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.

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.

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.

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.

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.

Left ventricular resynchronization is mandatory for response to cardiac resynchronization therapy: analysis in patients with echocardiographic evidence of left ventricular dyssynchrony at baseline.

BACKGROUND: Recent studies have demonstrated that a positive response to cardiac resynchronization therapy (CRT) is related to the presence of preimplantation left ventricular (LV) dyssynchrony. The time course and the extent of LV resynchronization after CRT implantation and their relationship to response are currently unknown. METHODS AND RESULTS: One hundred consecutive patients scheduled for implantation of a CRT device were prospectively included if they met the following criteria: New York Heart Association class III to IV, LV ejection fraction < or = 35%, QRS duration > 120 ms, and LV dyssynchrony (> or = 65 ms) on color-coded tissue Doppler imaging. Immediately after CRT implantation, LV dyssynchrony was reduced from 114+/-36 to 40+/-33 ms (P<0.001), which persisted at the 6-month follow-up (35+/-31 ms; P<0.001 versus baseline; P=0.14 versus immediately after implantation). At the 6-month follow-up, 85% of patients were classified as responders to CRT (defined as > 10% reduction in LV end-systolic volume). Immediately after implantation, the responders to CRT demonstrated a significant reduction in LV dyssynchrony from 115+/-37 to 32+/-23 ms (P<0.001). The nonresponders, however, did not show a significant reduction in LV dyssynchrony (106+/-29 versus 79+/-44 ms; P=0.08). If the extent of acute LV resynchronization was < 20%, response to CRT at the 6-month follow-up was never observed. Conversely, 93% of patients with LV resynchronization > or = 20% responded to CRT. CONCLUSIONS: LV resynchronization after CRT is an acute phenomenon and predicts response to CRT at 6-month follow-up in patients with echocardiographic evidence of LV dyssynchrony at baseline.

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.

Real-time three-dimensional echocardiography permits quantification of left ventricular mechanical dyssynchrony and predicts acute response to cardiac resynchronization therapy.

OBJECTIVE: To evaluate the value of real-time three-dimensional echocardiography (RT3DE) to predict acute response to cardiac resynchronization therapy (CRT). METHODS: Sixty consecutive heart failure patients scheduled for CRT were included. RT3DE was performed before and within 48 hours after pacemaker implantation to calculate both left ventricular (LV) volumes and LV dyssynchrony. LV dyssynchrony was defined as the standard deviation of the time taken to reach the minimum systolic volume for 16 LV segments (referred to as the systolic dyssynchrony index, SDI). Patients were subsequently divided into acute responders or nonresponders, based on a reduction > or = 15% in LV end-systolic volume immediately after CRT. RESULTS: Four patients (7%) were excluded from further analysis because of either suboptimal apical acquisitions or significant translation artifacts. Out of the remaining 56 patients, 35 patients (63%) were classified as acute responders. Baseline characteristics were similar between responders and nonresponders, except for the SDI, which was larger in responders. Moreover, responders demonstrated a significant reduction of SDI immediately after CRT (from 9.7 +/- 4.1% to 3.6 +/- 1.8%, P < 0.0001), whereas SDI did not change in nonresponders (3.4 +/- 1.8% vs 3.1 +/- 1.1%, NS). ROC curve analysis revealed that a cut-off value for SDI of 5.6% yielded a sensitivity of 88% with a specificity of 86% to predict acute echocardiographic response to CRT (AUC 0.96). CONCLUSION: RT3DE is highly predictive for acute response to CRT (sensitivity 88% and specificity 86%). In addition, RT3DE allows assessment of changes in LV volumes and LV ejection fraction before and after CRT implantation.

Left ventricular dyssynchrony assessed by two three-dimensional imaging modalities: phase analysis of gated myocardial perfusion SPECT and tri-plane tissue Doppler imaging.

