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

Long-Term Survival of Patients With Left Bundle Branch Block Who Are Hypo-Responders to Cardiac Resynchronization Therapy

Guidelines support cardiac resynchronization therapy with a defibrillator (CRT-D) in mild heart failure (HF) patients with left bundle branch block (LBBB). However, not all patients demonstrate echocardiographic or clinical response to CRT-D. We aimed to evaluate the long-term outcomes of echocardiographic hypo-responders and clinical hypo-responders to CRT-D with LBBB in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy. Five-hundred thirty-four patients with LBBB in the CRT-D arm were followed for 5.6 years (median). Clinical hypo-response was defined as HF event in the first year after CRT-D implantation. Echocardiographic hypo-response was defined as ≤35% reduction (median) in left ventricular end-systolic volume 1 year after CRT-D implantation without evidence of clinical hypo-response. Echocardiographic and clinical response was observed in 257 patients (48%). Two-hundred fifty patients (47%) were echocardiographic hypo-responders and 27 patients (5%) were clinical hypo-responders. Echocardiographic hypo-responders had increased risk of all-cause mortality compared with echocardiographic + clinical responders (hazard ratio [HR] 2.85, 95% confidence interval [CI]: 1.37 to 5.94, p = 0.005). Clinical hypo-responders had increased risk of mortality compared with echocardiographic + clinical responders (HR 7.49, 95% CI: 2.88 to 19.48, p <0.0001) and compared with echocardiographic hypo-responders (HR 2.63, 95% CI: 1.17 to 5.92, p = 0.020). In conclusion, during long-term follow-up, patients with mild HF and LBBB who have echocardiographic hypo-response to CRT, with or without clinical signs of worsening HF, have increased risk of mortality. This study emphasizes the prognostic significance of echocardiographic assessment of left ventricular volume after CRT implantation in LBBB patients with mild HF.

Extracellular cardiac matrix biomarkers in patients with reduced ejection fraction heart failure as predictors of response to cardiac resynchronisation therapy: a systematic review

OBJECTIVE

Cardiac resynchronisation therapy (CRT) is an effective therapy for selected patients with heart failure (HF); however, a significant non-response rate exists. We examined current evidence on extracellular cardiac matrix (ECM) biomarkers in predicting response following CRT.

METHODS

Complete literature review of PubMed, Ovid SP MEDLINE, Cochrane Library and TRIP, reference lists, international cardiology conferences and ongoing studies between December 1999 and December 2015 conducted according to prospectively registered study selection and analysis criteria (PROSPERO:CRD42016025864) was performed. All observational and randomised control trials (RCT) were included if they tested prespecified ECM biomarkers' ability to predict CRT response. Risk of bias assessment and data extraction determined pooling of included studies was not feasible due to heterogeneity of the selected studies.

RESULTS

A total of 217 studies were screened; six (five prospective cohort and one RCT substudy) were included in analysis with 415 participants in total. Study sizes varied (n=55-260), cohort characteristics contrasted (male: 67.8%-83.6%, ischaemic aetiology: 40.2%-70.3%) and CRT response definitions differed (three clinical/functional, three echocardiographic). Consistent observation in all ECM biomarker behaviour before and after CRT implantation was not observed between studies. Lower type I and type III collagen synthesis biomarkers (N-terminal propeptides of type I and III procollagens) expression demonstrated replicated ability to predict reverse left ventricular remodelling.

CONCLUSION

Collagen synthesis biomarkers offer the most potential as ECM biomarkers for predicting CRT response. Heterogeneity between these studies was large and limited the ability to pool and compare results numerically. Use of different response definitions was one of the biggest challenges.

Accuracy of Multi-Slice Spiral Computed Tomography for Preoperative Tumor Node Metastasis (TNM) Staging of Colorectal Carcinoma

Background

With the advances in imaging technologies, multi-slice spiral computed tomography (MSCT) has demonstrated superiority in the diagnosis and staging of colorectal carcinoma. In the current study, preoperative TNM staging of colorectal carcinoma by using MSCT was conducted and compared with the corresponding postoperative pathological examination findings, in order to evaluate the accuracy of preoperative MSCT for TNM staging.

Material/Methods

Combinations of biphasic or triphasic enhanced-phase MSCT scans were obtained for 76 patients with colorectal carcinoma, and the TNM stage was determined based on imaging reconstruction from various angles and perspectives to display the size, location, and affected range of tumors. The preoperative TNM stage was compared with the postoperative pathological stage, and the consistency between the 2 methods was tested by the κ test using SPSS 17.0 software.

