Site of latest activation in patients eligible for cardiac resynchronization therapy: patterns of dyssynchrony among different QRS configurations and impact of heart failure etiology.

INTRODUCTION: Cardiac resynchronization therapy (CRT) has emerged as a treatment option for patients with end-stage heart failure and a QRS duration ≥120 ms. Nonetheless, many patients with a prolonged QRS do not demonstrate left ventricular (LV) mechanical dyssynchrony, and discrepancies between electrical and mechanical dyssynchrony have been observed. In addition, several studies demonstrated that superior benefits after CRT could be achieved when the LV pacing lead was positioned at the most delayed myocardial segment. METHODS: A total of 248 heart failure patients scheduled for CRT were included. In all patients, a 12-lead electrocardiogram and 2-dimensional echocardiogram were obtained. Patients were divided into 5 QRS configuration subgroups: narrow, left bundle-branch block, right bundle-branch block, intraventricular conduction delay, and right ventricular pacing. With speckle-tracking radial strain analysis, we evaluated time to peak radial strain. Next, the segments with the least and with the most mechanical activation delay were identified, and LV dyssynchrony was defined as the time delay between the two. RESULTS: Mean QRS duration was 164 ± 31 ms. Mean LV dyssynchrony in all patients was 186 ± 122 ms. Site of latest activation was predominantly located in the lateral (27%), posterior (26%), and inferior (20%) segments. Furthermore, extent of LV dyssynchrony was comparable between QRS configuration subgroups. An unequal distribution of LV segments with the most mechanical delay was observed in the left bundle-branch block and right ventricular pacing subgroups (P < .001 for both), whereas in the narrow, right bundle-branch block, and intraventricular conduction delay subgroups, a more homogeneous distribution was noted. No differences in distribution pattern or in extent of LV dyssynchrony were observed between ischemic and nonischemic heart failure patients. CONCLUSION: The lateral, posterior, and inferior segments take up 73% of the total latest activated segments in heart failure patients eligible for CRT. Presence of LV dyssynchrony can be observed in all QRS configurations. The site of latest activation may be outside the lateral or posterior segment, making echocardiographic assessment of LV dyssynchrony and site of latest activation a valuable technique to optimize patient outcome after CRT.

Impaired renal function is associated with echocardiographic nonresponse and poor prognosis after cardiac resynchronization therapy.

OBJECTIVES: Aims of this study were to investigate the effect of renal function on left ventricular (LV) reverse remodeling and long-term outcome after cardiac resynchronization therapy (CRT), and to explore the relation between LV reverse remodeling and changes in renal function at 6-month follow-up. BACKGROUND: Renal insufficiency is highly prevalent in heart failure patients, including patients eligible for CRT, and is associated with poor prognosis. METHODS: The study comprised 490 patients undergoing CRT. Response to CRT was defined as a decrease in LV end-systolic volume ≥15% at 6-month follow-up. Primary end point during long-term follow-up was all-cause mortality. RESULTS: At baseline, mean estimated glomerular filtration rate (eGFR) was 70 ± 28 ml/min/1.73 m². At 6-month follow-up, 263 patients (54%) demonstrated response to CRT. Responders had an eGFR of 74 ± 26 ml/min/1.73 m² versus 64 ± 28 ml/min/1.73 m² in nonresponders (p < 0.001). During long-term follow-up, patients with an eGFR <60 ml/min/1.73 m² had higher mortality than patients with an eGFR of 60 to 90 ml/min/1.73 m² or an eGFR >90 ml/min/1.73 m² (p < 0.001). Finally, responders to CRT had preservation of renal function (ΔeGFR -0.6), whereas nonresponders had a slight worsening in renal function (ΔeGFR -4.7, p < 0.05). CONCLUSIONS: Impaired renal function in CRT candidates is associated with nonresponse during 6-month follow-up. Additionally, patients with impaired renal function have worse long-term survival after CRT. Response to CRT results in preservation of renal function.

Relative merits of left ventricular dyssynchrony, left ventricular lead position, and myocardial scar to predict long-term survival of ischemic heart failure patients undergoing cardiac resynchronization therapy.