PURPOSE: To compare left ventricular (LV) dyssynchrony assessment by phase analysis from gated myocardial perfusion SPECT (GMPS) with LV dyssynchrony assessment by tri-plane tissue Doppler imaging (TDI). Baseline LV dyssynchrony assessed with standard deviation (SD) of time-to-peak systolic velocity of 12 LV segments (Ts-SD) with TDI has proven to be a powerful predictor of response to CRT. Information on LV dyssynchrony can also be provided by GMPS with phase analysis of regional LV maximal count changes throughout the cardiac cycle. METHODS: Forty heart failure patients, referred for evaluation of potential eligibility for CRT, underwent both 3D echocardiography, with tri-plane TDI, and resting GMPS. From tri-plane TDI, Ts-SD was used as a validated parameter of LV dyssynchrony and compared with different indices (histogram bandwidth, phase SD, histogram skewness and kurtosis) derived from phase analysis of GMPS. RESULTS: Histogram bandwidth and phase SD showed good correlation with Ts-SD (r=0.77 and r=0.74, p<0.0001, respectively). Patients with substantial LV dyssynchrony assessed with tri-plane TDI (Ts-SD >or=33 ms) had also significantly higher values of histogram bandwidth and phase SD. CONCLUSIONS: The results of this study support the use of phase analysis by GMPS to evaluate LV dyssynchrony. Histogram bandwidth and phase SD showed the best correlation with Ts-SD assessed with tri-plane TDI and appeared the most optimal variables for assessment of LV dyssynchrony with GMPS.

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.

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.

Myocardial contractile reserve predicts improvement in left ventricular function after cardiac resynchronization therapy.

BACKGROUND: Myocardial contractile reserve has been shown to provide important prognostic information in patients with heart failure. We hypothesized that myocardial contractile reserve would predict left ventricular (LV) reverse remodeling after cardiac resynchronization therapy (CRT). METHODS: Thirty-one consecutive patients with heart failure (LV ejection fraction [LVEF] 26% +/- 7%, 35% nonischemic cardiomyopathy) underwent echocardiography during low-dose dobutamine infusion before CRT implantation to assess global contractile reserve (improvement in LVEF) and local contractile reserve in the region of the LV pacing lead (assessed by radial strain using speckle tracking analysis). Responders were defined by a decrease in LV end-systolic volume > or = 15% after 6 months of CRT. RESULTS: During low-dose dobutamine infusion, responders showed a greater increase in LVEF compared with nonresponders (delta 13% +/- 8% vs 3% +/- 4%, P < .001). Furthermore, contractile reserve was directly related to improvement in LVEF after 6 months of CRT (r = 0.80, P < .001). Moreover, a cutoff value of > 7.5% increase in dobutamine-induced LVEF exhibited a sensitivity of 76% and a specificity of 86% to predict response after 6 months of CRT (area under the curve 0.87). Lastly, contractile reserve in the region in the LV pacing lead was present only in responders (delta strain during low-dose dobutamine 6% +/- 5% in responders vs -1% +/- 4% in nonresponders, P = .002). CONCLUSIONS: The current study demonstrates that myocardial contractile reserve (> 7.5% increase in LVEF during low-dose dobutamine infusion) predicts LV reverse remodeling after CRT.

Nuclear imaging in cardiac resynchronization therapy.

Recently, cardiac resynchronization therapy (CRT) has become implemented in the treatment of patients with severe heart failure. Although the improvement in systolic function after CRT implantation can be considerable, 20%-30% of patients do not respond to CRT. Evidence is accumulating that the presence of left ventricular (LV) dyssynchrony is mandatory for a response to CRT. Since the early 1980s attempts have been made to assess cardiac dyssynchrony with nuclear imaging, and it has been reported recently that information on LV dyssynchrony can be obtained from gated myocardial perfusion SPECT with phase analysis. Other studies with SPECT have shown that extensive scar tissue will limit the response to CRT; similarly, it has been demonstrated that viable tissue (assessed with SPECT) in the target zone for the LV pacing lead (usually the lateral wall) is needed for a response to CRT. Moreover, studies with PET have provided insight into the changes in myocardial perfusion, metabolism, and efficiency after CRT. In the current review, a comprehensive summary is provided on the potential role of nuclear imaging in the selection of heart failure patients for CRT. The value of other imaging techniques is also addressed.

