Combined longitudinal and radial dyssynchrony predicts ventricular response after resynchronization therapy. J Am Coll Cardiol. 2007;50:1476-1483. [PMID: 17919568 DOI: 10.1016/j.jacc.2007.06.043]

Dyssynchrony, contractile function, and response to cardiac resynchronization therapy

BACKGROUND

Despite benefits of cardiac resynchronization therapy (CRT) in patients with severe but less symptomatic heart failure, approximately 30% of patients do not fully respond to treatment. We hypothesized that a combined assessment of left ventricular (LV) dyssynchrony and contractile function by strain-based imaging would identify patients who would most benefit from CRT.

METHODS AND RESULTS

We studied 1077 patients with New York Heart Association class I/II, LV ejection fraction ≤30% and QRS width ≥130 ms enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy trial with sufficient echocardiographic image quality for cardiac deformation analysis (implantable cardioverter-defibrillator [ICD], n=416; CRT, n=661). Patients were assigned to CRT plus an ICD or to ICD alone in 3:2 random assignment. We assessed the degree to which baseline echocardiographic assessments of dyssynchrony, measured as the standard deviation of time-to-peak transverse strain over 12 segments, contractile function, measured as global longitudinal strain, or both predicted the effect of treatment on the primary outcome of death or heart failure. With 213 primary events occurring over a mean of 2.4 years, the benefit of CRT plus an ICD relative to ICD alone was greatest in patients with mild to moderate dyssynchrony (time-to-peak transverse strain standard deviation, 142 to 230 ms) and greater baseline contractile function (global longitudinal strain ≤-8.7%). Overall, those patients with mild to moderate dyssynchrony and those with best contractile function at baseline demonstrated the greatest benefit from CRT (adjusted hazards ratio, 0.20; 95% confidence interval, 0.09 to 0.44). Dyssynchrony and global longitudinal strain predicted response to CRT independent of each other, QRS width, LV ejection fraction, and presence versus absence of left bundle-branch block, although the observed benefit remained greatest in patients with left bundle-branch block.

CONCLUSIONS

Both mechanical dyssynchrony and contractile function are important independent correlates of benefit from CRT.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.

Strain dyssynchrony index determined by three-dimensional speckle area tracking can predict response to cardiac resynchronization therapy

BACKGROUND

We have previously reported strain dyssynchrony index assessed by two-dimensional speckle tracking strain, and a marker of both dyssynchrony and residual myocardial contractility, can predict response to cardiac resynchronization therapy (CRT). A newly developed three-dimensional (3-D) speckle tracking system can quantify endocardial area change ratio (area strain), which coupled with the factors of both longitudinal and circumferential strain, from all 16 standard left ventricular (LV) segments using complete 3-D pyramidal datasets. Our objective was to test the hypothesis that strain dyssynchrony index using area tracking (ASDI) can quantify dyssynchrony and predict response to CRT.

METHODS

We studied 14 heart failure patients with ejection fraction of 27 ± 7% (all≤35%) and QRS duration of 172 ± 30 ms (all≥120 ms) who underwent CRT. Echocardiography was performed before and 6-month after CRT. ASDI was calculated as the average difference between peak and end-systolic area strain of LV endocardium obtained from 3-D speckle tracking imaging using 16 segments. Conventional dyssynchrony measures were assessed by interventricular mechanical delay, Yu Index, and two-dimensional radial dyssynchrony by speckle-tracking strain. Response was defined as a ≥15% decrease in LV end-systolic volume 6-month after CRT.

RESULTS

ASDI ≥ 3.8% was the best predictor of response to CRT with a sensitivity of 78%, specificity of 100% and area under the curve (AUC) of 0.93 (p < 0.001). Two-dimensional radial dyssynchrony determined by speckle-tracking strain was also predictive of response to CRT with an AUC of 0.82 (p < 0.005). Interestingly, ASDI ≥ 3.8% was associated with the highest incidence of echocardiographic improvement after CRT with a response rate of 100% (7/7), and baseline ASDI correlated with reduction of LV end-systolic volume following CRT (r = 0.80, p < 0.001).

CONCLUSIONS

ASDI can predict responders and LV reverse remodeling following CRT. This novel index using the 3-D speckle tracking system, which shows circumferential and longitudinal LV dyssynchrony and residual endocardial contractility, may thus have clinical significance for CRT patients.

Utility of comprehensive assessment of strain dyssynchrony index by speckle tracking imaging for predicting response to cardiac resynchronization therapy