BACKGROUND: The relative merits of left ventricular (LV) dyssynchrony, LV lead position, and myocardial scar to predict long-term outcome after cardiac resynchronization therapy remain unknown and were evaluated in the present study. METHODS AND RESULTS: In 397 ischemic heart failure patients, 2-dimensional speckle tracking imaging was performed, with comprehensive assessment of LV radial dyssynchrony, identification of the segment with latest mechanical activation, and detection of myocardial scar in the segment where the LV lead was positioned. For LV dyssynchrony, a cutoff value of 130 milliseconds was used. Segments with <16.5% radial strain in the region of the LV pacing lead were considered to have extensive myocardial scar (>50% transmurality, validated in a subgroup with contrast-enhanced magnetic resonance imaging). The LV lead position was derived from chest x-ray. Long-term follow-up included all-cause mortality and hospitalizations for heart failure. Mean baseline LV radial dyssynchrony was 133±98 milliseconds. In 271 patients (68%), the LV lead was placed at the latest activated segment (concordant LV lead position), and the mean value of peak radial strain at the targeted segment was 18.9±12.6%. Larger LV radial dyssynchrony at baseline was an independent predictor of superior long-term survival (hazard ratio, 0.995; P=0.001), whereas a discordant LV lead position (hazard ratio, 2.086; P=0.001) and myocardial scar in the segment targeted by the LV lead (hazard ratio, 2.913; P<0.001) were independent predictors of worse outcome. Addition of these 3 parameters yielded incremental prognostic value over the combination of clinical parameters. CONCLUSIONS: Baseline LV radial dyssynchrony, discordant LV lead position, and myocardial scar in the region of the LV pacing lead were independent determinants of long-term prognosis in ischemic heart failure patients treated with cardiac resynchronization therapy. Larger baseline LV dyssynchrony predicted superior long-term survival, whereas discordant LV lead position and myocardial scar predicted worse outcome.

Morbidity and mortality in heart failure patients treated with cardiac resynchronization therapy: influence of pre-implantation characteristics on long-term outcome.

AIMS: Cardiac resynchronization therapy (CRT) improves cardiac function, heart failure symptoms, and prognosis in selected patients. Many baseline characteristics associated with heart failure may influence prognosis after CRT. The objective of this study was to evaluate the effect of several baseline characteristics in relation to long-term prognosis in heart failure patients treated with CRT. METHODS AND RESULTS: A total of 716 consecutive heart failure patients treated with CRT were included in an observational registry. All available data, including clinical and echocardiographic measurements, were analysed in relation to two endpoints: all-cause mortality and a combined endpoint of all-cause mortality or major cardiovascular event. Outcome data were collected by chart review, device interrogation, and telephone contact. Mean follow-up was 25 ± 19 months. During follow-up, 141 patients (20%) died (primary endpoint). Most of these patients (61%) died due to worsening heart failure. A total of 214 patients (30%) reached the secondary endpoint. Larger left ventricular end-systolic volume, less distance covered in the 6 min walking test, poor renal function, more severe heart failure, male gender, presence of atrial fibrillation, no posterolateral left ventricular (LV) lead, and no LV dyssynchrony were associated with poor prognosis after CRT. CONCLUSION: In this large single-centre registry, several baseline clinical and echocardiographic characteristics were associated with prognosis after CRT. Worsening heart failure was the main cause of death in heart failure patients treated with CRT.

Effect of cardiac resynchronization therapy on cerebral blood flow.

