TVaT and 37% difference in VaT_10-90.

CONCLUSION

Changes in the configuration of an LV quadripolar lead significantly affected ventricular activation timings in both ischaemic and non-ischaemic subjects. This suggests that programming of the optimal pacing vector may need to be individually tailored.

LVOT-VTI is a Useful Indicator of Low Ventricular Function in Young Patients

Left ventricular outflow tract velocity time integral (LVOT-VTI), a Doppler-derived measure of stroke distance, is used as a surrogate marker of cardiac function in adults. LVOT-VTI is easily obtained, independent of ventricular geometry and wall motion abnormalities. We investigated the relationship between LVOT-VTI and conventional measures of function in young patients by comparing controls to children with dilated cardiomyopathy (DCM). Sixty-two healthy and 52 DCM patients over 1 year were studied retrospectively. The average pulsed (PW) and continuous wave (CW) LVOT-VTIs from apical views were measured from three cycles. Body surface area (BSA) and Ejection fraction (EF) were obtained. We compared LVOT-VTIs between study and control groups and assessed BSA's impact on LVOT-VTI. The entire cohort was classified into three levels of LV function which were compared. We determined LVOT-VTI cutoff values that indicated an EF <50%. The mean PW-LVOT-VTI in the DCM group was significantly lower than that of the normal group (0.15 vs. 0.18 m; p < 0.0012). The mean CW-LVOT-VTI was significantly lower in DCM (0.20 vs. 0.24 m; p < 0.0001). There was no impact of BSA on LVOT-VTI except when comparing BSA and CW-LVOT-VTI in the normal group. There was a positive relationship between LVOT-VTI and EF for PW (Rs = 0.29, p = 0.0022) and CW (Rs = 0.22, p = 0.0364) and a difference in mean LVOT-VTI between EF groups (p < 0.0001). ROC analysis demonstrated that PW-LVOT-VTI <0.17 m (AUC = 0.73; p < 0.0001) and CW-LVOT-VTI <0.22 m (AUC = 0.76; p < 0.0001) was associated with EF <50%. This study indicates that LVOT-VTI can be a useful alternative measure of LV performance in children over 1 year.

Comparison between IEGM-based approach and echocardiography in AV/PV and VV delay optimization in CRT-D recipients (Quicksept study)

BACKGROUND

AtrioVentricular (AV) and InterVentricular (VV) delay optimization can improve ventricular function in Cardiac Resynchronization Therapy (CRT) and is usually performed by means of echocardiography. St Jude Medical has developed an automated algorhythm which calculates the optimal AV and VV delays (QuickOpt™) based on Intracardiac ElectroGrams, (IEGM), within 2 min. So far, the efficacy of the algorhythm has been tested acutely with standard lead position at right ventricular (RV) apex. Aim of this project is to evaluate the algorhythm performance in the mid- and long-term with RV lead located in mid-septum.

METHODS

AV and VV delays optimization data were collected in 13 centers using both echocardiographic and QuickOpt™ guidance in CRTD implanted patients provided with this algorhythm. Measurements of the aortic Velocity Time Integral (aVTI) were performed with both methods in a random order at pre-discharge, 6-month and 12-month follow-up.

RESULTS

Fifty-three patients were studied (46 males; age 68 ± 10y; EF 28 ± 7%). Maximum aVTI obtained by echocardiography at different AV delays, were compared with aVTI acquired at AV delays suggested by QuickOpt. The AV Pearson correlations were 0.96 at pre-discharge, 0.95 and 0,98 at 6- and 12- month follow-up respectively. After programming optimal AV, the same approach was used to compare echocardiographic aVTI with aVTI corresponding to the VV values provided by QuickOpt. The VV Pearson Correlation were 0,92 at pre-discharge, 0,88 and 0.90 at 6-month and 12- month follow-up respectively.

CONCLUSIONS

IEGM-based optimization provides comparable results with echocardiographic method (maximum aVTI) used as reference with mid-septum RV lead location.

The clinical dilemma of quantifying mechanical left ventricular dyssynchrony for cardiac resynchronization therapy: segmental or global?