The strain delay index is reportedly a marker of dyssynchrony and residual myocardial contractility. The aim of this study was to test the hypothesis that a relatively simple version of the strain dyssynchrony index (SDI) can predict response to cardiac resynchronization therapy (CRT) and that combining assessment of radial, circumferential, and longitudinal SDI can further improve the prediction of responders. A total of 52 patients who underwent CRT were studied. The SDI was calculated as the average difference between peak and end-systolic strain from 6 segments for radial and circumferential SDI and 18 segments for longitudinal SDI. Conventional dyssynchrony measures were assessed by interventricular mechanical delay, the Yu index, and radial dyssynchrony by speckle tracking strain. Response was defined as a ≥15% decrease in end-systolic volume after 3 months. Of the individual parameters, radial SDI ≥6.5% was the best predictor of response to CRT, with sensitivity of 81%, specificity of 81%, and an area under the curve of 0.87 (p <0.001). Circumferential SDI ≥3.2% and longitudinal SDI ≥3.6% were also found to be predictive of response to CRT, with areas under the curve of 0.81 and 0.80, respectively (p <0.001). Moreover, radial, circumferential, and longitudinal SDI at baseline were correlated with reduction of end-systolic volume with CRT. In addition, the response rate in patients with 3 positive SDIs was 100%. In contrast, rates in patients with either 1 or no positive SDIs were 42% and 22%, respectively (p <0.005 and p <0.001 vs 3 positive SDIs). In conclusion, the SDI can successfully predict response to CRT, and the combined approach leads to more accurate prediction than using individual parameters.

Improvement in left ventricular systolic dyssynchrony in hypertensive patients after treatment of hypertension

BACKGROUND AND OBJECTIVES

Left ventricular (LV) dyssynchrony has been commonly detected among hypertensive patients with normal LV systolic function and no evidence of congestive heart failure. The purpose of our study was to assess the changes in LV systolic dyssynchrony (SDS(LV)) among hypertensive patients after antihypertensive treatment, and to determine the relationship between SDS(LV) and other conventional echocardiographic parameters.

SUBJECTS AND METHODS

Forty one hypertensive patients with normal LV ejection fraction were enrolled. By performing a conventional echocardiographic study, the SDS(LV) was measured as the time difference between the shortest and longest time of the peak myocardial systolic velocities among 12 segments of the basal and mid-levels of the 3 apical views, and radial dyssynchrony of the basal (RDS(base)) and mid-levels (RDS(mid)) measured as the time difference between the earliest and latest peak values on the radial strain curves of each level of the parasternal short-axis views.

RESULTS

Compared to baseline after six months of antihypertensive treatment, the SDS(LV) improved significantly (48.7±37.9 ms vs. 29.5±34.1 ms, p=0.020). Also the RDS(base) and RDS(mid) improved significantly in respect to the baseline values (129.9±136.3 ms vs. 38.8±45.4 ms, p=0.002 and 75.2±63.8 ms vs. 28.2±37.7 ms, respectively, p<0.001).

CONCLUSION

The severity of SDS(LV) improved with antihypertensive treatment, and was associated with the regression of LV mass. Furthermore, it might precede improvement in the mitral inflow pattern, as assessed by conventional echocardiography, so that early detection of the benefit of antihypertensive treatment may be possible.

Left ventricular systolic torsion correlates global cardiac performance during dyssynchrony and cardiac resynchronization therapy

Left ventricular (LV) systolic torsion is a primary mechanism contributing to stroke volume (SV). We hypothesized that change in LV torsion parallels changes in global systolic performance during dyssynchrony and cardiac resynchronization therapy (CRT). Seven anesthetized open chest dogs had LV pressure-volume relationship. Apical, basal, and mid-LV cross-sectional echocardiographic images were studied by speckle tracking analysis. Right atrial (RA) pacing served as control. Right ventricular (RV) pacing simulated left bundle branch block. Simultaneous RV-LV free wall and RV-LV apex pacing (CRTfw and CRTa, respectively) modeled CRT. Dyssynchrony was defined as the time difference in peak strain between earliest and latest segments. Torsion was calculated as the maximum difference between the apical and basal rotation. RA pacing had minimal dyssynchrony (52 ± 36 ms). RV pacing induced dyssynchrony (189 ± 61 ms, P < 0.05). CRTa decreased dyssynchrony (46 ± 36 ms, P < 0.05 vs. RV pacing), whereas CRTfw did not (110 ± 96 ms). Torsion during baseline RA was 6.6 ± 3.7°. RV pacing decreased torsion (5.1 ± 3.6°, P < 0.05 vs. control), and reduced SV, stroke work (SW), and dP/dt(max) compared with RA (21 ± 5 vs. 17 ± 5 ml, 252 ± 61 vs. 151 ± 64 mJ, and 2,063 ± 456 vs. 1,603 ± 424 mmHg/s, respectively, P < 0.05). CRTa improved torsion, SV, SW, and dP/dt(max) compared with RV pacing (7.7 ± 4.7°, 23 ± 3 ml, 240 ± 50 mJ, and 1,947 ± 647 mmHg/s, respectively, P < 0.05), whereas CRTfw did not (5.1 ± 3.6°, 18 ± 5 ml, 175 ± 48 mJ, and 1,699 ± 432 mmHg/s, respectively, P < 0.05). LV torsion changes covaried across conditions with SW (y = 0.94x+12.27, r = 0.81, P < 0.0001) and SV (y = 0.66x+0.91, r = 0.81, P < 0.0001). LV dyssynchrony changes did not correlate with SW or SV (r = -0.12, P = 0.61 and r = 0.08, P = 0.73, respectively). Thus, we conclude that LV torsion is primarily altered by dyssynchrony, and CRT that restores LV performance also restores torsion.

Relationship of echocardiographic dyssynchrony to long-term survival after cardiac resynchronization therapy

BACKGROUND

The ability of echocardiographic dyssynchrony to predict response to cardiac resynchronization therapy (CRT) has been unclear.