Decreased cerebral blood flow is frequently observed in patients with heart failure, and this could be the result of impaired cardiac systolic function. Cardiac resynchronization therapy (CRT) improves cardiac function and heart failure symptoms in selected patients. The effects of CRT on cerebral blood flow have not been previously evaluated. In the present study, left ventricular systolic function and cerebral blood flow were assessed in 35 patients with heart failure, before and 6 months after CRT. Additionally, 15 patients with heart failure, who were not candidates for CRT, were included as a control group. The peak systolic velocity, end-diastolic velocity, mean velocity, and pulsatility index ([peak systolic velocity--end-diastolic velocity]/mean velocity) were obtained using transcranial Doppler from the right middle cerebral artery from the temporal window in all subjects. Response to CRT was defined as a reduction in the left ventricular end-systolic volume of > or =15%. At 6 months of follow-up, the peak systolic velocity had significantly increased from 83 +/- 20 cm/s to 100 +/- 20 cm/s (p = 0.001), the end-diastolic velocity had increased from 29 +/- 7 cm/s to 37 +/- 8 cm/s (p <0.001), and the mean velocity had increased from 47 +/- 10 cm/s to 58 +/- 11 cm/s (p <0.001) only in the responders to CRT. In contrast, no significant changes in cerebral blood flow were observed in the nonresponders and the controls. In conclusion, CRT induced an increase in cerebral blood flow in patients with heart failure. This increase in cerebral blood flow was related to the improvement in left ventricular systolic function.

Value of tissue Doppler echocardiography in predicting response to cardiac resynchronization therapy in patients with heart failure.

Several studies have demonstrated a relation between left ventricular (LV) dyssynchrony and response to cardiac resynchronization therapy (CRT). Many methods of determining LV dyssynchrony have been proposed, including a value of 65 ms as assessed by tissue Doppler imaging. The aim of the present validation study was to prospectively test the predictive accuracy of the 65-ms cutoff for LV dyssynchrony in a large cohort of patients with heart failure undergoing CRT. The study included 361 patients who had undergone CRT. The clinical and echocardiographic parameters were assessed at baseline and at 6 months of follow-up. The clinical response was defined as an improvement of > or = 1 New York Heart Association class, and the echocardiographic response was defined as a reduction in LV end-systolic volume of > or = 15%. At 6 months of follow-up, 259 patients (72%) had a clinical response and 187 patients (52%) had an echocardiographic response. The patients with a response had more LV dyssynchrony than did those without a response (91 + or - 49 ms vs 50 + or - 44 ms for the clinical response and 101 + or - 46 ms vs 55 + or - 45 ms for the echocardiographic response). On multivariate analysis, LV dyssynchrony remained predictive of the response, independent of other characteristics. In conclusion, LV dyssynchrony of > or = 65 ms was an independent predictor of both the clinical and the echocardiographic response in patients with heart failure who underwent CRT in this validation study.

Quantification of functional mitral regurgitation by real-time 3D echocardiography: comparison with 3D velocity-encoded cardiac magnetic resonance.

OBJECTIVES: The aim of this study was to evaluate feasibility and accuracy of real-time 3-dimensional (3D) echocardiography for quantification of mitral regurgitation (MR), in a head-to-head comparison with velocity-encoded cardiac magnetic resonance (VE-CMR). BACKGROUND: Accurate grading of MR severity is crucial for appropriate patient management but remains challenging. VE-CMR with 3D three-directional acquisition has been recently proposed as the reference method. METHODS: A total of 64 patients with functional MR were included. A VE-CMR acquisition was applied to quantify mitral regurgitant volume (Rvol). Color Doppler 3D echocardiography was applied for direct measurement, in "en face" view, of mitral effective regurgitant orifice area (EROA); Rvol was subsequently calculated as EROA multiplied by the velocity-time integral of the regurgitant jet on the continuous-wave Doppler. To assess the relative potential error of the conventional approach, color Doppler 2-dimensional (2D) echocardiography was performed: vena contracta width was measured in the 4-chamber view and EROA calculated as circular (EROA-4CH); EROA was also calculated as elliptical (EROA-elliptical), measuring vena contracta also in the 2-chamber view. From these 2D measurements of EROA, the Rvols were also calculated. RESULTS: The EROA measured by 3D echocardiography was significantly higher than EROA-4CH (p < 0.001) and EROA-elliptical (p < 0.001), with a significant bias between these measurements (0.10 cm(2) and 0.06 cm(2), respectively). Rvol measured by 3D echocardiography showed excellent correlation with Rvol measured by CMR (r = 0.94), without a significant difference between these techniques (mean difference = -0.08 ml/beat). Conversely, 2D echocardiographic approach from the 4-chamber view significantly underestimated Rvol (p = 0.006) as compared with CMR (mean difference = 2.9 ml/beat). The 2D elliptical approach demonstrated a better agreement with CMR (mean difference = -1.6 ml/beat, p = 0.04). CONCLUSIONS: Quantification of EROA and Rvol of functional MR with 3D echocardiography is feasible and accurate as compared with VE-CMR; the currently recommended 2D echocardiographic approach significantly underestimates both EROA and Rvol.

