Utility of three-dimensional echocardiography in assessing and predicting response to cardiac resynchronization therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) can be a valuable treatment for heart failure. However, there are high nonresponse rates using current CRT inclusion criteria.

OBJECTIVE

To assess the value of three-dimensional echocardiography (3DE) in predicting response to CRT.

METHODS

Functional assessments and 3DE were performed in heart failure patients pre-CRT, 24 h post-CRT and six to 12 months after CRT. The dyssynchrony index (DI) was calculated as the SD of the time to minimum volume in 16 left ventricle segments corrected by heart rate. Response to CRT was defined as functional improvement (alive at late follow-up with improvement by one New York Heart Association class) and a decrease in left ventricular end-systolic volume by 15% or greater at six to 12 months follow-up.

RESULTS

A total of 53 patients were enrolled. Average 3DE acquisition time was less than 5 min. Seventy-two per cent of patients showed functional improvement, while 43% showed functional and echocardiographic evidence of response. Baseline DI and the decrease in DI at 24 h were both correlated with reverse remodelling. Responders had higher baseline DI values compared with nonresponders (mean 16.8 versus 7.1, P<0.001), and showed a greater decrease in DI values at 24 h (mean decrease 7.9 versus 0.7, P<0.001). All responders had baseline DI values of greater than 10 (negative predictive value of 100%). A decrease in the DI value by more than 5 at 24 h in patients with a baseline DI of greater than 10 identified responders with a positive predictive value of 83%.

CONCLUSIONS

3DE may be valuable in predicting response to CRT. A baseline DI cut-off of greater than 10 in our patients excluded reverse remodelling to CRT. In addition, the decrease in DI at 24 h had a high positive predictive value for long-term response to CRT.     

Cardiac resynchronization therapy for the causal treatment of heart failure with preserved ejection fraction: insight from a pressure–volume loop analysis

This case describes a middle‐aged patient with normal ejection fraction (64%) and significant dyspnoea which could not be explained by results from routine examinations. A pressure–volume loop analysis revealed severe left ventricular (LV) dyssynchrony to be the underlying mechanism of heart failure. The patient underwent implantation of a biventricular pacemaker. Cardiac resynchronization therapy (CRT) was associated with an immediate reduction in LV dyssynchrony from 32 to 13%, decrease in LV end‐diastolic pressure from 19 to 8 mmHg, and increased exercise tolerance during follow‐up. Thus, CRT may be considered a causal therapy in selected patients with heart failure and preserved ejection fraction.     

Cardiac resynchronization therapy – A comparison of VV delay optimization by 3D echocardiography using systolic dyssynchrony index and QRS width assessment at 6 months after CRT implantation

AimThe aim of this study was to compare the setting of interventricular (VV) delay by 3D echocardiography (3DE) using systolic dyssynchrony index (SDI) versus QRS width measurement in new cardiac resynchronization therapy (CRT) recipients. We observed the impact on the reduction of left ventricle volumes and increase in volumetric responders (defined as a ≥15% reduction in left ventricular end-systolic volume (LVESv)) at the 6-month follow-up.MethodsWe included 63 patients with recently implanted CRT in this open-label, randomized trial. Patients were randomized into two groups. VV delay was set by the QRS width in the group 1 (n 31) to obtain the narrowest QRS complex and by SDI in the group 2 (n 32) to achieve the lowest possible value. We evaluated LVESv, left ventricular ejection fraction (LVEF) by 3DE, before CRT implantation and at 6-month follow-up, in all patients. We also obtained clinical parameters and the level of NT-proBNP.ResultsThe second group showed only a trend toward greater reduction of LVESv (−33 ± 55 ml vs. −48 ± 43 ml; P 0.367), increase in LVEF (+7.3 ± 10.9% vs. +10.2 ± 9.4%; P 0.210) and greater number of volumetric responders (14 vs. 18; P 0.612) compared with the group 1 at 6-month follow-up. There were also no significant differences in clinical outcomes and the level of NT-proBNP.ConclusionIndividual CRT optimization using SDI compared with QRS duration assessment did not reveal any significant differences in echocardiographic parameters and clinical outcomes at 6-month follow-up.     

