Is the outcome of cardiac resynchronization therapy related to the underlying etiology?

Cardiac resynchronization therapy (CRT) non-responders in the contemporary era: A State-of-the-Art review

Since 2000s CRT became a revolutionary therapy for heart failure with reduced left ventricular ejection fraction (HFrEF) and wide QRS. However, about one third of CRT recipients do not show a favorable response. This review of current literature aims to better define the concept of CRT response/non-response. The diagnosis of CRT non-responder should be viewed as a continuum, and it cannot rely solely on a single parameter. Moreover, several patients' baseline features might predict an unfavorable response. A strong collaboration between HF specialists and electrophysiologists is key to overcoming this challenge with multiple strategies. In the contemporary era, new pacing modalities, such as His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) represent a promising alternative to CRT. Observational studies demonstrated their potential; however, several limitations should be addressed. Large randomized controlled trials are needed to prove their efficacy in HFrEF with electromechanical dyssynchrony.

Echocardiographic mechanical dyssynchrony predicts long-term mortality in patients with cardiac resynchronisation therapy

Cardiac resynchronisation therapy (CRT) is an established treatment for patients with symptomatic heart failure with reduced left ventricular ejection fraction (LVEF ≤ 35%; HFrEF) and conduction disturbances (QRS duration ≥ 130 ms). The presence of mechanical dyssynchrony (MD) on echocardiography has been hypothesised to be of predictive value in determining indication for CRT. This study investigated the impact of MD (apical rocking [AR] and septal flash [SF]) on long-term survival in CRT recipients. HFrEF patients (n = 425; mean age 63.0 ± 10.6 years, 72.3% male, 60.7% non-ischaemic aetiology) with a guideline-derived indication for CRT underwent device implantation. MD markers were determined at baseline and after a mean follow-up of 11.5 ± 8.0 months; long-term survival was also determined. AR and/or SF were present in 307 (72.2%) participants at baseline. During post-CRT follow-up, AR and/or SF disappeared in 256 (83.4%) patients. Overall mean survival was 95.9 ± 52.9 months, longer in women than in men (109.1 ± 52.4 vs. 90.9 ± 52.4 months; p < 0.001) and in younger (< 60 years) versus older patients (110.6 ± 53.7 vs. 88.6 ± 51.1 months; p < 0.001). Patients with versus without MD markers at baseline generally survived for longer (106.2 ± 52.0 vs. 68.9 ± 45.4 months; p < 0.001), and survival was best in patients with resolved versus persisting MD (111.6 ± 51.2 vs. 79.7 ± 47.6 months p < 0.001). Age and MD at baseline were strong predictors of long-term survival in HFrEF patients undergoing CRT on multivariate analysis. Novel echocardiography MD parameters in HFrEF CRT recipients predicted long-term mediated better outcome, and survival improved further when AR and/or SF disappear after CRT implantation.

Predictors for Super-Responders in Cardiac Resynchronization Therapy

BACKGROUND

Prediction of cardiac resynchronization therapy (CRT) response, particularly a super-response, is of great importance.

STUDY QUESTION

The aim of our study was to assess the predictors for super-responders in CRT.

STUDY DESIGN

We conducted a retrospective, observational study, which finally included 622 patients with heart failure treated with CRT between January 2008 and May 2020 who had a minimal follow-up of 6 months after CRT.

MEASURES AND OUTCOMES

A total of 192 super-responders, defined by a left ventricular ejection fraction (LVEF) of at least 45%, and/or minimum 15% increase in LVEF and an improvement of the New York Heart Association functional class by at least 2 degrees at the last follow-up, and the rest of 430 patients who did not fulfill the super-responder criteria.

RESULTS

The highest rate of super-responders (41.91%, n = 171) was at patients with left ventricle-only pacing with optimal fusion (OPT) compared with patients with biventricular (BiV) pacing (9.81%, n = 21, P < 0.000). In the OPT group, univariable analysis showed that nonischemic cardiomyopathy, a smaller degree of mitral regurgitation, and better left ventricle function at enrollment were predictors for super-response compared with the BiV group where a narrower QRS after implantation, nonischemic cardiomyopathy, and a better baseline LVEF were predictors for super-responders. In the multivariable analysis, both narrower QRS after implantation and nonischemic cardiomyopathy were independent predictors for super-response in the BiV group compared with OPT where nonischemic cardiomyopathy remained the only independent predictor for super-response.

CONCLUSIONS

In this retrospective study, OPT CRT programing was an additional predictor of super-response to CRT besides nonischemic cardiomyopathy.

Clinical impact of MultiPoint pacing in responders to cardiac resynchronization therapy

BACKGROUND

Cardiac resynchronization therapy demonstrated benefits in heart failure. However, only 60-70% are responders and only 22% are super-responders. MultiPoint pacing (MPP) improves structural remodeling, but data in responder patients is scarce.

METHODS

A prospective, randomized study of the efficacy of MPP was conducted in patients who were CRT responders after 6 months of bi-ventricular (BiV) therapy. At 6 months, responder patients (LV end-systolic volume [LVESV] reduction ≥15%) were randomized to either continued BiV therapy or to MPP programmed with wide anatomical separation ≥30 mm, and followed until 12 months. Efficacy was determined by 6-12 month changes in LVESV and LV ejection fraction (LVEF). Evaluations of super-responder rate (LVESV reduction ≥30%) and quality of life (NYHA, EQ-5D, MLHFQ) were also performed.

RESULTS

From February 2017 to February 2019, 73 CRTs with Quartet LV leads were implanted (42.9% female, 65.7 ± 10.8 years old, 79.5% dilated cardiomyopathy). At 6 months, 74.2% responded to BiV and were randomized to BiV (n = 25) or MPP (n = 24). MPP versus BiV delivered greater LVESV improvement (8.3% decrease in MPP vs. 10.3% increase in BiV patients, p = .047), greater increase in LVEF (7.7% vs. 1.8%, p = .008), and higher 0-12 month super-responder rate (86.4% vs. 56.0%, p = .027). More MPP vs. BiV patients experienced an improvement in NYHA (84.6% vs. 50.0%, p = .047) and EQ-5D (94.4% vs. 54.0%, p = .006).