Magnetic resonance imaging and response to cardiac resynchronization therapy: relative merits of left ventricular dyssynchrony and scar tissue.

AIM: To assess the relative value of a novel measure of left ventricular (LV) dyssynchrony derived from magnetic resonance imaging (MRI) and the extent of scar tissue for prediction of response to cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Thirty-five heart failure patients scheduled for CRT were included. Left ventricular dyssynchrony was defined as the standard deviation of 16 segment time-to-maximum radial wall thickness (SDt-16) obtained from a cine-set of short-axis slices. Delayed-enhanced MRI was performed for scar analysis. Echocardiography was used to determine response to CRT (reduction > or =15% in LV end-systolic volume 6 months after implantation). At follow-up, 21 patients (60%) were classified as responders. On MRI, SDt-16 was significantly higher in responders compared with non-responders (median 97 vs. 60 ms, P < 0.001), whereas the total extent of scar was larger in non-responders (median 35% vs. 3% in responders, P < 0.001). At the logistic regression analysis, SDt-16 was directly associated (OR = 6.3, 95% CI 3.1-9.9, P < 0.001) and the total extent of scar was inversely associated (OR = 0.52, 95% CI 0.43-0.87, P < 0.001) with response to CRT. CONCLUSION: Magnetic resonance imaging offers the unique opportunity to assess LV dyssynchrony and scar extent in a single session. Both these parameters are important predictors of echocardiographic response to CRT.

Changes in global left ventricular function by multidirectional strain assessment in heart failure patients undergoing cardiac resynchronization therapy.

BACKGROUND: The aim of this study was to evaluate the acute and late effects of cardiac resynchronization therapy (CRT) on multidirectional left ventricular (LV) strain assessed by two-dimensional speckle-tracking imaging and automated function imaging (AFI). METHODS: Multidirectional LV strain (global radial strain [GRS Avg], global circumferential strain [GCS Avg], and global longitudinal peak systolic strain [GLPSS Avg]) were measured in 141 patients with heart failure before CRT implantation, immediately afterward, and after 3 to 6 months of follow-up. Moreover, the acute effects on multidirectional LV strain were evaluated after interrupting CRT at follow-up. Response to CRT was defined as a decrease in LV end-systolic volume > or = 15%. RESULTS: Responders (57%) and nonresponders (43%) showed similar baseline values for GRS Avg, GCS Avg, and GLPSS Avg. At follow-up, significant improvement in multidirectional LV strain, combined with significant reverse LV remodeling and improvement in LV ejection fraction, was noted only in responders. Importantly, no significant changes in multidirectional LV strain were observed immediately after CRT device implantation or after device interruption at follow-up. CONCLUSIONS: Two-dimensional speckle-tracking imaging and AFI enable the quantification of multidirectional LV mechanics. Improvement in LV strain in the 3 orthogonal directions after CRT appears to be a long-term effect and is related to the extent of reverse LV remodeling after CRT.

Quantitative gated SPECT-derived phase analysis on gated myocardial perfusion SPECT detects left ventricular dyssynchrony and predicts response to cardiac resynchronization therapy.