Heart failure (HF) represents a serious clinical and public cause of mortality, morbidity, as well as healthcare expenditures. Guidelines for treatment of HF join in recommending multimedical regimen at targeted doses as the best medical strategy, despite that a significant percentage of patients remain symptomatic. Studies have shown that these patients might benefit from cardiac resynchronization therapy (CRT), particularly those presenting with broad QRS duration, >135 msec. Trials have already shown that CRT results in improved morbidity and survival of these patients particularly those in New York Heart Association class III-IV HF, but almost 30% do not show any symptomatic or survival benefit, hence are classified as nonresponders. Exhaustive efforts have been made in using noninvasive methods of assessing left ventricle (LV) dyssynchrony in predicting nonresponders to CRT, including Doppler echocardiography, magnetic resonance imaging, and even single photon emission computed tomography analysis, but only with modest success. In this report, we aimed to review the available evidence for assessing markers of mechanical LV dyssynchrony by various echocardiographic modalities and their respective strength in predicting favorable response to CRT treatment, comparing global with segmental ones. While the accuracy of segmental markers of dyssynchrony in predicting satisfactory response to CRT remains controversial because of various technical limitations, global markers seem easier to measure, reproducible, and potentially accurate in reflecting overall cavity response and its clinical implications. More studies are needed to qualify this proposal.

Cardiac resynchronization therapy: Dire need for targeted left ventricular lead placement and optimal device programming

Cardiac resynchronization therapy (CRT) effected via biventricular pacing has been established as prime therapy for heart failure patients of New York Heart Association functional class II, III and ambulatory IV, reduced left ventricular (LV) function, and a widened QRS complex. CRT has been shown to improve symptoms, LV function, hospitalization rates, and survival. In order to maximize the benefit from CRT and reduce the number of non-responders, consideration should be given to target the optimal site for LV lead implantation away from myocardial scar and close to the latest LV site activation; and also to appropriately program the device paying particular attention to optimal atrioventricular and interventricular intervals. We herein review current data related to both optimal LV lead placement and device programming and their effects on CRT clinical outcomes.

Effects of AV delay and VV delay on left atrial pressure and waveform in ambulant heart failure patients: insights into CRT optimization

BACKGROUND

We hypothesized that left atrial pressure (LAP) obtained by a permanent implantable sensor is sensitive to changes in cardiac resynchronization therapy (CRT) settings and could guide CRT optimization to improve the response rate. We investigated the effect of CRT optimization on LAP and its waveform parameters in ambulant heart failure (HF) patients.

METHODS

CRT optimization was performed in eight ambulant HF patients, using echocardiography as reference. LAP waveform was acquired at each of eight atrioventricular (AV) intervals and five inter-ventricular (VV) intervals. Selected waveform parameters were also evaluated for their sensitivity to CRT changes and agreement with echocardiography-guided optimal settings.

RESULTS

Optimal AV and VV intervals varied considerably between patients. All patients exhibited significant changes in waveform morphology with AV optimization. Optimal AV delay determined from echocardiography ranged between 140 ms and 225 ms. Mean LAP tended to be lower at optimal setting 14 ± 3 mmHg compared to shorter (<100 ms) or longer (>160 ms) AV settings (P = 0.16). There were clear trends to smaller peak a-wave (P = 0.11) and gentler positive a-slope (P = 0.15) and positive v-slope (P = 0.09) with longer AV delays. Mean LAP and negative v-wave slope correlated well with echo-guided optimal setting, r = 0.91 (P = 0.001) and 0.79 (P = 0.03), respectively. No significant effects on LAP or waveform were seen during VV optimization.

CONCLUSIONS

LAP and its waveform changes considerably with AV optimization. There is good agreement between echo-guided optimal setting and LAP. LAP could provide an objective guide to CRT optimization. (Clinical Trial Registry information: URL: http://www.clinicaltrials.gov. Unique Identifier: NCT00632372).