CONCLUSIONS

MPP with wide anatomical spacing in CRT responder patients resulted in improved LV reverse remodeling with higher rates of super-responders, and better quality of life metrics.

Contemporary ICD Use in Patients with Heart Failure

Despite constant breakthroughs in heart failure (HF) therapy, the population of HF patients resume to grow and is linked to increased mortality and morbidity. Ventricular arrhythmias (VA) are one of the leading causes of mortality in HF subjects. Implantable cardioverter-defibrillators (ICDs) are currently the gold standard in treatment, preventing arrhythmic sudden cardiac death (SCD) episodes. However, the death rates related to HF remain elevated, as not all HF subjects benefit equally. Cardiac resynchronization therapy (CRT) has emerged as a novel approach for HF patients. These devices have been thoroughly investigated in major randomized controlled studies but continue to be underutilized in various countries. This review discusses the use of ICD in HF populations on top of treatments.

Cardiac Resynchronization Therapy in Non-Ischemic Cardiomyopathy: Role of Multimodality Imaging

Non-ischemic cardiomyopathy encompasses a heterogeneous group of diseases, with a generally unfavorable long-term prognosis. Cardiac resynchronization therapy (CRT) is a useful therapeutic option for patients with symptomatic heart failure, currently recommended by all available guidelines, with outstanding benefits, especially in non-ischemic dilated cardiomyopathy. Still, in spite of clear indications based on identifying a dyssynchronous pattern on the electrocardiogram (ECG,) a great proportion of patients are non-responders. The idea that multimodality cardiac imaging can play a role in refining the selection criteria and the implant technique and help with subsequent system optimization is promising. In this regard, predictors of CRT response, such as apical rocking and septal flash have been identified. Promising new data come from studies using cardiac magnetic resonance and nuclear imaging for showcasing myocardial dyssynchrony. Still, to date, no single imaging predictor has been included in the guidelines, probably due to lack of validation in large, multicenter cohorts. This review provides an up-to-date synthesis of the latest evidence of CRT use in non-ischemic cardiomyopathy and highlights the potential additional value of multimodality imaging for improving CRT response in this population. By incorporating all these findings into our clinical practice, we can aim toward obtaining a higher proportion of responders and improve the success rate of CRT.

Prognostic Usefulness of Systolic Blood Pressure One-Year Following Cardiac Resynchronization Therapy (from MADIT-CRT)

Low systolic blood pressure (SBP) is associated with increased mortality and heart failure in patients with left ventricular dysfunction. Data on the relation between SBP measured following cardiac resynchronization therapy implantation and subsequent clinical events are limited. We hypothesized that assessment of systolic blood pressure at 12 months after cardiac resynchronization therapy can be used to identify patients with increased risk for adverse cardiovascular outcomes. The study population comprised 1000 patients who underwent cardiac resynchronization therapy implantation in MADIT-CRT. Outcomes were compared between patients with low (<110 mm Hg) and preserved SBP (≥110 mm Hg) at 1 year. At 1 year following cardiac resynchronization therapy, 800 patients (80%) had preserved systolic blood pressure. Kaplan-Meier survival analysis showed that the rate of heart failure or death during subsequent follow-up was significantly higher among patients with low SBP as compared with a preserved SBP at 12 months (2-year rates: 20% vs 12%, respectively; log-rank p value = 0.009 for the overall difference during follow-up). Consistently, multivariate analysis showed that patients with preserved SBP at 1 year had a 29% lower risk of HF or death when compared with the low SBP group (p = 0.024). The association between SBP measured following cardiac resynchronization therapy implantation and subsequent clinical events was more pronounced among patients with nonischemic cardiomyopathy (p value for SBP-by-HF etiology interaction = 0.034). In conclusion, assessment of SBP following cardiac resynchronization therapy can be used for improved long-term risk stratification in this population.

Devices in Heart Failure Patients-Who Benefits From ICD and CRT?

Despite advances in heart failure treatment, this condition remains a relevant medical issue and is associated with a high morbidity and mortality. The cause of death in patients suffering from heart failure is not only a result of hemodynamic failure, but can also be due to ventricular arrhythmias. Implantable cardioverter defibrillators (ICDs) are these days the only tool to significantly reduce arrhythmic sudden death; but not all patients benefit to the same extend. In addition, cardiac resynchronization therapy (CRT) is another tool which is used in patients suffering from heart fialure. Even though both devices have been investigated in large randomized trials, both ICD and CRT remain underutilized in many countries. This brief review focuses on various aspects in this regard including a short overview on upcoming device novelties in the near future.

2D/3D Echocardiographic features of patients with reverse remodeling after cardiac resynchronization therapy

PURPOSE

To describe clinical and echocardiographic characteristics associated with reverse left ventricular (LV) remodeling after 6 months of cardiac resynchronization therapy (CRT) in patients with nonischemic dilated cardiomyopathy.

METHODS

Twenty-four consecutive patients underwent 2D and 3D echocardiography before and after 6 months of CRT implant. Several echocardiographic parameters including global longitudinal strain (GLS) and 3D mechanical dyssynchrony (MD) index were calculated. CRT response was defined as a decrease in LV end-systolic volume (LVESV) of at least 10% at follow-up. Patients were divided in two groups according to CRT response.

RESULTS

Cardiac resynchronization therapy responder (CRTR+) rate was 50%. Nonresponder (CRTR-) patients showed a less significant improvement in NYHA class at follow-up. At baseline, CRTR- presented with higher LV end-diastolic volume (LVEDV) (P = 0.031), LVESV (P = 0.024), lower left ventricular ejection fraction (LVEF) (P = 0.002) and less negative GLS (P = 0.03), and with higher diastolic dysfunction, more impaired right ventricle (RV), and higher pulmonary artery systolic pressure (PASP) (P = 0.002). No significant differences in echocardiographic parameters of MD were found. Univariate determinants of CRTR+ were LVEF (OR = 1.59, CI 95% = 1.13-2.22, P = 0.007) and TAPSE (OR 1.21, CI 95% = 1.024-1.429, P = 0.025). A ROC curve analysis showed a cutoff value of LVEF of 22.15% significantly related to CRTR+ (SE 80%, SP 50%).