UNLABELLED: The significance of left ventricular (LV) dyssynchrony for the prediction of response to cardiac resynchronization therapy (CRT) has been demonstrated. Parameters reflecting LV dyssynchrony (phase SD, histogram bandwidth) can be derived from gated myocardial perfusion SPECT (GMPS) using phase analysis. The feasibility of LV dyssynchrony assessment with phase analysis on GMPS using Quantitative Gated SPECT (QGS) software has not been demonstrated in patients undergoing CRT. The aim of the present study was to validate the QGS algorithm for phase analysis on GMPS in a direct comparison with echocardiography using tissue Doppler imaging (TDI) for LV dyssynchrony assessment. Also, prediction of response to CRT using GMPS and phase analysis was evaluated. METHODS: Patients (n = 40) with severe heart failure (New York Heart Association class III-IV), an LV ejection fraction of no more than 35%, and a QRS complex greater than or equal to 120 ms were evaluated for LV dyssynchrony using GMPS and echocardiography with TDI. At baseline and after 6 mo of CRT, clinical status, LV volumes, and LV ejection fraction were evaluated. Patients with functional improvement were classified as CRT responders. RESULTS: Both histogram bandwidth (r = 0.69, r(2) = 0.48, SEE = 25.4, P < 0.01) and phase SD (r = 0.65, r(2) = 0.42, SEE = 26.8, P < 0.01) derived from GMPS correlated significantly with TDI for assessment of LV dyssynchrony. At baseline, CRT responders showed a significantly larger histogram bandwidth (94 degrees +/- 23 degrees vs. 68 degrees +/- 21 degrees , P < 0.01) and a larger phase SD (26 degrees +/- 6 degrees vs. 18 degrees +/- 5 degrees , P < 0.01) than did nonresponders. Receiver-operating-characteristic curve analysis identified an optimal cutoff value of 72.5 degrees for histogram bandwidth to predict CRT response, yielding a sensitivity of 83% and a specificity of 81%. For phase SD, sensitivity and specificity similar to those for histogram bandwidth were obtained at a cutoff value of 19.6 degrees . CONCLUSION: QGS phase analysis on GMPS correlated significantly with TDI for the assessment of LV dyssynchrony. Moreover, a high accuracy for prediction of response to CRT was obtained using either histogram bandwidth or phase SD.

Clinical importance of new-onset atrial fibrillation after cardiac resynchronization therapy.

BACKGROUND: Data on the occurrence and implications of new-onset atrial fibrillation (AF) following cardiac resynchronization therapy (CRT) are scarce. We studied the incidence of new onset AF in CRT-defibrillator (CRT-D) recipients. The influence of new-onset AF on echocardiographic response to CRT and the rate of adverse events also were evaluated. OBJECTIVE: The purpose of this study was to assess the incidence and implications of new-onset AF following CRT. METHODS: The study population consisted of 223 consecutive patients with no history of AF. New-onset AF was defined as atrial high-rate episodes >180 bpm for more than 10 minutes/day as detected by the device. Echocardiography was performed at baseline and after 6 months of biventricular pacing. Long-term events included implantable cardioverter-defibrillator therapy for ventricular arrhythmias, hospitalization for heart failure, and all-cause mortality. RESULTS: Fifty-five (25%) patients developed new-onset AF during mean follow-up of 32 +/- 16 months. When compared to the patients who maintained sinus rhythm during follow-up, patients who developed AF showed less left ventricular (LV) reverse remodeling (DeltaLV end-systolic volume 37 +/- 53 vs >19 +/- 37 mL, P <.05) and less improvement in LV function (DeltaLV ejection fraction 6.7% +/- 8.9% vs 3.5% +/- 10.3%, P <.05). Importantly, patients who developed AF experienced more appropriate ICD shocks for ventricular arrhythmias, more inappropriate shocks, and more hospitalizations for heart failure. CONCLUSION: Recipients of CRT-D who develop new-onset AF show less echocardiographic response to CRT and more cardiac adverse events during long-term follow-up.

Long-term prognosis after cardiac resynchronization therapy is related to the extent of left ventricular reverse remodeling at midterm follow-up.