Hemodynamic benefit of rest and exercise optimization of cardiac resynchronization therapy

The optimal method of cardiac resynchronization therapy (CRT) optimization is as yet unknown. We sought to investigate the responses of optimization at rest and on exercise. This 2 stage study involved 59 patients (age 65 ± 10, 75% male), who had all recently undergone successful CRT implantation. In the first stage, the 6-month response was compared between 30 individuals who underwent resting echocardiographic optimization of CRT [atrioventricular (AV delay) plus ventriculo-ventricular delays (VV delay)], compared with the 29 who did not. In the second stage, a subset of 37 patients from the original cohort were randomized (double-blind) to either resting echocardiographic optimization (n = 20) or exercise echocardiographic optimization (n = 17) and followed for a further 6 months. Clinical and echocardiographic data were collected at each stage. Patients undergoing rest optimization demonstrated improvement in almost all variables and significantly in B-type natriuretic peptide (BNP) in contrast to those without optimization. In a linear regression model, the only significant predictor of BNP change was whether an individual underwent resting optimization or not (β = 0.38, P = 0.04). In those undergoing resting optimization, the degree of change in AV delay was correlated with improvement in left ventricle (LV) end-diastolic volume (r(2)  = 0.33, P < 0.01). Optimization on exercise was associated with a significant decrease in 6-minute walk test compared to those randomized to rest optimization possibly due to inducing nonoptimization at rest. In conclusion, echocardiographic optimization of CRT at rest is superior to no optimization or optimization on exercise. Patients with the greatest change in AV delay to reach optimal may undergo greater LV remodeling.

Three-dimensional echocardiographic optimization improves outcome in cardiac resynchronization therapy compared to ECG optimization: a randomized comparison

AIMS

There is little consensus on optimal atrioventricular (AV) and ventricular-to-ventricular (VV) intervals in cardiac resynchronization therapy (CRT). The aim of this study was to examine a novel combination of Doppler echocardiography (DE) and three-dimensional echocardiography (3DE) for individualized AV- and VV-interval optimization compared to conventional electrocardiogram (ECG) optimization.

METHODS

In this double-blind, randomized controlled trial, 77 patients (male: 57, age: 68 ± 10 years) with severely reduced ejection fraction (EF), New York Heart Association (NYHA) class III or IV, and wide QRS complex (>120 ms) have been included. Patients were randomized to either AV- and VV-interval optimization using DE and 3DE (group 1, n = 39) or ECG (group 2, n = 38). 3DE was performed in all patients for the evaluation of left ventricular (LV) dimensions, EF and systolic dyssynchrony index (SDI), and NYHA class obtained before CRT and after 3 months. Primary endpoint of the study was clinical response to CRT, defined as a reduction of NYHA class by ≥1 score. Secondary endpoints were change of EF, LV volumes, and SDI.

RESULTS

There were significantly more responders in group 1 (82%) than in group 2 (58%, P = 0.021). Similarly, group 1 showed a larger increase in EF (7.0 ± 6.0% vs 3.4 ± 5.6%, P = 0.015) and a more pronounced reduction of SDI (-4.5 ± 5.9% vs -1.5 ± 5.6%, P = 0.039) than group 2.

CONCLUSION

Compared with conventional ECG optimization, this novel echocardiographic optimization protocol resulted in a significantly higher response rate, improved LV systolic function, and may be used to select the optimal AV and VV intervals in CRT.

Comparison of dyssynchrony parameters for VV-optimization in CRT patients

BACKGROUND

Optimization of the interventricular delay (VV-optimization) in cardiac resynchronization therapy (CRT) patients can be performed by evaluation of mechanical dyssynchrony. However, there is no consensus on which method to use. In this study, three conceptually different methods were evaluated.

METHODS

Thirty consecutive CRT patients were included. At day 1, patients were atrioventricular and VV optimized by left ventricular outflow tract (LVOT) velocity time integral (VTI). At 6 months, 2D strain (2DS) echocardiography and tissue Doppler imaging (TDI) was performed at six different VV-programming delay in steps of 20 ms. LVOT and three indices of dyssynchrony were evaluated at each setting: standard deviation (SD) of time-to-peak strain in 12 segments (2DS-SD), SD of time-to-peak velocities in 12 segments (TDI-SD), and maximal activation delay (AD-max) by cross-correlation analysis (XCA) of TDI-derived myocardial acceleration curves.