CONCLUSIONS

Our findings suggest that end-stage HF patients, presenting before CRT with LVEF <22.15%, may not benefit from the procedure after 6 months. Mechanical dyssyncronicity did not provide additional information to improve candidate selection.

Incidence and predictors of super-response to cardiac resynchronization therapy

OBJECTIVES

Cardiac resynchronization therapy (CRT) has significantly improved management of patients with heart failure with reduced ejection fraction (HFrEF). A significant number of patients have a dramatic response and have been termed "super-responders". The characteristics of this subset of patients in Indian and Asian population have not been well studied. In this study, we sought to assess the prevalence and clinical characteristics of this cohort of patients.

METHODS

This was a retrospective study involving patients undergoing CRT. Changes in ejection fraction and LVESV at the end of one year of follow-up following device implantation were assessed, and patients were stratified into non-responders, responders, and super-responders. Responders had a 15-29% decrease in LVESV while super-responders had a >30% decrease in LVESV.

RESULTS

Of the 74 patients who had undergone CRT-P/CRT-D implantation, 16 patients did not have echocardiograms at the end of one year of follow-up and were excluded from the analysis. Thus, 58 patients were enrolled for analysis. We identified 16 patients (27.6%) to be super-responders, 26 patients (44.8%) to be responders, and 16 patients (27.6%) to be non-responders. Factors associated with a super-response were a diagnosis of dilated cardiomyopathy as against ischemic cardiomyopathy (93.7% vs 6.3%; p - 0.01), prior right ventricular (RV) apical pacing (25% vs 2.4%; p - 0.02) and absence of a prior history of myocardial infarction (MI) (0% vs 33.3%; p - 0.02).

CONCLUSION

In our study, 27.6% of patients were super-responders, and a diagnosis of dilated cardiomyopathy, absence of a prior history of MI and prior RV apical pacing predicted a super-response to CRT.

Cardiac Resynchronisation Therapy and Cellular Bioenergetics: Effects Beyond Chamber Mechanics

Cardiac resynchronisation therapy is a cornerstone in the treatment of advanced dyssynchronous heart failure. However, despite its widespread clinical application, precise mechanisms through which it exerts its beneficial effects remain elusive. Several studies have pointed to a metabolic component suggesting that, both in concert with alterations in chamber mechanics and independently of them, resynchronisation reverses detrimental changes to cellular metabolism, increasing energy efficiency and metabolic reserve. These actions could partially account for the existence of responders that improve functionally but not echocardiographically. This article will attempt to summarise key components of cardiomyocyte metabolism in health and heart failure, with a focus on the dyssynchronous variant. Both chamber mechanics-related and -unrelated pathways of resynchronisation effects on bioenergetics – stemming from the ultramicroscopic level – and a possible common underlying mechanism relating mechanosensing to metabolism through the cytoskeleton will be presented. Improved insights regarding the cellular and molecular effects of resynchronisation on bioenergetics will promote our understanding of non-response, optimal device programming and lead to better patient care.

Understanding non-response to cardiac resynchronisation therapy: common problems and potential solutions

Heart failure is a complex clinical syndrome associated with a significant morbidity and mortality burden. Reductions in left ventricular (LV) function trigger adaptive mechanisms, leading to structural changes within the LV and the potential development of dyssynchronous ventricular activation. This is the substrate targeted during cardiac resynchronisation therapy (CRT); however, around 30-50% of patients do not experience benefit from this treatment. Non-response occurs as a result of pre-implant, peri-implant and post implant factors but the technical constraints of traditional, transvenous epicardial CRT mean they can be challenging to overcome. In an effort to improve response, novel alternative methods of CRT delivery have been developed and of these endocardial pacing, where the LV is stimulated from inside the LV cavity, appears the most promising.

Twelve-Lead ECG Optimization of Cardiac Resynchronization Therapy in Patients With and Without Delayed Enhancement on Cardiac Magnetic Resonance Imaging

Background

Delayed enhancement (DE) on magnetic resonance imaging is associated with ventricular arrhythmias, adverse events, and worse left ventricular mechanics. We investigated the impact of DE on cardiac resynchronization therapy (CRT) outcomes and the effect of CRT optimization.

Methods and Results

We studied 130 patients with ejection fraction (EF) ≤40% and QRS ≥120 ms, contrast cardiac magnetic resonance imaging, and both pre‐ and 1‐year post‐CRT echocardiograms. Sixty‐three (48%) patients did not have routine optimization of CRT. The remaining patients were optimized for wavefront fusion by 12‐lead ECG. The primary end point in this study was change in EF following CRT. To investigate the association between electrical dyssynchrony and EF outcomes, the standard deviation of activation times from body‐surface mapping was calculated during native conduction and selected device settings in 52 of the optimized patients. Patients had no DE (n=45), midwall septal stripe (n=30), or scar (n=55). Patients without DE had better ∆EF (13±10 versus 4±10 units; P<0.01). Optimized patients had greater ∆EF in midwall stripe (2±9 versus 12±12 units; P=0.01) and scar (0±7 versus 5±10; P=0.04) groups, but not in the no‐DE group. Patients without DE had greater native standard deviation of activation times (P=0.03) and greater ∆standard deviation of activation times with standard programming (P=0.01). Device optimization reduced standard deviation of activation times only in patients with DE (P<0.01).

Conclusions

DE on magnetic resonance imaging is associated with worse EF outcomes following CRT. Device optimization is associated with improved EF and reduced electrical dyssynchrony in patients with DE.

Etiologic impact on difference on clinical outcomes of patients with heart failure after cardiac resynchronization therapy: A systematic review and meta-analysis

OBJECTIVE

To compare long-term clinical outcomes between patients with heart failure due to non-ischemic cardiomyopathy (NICM) and those due to ischemic cardiomyopathy (ICM) after cardiac resynchronization therapy (CRT).