OBJECTIVES: The aim of the current study was to evaluate the relation between the extent of left ventricular (LV) reverse remodeling and clinical/echocardiographic improvement after 6 months of cardiac resynchronization therapy (CRT) as well as long-term outcome. BACKGROUND: Despite the current selection criteria, individual response to CRT varies significantly. Furthermore, it has been suggested that reduction in left ventricular end-systolic volume (LVESV) after CRT is related to outcome. METHODS: A total of 302 CRT candidates were included. Clinical status and echocardiographic evaluation were performed before implantation and after 6 months of CRT. Long-term follow-up included all-cause mortality and hospitalizations for heart failure. RESULTS: Based on different extents of LV reverse remodeling, 22% of patients were classified as super-responders (decrease in LVESV > or =30%), 35% as responders (decrease in LVESV 15% to 29%), 21% as nonresponders (decrease in LVESV 0% to 14%), and 22% negative responders (increase in LVESV). More extensive LV reverse remodeling resulted in more clinical improvement, with a larger increase in LV function and more reduction in mitral regurgitation. In addition, more LV reverse remodeling resulted in less heart failure hospitalizations and lower mortality during long-term follow-up (22 +/- 11 months); 1- and 2-year hospitalization-free survival rates were 90% and 70% in the negative responder group compared with 98% and 96% in the super-responder group (log-rank p value <0.001). CONCLUSIONS: The extent of LV reverse remodeling at midterm follow-up is predictive for long-term outcome in CRT patients.

Comparison of time course of response to cardiac resynchronization therapy in patients with ischemic versus nonischemic cardiomyopathy.

The time course of the effects of cardiac resynchronization therapy (CRT) on left ventricular (LV) systolic function and reverse remodeling is still unknown and was the subject of this study. In particular, whether the acute benefit of CRT translates in late response was explored. Furthermore, the time course of response was compared between ischemic and nonischemic patients. A total of 222 consecutive patients with heart failure (135 ischemic) scheduled for CRT were included. Standard echocardiography was performed before, immediately after CRT, and at 6-month follow-up to measure LV end-systolic volume (ESV), LV end-diastolic volume (EDV), and ejection fraction. Immediately after CRT, significant improvements in LV ejection fraction (from 25 +/- 8% to 31 +/- 9%, p <0.001) and LVESV (from 163 +/- 68 to 149 +/- 63 ml, p <0.001) were observed, followed by an additional improvement at 6-month follow-up (to 34 +/- 9% and 132 +/- 62 ml, respectively, p <0.001 for the 2 comparisons). A significant decrease in LVEDV was observed only at 6-month follow-up (from 217 +/- 73 to 194 +/- 72 ml, p <0.001). An acute decrease in LVESV of 6% could predict response to CRT at 6-month follow-up (defined as a decrease >or=15% in LVESV) with a sensitivity and specificity of 79% and 75%, respectively. The time course of response to CRT was similar in ischemic and nonischemic patients, but decreases in LVESV and LVEDV were significantly greater in nonischemic patients (p <0.001). In conclusion, the beneficial effect of CRT on LV systolic function occurs immediately after CRT, with additional improvement at 6-month follow-up. An acute decrease in LVESV can predict response to CRT at 6-month follow-up. Nonischemic patients show significantly greater LV reverse remodeling compared with ischemic patients.

Noninvasive imaging in cardiac resynchronization therapy--Part 2: Follow-up and optimization of settings.

Cardiac resynchronization therapy (CRT) has become a therapeutic option for drug-refractory heart failure. Several noninvasive imaging techniques play an increasingly important role before and after device implantation. This review highlights the acute and long-term CRT benefits after implantation as assessed with echocardiography and nuclear imaging. Furthermore, optimization of CRT settings, in particular atrioventricular and interventricular delay, will be discussed using echocardiography and other (device-based) techniques.

Relation between global left ventricular longitudinal strain assessed with novel automated function imaging and biplane left ventricular ejection fraction in patients with coronary artery disease.