METHODS AND RESULTS

A prospective, longitudinal study was designed with predefined dyssynchrony indexes and outcome variables to test the hypothesis that baseline dyssynchrony is associated with long-term survival after CRT. We studied 229 consecutive class III to IV heart failure patients with ejection fraction ≤35 and QRS duration ≥120 milliseconds for CRT. Dyssynchrony before CRT was defined as tissue Doppler velocity opposing-wall delay ≥65 milliseconds, 12-site SD (Yu Index) ≥32 milliseconds, speckle tracking radial strain anteroseptal-to-posterior wall delay ≥130 milliseconds, or pulsed Doppler interventricular mechanical delay ≥40 milliseconds. Outcome was defined as freedom from death, heart transplantation, or left ventricular assist device implantation. Of 210 patients (89) with dyssynchrony data available, there were 62 events: 47 deaths, 9 transplantations, and 6 left ventricular assist device implantations over 4 years. Event-free survival was associated with Yu Index (P=0.003), speckle tracking radial strain (P=0.003), and interventricular mechanical delay (P=0.019). When adjusted for confounding baseline variables of ischemic origin and QRS duration, Yu Index and radial strain dyssynchrony remained independently associated with outcome (P<0.05). Lack of radial dyssynchrony was particularly associated with unfavorable outcome in those with QRS duration of 120 to 150 milliseconds (P=0.002).

CONCLUSIONS

The absence of echocardiographic dyssynchrony was associated with significantly less favorable event-free survival after CRT. Patients with narrower QRS duration who lacked dyssynchrony had the least favorable long-term outcome. These observations support the relationship of dyssynchrony and CRT response.

Impact of scar burden by single-photon emission computed tomography myocardial perfusion imaging on patient outcomes following cardiac resynchronization therapy

AIMS

Ischaemic heart disease negatively impacts response to cardiac resynchronization therapy (CRT), yet the impact of infarct scar burden on clinical outcomes and its interaction with mechanical dyssynchrony have not been well described.

METHODS AND RESULTS

We studied 620 NYHA classes III-IV heart failure patients with ejection fraction (EF) ≤ 35% and QRS duration ≥120 ms referred for CRT. Included were 190 ischaemic cardiomyopathy (ICM) CRT recipients with scar burden quantified by rest-redistribution Tl(201) myocardial perfusion imaging using a 17-segment (0 = normal to 4 = absence of uptake) summed rest score (SRS). Non-ICM (NICM) CRT recipients (n = 380) and 50 patients referred for CRT with unsuccessful LV lead implant comprised the comparison groups. Echocardiographic dyssynchrony analysis was performed in a subgroup of 150 patients. Follow-up left ventricular EF (LVEF) and volumes were examined at 7 ± 3 months in 143 patients. The outcome of death, cardiac transplant, or mechanical circulatory support was assessed in all. Over 2.1 ± 1.6 years, ICM patients had significantly worse survival and less LVEF improvement than NICM patients (P < 0.01). Ischaemic cardiomyopathy patients with low scar burden (SRS < 27) had favourable survival and LVEF improvement, similar to NICM patients. A high scar burden (SRS ≥ 27) was associated with reduced survival and lack of LV functional improvement (P ≤ 0.01), similar to those with unsuccessful LV lead implant, whereas baseline dyssynchrony was not predictive of outcome in these patients.

CONCLUSION

Extensive scar burden in ICM patients unfavourably affected clinical and LV functional outcomes after CRT, regardless of baseline dyssynchrony measures. Patients with ICM and lower scar burden had significantly better outcomes, similar to NICM patients.

Selecting the best site for pacing leads after cardiac surgery by evaluating the asynchrony of myocardial deformation observed with different pacing sites

INTRODUCTION AND OBJECTIVES

After cardiac surgery, temporary pacing leads are routinely implanted in the right ventricle (RV). The objective was to investigate the effect of different ventricular pacing locations on cardiac synchrony (by evaluating myocardial deformation, or strain) and efficiency in patients undergoing cardiac surgery.

METHODS

Interventricular asynchrony (i.e. the difference in the time of onset of deformation between right and left ventricles; Tε-R/L) and intraventricular asynchrony (i.e. the standard deviation and maximum difference in the time of onset of deformation in six segments of the left ventricle [LV]; Tε-SD and Tε-MD, respectively) were assessed in 19 patients. Doppler echocardiography was used to evaluate these parameters and cardiac output after pacing in the RV and in three different LV segments.

RESULTS

Pacing in the RV resulted in the greatest increases in asynchrony parameters from baseline: Tε-R/L 59.8 ms (standard deviation [SD] 40.5 ms) vs. 28.23 ms (SD 56.9 ms), P=.002; Tε-SD 53.2 ms (SD 34.4 ms) vs. 36.6 ms (SD 34.9 ms), P=.007; and Tε-MD 135.3 ms (SD 82.9 ms) vs. 90.5 ms (SD 87.4 ms), P=.007. Pacing in the LV resulted in less asynchrony: for anterior LV pacing, Tε-R/L was 17.2 ms (SD 53.8 ms), Tε-SD was 35.8 ms (SD 17.9 ms), and Tε-MD was 91.3 ms (SD 45.2). The change from baseline was not significant. Cardiac output was lower after RV pacing than after anterior LV pacing: 4.36 (SD 1) vs. 4.70 (SD 1); P=.001.