Cardiac resynchronization therapy in clinical practice: Need for electrical, mechanical, clinical and logistic synchronization

Considering the relatively short history of cardiac resynchronization therapy (CRT), the amount of available evidence of efficacy is impressive, and effectiveness studies are now required. Transfer of our experimentally gained knowledge into the real world raises issues that call for synchronization among the many specialists involved in chronic heart failure (CHF) management and CRT decision making. From an economic perspective, the demonstrated ability of CRT to reduce hospitalizations could help ease the burden on health systems derived from the growing incidence of CHF. Recent American College of Cardiology/American Heart Association guideline revisions should encourage a synchronized approach to rational deployment of CRT in selected patients. Nevertheless, current QRS criteria for CRT candidacy do not directly address the key issue of identification of patients with a pacing-correctable mechanical dyssynchrony (and in clinical trials, 25–30% of implanted patients did not respond to CRT). Echocardiography could become an important adjunct (or even an alternative) to QRS duration for patient selection; routine implementation would require use of straightforward, reproducible measurements, possibly obtainable on standard equipment. Echocardiography could also help optimize site location, although this would not eliminate lead placement problems. A series of issues remain open for investigation, including the potential of CRT in patients with atrial fibrillation, impact of devices with defibrillation ability, effects of electrical/pharmacological tailoring, need for confirmation that efficacy of CRT extends into the long term and possible use of CRT in mild CHF. Interdisciplinary synchronization in the various phases of CRT (screening, proposing, implementing, optimizing and monitoring) should eventually help develop a coordinated system for patient referral.     

Presence of left ventricular contractile reserve, evaluated by means of dobutamine stress-echo test, is able to predict response to cardiac resynchronization therapy

Introduction  We evaluated whether the dobutamine stress-echo test can select responders to cardiac resynchronization therapy (CRT). Up to 50% of patients do not respond to CRT. Lack of response may be due to a significant amount of scar or fibrotic tissue at myocardial level. Methods and Results  We studied 42 CRT patients. After clinical and echocardiographic evaluation, all patients underwent a dobutamine stress-echo test to assess contractile reserve. Cut-off for the test was an increase of 25% of the left ventricular ejection fraction. Patients were implanted with a CRT–defibrillator and followed up at 6 months. Cut-off for CRT response was a reduction of 15% of left ventricular end-systolic volume. Twenty-five patients responded to CRT; all of them showed presence of contractile reserve. The test showed a sensitivity of 100% and a specificity of 88%. Conclusion  Contractile reserve was a strong predictive factor of response to CRT in the studied population.     

Triple site biventricular pacing in a patient with congestive heart failure and severe mechanical dyssynchrony

We report on a case of a 62-year-old patient with symptomatic heart failure and severe ventricular electrical and mechanical dyssynchrony, who was implanted percutaneously with a triple site (dual-left single-right) resynchronization device. At 3-months follow-up, the patient’s functional status improved significantly as shown by subjective and objective tests. Furthermore, this mode of pacing has allowed nearly complete inter- and intraventricular mechanical resynchronization. All authors state that they have no conflict of interest to disclose.     

实时三维超声心动图评价扩张型心肌病左室不同步性的研究

目的：探讨实时三维超声心动图在评价左心室不同步性方面的应用价值。方法：选择30例扩张型心肌病患者,对他们的实时三维超声心动图各节段的时间-容积曲线变化进行分析。结果：30例患者中有26例RT3DE检出存在左室收缩不同步,其中QRS间期延长的21例患者中有19例,QRS间期正常的9例患者中有7例。2例QRS间期延长的患者和2例QRS间期正常患者,RT3DE未检出存在左室收缩不同步。结论：实时三维超声心动图能有效评价左室机械不同步性。