OBJECTIVE: Automated function imaging (AFI) is a novel algorithm based on speckle-tracking imaging that can be used for assessment of global longitudinal strain of the left ventricle. The purpose of this study was to evaluate the relation between global longitudinal peak systolic strain average (GLPSS Avg) assessed by AFI and left ventricular ejection fraction (LVEF). METHODS: The study population consisted of 222 consecutive patients with coronary artery disease (99 patients with acute ST-segment elevation myocardial infarction [STEMI] and 123 patients with advanced ischemic heart failure) and 20 age-matched controls. LVEF was calculated by Simpson's rule. The GLPSS Avg was obtained by AFI. RESULTS: In the overall study group (65 +/- 10 years, 77% were men), mean GLPSS Avg was 11.1% +/- 4.8% and mean LVEF was 37% +/- 14%. Linear regression analysis showed a good correlation between GLPSS Avg and biplane LVEF for the overall study population (r = 0.83; P < .001). However, in patients with STEMI or heart failure the correlations were less strong (r = 0.42 and r = 0.62, both P < .001). CONCLUSION: Systolic global longitudinal strain assessed by AFI was linearly related to biplane LVEF. In patients with STEMI or heart failure, less strong correlations were observed, suggesting that these 2 parameters reflect different aspects of systolic left ventricular function.

Comparison between tissue Doppler imaging and velocity-encoded magnetic resonance imaging for measurement of myocardial velocities, assessment of left ventricular dyssynchrony, and estimation of left ventricular filling pressures in patients with ischemic cardiomyopathy.

Velocity-encoded magnetic resonance imaging (VE-MRI), commonly used to perform flow measurements, can be applied for myocardial velocity analysis, similar to tissue Doppler imaging (TDI). In this study, a comparison between VE-MRI and TDI was performed for the assessment of left ventricular dyssynchrony and left ventricular filling pressures. Ten healthy volunteers and 22 patients with heart failure secondary to ischemic cardiomyopathy underwent both VE-MRI and TDI. Longitudinal myocardial peak systolic and diastolic velocities and time to peak systolic velocity (Ts) were measured with both techniques at the level of left ventricular septum and lateral wall. To quantify left ventricular dyssynchrony, the delay in Ts between basal septum and lateral wall was calculated (SLD) and patients were categorized into 3 groups: minimal (SLD <30 ms), intermediate (SLD = 30 to 60 ms) and extensive (SLD >60 ms) left ventricular dyssynchrony. The ratio of transmitral E wave velocity and mitral annulus septal early velocity (E/E' ratio) was also assessed, and patients were divided into 3 groups: normal (E/E' <8), probably abnormal (E/E' = 8 to 15), and elevated (E/E' >15) left ventricular filling pressures. Excellent correlations were observed for peak systolic velocity and peak diastolic velocity (r = 0.95, p <0.001) measured with TDI and VE-MRI. A small bias (p <0.001) of -1.1 +/- 1.1 cm/s for peak systolic velocity and of -0.45 +/- 1.03 cm/s for peak diastolic velocity was noted between the 2 techniques. A strong correlation was also noted between Ts measured with TDI and VE-MRI (r = 0.97, p <0.001) without a significant difference. TDI and VE-MRI showed an excellent agreement for left ventricular dyssynchrony and left ventricular filling pressures classification with a weighted kappa of 0.96 and 0.91, respectively. In conclusion, TDI and VE-MRI are highly concordant and can be used interchangeably for the assessment of left ventricular dyssynchrony and filling pressures.

Noninvasive imaging in cardiac resynchronization therapy--part 1: selection of patients.

Cardiac resynchronization therapy (CRT) is an established therapy for patients with advanced heart failure, depressed left ventricular function, and wide QRS complex. However, individual response varies, and a substantial amount of patients do not respond to CRT. Recent studies observed that assessment of inter- and particularly intraventricular dyssynchrony may allow identification of potential responders to CRT. In addition, presence of scar tissue and venous anatomy may play a role in the selection of candidates. In this review, an extensive overview of the available dyssynchrony measurements is provided using echocardiography as well as magnetic resonance imaging (MRI) and nuclear imaging. Furthermore, other information derived from MRI, nuclear imaging, and computed tomography useful for the selection of potential candidates for CRT will be discussed.

Optimal left ventricular lead position predicts reverse remodeling and survival after cardiac resynchronization therapy.