METHODS AND RESULTS

EMbase, PubMed, and Cochrane Library were searched for published studies up to December 2017. Twenty-one observational studies with 12,331 patients were enrolled in the present meta-analysis. The results demonstrated that the all-cause mortality in NICM patients was significantly lower than that in ICM patients (RR 1.37, 95% CI 1.16-1.61). In terms of echocardiographic parameters, NICM patients exhibited statistically significant improvement in left ventricular ejection fraction (LVEF) (MD 2.70, 95%CI -4.13 to -1.28), and a significant decrement in left ventricular end-systolic volume (LVESV) (MD 10.41,95% CI 2.10-18.73) and left ventricular end diastolic diameter (LVEDD) (MD 7.63, 95% CI 2.59-12.68) as compared with ICM patients. No significant difference was observed in the improvement of New York Heart Association Functional Classification (MD 0.05, 95% CI -0.05 to 0.15), pulmonary arterial systolic pressure (PASP) (MD -0.61, 95% CI -4.36 to 3.14), and severity of mitral regurgitation (MD 0.00, 95% CI -0.08 to 0.07) between the 2 groups.

CONCLUSIONS

Our meta-analysis illustrated that patients with HF due to NICM tended to have better clinical outcomes and LV reverse remodeling as compared with those due to ICM. This finding may help clinicians select patients who respond favorably to CRT, though further research is required to clarify the potential confounding factors and underlying mechanisms for this phenomenon.

Variation in activation time during bipolar vs extended bipolar left ventricular pacing

BACKGROUND

Cardiac resynchronization therapy (CRT) is typically delivered via quadripolar leads that allow stimulation using either true bipolar pacing, where stimulation occurs between two electrodes (BP) on the quadripolar lead, or extended bipole (EBP) left ventricular (LV) pacing, with the quadripolar electrodes and right ventricular coil acting as the cathode and anode, respectively. True bipolar pacing is associated with reductions in mortality and it has been postulated that these differences are the result of enhanced electrical activation.

MATERIALS AND METHODS

Patients undergoing a CRT underwent an electrocardiographic imaging study where electrical activation data were recorded while different LV pacing vectors were temporarily programmed.

RESULTS

There were no differences in the total electrical activation times or dispersion of electrical activation between biventricular pacing with bipolar or corresponding EBP LV vector configurations (left ventricular total activation time [LVtat] BP 74.70 ± 18.07 vs EBP 72.4 ± 22.64; P = 0.45). When dichotomized according to etiology, no difference was observed in the activation time with either BP or EBP pacing (LVtat BP ischemic cardiomyopathy 72.2 ± 17.4 vs BP dilated cardiomyopathy 79.9 ± 18.9; P = 0.38).

CONCLUSIONS

Bipolar pacing alters the mechanical activation sequence of the LV and is associated with reductions in all-cause mortality. It has been postulated these benefits derive from improvements in electromechanical activation of the LV. Our study would suggest that true bipolar pacing does not necessarily result in more favorable activation of the LV or improved electrical resynchronization and other mechanisms should be explored.

Pharmacological treatment changes of chronic heart failure during cardiac resynchronization therapy: A 1-year follow-up study

BACKGROUND

Cardiac resynchronization therapy (CRT) is associated with improved morbidity and mortality in patients with chronic heart failure (HF) on optimal medical therapy. We aimed to evaluate changes of medical therapy during CRT and its influence on the CRT response.

METHODS

We evaluated 85 HF patients' pharmacological treatment changes during 1-year follow-up of CRT. Statistical analysis was performed using IBM SPSS statistical software (SPSS v.21.0 for Mac OS X).

RESULTS

Beta-blockers (BAB) were used in 81.2% of patients before CRT, and consumption increased after CRT implantation (96.5% at 1-year follow-up visit) (p<0.002). Angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) consumption and dose didn't significantly change statistically during the study. 55.3% of patients were taking spironolactone before CRT, and this number increased at discharge till 76.5% (p<0.001) and till 70.6% (p=0.01) at 1-year follow-up visit. The average dose of spironolactone during the study significantly decreased statistically. The use of diuretics was higher after CRT device implantation, compared with the period before CRT 80% to 84.7% (p<0.001), but torasemide dose hadn't significantly changed statistically and remained almost the same. Cardiovascular medication consumption was significantly lower before CRT, compared with discharge (p<0.001) and follow-up (p<0.001) periods. However, no statistically significant relation between pharmacological treatment and echocardiographic response was found.

CONCLUSIONS

The present study confirmed that pharmacological treatment has changed during the period before and after CRT. But no statistically significant relation between pharmacological treatment and echocardiographic response was found.

Cardiac resynchronization therapy in ischemic and non-ischemic cardiomyopathy

Cardiac resynchronization therapy (CRT) using a biventricular pacing system has been an effective therapeutic strategy in patients with symptomatic heart failure with a reduced left ventricular ejection fraction (LVEF) of 35% or less and a QRS duration of 130 ms or more. The etiology of heart failure can be classified as either ischemic or non-ischemic cardiomyopathy. Ischemic etiology of patients receiving CRT is prevalent predominantly in North America, moderately in Europe, and less so in Japan. CRT reduces mortality similarly in both ischemic and non-ischemic cardiomyopathy, whereas reverse structural left ventricular remodeling occurs more favorably in non-ischemic cardiomyopathy. Because the substrate for ventricular arrhythmias appears to be more severe in cases of ischemic as compared with non-ischemic cardiomyopathy, the use of an implantable cardioverter-defibrillator (ICD) backup method could prolong the long-term survival, especially of patients with ischemic cardiomyopathy, even in the presence of CRT. The aim of this review article is to summarize the effects of CRT on outcomes and the role of ICD backup in ischemic and non-ischemic cardiomyopathy.

Heart Failure in Systemic Lupus Erythematosus Treated by Cardiac Resynchronization

The presented case report describes a female patient suffering from systemic lupus erythematosus, in whom dilated cardiomyopathy with progressive heart failure was a very first symptom of the disease. The advanced invasive treatment method, cardiac resynchronization therapy, was successfully applied to improve the quality of life, clinical symptoms, and exercise tolerance.

Haemodynamic effects of cardiac resynchronization therapy using single-vein, three-pole, multipoint left ventricular pacing in patients with ischaemic cardiomyopathy and a left ventricular free wall scar: the MAESTRO study

AIMS

The clinical response to cardiac resynchronization therapy (CRT) is variable. Multipoint left ventricular (LV) pacing could achieve more effective haemodynamic response than single-point LV pacing. Deployment of an LV lead over myocardial scar is associated with a poor haemodynamic response to and clinical outcome of CRT. We sought to determine whether the acute haemodynamic response to CRT using three-pole LV multipoint pacing (CRT3P-MPP) is superior to that to conventional CRT using single-site LV pacing (CRTSP) in patients with ischaemic cardiomyopathy and an LV free wall scar.