CONCLUSIONS

Pacing in the LV produced less asynchrony than RV pacing. In addition, anterior LV pacing resulted in a higher cardiac output than RV pacing. These findings suggest that the location normally used for temporary leads after cardiac surgery should be changed.

Association of intraventricular mechanical dyssynchrony with response to cardiac resynchronization therapy in heart failure patients with a narrow QRS complex

AIMS

current criteria for cardiac resynchronization therapy (CRT) are restricted to patients with a wide QRS complex (>120 ms). Overall, only 30% of heart failure patients demonstrate a wide QRS complex, leaving the majority of heart failure patients without this treatment option. However, patients with a narrow QRS complex exhibit left ventricular (LV) mechanical dyssynchrony, as assessed with echocardiography. To further elucidate the possible beneficial effect of CRT in heart failure patients with a narrow QRS complex, this two-centre, non-randomized observational study focused on different echocardiographic parameters of LV mechanical dyssynchrony reflecting atrioventricular, interventricular and intraventricular dyssynchrony, and the response to CRT in these patients.

METHODS AND RESULTS

a total of 123 consecutive heart failure patients with a narrow QRS complex (<120 ms) undergoing CRT was included at two centres. Several widely accepted measures of mechanical dyssynchrony were evaluated: LV filling ratio (LVFT/RR), LV pre-ejection time (LPEI), interventricular mechanical dyssynchrony (IVMD), opposing wall delay (OWD), and anteroseptal posterior wall delay with speckle tracking (ASPWD). Response to CRT was defined as a reduction ≥15% in left ventricular end-systolic volume at 6 months follow-up. Measures of dyssynchrony can frequently be observed in patients with a narrow QRS complex. Nonetheless, for LVFT/RR, LPEI, and IVMD, presence of predefined significant dyssynchrony is <20%. Significant intraventricular dyssynchrony is more widely observed in these patients. With receiver operator characteristic curve analyses, both OWD and ASPWD demonstrated usefulness in predicting response to CRT in narrow QRS patients with a cut-off value of 75 and 107 ms, respectively.

CONCLUSION

mechanical dyssynchrony can be widely observed in heart failure patients with a narrow QRS complex. In particular, intraventricular measures of mechanical dyssynchrony may be useful in predicting LV reverse remodelling at 6 months follow-up in heart failure patients with a narrow QRS complex, but with more stringent cut-off values than currently used in 'wide' QRS patients.

Assessment of myocardial mechanics using speckle tracking echocardiography: fundamentals and clinical applications

The authors summarize the recent developments in speckle-tracking echocardiography (STE), a relatively new technique that can be used in conjunction with two-dimensional or three-dimensional echocardiography for resolving the multidirectional components of left ventricular (LV) deformation. The tracking system is based on grayscale B-mode images and is obtained by automatic measurement of the distance between 2 pixels of an LV segment during the cardiac cycle, independent of the angle of insonation. The integration of STE with real-time cardiac ultrasound imaging overcomes some of the limitations of previous work in the field and has the potential to provide a unified framework to more accurately quantify the regional and global function of the left ventricle. STE holds promise to reduce interobserver and intraobserver variability in assessing regional LV function and to improve patient care while reducing health care costs through the early identification of subclinical disease. Following a brief overview of the approach, the authors pool the initial observations from clinical studies on the development, validation, merits, and limitations of STE.

Left ventricular dyssynchrony in patients showing diastolic dysfunction without overt symptoms of heart failure

BACKGROUND/AIMS

Few studies have assessed left ventricular (LV) dyssynchrony in cases of diastolic dysfunction that do not include overt symptoms of heart failure. We hypothesized that systolic or diastolic dyssynchrony involves unique features with respect to the degree of diastolic impairment in isolated diastolic dysfunction.

METHODS

We examined 105 subjects with no history of overt symptoms of heart failure and a left ventricular ejection fraction > 50% for mechanical dyssynchrony using tissue Doppler imaging.

RESULTS

In terms of longitudinal dyssynchrony, four cases showed (6.3%) LV intraventricular systolic dyssynchrony (SDS(LV)), whereas none had LV intraventricular diastolic dyssynchrony (DDS(LV)) or co-existing systolic dyssynchrony. Radial dyssynchrony (RD) was found in six cases (9.4%). After adjusting for age, SDS(LV) and DDS(LV) were found to be significantly related to increases in the E/E' ratio (r = 0.405 and p < 0.001 vs. r = 0.216 and p = 0.045, respectively). RD at the base and apex was also significantly related to increases in E/E' (r = 0.298 and p = 0.002 vs. r = 0.196 and p = 0.045, respectively).

CONCLUSIONS

Systolic and diastolic dyssynchrony in subjects with isolated diastolic dysfunction but without overt symptoms of heart failure was not as common as in patients with diastolic heart failure; however, the systolic and diastolic intraventricular time delay increased with increases in the E/E' ratio, an indicator of diastolic dysfunction.