RESULTS

Feasibility was 90% for 2DS-SD and TDI-SD and 97% for AD-max. Coefficients of variation for intraobserver variability were 13% for 2DS-SD, 11% for TDI-SD, and 6% for AD-max. A relative increase in LVOT VTI > 10% was observed in 5/12 (42%) nonresponders and 7/18 (39%) responders to CRT. Optimization by all three dyssynchrony indices significantly increased LVOT VTI compared to simultaneous pacing and optimal setting at day 1 (P < 0.05, all). LVOT VTI was highest when using AD-max, and AD-max showed the best agreement (k = 0.71).

CONCLUSION

VV optimization at 6 months acutely benefits both responders and nonresponders; however, dyssynchrony indices do not perform equally well. XCA has a high feasibility and reproducibility and appears to be superior to time-to-peak techniques.

Effect of atrioventricular and ventriculoventricular delay optimization on clinical and echocardiographic outcomes of patients treated with cardiac resynchronization therapy: a meta-analysis

BACKGROUND

Optimization of atrioventricular (AV) and ventriculoventricular (VV) delays of cardiac resynchronization therapy (CRT) devices maximizes left ventricular filling and stroke volume. However, the incremental value of these optimizations over empiric device programming remains unclear. The objective of this analysis was to perform a systematic review and meta-analysis of the effects of AV and VV delay optimization on clinical and echocardiographic end points of patients with heart failure treated with CRT.

METHODS

A standardized search strategy was performed and identified 12 trials comparing AV and/or VV delay optimization and conventional CRT device programming and their effects on various clinical and echocardiographic outcomes. Pooled odds ratios were analyzed using random-effect meta-analysis with Mantel-Haenszel method.

RESULTS

Combined data from a total of 4,356 patients with heart failure treated with CRT showed no differences in clinical or echocardiographic outcomes between patients who underwent AV and/or VV delay optimization and patients who underwent empiric device programming (Mantel-Haenszel odds ratio 0.86 [95% CI 0.68-1.09], P value for overall effect = .21 by intention-to-treat analysis).

CONCLUSION

The current literature suggests that routine AV and/or VV delay optimization has a neutral effect on clinical and echocardiographic outcomes based on pooled data from randomized and nonrandomized studies. Standardization of patient selection and optimization timing and method may help to further define the role of CRT device optimization.

Optimized temporary bi-ventricular pacing improves haemodynamic function after on-pump cardiac surgery in patients with severe left ventricular systolic dysfunction: a two-centre randomized control trial

OBJECTIVES

Optimized temporary bi-ventricular (BiV) pacing may benefit heart failure patients after on-pump cardiac surgery compared with conventional dual-chamber right ventricular (RV) pacing. An improvement in haemodynamic function with BiV pacing may reduce the duration of ‘Level 3’ intensive care.

METHODS

Thirty-eight patients in sinus rhythm, ejection fraction ≤35%, undergoing on-pump surgical revascularization, valve surgery or both were enrolled in this study. Before closing the sternum, temporary epicardial pacing wires were attached to the right atrium, RV outflow tract and basal posterolateral wall of the left ventricle. Patients were randomly assigned to postoperative BiV pacing with the optimization of the atrio- (AV) and inter-ventricular (VV) pacing intervals (Group 1) or conventional dual-chamber right AV pacing (Group 2). The primary end-point was the duration of ‘Level 3’ intensive care. Secondary end-points included cardiac output which was measured by thermodiluation at admission to the intensive care unit and at 6 and 18 h later, in five different pacing modes.

RESULTS

The duration of ‘Level 3’ care was similar between groups (40 ± 35 vs 54 ± 63 h; Group 1 vs 2; P = 0.43). Cardiac output was similar in all pacing modes at baseline. At 18 h, cardiac output with BiV pacing (5.8 l/min) was 7% higher than atrial inhibited (5.4 l/min) and 9% higher than dual-chamber RV pacing (5.3 l/min; P = 0.02 and 0.001, respectively). Optimization of the VV interval produced a further 4% increase in cardiac output compared with baseline settings (P = 0.005).