OBJECTIVES: The aim of the current study was to evaluate echocardiographic parameters after 6 months of cardiac resynchronization therapy (CRT) as well as long-term outcome in patients with the left ventricular (LV) lead positioned at the site of latest activation (concordant LV lead position) as compared with that seen in patients with a discordant LV lead position. BACKGROUND: A nonoptimal LV pacing lead position may be a potential cause for nonresponse to CRT. METHODS: The site of latest mechanical activation was determined by speckle tracking radial strain analysis and related to the LV lead position on chest X-ray in 244 CRT candidates. Echocardiographic evaluation was performed after 6 months. Long-term follow-up included all-cause mortality and hospitalizations for heart failure. RESULTS: Significant LV reverse remodeling (reduction in LV end-systolic volume from 189 +/- 83 ml to 134 +/- 71 ml, p < 0.001) was noted in the group of patients with a concordant LV lead position (n = 153, 63%), whereas patients with a discordant lead position showed no significant improvements. In addition, during long-term follow-up (32 +/- 16 months), less events (combined for heart failure hospitalizations and death) were reported in patients with a concordant LV lead position. Moreover, a concordant LV lead position appeared to be an independent predictor of hospitalization-free survival after long-term CRT (hazard ratio: 0.22, p = 0.004). CONCLUSIONS: Pacing at the site of latest mechanical activation, as determined by speckle tracking radial strain analysis, resulted in superior echocardiographic response after 6 months of CRT and better prognosis during long-term follow-up.

Real-time three-dimensional echocardiography as a novel approach to assess left ventricular and left atrium reverse remodeling and to predict response to cardiac resynchronization therapy.

BACKGROUND: Real-time 3-dimensional echocardiography (RT3DE) is a novel promising technique for the assessment of left ventricular (LV) dyssynchrony. OBJECTIVE: This study sought to explore the value of RT3DE to assess LV and left atrium (LA) reverse remodeling and to predict response to cardiac resynchronization therapy (CRT). METHODS: A total of 57 consecutive heart failure patients scheduled for CRT were included, and RT3DE was performed before and 6 months after implantation. LV dyssynchrony was defined as the standard deviation of the time to reach the minimum systolic volume for 16 LV segments, expressed in percentage of cardiac cycle (systolic dyssynchrony index, SDI). Patients were divided into responders or nonresponders, based on a reduction >or=15% in LV end-systolic volume after CRT. RESULTS: Six patients (10%) were excluded from further analysis because of suboptimal images. Of the remaining 51 patients, 34 (67%) were classified as responders. Baseline characteristics were similar between responders and nonresponders, except for the SDI, which was larger in responders (9.7% +/- 3.6% versus 5.1% +/- 1.8%, P <.0001). ROC curve analysis revealed that a cutoff value for SDI of 6.4% yielded a sensitivity of 88% with a specificity of 85% to predict response to CRT. In responders, RT3DE also showed beneficial effects of CRT on LA: (1) significant LA reverse remodeling; (2) significant improvement in LA total emptying fraction and in LA conduit and reservoir function. CONCLUSION: RT3DE allows assessment of changes in LV and LA volumes and function after CRT, and it is highly predictive for response to CRT.

Effects of interruption of long-term cardiac resynchronization therapy on left ventricular function and dyssynchrony.

Interruption of short-term cardiac resynchronization therapy (CRT) has been shown to acutely worsen left ventricular (LV) function, mitral regurgitation, and LV dyssynchrony. The present study aims to assess whether LV reverse remodeling influences interruption of CRT, and, more practically, whether long-term continuous pacing is necessary in patients with reverse LV remodeling. A total of 135 recipients of CRT were selected after showing LV reverse remodeling defined as a decrease in LV end-systolic volume > or =15% after 6 months of CRT ("responders"). Echocardiography was performed at baseline and after 6 months with intermittent CRT on and off. LV dyssynchrony was determined using tissue Doppler imaging. During interruption of CRT, an acute deterioration in LV function, mitral regurgitation, and LV desynchronization were noted in responder patients. Of note, worsening of these echocardiographic measurements was observed, but they did not return to baseline values. For comparison, 100 nonresponder patients (without LV reverse remodeling) showed no significant echocardiographic changes during interruption. In conclusion, despite the presence of LV reverse remodeling, interruption of CRT resulted in worsening of LV function and desynchronization. Therefore, continuous long-term pacing is warranted to maintain the beneficial effects.