Comparative mechanical activation mapping of RV pacing to LBBB by 2D and 3D speckle tracking and association with response to resynchronization therapy

OBJECTIVES

The goals of this study were to compare patterns of mechanical activation in patients with chronic right ventricular (RV) pacing with those with left bundle branch block (LBBB) using 2-dimensional and novel 3-dimensional speckle tracking, and to compare ejection fraction (EF) response and long-term survival after cardiac resynchronization therapy (CRT).

BACKGROUND

Several randomized CRT trials have excluded patients with chronic RV pacing, and current guidelines for CRT include patients with intrinsically widened QRS, typically LBBB.

METHODS

We studied 308 patients who were referred for CRT: 227 had LBBB, 81 were RV paced. Dyssynchrony was assessed by tissue Doppler, routine pulsed Doppler, and 2-dimensional speckle-tracking radial strain. 3D strain was assessed using speckle tracking from a pyramidal dataset in a subset of 57 patients for mechanical activation mapping. Survival after CRT was compared with survival in a group of 46 patients with attempted, but failed, CRT.

RESULTS

Patients with chronic RV pacing and LBBB had similar intraventricular dyssynchrony, with opposing wall delays by tissue Doppler of 82 +/- 45 ms versus 87 +/- 63 ms and anteroseptum-to-posterior delays by speckle tracking of 225 +/- 142 ms, versus 211 +/- 107 ms, respectively. RV-paced patients, however, had greater interventricular dyssynchrony: 44 +/- 24 ms versus 35 +/- 21 ms (p < 0.01), which correlated with their greater QRS duration (p < 0.001). Sites of latest mechanical activation were most often posterior or lateral in both groups, but RV-paced patients had sites of earliest activation more often from the inferior-septum and apex (p < 0.05). EF response was similar in RV-paced and LBBB groups, and survival free from transplantation or mechanical support after CRT was similarly favorable as compared with failed CRT patients over 5 years (p < 0.01).

CONCLUSIONS

RV-paced patients, when compared with LBBB patients, had similar dyssynchronous patterns of mechanical activation and greater interventricular dyssynchrony. Importantly, RV-paced patients had similar EF response and long-term outcome as those with LBBB, which supports their candidacy for CRT.

Echocardiography, dyssynchrony, and the response to cardiac resynchronization therapy

Biventricular pacing or cardiac resynchronization therapy (CRT) has been a considerable advance in the therapy of chronic heart failure. However, it is clear that not all patients benefit either in terms of symptoms or cardiac function, and some may be worsened by CRT. In this review, we consider the arguments, both clinical and economical, in favour of improved selection of patients for CRT other than those in current guidelines. It also seems clear that the fundamental mechanism of CRT is correction of dyssynchrony, and we review the various methodologies available to detect dyssynchrony. Other factors are probably also important in determining outcomes such as lead position, the extent and form of myocardial damage, optimizing pacemaker performance, and clinical expertise. The potential costs of inappropriate CRT implantation are high to our patients and to the health economy, and it behooves the cardiology community to develop better selection criteria. The current guidelines can and should be improved.

Multi-plane mechanical dyssynchrony in cardiac resynchronization therapy

BACKGROUND

The aims of this study were to assess the ability of several echo measures of dyssynchrony to predict CRT response and to characterize the global effect of CRT.

HYPOTHESIS

We hypothesized that after CRT there would be significant reductions in mechanical dyssynchrony in all 3 orthogonal planes of cardiac motion and that those patients with significant dyssynchrony prior to implant would have the best echocardiographic response.

METHODS

Standard echocardiograms were performed pre-CRT and post-CRT (138 +/- 63d) in 70 heart failure patients. Longitudinal dyssynchrony was calculated as the standard deviation (SD) of time to peak systolic displacement and velocity of 12 segments from 3 apical views. Using midventricular short axis views and speckle-tracking methods, the SD of time to peak radial and circumferential strain in 6 segments were calculated. Cardiac resynchronization therapy echo response was defined as > or = 15% decrease in left ventricular end-systolic volume.

RESULTS

Cardiac resynchronization therapy significantly improved systolic function in the longitudinal, radial, and circumferential planes. The CRT echo response rate was 57%. Echo responders (CRT(R)) had significantly (P < .05) more dyssynchrony at baseline as compared to nonresponders (CRT(NR)). Cardiac resynchronization therapy significantly (P < .05) reduced longitudinal and radial, but not circumferential, dyssynchrony in CRT(R). Dyssynchrony was unchanged in CRT(NR). Receiver-operator characteristic (ROC) curve analysis indicated significant, but modest sensitivity and specificity for longitudinal and radial intraventricular dyssynchrony and for interventricular dyssynchrony. Combining radial and longitudinal dyssynchrony measures improved positive prediction of CRT response.

CONCLUSIONS

Cardiac resynchronization therapy improves left ventricular function in 3 orthogonal planes of motion. Longitudinal, radial, and interventricular dyssynchrony modestly predict reverse remodeling.

Dyssynchrony by speckle-tracking echocardiography and response to cardiac resynchronization therapy: results of the Speckle Tracking and Resynchronization (STAR) study

Aims

The Speckle Tracking and Resynchronization (STAR) study used a prospective multi-centre design to test the hypothesis that speckle-tracking echocardiography can predict response to cardiac resynchronization therapy (CRT).