METHODS AND RESULTS

Sixteen patients with ischaemic cardiomyopathy [aged 72.6 ± 7.7 years (mean ± SD), 81.3% male, QRS: 146.0 ± 14.2 ms, LBBB in 14 (87.5%)] in whom the LV lead was intentionally deployed straddling an LV free wall scar (assessed using cardiac magnetic resonance), underwent assessment of LV + dP/dtmax during CRT3P-MPP and CRTSP. Interindividually, the ΔLV + dP/dtmax in relation to AAI pacing with CRT3P-MPP (6.2 ± 13.3%) was higher than with basal and mid CRTSP (both P < 0.001), but similar to apical CRTSP. Intraindividually, significant differences in the ΔLV + dP/dtmax to optimal and worst pacing configurations were observed in 10 (62.5%) patients. Of the 8 patients who responded to at least one configuration, CRT3P-MPP was optimal in 5 (62.5%) and apical CRTSP was optimal in 3 (37.5%) (P = 0.0047).

CONCLUSIONS

In terms of acute haemodynamic response, CRT3P-MPP was comparable an apical CRTSP and superior to basal and distal CRTSP. In the absence of within-device haemodynamic optimization, CRT3P-MPP may offer a haemodynamic advantage over a fixed CRTSP configuration.

Patients with nonischemic cardiomyopathy requiring cardiac resynchronization therapy should also undergo implantation of a primary prevention defibrillator: the con perspective

This article describes a 45-year-old lady with longstanding dilated cardiomyopathy, who has progressed to New York Heart Association class III and has failed to respond to optimal pharmacologic therapy. On the basis of gender and the presence of an left bundle branch block, she has good prospects of responding to cardiac resynchronization therapy. In the background of nonischemic cardiomyopathy and the absence of myocardial scarring on cardiovascular magnetic resonance, her annualized risk of sudden cardiac death is low, estimated at 2.6%.

Predictors of positive response to cardiac resynchronization therapy

BACKGROUND

Approximately 30% of patients treated with cardiac resynchronization therapy (CRT) do not achieve favourable response. The purpose of the present study was to identify echocardiographic and clinical predictors of a positive response to CRT.

METHODS

The study included 82 consecutive heart failure (HF) patients in New York Heart Association (NYHA) functional class III or IV with left bundle branch block (LBBB), QRS duration ≥ 120 ms and left ventricular ejection fraction (LVEF) ≤ 35%. Statistical analysis was performed using IBM SPSS statistical software (SPSS v.21.0 for Mac OS X). A p value < 0.05 was considered statistically significant.

RESULTS

Echocardiographic response was established in 81.6% and clinical response was achieved in 82.9% of patients. Significant univariate predictors of favourable echocardiographic response after 12 months were smaller left ventricular end-diastolic diameter (LVEDD) (odds ratio [OR] 0.89; 95% confidence interval [CI] 0.82 - 0.97, p = 0.01), and smaller left ventricular end-systolic diameter (LVESD) (OR 0.91; 95% CI 0.85 - 0.98, p = 0.01). Lower uric acid concentration was associated with better echocardiographic response (OR 0.99; 95% CI 0.99 - 1.0, p = 0.01). Non-ischemic HF etiology (OR 4.89; 95% CI 1.39 - 17.15, p = 0.01) independently predicted positive clinical response. Multiple stepwise regression analysis demonstrated that LVEDD lower than 75 mm (OR 5.60; 95% confidence interval [CI] 1.36 - 18.61, p = 0.01) was the strongest independent predictor of favourable echocardiographic response.

CONCLUSIONS

Smaller left ventricular end-diastolic and end-systolic diameters and lower serum uric acid concentration were associated with better response to CRT. Left ventricular end-diastolic diameter and non-ischemic heart failure etiology were the strongest independent predictors of positive response to CRT.

Impact of etiology on the outcomes in heart failure patients treated with cardiac resynchronization therapy: a meta-analysis

BACKGROUND

Cardiac resynchronization therapy (CRT) has been extensively demonstrated to benefit heart failure patients, but the role of underlying heart failure etiology in the outcomes was not consistently proven. This meta-analysis aimed to determine whether efficacy and effectiveness of CRT is affected by underlying heart failure etiology.

METHODS AND RESULTS

Searches of MEDLINE, EMBASE and Cochrane databases were conducted to identify RCTs and observational studies that reported clinical and functional outcomes of CRT in ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM) patients. Efficacy of CRT was assessed in 7 randomized controlled trials (RCTs) with 7072 patients and effectiveness of CRT was evaluated in 14 observational studies with 3463 patients In the pooled analysis of RCTs, we found that CRT decreased mortality or heart failure hospitalization by 29% in ICM patients (95% confidence interval [CI], 21% to 35%), and by 28% (95% CI, 18% to 37%) in NICM patients. No significant difference was observed between the 2 etiology groups (P = 0.55). In the pooled analysis of observational studies, however, we found that ICM patients had a 54% greater risk for mortality or HF hospitalization than NICM patients (relative risk: 1.54; 95% CI: 1.30-1.83; P<0.001). Both RCTs and observational studies demonstrated that NICM patients had greater echocardiographic improvements in the left ventricular ejection fraction and end-systolic volume, as compared with ICM patients (both P<0.001).

CONCLUSION

CRT might reduce mortality or heart failure hospitalization in both ICM and NICM patients similarly. The improvement of the left ventricular function and remodeling is greater in NICM patients.