Can LV dyssynchrony as assessed with phase analysis on gated myocardial perfusion SPECT predict response to CRT?

UNLABELLED: Cardiac resynchronization therapy (CRT) is now a well-recognized therapeutic option for patients with end-stage heart failure. However, not all patients respond to CRT, and, therefore, preimplantation identification of responders is desirable. The aim of the present study was to investigate whether the degree of left ventricular (LV) dyssynchrony, as assessed with phase analysis from gated myocardial perfusion SPECT (GMPS), can predict which patients will respond to CRT. METHODS: Forty-two patients with severe heart failure, depressed LV ejection fraction, and wide QRS complex were prospectively included for implantation of a CRT device and underwent GMPS and 2-dimensional echocardiography as part of the clinical protocol. Clinical status was evaluated using the New York Heart Association (NYHA) classification, 6-min walk test, and quality-of-life score. The histogram bandwidth and phase SD (parameters indicating LV dyssynchrony) were assessed from GMPS, and the clinical status and echocardiographic variables were reassessed at 6-mo follow-up. RESULTS: Responders (71%) and nonresponders (29%) had comparable baseline characteristics, except for histogram bandwidth (175 degrees +/- 63 degrees vs. 117 degrees +/- 51 degrees [P < 0.01]) and phase SD (56.3 degrees +/- 19.9 degrees vs. 37 degrees .1 +/- 14.4 degrees [P < 0.01]), which were significantly larger in responders compared with nonresponders. Moreover, receiver-operating-characteristic curve analysis demonstrated an optimal cutoff value of 135 degrees for histogram bandwidth (sensitivity and specificity of 70%) and of 43 degrees for phase SD (sensitivity and specificity of 74%) for the prediction of response to CRT. CONCLUSION: Response to CRT is related to the presence of LV dyssynchrony assessed by phase analysis with GMPS. A cutoff value of 135 degrees for histogram bandwidth and of 43 degrees for phase SD could be used to predict response to CRT. Larger prospective studies are warranted to confirm the present findings.

Intrathoracic impedance monitoring to predict decompensated heart failure.

Intrathoracic impedance measurement has been introduced in the InSync Sentry biventricular implantable cardioverter-defibrillator and may permit the early identification of pulmonary fluid accumulation secondary to left-sided heart failure (HF). An audible alarm (the OptiVol alert) can be triggered when the impedance index increases to greater than a predefined level of 60 Omega . day. The aim of this study was to evaluate the clinical value of the OptiVol alert and its prediction for decompensated HF. One hundred fifteen consecutive patients (mean New York Heart Association class 2.8 +/- 0.5, mean left ventricular ejection fraction 26 +/- 8%) who received InSync Sentry biventricular implantable cardioverter-defibrillators were included. When presenting with the OptiVol alert, current hemodynamic status was evaluated. During follow-up (mean 9 +/- 5 months), there were 45 presentations with the OptiVol alert in 30 patients. Clinical signs and symptoms of HF were present in only 15 patients (33%), whereas in the remaining patients, clinical signs of HF were absent (p <0.05). Receiver-operating characteristic curve analysis showed that increasing the threshold for the OptiVol alert provided a substantial increase in specificity for the detection of HF, with the optimal cut-off value identified at 120 Omega . day, yielding sensitivity of 60% and specificity of 73%. In conclusion, intrathoracic impedance measurement as present in the InSync Sentry biventricular implantable cardioverter-defibrillator may be a useful tool for monitoring pulmonary fluid status. The proposed threshold for the OptiVol alert of 60 Omega. day is very sensitive but not specific for the assessment of HF; adjustment of threshold settings may yield a superior balance between sensitivity and specificity.

Effect of total scar burden on contrast-enhanced magnetic resonance imaging on response to cardiac resynchronization therapy.