Methods and results

We studied 132 consecutive CRT patients with class III and IV heart failure, ejection fraction (EF) ≤35%, and QRS ≥120 ms from three international centres. Baseline dyssynchrony was evaluated by four speckle tracking strain methods; radial, circumferential, transverse, and longitudinal (≥130 ms opposing wall delay for each). Pre-specified outcome variables were EF response and three serious long-term events: death, transplant, or left ventricular assist device. Of 120 patients (91%) with baseline dyssynchrony data, both short-axis radial strain and transverse strain from apical views were associated with favourable EF response 7 ± 4 months and long-term outcome over 3.5 years (P < 0.01). Radial strain had the highest sensitivity at 86% for predicting EF response with a specificity of 67%. Serious long-term unfavourable events occurred in 20 patients after CRT, and happened three times more frequently in those who lacked baseline radial or transverse dyssynchrony than in patients with dyssynchrony (P < 0.01). Patients who lacked both radial and transverse dyssynchrony had unfavourable clinical events occur in 53%, in contrast to events occurring in 12% if baseline dyssynchrony was present (P < 0.01). Circumferential and longitudinal strains predicted response when dyssynchrony was detected, but failed to identify dyssynchrony in one-third of patients who responded to CRT.

Conclusion

Dyssynchrony by speckle-tracking echocardiography using radial and transverse strains is associated with EF response and long-term outcome following CRT.

Agreement is poor among current criteria used to define response to cardiac resynchronization therapy

BACKGROUND

Numerous criteria believed to define a positive response to cardiac resynchronization therapy have been used in the literature. No study has investigated agreement among these response criteria. We hypothesized that the agreement among the various response criteria would be poor.

METHODS AND RESULTS

A literature search was conducted with the keywords "cardiac resynchronization" and "response." The 50 publications with the most citations were reviewed. After the exclusion of editorials and reviews, 17 different primary response criteria were identified from 26 relevant articles. The agreement among 15 of these 17 response criteria was assessed in 426 patients from the Predictors of Response to Cardiac Resynchronization Therapy (PROSPECT) study with Cohen's kappa-coefficient (2 response criteria were not calculable from PROSPECT data). The overall response rate ranged from 32% to 91% for the 15 response criteria. Ninety-nine percent of patients showed a positive response according to at least 1 of the 15 criteria, whereas 94% were classified as a nonresponder by at least 1 criterion. kappa-Values were calculated for all 105 possible comparisons among the 15 response criteria and classified into standard ranges: Poor agreement (kappa< or =0.4), moderate agreement (0.4<kappa<0.75), and strong agreement (kappa> or =0.75). Seventy-five percent of the comparisons showed poor agreement, 21% showed moderate agreement, and only 4% showed strong agreement.

CONCLUSIONS

The 26 most-cited publications on predicting response to cardiac resynchronization therapy define response using 17 different criteria. Agreement between different methods to define response to cardiac resynchronization therapy is poor 75% of the time and strong only 4% of the time, which severely limits the ability to generalize results over multiple studies.

Echo/Doppler-derived time intervals are able to predict left ventricular reverse remodeling after cardiac resynchronization therapy

AIM

We evaluated the predictive value of echo/Doppler derived indices, which reflect the duration of the isovolumic phases of the cardiac cycle, in identifying cardiac resynchronization therapy (CRT) responders.

METHODS AND RESULTS

In 105 patients before and 6 months after CRT the following echo/Doppler parameters were evaluated: myocardial performance index (MPI) as the sum of isovolumic contraction time (IVCT) and isovolumic relaxation time (IVRT) divided by ejection time; total isovolumic time (t-IVT) as the sum of IVCT and IVRT divided by the RR interval; and standard deviation of the time to systolic peak velocity (Ts-SD) as asynchrony index. After 6 months, patients were defined responders according to 15% left ventricle (LV) end-systolic volume reduction or more. At baseline, responders (53.3%) had higher t-IVT and MPI than nonresponders (0.30 +/- 0.06 versus 0.22 +/- 0.05, P < 0.0001 and 1.01 +/- 0.27 versus 0.73 +/- 0.19, P < 0.0001, respectively). Receiving operating characteristic curve analysis showed that both t-IVT (80.3% sensitivity and 83.7% specificity, cut-off = 0.263) and MPI (78.6% sensitivity and 81.6% specificity, cut-off = 0.84) could predict CRT response. Baseline t-IVT correlated well to end-systolic volume reduction (r = -0.56, P < 0.00001).

CONCLUSION

Echo/Doppler derived indices, describing physiologic abnormalities of the isovolumic contraction and relaxation phase, are able to predict CRT-induced reverse remodeling.

Patient assessment for cardiac resynchronization therapy: Past, present and future of imaging techniques

It has been proposed that dyssynchrony assessment before cardiac resynchronization therapy (CRT) implantation could help predict response to CRT. It is known that up to 40% of patients who receive a CRT device for established indications do not respond to CRT. Great expectations came from the Predictors of Response to Cardiac Resynchronization Therapy (PROSPECT) study, which would finally identify the ultimate echocardiographic dyssynchrony criteria to help select responders. The recently published PROSPECT trial failed to identify an ideal parameter of dyssynchrony. Patient selection for CRT should involve a multimodal approach, and new promising tools are being investigated in that view. The present review integrated new data coming from the exciting field of imaging with currently available evidence to generate a stepwise approach to patient selection.