CONCLUSIONS

Postoperative haemodynamic function may be enhanced by temporary BiV pacing of high-risk patients after on-pump cardiac surgery.

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.

High-sensitive cardiac Troponin T is superior to echocardiography in predicting 1-year mortality in patients with SIRS and shock in intensive care

Background

Left ventricular (LV) dysfunction is well documented in the critically ill. We assessed 1-year mortality in relation to cardiac biomarkers and LV function parameters by echocardiography in patients with shock.

Methods

A prospective, observational, cohort study of 49 patients. B-natriuretic peptide (BNP), high-sensitive troponin T (hsTNT) and transthoracic echocardiography (TTE) were assessed within 12 h of study inclusion. LV systolic function was measured by ejection fraction (LVEF), mean atrioventricular plane displacement (AVPDm), peak systolic tissue Doppler velocity imaging (TDIs) and velocity time integral in the LV outflow tract (LVOT VTI). LV diastolic function was evaluated by transmitral pulsed Doppler (E, A, E/A, E-deceleration time), tissue Doppler indices (é, á, E/é) and left atrial volume (La volume). APACHE II (Acute Physiology and Chronic Health Evaluation) and SOFA (Sequential Organ Failure Assessment) scores were calculated.

Results

hsTNT was significantly higher in non-survivors than in survivors (60 [17.0-99.5] vs 168 [89.8-358] ng/l, p = 0.003). Other univariate predictors of mortality were APACHE II (p = 0.009), E/é (p = 0.023), SOFA (p = 0.024) and age (p = 0.031). Survivors and non-survivors did not differ regarding BNP (p = 0.26) or any LV systolic function parameter (LVEF p = 0.87, AVPDm p = 0.087, TDIs p = 0.93, LVOT VTI p = 0.18). Multivariable logistic regression analysis identified hsTNT (p = 0.010) as the only independent predictor of 1-year mortality; adjusted odds ratio 2.0 (95% CI 1.2- 3.5).

Conclusions

hsTNT was the only independent predictor of 1-year mortality in patients with shock. Neither BNP nor echocardiographic parameters had an independent prognostic value. Further studies are needed to establish the clinical significance of elevated hsTNT in patients in shock.

Predictive factors and clinical effect of optimized cardiac resynchronization therapy

The aim of this study was to assess the effectiveness of cardiac resynchronization therapy (CRT) by intracardiac delay optimization using echocardiography. Sixty-five patients were implanted with a CRT device randomly assigned to receive simultaneous biventricular pacing or echo-optimized sequential CRT. Forty-two patients were defined as responders and 23 patients were classified as non-responders. During a 12-month follow-up period, the positive response rate, QRS duration, New York Heart Association class, mitral insufficiency grade, left ventricular end-systolic volume and LV end-diastolic volume were similar in the optimized and non-optimized groups (P>0.05), whereas 6-minute walking distance, quality-of-life score, left ventricular (LV) ejection fraction and aortic velocity time integral were significantly improved in the optimized group (P<0.05). The baseline QRS durations of the responders and non-responders were similar (P>0.05), whereas heart failure aetiology, clinical and echocardiographic measurements showed significant differences (P<0.05). The mean decrease in QRS duration after 12 months of CRT used for separating responders and non-responders was significantly different (P<0.05), and significant differences were observed in the mean decrease of QRS duration between responders and non-responders (P<0.05). Echocardiographic optimization may further improve the effectiveness of CRT. Moreover, severe mitral regurgitation and greater LV volume are likely to indicate a poor response to CRT.

Acute beneficial hemodynamic effects of a novel 3D-echocardiographic optimization protocol in cardiac resynchronization therapy

BACKGROUND

Post-implantation therapies to optimize cardiac resynchronization therapy (CRT) focus on adjustments of the atrio-ventricular (AV) delay and ventricular-to-ventricular (VV) interval. However, there is little consensus on how to achieve best resynchronization with these parameters. The aim of this study was to examine a novel combination of doppler echocardiography (DE) and three-dimensional echocardiography (3DE) for individualized optimization of device based AV delays and VV intervals compared to empiric programming.