Effect of carvedilol versus metoprolol CR/XL on mortality in patients with heart failure treated with cardiac resynchronization therapy: a COX multivariate regression analysis

We investigated in 136 consecutive patients with heart failure receiving cardiac resynchronization therapy (CRT) the effect of carvedilol versus metoprolol CR/XL versus no beta blocker on mortality. Of the 136 patients, 42 (31%) were on carvedilol, 80 (59%) were on metoprolol CR/XL, and 14 (10%) were not on a beta blocker. A decrease of left ventricular end-systolic volume ≥15% after CRT was defined as a positive response to CRT. Of the 136 patients, 62 (46%) responded to CRT. It was found that both carvedilol and metoprolol CR/XL were not related to CRT response on using Cox univariate regression analysis. Twenty-two of the 136 patients (16%) died during follow-up of 17 ± 10 months after initiating CRT. Mortality occurred in 14 of 80 patients (18%) on metoprolol CR/XL, in 3 of 42 patients (7%) on carvedilol, and in 5 of 14 patients (36%) not on beta blockers (P = 0.04). After adjustment for age, gender, and the variables with significant differences by Cox univariate regression, both carvedilol (hazard ratio = 0.14; P = 0.03; 95% confidence interval = 0.02-0.86) and metoprolol CR/XL (hazard ratio = 0.19; P = 0.02; 95% confidence interval = 0.04-0.80) were found to be related to mortality by Cox multivariate regression.

How to improve outcomes: should we put more emphasis on programming and medical care and less on patient selection?

Many factors contribute to the pathophysiology and progression of heart failure (HF), offering the potential for many synergistic therapeutic approaches to its management. For patients, who have systolic HF, prolonged QRS and receiving guideline-indicated pharmacological therapy, cardiac resynchronization therapy (CRT) may provide additional benefits in terms of symptom improvement and mortality reduction. Nevertheless, in many patients, moderate or severe symptoms may persist or recur after CRT implantation due to either the severity or progression of the underlying disease, the presence of important co-morbidities or suboptimal device programming. Identifying and, where possible, treating the reasons for persistent or recurrent symptoms in patients who have received CRT is an important aspect of patient care. The present review summarizes the available evidence on this topic.

Left ventricular midwall fibrosis as a predictor of mortality and morbidity after cardiac resynchronization therapy in patients with nonischemic cardiomyopathy

OBJECTIVES

The aim of this study was to determine whether left ventricular (LV) midwall fibrosis, detected by midwall hyperenhancement (MWHE) on late gadolinium enhancement cardiovascular magnetic resonance (CMR) imaging, predicts mortality and morbidity in patients with dilated cardiomyopathy (DCM) undergoing cardiac resynchronization therapy (CRT).

BACKGROUND

Midwall fibrosis predicts mortality and morbidity in patients with DCM.

METHODS

Patients with DCM with (+) or without (-) MWHE (n = 20 and n = 77, respectively) as well as 161 patients with ischemic cardiomyopathy (ICM) undergoing CRT (n = 258) were followed up for a maximum of 8.7 years.

RESULTS

Among patients with DCM, +MWHE predicted cardiovascular mortality (hazard ratio [HR]: 18.6; 95% confidence intervals [CI]: 3.51 to 98.5; p = 0.0008), total mortality or hospitalization for major adverse cardiovascular events (HR: 7.57; 95% CI: 2.71 to 21.2; p < 0.0001), and cardiovascular mortality or heart failure hospitalizations (HR: 9.56; 95% CI: 2.72 to 33.6; p = 0.0004), independent of New York Heart Association class, QRS duration, atrial fibrillation, LV volumes, LV ejection fraction, and a CMR-derived measure of dyssynchrony. Among patients with DCM and ICM, the risk of cardiovascular mortality for DCM +MWHE (adjusted HR: 18.5; 95% CI: 3.93 to 87.3; p = 0.0002) was similar to that for ICM (adjusted HR: 21.0; 95% CI: 5.06 to 87.2; p < 0.0001). Both DCM +MWHE and ICM were predictors of pump failure death as well as sudden cardiac death. LV reverse remodeling was observed in DCM -MWHE and in ICM but not in DCM +MWHE.

CONCLUSIONS

Midwall fibrosis is an independent predictor of mortality and morbidity in patients with DCM undergoing CRT. The outcome of DCM with midwall fibrosis is similar to that of ICM. This relationship is mediated by both pump failure and sudden cardiac death.

Presence of extensive LV remodeling limits the benefits of CRT in patients with intraventricular dyssynchrony

OBJECTIVES

The aim of this study was to evaluate whether, in patients with evidence of both electrical and mechanical left ventricular (LV) dyssynchrony, extensive LV dilation would affect response to cardiac resynchronization therapy (CRT).

BACKGROUND

Cardiac resynchronization therapy is effective in heart failure patients with LV dysfunction and wide QRS complex. However, many patients still fail to respond. We hypothesized that presence of extensive LV dilation might prevent response to CRT, despite LV mechanical dyssynchrony.

METHODS

We studied 78 heart failure patients (68 ± 9 years of age, 77% men) with both electrical (QRS width >120 ms) and mechanical intraventricular dyssynchrony (by tissue Doppler imaging and/or left lateral wall post-systolic contraction). Echocardiographic evaluation was performed at baseline and 6 to 8 months after CRT. As an indication of LV remodeling, end-diastolic volume index and end-systolic volume index (ESVI) and sphericity index were measured. Long-term (40 ± 23 months) clinical follow-up (events: cardiac death and hospital admission for heart failure) was also obtained.

RESULTS

At follow-up after CRT, in the overall population, ejection fraction increased from 26 ± 6% to 35 ± 11% (p < 0.0001), whereas end-diastolic volume index (from 144 ± 43 ml/m(2) to 119 ± 55 ml/m(2)), ESVI (from 108 ± 37 ml/m(2) to 82 ± 49 ml/m(2), p < 0.0001 for both), and sphericity index (from 0.60 ± 0.22 to 0.53 ± 0.15, p = 0.0036) all significantly decreased. By multiple linear regression analysis, after controlling for confounding factors, change in LV ejection fraction at follow-up resulted independently and negatively associated with baseline ESVI (p = 0.001), with much lower improvement after implant in the highest tertile of baseline ESVI. During follow-up, 31 patients (39.7%) had a cardiac event. By Cox regression model, baseline ESVI was the most powerful predictor of events, with event-rate/year increasing with increasing tertiles of ESVI (6.3%, 10.1%, and 23.8%, respectively, p < 0.05).

CONCLUSIONS

In this nonrandomized, open-label clinical study, despite intraventricular electrical and mechanical dyssynchrony, extensive LV remodeling at baseline negatively impacted CRT results in terms of LV function improvement and incidence of cardiac events at follow-up.