Dynamic and site-specific impact of ventricular pacing on left ventricular ejection fraction

BACKGROUND

Some studies suggest that right ventricular (RV) pacing has an adverse impact on left ventricular ejection fraction (LVEF), particularly in subjects with preexisting left ventricular (LV) dysfunction, and that direct LV pacing may be relatively protective. Interactions between pacing site and LVEF remain unclear.

OBJECTIVE

The purpose of this study was to examine the relative impact of RV and LV pacing on LVEF by serial study during a period in which LV dysfunction, induced by tachypacing, was introduced and then resolved.

METHODS

In each of five dogs, RV, LV, and simultaneous RV and LV (BiV) pacing modes were compared to native ventricular activation (1) prior to tachypacing (baseline), (2) weekly during a 5-week continuous tachypacing period, and (3) weekly during a 3-week post-tachypacing recovery period. At each evaluation, LVEF and LV contraction synchrony were assessed during each pacing mode.

RESULTS

The decrease in LVEF during the tachypacing period was more pronounced during RV pacing than during native activation or LV or BiV pacing. The magnitude of this effect correlated with a diminishment in LV contraction synchrony that was not observed during native activation or LV or BiV pacing. During the post-tachypacing period, gradual reversal of these changes toward baseline was observed.

CONCLUSION

Compared to native activation, RV pacing worsens LVEF in a manner proportional to the severity of preexisting LV dysfunction, attributable to reduced LV contraction synchrony. In comparison, both LV and BiV pacing preserve LVEF and contraction synchrony.

Combined assessment of left ventricular dyssynchrony and contractility by speckled tracking strain imaging: a novel index for predicting responders to cardiac resynchronization therapy

BACKGROUND

Mechanical dyssynchrony is an important factor in the response to cardiac resynchronization therapy (CRT). However, no echocardiographic measure can improve prediction of case selection for CRT.

OBJECTIVE

The purpose of this study was to assess the efficacy of a newly combined echocardiographic index for ventricular dyssynchrony and contractility using speckled tracking strain analysis to predict responders to CRT.

METHODS

Forty-seven patients with severe heart failure in New York Heart Association functional class III/IV, left ventricular ejection fraction </=35%, and QRS duration >/=130 ms were included in the study. Echocardiography was performed, and a novel index (i-Index), the product of radial dyssynchrony and radial strain, was calculated. Responder to CRT was defined as a patient with a >/=15% decrease in left ventricular end-systolic volume at 6-month follow-up.

RESULTS

Thirty-two patients (68%) were classified as responders. The i-Index was significantly higher in responders than in nonresponders (3,450 +/- 1180 vs 1,481 +/- 841, P <.001). The area under receiver operator characteristic curve was 0.92 for the i-Index, which was better than the index of radial dyssynchrony only (0.74). A cutoff value of i-Index >2,000 predicted responders with 94% sensitivity and 80% specificity. The index using only radial dyssynchrony had 81% sensitivity and 53% specificity. Furthermore, i-Index decreased in responders (1,985 +/- 1261, P <.001) but not in nonresponders (1,684 +/- 866, P = .48).

CONCLUSION

Our findings suggest that a novel combined index by radial strain echocardiography might be a predictor of response to CRT. The value of this novel echocardiographic index requires further assessment in larger studies.

Usefulness of three-dimensional speckle tracking strain to quantify dyssynchrony and the site of latest mechanical activation

Previous methods to quantify dyssynchrony could not determine regional 3-dimensional (3-D) strain. We hypothesized that a novel 3-D speckle tracking strain imaging system can quantify left ventricular (LV) dyssynchrony and site of latest mechanical activation. We studied 64 subjects; 54 patients with heart failure were referred for cardiac resynchronization therapy (CRT) with an ejection fraction 25 +/- 6% and QRS interval 165 +/- 29 ms and 10 healthy volunteer controls. The 3-D speckle tracking system determined radial strain using a 16-segment model from a pyramidal 3-D dataset. Dyssynchrony was quantified as maximal opposing wall delay and SD in time to peak strain. The 3-D analysis was compared to standard 2-dimensional (2-D) strain datasets and site of 3-D latest mechanical activation, not possible by 2D was quantified. As expected, dyssynchrony in patients on CRT was significantly greater than in controls (maximal opposing wall delay 316 +/- 112 vs 59 +/- 12 ms and SD 124 +/- 48 vs 28 +/- 11 ms, p <0.001 vs normal). The 3-D opposing wall delay was closely correlated with 3-D 16-segment SD (r = 0.95) and 2-D mid-LV strain (r = 0.83) and SD (r = 0.85, all p values <0.001). The 3-D site of the latest mechanical activation was most commonly midposterior (26%), basal posterior (22%), midlateral (20%), and basal lateral (17%). Eleven patients studied after CRT demonstrated improvements in 3-D synchrony (300 +/- 124 to 94 +/- 37 ms) and ejection fraction (24 +/- 6% to 31 +/- 7%, p <0.05). In conclusion, 3-D speckle tracking can successfully quantify 3-D dyssynchrony and site the latest mechanical activation. This approach may play a clinical role in management of patients on CRT.