METHODS

25 recipients of CRT (male: 56%, mean age: 67 years) were included in this study. Ejection fraction (EF), the primary outcome parameter, and left ventricular (LV) dimensions were evaluated by 3DE before CRT (baseline), after AV delay optimization while pacing the ventricles simultaneously (empiric VV interval programming) and after individualized VV interval optimization. For AV delay optimization aortic velocity time integral (AoVTI) was examined in eight different AV delays, and the AV delay with the highest AoVTI was programmed. For individualized VV interval optimization 3DE full-volume datasets of the left ventricle were obtained and analyzed to derive a systolic dyssynchrony index (SDI), calculated from the dispersion of time to minimal regional volume for all 16 LV segments. Consecutively, SDI was evaluated in six different VV intervals (including LV or right ventricular preactivation), and the VV interval with the lowest SDI was programmed (individualized optimization).

RESULTS

EF increased from baseline 23±7% to 30±8 (p<0.001) after AV delay optimization and to 32±8% (p<0.05) after individualized optimization with an associated decrease of end-systolic volume from a baseline of 138±60 ml to 115±42 ml (p<0.001). Moreover, individualized optimization significantly reduced SDI from a baseline of 14.3±5.5% to 6.1±2.6% (p<0.001).

CONCLUSIONS

Compared with empiric programming of biventricular pacemakers, individualized echocardiographic optimization with the integration of 3-dimensional indices into the optimization protocol acutely improved LV systolic function and decreased ESV and can be used to select the optimal AV delay and VV interval in CRT.

Assessing left ventricular systolic function in shock: evaluation of echocardiographic parameters in intensive care

Introduction

Assessing left ventricular (LV) systolic function in a rapid and reliable way can be challenging in the critically ill patient. The purpose of this study was to evaluate the feasibility and reliability of, as well as the association between, commonly used LV systolic parameters, by using serial transthoracic echocardiography (TTE).

Methods

Fifty patients with shock and mechanical ventilation were included. TTE examinations were performed daily for a total of 7 days. Methods used to assess LV systolic function were visually estimated, "eyeball" ejection fraction (EBEF), the Simpson single-plane method, mean atrioventricular plane displacement (AVPDm), septal tissue velocity imaging (TDIs), and velocity time integral in the left ventricular outflow tract (VTI).

Results

EBEF, AVPDm, TDIs, VTI, and the Simpson were obtained in 100%, 100%, 99%, 95% and 93%, respectively, of all possible examinations. The correlations between the Simpson and EBEF showed r values for all 7 days ranging from 0.79 to 0.95 (P < 0.01). the Simpson correlations with the other LV parameters showed substantial variation over time, with the poorest results seen for TDIs and AVPDm. The repeatability was best for VTI (interobserver coefficient of variation (CV) 4.8%, and intraobserver CV, 3.1%), and AVPDm (5.3% and 4.4%, respectively), and worst for the Simpson method (8.2% and 10.6%, respectively).

Conclusions

EBEF and AVPDm provided the best, and Simpson, the worst feasibility when assessing LV systolic function in a population of mechanically ventilated, hemodynamically unstable patients. Additionally, the Simpson showed the poorest repeatability. We suggest that EBEF can be used instead of single-plane Simpson when assessing LV ejection fraction in this category of patients. TDIs and AVPDm, as markers of longitudinal function of the LV, are not interchangeable with LV ejection fraction.

Atrioventricular and interventricular delay optimization in cardiac resynchronization therapy: physiological principles and overview of available methods

In this review, the physiological rationale for atrioventricular and interventricular delay optimization of cardiac resynchronization therapy is discussed including the influence of exercise and long-term cardiac resynchronization therapy. The broad spectrum of both invasive and non-invasive optimization methods is reviewed with critical appraisal of the literature. Although the spectrum of both invasive and non-invasive optimization methods is broad, no single method can be recommend for standard practice as large-scale studies using hard endpoints are lacking. Current efforts mainly investigate optimization during resting conditions; however, there is a need to develop automated algorithms to implement dynamic optimization in order to adapt to physiological alterations during exercise and after anatomical remodeling.