It was shown that improvement in left ventricular (LV) function and reverse remodeling after cardiac resynchronization therapy (CRT) were greater in patients with nonischemic cardiomyopathy than in those with ischemic cardiomyopathy. The aim of this study is to evaluate the influence of scar burden on response to CRT. We included 34 patients with ischemic cardiomyopathy (New York Heart Association class 3.1 +/- 0.4, LV ejection fraction 23 +/- 7%). Contrast-enhanced magnetic resonance imaging was used to determine total scar burden, using a 17-segment model with a 5-point hyperenhancement scale (from score 0 = no hyperenhancement, indicating no scar, to score 4 = hyperenhancement >76%, transmural scar). Linear regression analysis showed a significant correlation (r = -0.91, p <0.05) between total scar burden at baseline and change in LV end-systolic volume after 6 months of CRT. Also, patients not responding to CRT had significantly more scar tissue than responders. A scar burden >1.20 resulted in complete functional nonresponse. In conclusion, total scar burden, assessed using contrast-enhanced magnetic resonance imaging, is an important factor influencing response to CRT and may be included in the selection process for CRT candidates.

Usefulness of triplane tissue Doppler imaging to predict acute response to cardiac resynchronization therapy.

This study evaluated the value of triplane tissue Doppler imaging (TDI) to predict acute response after cardiac resynchronization therapy (CRT). Forty-nine patients scheduled for CRT underwent triplane echocardiography with simultaneous TDI acquisition before and 48 hours after implantation. A 3-dimensional left ventricular (LV) volume was generated and LV volumes and ejection fraction were calculated. A parametric imaging technique, tissue synchronization imaging, was applied to portray the area of latest mechanical activation. LV dyssynchrony was quantitatively analyzed by evaluating time from QRS onset to peak myocardial velocity in 12 LV segments from the triplane dataset. Acute response was defined as > or =15% decrease in LV end-systolic volume. Receiver-operating characteristic curves of dyssynchrony parameters were analyzed to identify predictors of response to CRT. Acute response was observed in 47% of patients. Responders had a significantly larger extent of LV dyssynchrony at baseline compared with nonresponders. Optimal prediction of acute response to CRT was obtained with the SD of time delays in all LV segments (sensitivity 91%, specificity 85%). In conclusion, 3-dimensional TDI echocardiography permits parametric and quantitative analyses of LV dyssynchrony and assessment of LV volumes and ejection fraction. LV dyssynchrony parameters, derived from the triplane TDI dataset, were highly predictive for acute volumetric response to CRT.

Extent of viability to predict response to cardiac resynchronization therapy in ischemic heart failure patients.

UNLABELLED: The response to cardiac resynchronization therapy (CRT) varies significantly among individuals. Preliminary data suggest that the presence of myocardial viability may be important for response to CRT. The aim of this study was to evaluate whether the extent of viability could predict response to CRT after 6 mo. METHODS: Sixty-one consecutive patients with advanced heart failure, left ventricular ejection fraction < 35%, QRS duration > 120 ms, and chronic coronary artery disease were included. To determine the extent of viability all patients underwent nuclear imaging with 18F-FDG SPECT before implantation. Clinical and echocardiographic parameters were assessed at baseline and after 6 mo of follow-up. RESULTS: The presence of myocardial viability was directly related to an increase in left ventricular ejection fraction after 6 mo of CRT. Furthermore, the extent of viability in responders (n = 38) was significantly larger compared with that of nonresponders (n = 23; 12 +/- 3 vs. 7 +/- 3 viable segments, P < 0.01). Moreover, the optimal cutoff value to predict clinical response to CRT was identified at an extent of 11 viable segments or more (in a 17-segment model), yielding a sensitivity of 74% and a specificity of 87%. CONCLUSION: The presence of myocardial viability is directly related to response to CRT in patients with ischemic heart failure. Interestingly, using a cutoff level of 11 viable segments or more, the extent of viability could be used to predict response. Therefore, evaluation for myocardial viability may be considered in the selection process for 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.