Echocardiography for the clinician: a practical update

Echocardiography is the mainstay of cardiovascular diagnostics, and is the most performed test for the evaluation of cardiac function. Critical and costly management decisions are based on quantification of left ventricular volumes and ejection fraction. Recent advances in echocardiography, such as microsphere contrast echocardiography for left ventricular opacification and perfusion imaging, three-dimensional transthoracic and trans-oesophageal imaging, strain and tissue Doppler imaging, all contribute to improving accuracy and reproducibility of these important measurements. Such techniques are now routinely available on standard echocardiography equipment in Australian centres for daily use. Hand-carried ultrasound devices have been developed, which are portable, are affordable and offer increased availability of echocardiography to the wider community. Clinicians should be actively encouraged to adopt these technologies to improve the diagnostic quality and reproducability of echocardiography for our patients. This article provides an overview of important recent advances in echocardiographic imaging with an emphasis on their role in clinical practice today.

Impact of right ventricular contractility on left ventricular dyssynchrony in patients with chronic systolic heart failure

BACKGROUND

Cardiac resynchronization therapy (CRT) is an important therapeutic approach for patients with symptomatic heart failure. The assessment of mechanical dyssynchrony, however, remains an issue. Little data are available regarding the influence of the right ventricle (RV) on left ventricle (LV) mechanical dyssynchrony as assessed by echocardiography.

AIMS

We sought to assess the impact of RV contractility on LV function and dyssynchrony.

METHODS

A total of 40 patients with congestive heart failure were analyzed. Twenty had RV dysfunction, as defined by a tricuspid annular systolic peak of tissue Doppler (SaRV)<11.5 cm/s, while the remaining 20 had SaRV>11.5 cm/s. All patients underwent echocardiography in order to determine RV function, LV function, and dyssynchrony.

RESULTS

The two populations were similar regarding diastolic function, atrio-ventricular conduction and interventricular dyssynchrony. Patients with RV dysfunction showed significantly more severe LV longitudinal dyssynchrony (130±103 ms vs. 62±59 ms; p=0.01). In addition, SaRV (systolic peak recorded at the tricuspid annulus) was correlated with LV longitudinal dyssynchrony (r=0.47; p=0.001). In contrast, LV radial contractility and dyssynchrony (103±110 ms vs. 100±78 ms; p=0.5) were not affected by RV function.

CONCLUSION

Quantitative analysis of RV function is important when assessing LV function and dyssynchrony in patients with systolic heart failure. RV function is associated with intra-LV dyssynchrony, particularly when considering longitudinal function.

Health-e-Child project: mechanical dyssynchrony in children with dilated cardiomyopathy

OBJECTIVE

Left ventricular mechanical dyssynchrony has been poorly studied in the pediatric population with dilated cardiomyopathy. We investigated the degree of dyssynchrony in children with dilated cardiomyopathy using tissue Doppler imaging and speckle tracking strain.

METHODS

Twenty-five children with dilated cardiomyopathy were compared with healthy subjects. Left ventricular mechanical dyssynchrony was assessed by speckle tracking strain and tissue Doppler imaging. Both radial and longitudinal dyssynchrony were analyzed. Left ventricular end-diastolic diameter was measured to assess the relation between dyssynchrony and ventricular function and remodeling.

RESULTS

Radial and longitudinal dyssynchrony parameters were significantly higher in the dilated cardiomyopathy group and correlated with Z-score left ventricular end-diastolic diameter. A logarithmic correlation between left ventricular ejection fraction and left ventricular end-diastolic diameter parameters was found.

CONCLUSION

In children with dilated cardiomyopathy, tissue Doppler imaging and speckle tracking strain allowed the detection of dyssynchrony, which correlates with the severity of left ventricular function.

Usefulness and limitation of dobutamine stress echocardiography to predict acute response to cardiac resynchronization therapy

BACKGROUND

It has been hypothesized that a long-term response to cardiac resynchronization therapy (CRT) could correlate with myocardial viability in patients with left ventricular (LV) dysfunction. Contractile reserve and viability in the region of the pacing lead have not been investigated in regard to acute response after CRT.

METHODS

Fifty-one consecutive patients with advanced heart failure, LV ejection fraction <or= 35%, QRS duration > 120 ms, and intraventricular asynchronism >or= 50 ms were prospectively included. The week before CRT implantation, the presence of viability was evaluated using dobutamine stress echocardiography. Acute responders were defined as a >or=15% increase in LV stroke volume.

RESULTS

The average of viable segments was 5.8 +/- 1.9 in responders and 3.9 +/- 3 in nonresponders (P = 0.03). Viability in the region of the pacing lead had an excellent sensitivity (96%), but a low specificity (56%) to predict acute response to CRT. Mitral regurgitation (MR) was reduced in 21 patients (84%) with acute response. The presence of MR was a poor predictor of response (sensibility 93% and specificity 17%). However, combining the presence of MR and viability in the region of the pacing lead yields a sensibility (89%) and a specificity (70%) to predict acute response to CRT.

CONCLUSION

Myocardial viability is an important factor influencing acute hemodynamic response to CRT. In acute responders, significant MR reduction is frequent. The combined presence of MR and viability in the region of the pacing lead predicts acute response to CRT with the best accuracy.