Low-dose dobutamine test associated with interventricular dyssynchrony: a useful tool to identify cardiac resynchronization therapy responders: data from the LOw dose DObutamine stress-echo test in Cardiac Resynchronization Therapy (LODO-CRT) phase 2 study

BACKGROUND

Cardiac resynchronization therapy (CRT) is effective in patients with heart failure, but 30% to 50% of subjects are classified as nonresponders. Identifying responders remains a challenging task.

AIMS

The LODO-CRT trial investigated the association between left ventricular contractile reserve (LVCR) and clinical and echocardiographic long-term CRT response.

METHODS

This is a multicenter, prospective, observational study. Left ventricular contractile reserve was detected using a dobutamine stress echocardiography test, defined as an ejection fraction increase of >5 points. Clinical CRT response was defined as the absence of major cardiovascular events (ie, cardiovascular death or heart failure hospitalization). Echocardiographic response was defined as a left ventricle end-systolic volume reduction of >10%.

RESULTS

A total of 221 CRT-indicated patients were studied (80% presented LVCR). During a mean follow-up of 15 ± 5 months, 17 patients died and 16 were hospitalized due to heart failure. The proportion of clinical responders was 155 (88%) of 177 and 33 (75%) of 44 (P = .036) in the groups with and without LVCR, respectively. Kaplan-Meier analysis showed a significant difference in cardiac survival/hospitalization between patients with and without LVCR. The proportion of echocardiographic responders was 144 (87%) of 166 and 16 (42%) of 38 in the groups with and without LVCR (P < .001), respectively; LVCR showed 90% sensitivity and 87% positive predictive value to prefigure echocardiographic CRT responders. Multivariable analysis identified LVCR and interventricular dyssynchrony as independent predictors of CRT response. The concomitant presence of both factors showed 99% specificity and 83% sensitivity in detecting responders.

CONCLUSION

The presence of LVCR helps in predicting a clinical and echocardiographic CRT response. Concomitant assessment of LVCR and interventricular dyssynchrony accurately stratifies responder and nonresponder patients.

[Cardiac resynchronization therapy: preoperative screening. How can we reliably predict response to CRT?]

Cardiac resynchronization therapy (CRT) is an established therapy for patients with advanced heart failure, depressed left ventricular function, and wide QRS complex. However, about 30 to 45% of patients do not respond to CRT. Assuming that the main therapeutic action of CRT is the correction of dyssynchronous myocardial contraction, a plethora of echocardiographic dyssynchrony parameters have been proposed to improve the prediction of response to CRT. However, one multicenter study has recently questioned the utility of any of these indexes. This review delineates the various causes of non-response to CRT, explains the different levels and mechanisms of dyssynchrony and gives a critical overview of currently available echocardiographic techniques for assessment of dyssynchrony. Based upon a discussion of the evidence coming from randomized multicenter studies and against the background of national and international cardiac societies' guideline recommendations on CRT, a rational basis for the evaluation of patients for CRT is proposed.

A new baseline scoring system may help to predict response to cardiac resynchronization therapy

INTRODUCTION

The PROSPECT trial reported no single echocardiographic measurement of dyssynchrony is recommended to improve patient selection for cardiac resynchronization therapy (CRT).

MATERIAL AND METHODS

In 100 consecutive patients who received CRT, we analyzed 27 ECG and echocardiographic variables to predict a positive response to CRT defined as a left ventricular (LV) end systolic volume decrease of ≥ 15% after CRT.

RESULTS

Right ventricular (RV) pacing-induced left bundle branch block (LBBB), time difference between LV ejection measured by tissue Doppler and pulsed wave Doppler (T(TDI-PW)), and wall motion score index (WMSI) were significantly associated with positive CRT response by multivariate regression. We assigned 1 point for RV pacing-induced LBBB, 1 point for WMSI ≤ 1.59, and 2 points for T(TDI-PW) > 50 ms. Overall mean response score was 1.79 ±1.39. Cutoff point for response score to predict positive response to CRT was > 2 by receiver operating characteristic (ROC) analysis. Area under ROC curve was 0.97 (p = 0.0001). Cardiac resynchronization therapy responders in patients with response score > 2 and ≤ 2 were 36/38 (95%) and 7/62 (11%, p < 0.001), respectively. After age and gender adjustment, the response score was related to CRT response (OR = 45.4, p < 0.0001).

CONCLUSIONS

A response score generated from clinical, ECG and echocardiographic variables may be a useful predictor for CRT response. However, this needs to be validated.

Echocardiographic assessment of interventricular and intraventricular mechanical synchrony in normal dogs

OBJECTIVES

The aims of this prospective study are to (1) generate normal ranges for interventricular and intraventricular mechanical synchrony in dogs, and (2) generate normal ranges for tissue Doppler imaging (TDI) velocity imaging and speckle tracking strain imaging assessment of segmental intraventricular mechanical synchrony in dogs.

ANIMALS

10 prospectively recruited healthy dogs.

METHODS

Dogs were excluded if they had abnormal historical, physical examination, echocardiographic, ECG or systolic blood pressure findings. Interventricular mechanical synchrony was assessed using time difference between left and right ventricular pre-ejection periods. Intraventricular mechanical synchrony was assessed using both M-mode and color M-mode septal to posterior wall mechanical delay (SPWMD). Intraventricular segmental mechanical synchrony was assessed using both color TDI and speckle tracking strain analysis of segmental myocardial motion during systole and diastole.

RESULTS

All synchrony measures were found to be independent of age or body weight. Normal range for mechanical interventricular synchrony was found to be -10.2 to 12.6 ms. Assessment of mechanical intraventricular synchrony using either M-mode or color M-mode SPWMD was found to be associated with an extremely wide normal range, limiting clinical applicability. Normal ranges for segmental intraventricular mechanical synchrony assessed using either color TDI or speckle tracking were found to be comparable to those published for human subjects.

CONCLUSIONS

Interventricular and intraventricular mechanical synchrony in dogs is independent of age and body weight. The normal ranges identified in this study form a basis for assessment of normal versus abnormal mechanical synchrony in canine cardiovascular disease patients.

A patient selection score for cardiac resynchronization therapy

BACKGROUND

We hypothesized a patient selection score (PSS) may improve patient selection for cardiac resynchronization therapy (CRT).