Results

Among the different combinations of enhanced-phase MSCT scanning, triphasic MSCT imaging, comprising the arterial, portal venous, and delayed phases, showed the highest accuracy rates, at 81.6% (62/76), 82.89% (63/76), and 96.1% (73/76) for T, N, and M staging, respectively, with κ values of 0.72, 0.65, and 0.56, respectively, indicating consistency with the postoperative pathological staging.

Conclusions

Combined MSCT scanning comprising the arterial phase, portal venous phase, and delayed phase showed satisfying consistency with the postoperative pathological analysis results for TNM staging of colorectal carcinoma. Thus, MSCT is an important clinical value for improving the accuracy of TNM staging and for planning the appropriate colorectal cancer treatment.

Implantable Cardioverter-Defibrillators With Versus Without Resynchronization Therapy in Patients With a QRS Duration >180 ms

BACKGROUND

More than 20% of Medicare beneficiaries receiving cardiac resynchronization therapy defibrillators (CRT-D) have a very wide (≥180 ms) QRS complex duration (QRSD). Outcomes of CRT-D in these patients are not well-established because they have been underrepresented in clinical trials.

OBJECTIVES

This study examined outcomes in patients with CRT-D in a very wide QRSD with left bundle branch block (LBBB) versus those without LBBB.

METHODS

Medicare patients from the Implantable Cardioverter Defibrillator Registry (January 1, 2005, through April 30, 2006) with a CRT-D and confirmed Class I or IIa indications for CRT-D were matched to implantable cardioverter-defibrillator (ICD) patients without CRT despite having Class I or IIa indications for CRT. Mortality and heart failure hospitalizations longer than 4 years with CRT-D versus standard ICDs based on a QRSD and morphology were analyzed.

RESULTS

We analyzed 24,960 patients. Among those with LBBB, patients with a QRSD ≥180 ms had a greater adjusted survival benefit with CRT-D versus standard ICD (hazard ration [HR] for death: 0.65; 95% confidence interval [CI]: 0.59 to 0.72) compared with those having a QRSD 120 to 149 ms (HR: 0.85; 95% CI: 0.80 to 0.92) and 150 to 179 ms (HR: 0.87; 95% CI: 0.81 to 0.93). CRT-D versus ICD was associated with an improvement in survival in those with LBBB and a QRSD ≥180 ms (adjusted HR for death: 0.78; 95% CI: 0.68 to 0.91), but not in those with LBBB and a QRSD 150 to 179 ms (adjusted HR for death: 1.06; 95% CI: 0.95 to 1.19).

CONCLUSIONS

Improvements in both survival and heart failure hospitalizations with CRT-D were greatest in patients with a QRSD ≥180 ms with or without LBBB, whereas patients with a QRSD 150 to 179 ms without LBBB had no improvement in survival with CRT-D, and those with a QRSD 150 to 179 ms and LBBB had only a modest improvement.

Combined myocardial deformation to predict cardiac resynchronization therapy response in nonischemic cardiomyopathy

BACKGROUND

20-30% of patients do not benefit from cardiac resynchronization therapy (CRT) when the established selection criteria were applied. We hypothesized that a combined assessment of mechanical dyssynchrony, myocardial deformation, and diastolic function would identify patients who would benefit most from CRT.

METHOD

In 36 CRT patients, clinical evaluation and echocardiography were performed before and after CRT. Patients were classified into three subgroups according to their amount of response: echocardiographic responders, clinical responders, and nonresponders. Radial dyssynchrony and left ventricular (LV) global longitudinal, radial, and circumferential peak strain was assessed by speckle-tracking image. Diastolic function was quantified by conventional echocardiography.

RESULT

In addition to left bundle branch block, nonspecific intraventricular conduction disturbance with intraventricular dyssynchrony could also improve LV remodeling. Echocardiographic responders had better global longitudinal strain, global circumferential peak strain, and global radial strain at baseline which significantly increased at 12-month follow-up. An improvement in estimates of LV filling pressure and a decrease in mitral regurgitation and left atrial dimensions were observed only in echocardiographic responders to CRT. Patients with clinical but without echocardiographic response showed a significant improvement in atrioventricular (AV) synchrony and a nonsignificant improvement in other parameters. The nonresponder group did not improve the AV and intraventricular dyssynchrony. CRT could not improve restrictive filling pattern with normal filling time. Overall, those patients with AV and intraventricular dyssynchrony and those with best contractile function and short diastolic filling time of restrictive filling pattern at baseline demonstrated the greatest benefit from CRT.

CONCLUSIONS

Mechanical dyssynchrony, contractile function, and filling pattern are important determinants of the benefits in CRT.