METHODS

Of 136 patients who received CRT, group A included 100 study patients and group B 36 patients for validation. A positive response to CRT was a left ventricular (LV) end-systolic volume decrease of ≥15% and survival from heart failure at end of follow-up.

RESULTS

Of 100 group A patients, 37 (37%) were CRT responders during 14-month follow-up. A 7-point PSS was generated based on six variables. The cutoff point for PSS to predict a positive response to CRT was >4 by receiver operating characteristic (ROC) analysis. The area under the ROC curve (AUC) for PSS to predict CRT response was 0.94 (P = 0.0001). CRT responders in patients with a PSS > 4 and ≤4 were 33/40 (83%), and 4/60 (7%), respectively (P < 0.001). Multivariate Cox proportional regression analysis showed that PSS was related to CRT response (hazard ratio = 10.3, P < 0.0001). The CRT response rate in patients with a PSS > 4 in Group B was also significantly higher compared to a PSS ≤ 4 (88% vs. 16%, P < 0.001). The AUC for PSS to predict a CRT response in Group B was 0.91 (P = 0.0001).

CONCLUSIONS

Patients with a PSS >4 are the most likely to respond to CRT. Using this score system, a PSS score >4 can predict the probability of a CRT response up to 88% in patients with heart failure and a wide QRS duration.

Maximum derivative of left ventricular pressure predicts cardiac mortality after cardiac resynchronization therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) has been reported to improve cardiac performance. However, CRT in patients with advanced heart failure is not always accompanied by an improvement in survival rates. We investigated the association between hemodynamic studies and long-term prognosis after CRT.

METHODS

A total of 68 consecutive patients receiving CRT devices due to advanced heart failure were assessed by hemodynamic study and long-term outcome after implantation of the device. Hemodynamic parameters were measured both with the CRT on and off.

RESULTS

Patients demonstrated significant improvement in the maximum first derivative of left ventricular (LV) pressure (LV dP/dt(max) ) and QRS duration after periods with the CRT on. During the follow-up period of 34.9 ± 17.6 months, basal LV dP/dt(max) and isovolemic LV pressure half-time (T½), but not percent change in LV dP/dt(max) , were independent predictors of cardiac mortality or hospitalization due to heart failure after multivariate Cox regression analysis. The Kaplan-Meier survival analysis revealed that patients in the lowest basal LV dP/dt(max) tertile or the longest basal T½ tertile exhibited a significantly higher cardiac-caused mortality or heart failure hospitalization.

CONCLUSIONS

Lower LV dP/dt(max) or longer T½ independently predicts cardiac mortality or heart failure hospitalization in patients receiving CRT. The assessment of the basal LV dP/dt(max) and T½ could provide useful information in long-term prognosis after CRT.

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.

Evaluation of left ventricular dyssynchrony using combined pulsed wave and tissue Doppler imaging

INTRODUCTION

The combination of pulsed wave (PW) and tissue Doppler imaging (TDI) has been proposed as a new method to assess left ventricular (LV) mechanical dyssynchrony (LVMD), but results have not been validated. We investigated the correlation of a combination of PW and TDI with a positive response to cardiac resynchronization therapy (CRT).

MATERIAL AND METHODS

We studied 108 consecutive patients who received CRT. Patients with atrial fibrillation were excluded. The time difference (T(PW-TDI)) between onset of QRS to the end of LV ejection by PW (T(PW)) and onset of QRS to the end of the systolic wave in LV basal segments with greatest delay by TDI (T(TDI)) was measured before CRT and during short-term and long-term follow-up.

RESULTS

The T(PW-TDI) interval before CRT was 74 ±48 ms. Intra-observer variabilities for T(PW) and T(TDI) were 1.5 ±0.24% and 1 ±0.17%. Inter-observer variabilities for T(PW) and T(TDI) were 1 ±0.36% and 1 ±0.64%, respectively. T(PW-TDI) > 50 ms was defined as the cutoff value for diagnosis of LVMD by receiver operating curve (ROC) analysis. During follow-up of 15 ±11 months, the sensitivity and specificity of TP(PW-TDI) to predict a positive response to CRT were 98% and 82%, respectively. The area under the ROC curve was 0.92. There was a significant agreement between LVMD determined by T(PW-TDI) and the positive response to CRT (κ=0.80).

CONCLUSIONS

Left vertricular dyssynchrony detected by the method combining PW and TDI demonstrated a high reproducibility, sensitivity, specificity and agreement with a positive response to CRT.

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.

Effect of medical therapy on left ventricular ejection fraction in patients with systolic heart failure and narrow QRS duration with and without ischemic heart disease and left ventricular mechanical dyssynchrony

We studied 99 consecutive patients with class III-IV systolic heart failure with a left ventricular ejection fraction (LVEF) < or =35% and a QRS duration <120 milliseconds. Patients with cardiac resynchronization therapy were excluded. Echocardiography was performed in all patients before and after optimal standard heart failure therapy. The septal-to-posterior wall motion delay (SPWMD) > or =130 milliseconds on echocardiogram was defined as left ventricular mechanical dyssynchrony (LVMD). Sixty-nine of 99 patients (70%) had ischemic heart disease. During follow-up of 15.2 +/- 9.8 months, LVEF improvement > or =15% was greater patients in nonischemic group (50%, 15/30) than in ischemic group (9%, 6/69; P < 0.001). After adjustment for age, gender, and clinical and echocardiographic characteristics, ischemic heart disease and grade of coronary disease were persistently related to LVEF improvement > or =15% (P = 0.03 and 0.02, respectively). Twenty of 99 patients (20%) had SPWMD > or =130 milliseconds (LVMD group), and 79 of 99 patients (80%) had SPWMD <130 milliseconds (non-LVMD group). LVEF increased in both groups (P = 0.005) during follow-up, but the percentage of patients with LVEF improvement > or =15% in LVMD was greater compared with patients without LVMD (40% versus 16%, respectively, P = 0.03). In conclusion, the improvement of LVEF in patients with systolic heart failure and narrow QRS was greater in patients with nonischemic heart disease and LVMD compared with patients with ischemic heart disease and absence of LVMD during medical therapy without cardiac resynchronization therapy.