Cardiac resynchronization therapy and its role in the management of heart failure

The prevalence of heart failure is increasing and it is associated with significant mortality and morbidity. Optimal medical therapy improves outcome, but heart failure continues to have a substantial impact on both the individual patient and wider society. Over the last two decades, cardiac resynchronization therapy has revolutionized the treatment of selected patients who have heart failure. Cardiac resynchronization therapy significantly reduces mortality and hospitalization through reverse cardiac remodelling. This review informs non-specialists about cardiac resynchronization therapy and for which patients it should be considered.

Predictors of response to cardiac resynchronization therapy: A prospective cohort study

INTRODUCTION

Cardiac resynchronization therapy (CRT) has modified the prognosis of chronic heart failure (HF) with left ventricular systolic dysfunction. However, 30% of patients do not have a favorable response. The big question is how to determine predictors of response.

AIMS

To identify baseline characteristics that might influence echocardiographic response to CRT.

METHODS AND RESULTS

We performed a prospective single-center hospital-based cohort study of consecutive HF patients selected to CRT (NYHA class II-IV, left ventricular ejection fraction (LVEF) <35% and QRS complex ≥120 ms). Responders were defined as those with a ≥5% absolute increase in LVEF at six months. Clinical, electrocardiographic, laboratory, echocardiographic, autonomic, endothelial and cardiopulmonary function parameters were assessed before CRT device implantation. Logistic regression models were used. Seventy-nine patients were included, 54 male (68.4%), age 68.1 years (standard deviation 10.2), 19 with ischemic etiology (24%). At six months, 51 patients (64.6%) were considered responders. Although by univariate analysis baseline tricuspid annular plane systolic excursion (TAPSE) and serum creatinine were significantly different in responders, on multivariate analysis only TAPSE was independently associated with response, with higher values predicting a positive response to CRT (OR=1.13; 95% CI: 1.02-1.26; p=0.020). TAPSE ≥15 mm was strongly associated with response, and TAPSE <15 mm with non-response (p=0.005). Responders had no TAPSE values below 10 mm.

CONCLUSION

From a range of clinical and technical baseline characteristics, multivariate analysis only identified TAPSE as an independent predictor of CRT response, with TAPSE <15 mm associated with non-response. This study highlights the importance of right ventricular dysfunction in CRT response. ClinicalTrials.gov identifier: NCT02413151.

Development and Evolution of a Hierarchical Clinical Composite End Point for the Evaluation of Drugs and Devices for Acute and Chronic Heart Failure: A 20-Year Perspective

Traditional approaches to the assessment of new treatments for heart failure have generally evaluated individual components of the syndrome at fixed points in time or have relied on surrogate physiological measures that are poorly correlated with the clinical status of patients. Conventional time-to-event trials that focus on morbidity and mortality represent an important methodological advance, but they generally assign undue weight to clinical events of less importance and are insensitive to difference in functional capacity among individuals who do not experience a clinical event during follow-up. Twenty years ago, a hierarchical clinical composite was developed to address these limitations; it aims to assess the clinical course of patients as a physician would in practice by combining a symptomatic assessment of the patient at each visit with an evaluation of the clinical stability of the patient between visits. The composite does not generate a numeric score by summing arbitrarily assigned weights to certain symptoms or events; instead, the composite ranks relevant measures and outcomes according to clinical priority. In doing so, the clinical composite minimizes the biases created by noncompleting patients in the assessment of symptoms or exercise tolerance while expanding the range of patients who contribute to the treatment difference in a typical morbidity and mortality trial. When applied appropriately, the hierarchical clinical composite end point has reliably distinguished effective from ineffective treatments. The composite may have particular advantages in the evaluation of new devices and transcatheter interventions in chronic heart failure and of new drugs for acute heart failure. Recent modifications enhance its discriminant characteristics and its ability to accurately assess the efficacy of novel interventions for heart failure.

Echocardiographic Predictors of Long-Term Survival in Patients Undergoing Cardiac Resynchronization Therapy: What Is the Optimal Metric?

BACKGROUND

Multiple definitions of reverse ventricular remodeling (RVR) employing various changes in left ventricular end-systolic (LVESV) or diastolic volumes (LVEDVs) or left ventricular ejection fraction (LVEF) have been used in determining cardiac resynchronization therapy (CRT) response, making comparability across studies difficult. We compared different metrics to each other, and in combination, in terms of association with long-term outcomes.

METHODS

We collected clinical and echocardiographic data on 436 patients undergoing CRT. LVEF was assessed via a combined volumetric and visual assessment. Volumes were manually traced. Using a nested multivariate model of a priori determined predictors of long-term survival free of left ventricular assist device (LVAD) or heart transplant, multiple definitions of RVR were added to the model individually to determine which provided the best model fit.

RESULTS

Over a mean follow-up of 5.4 ± 2.3 years, there were 198 endpoints (10 LVADs, 15 heart transplants, and 173 deaths). When added to a nested model controlling for multiple potential confounders, all definitions of RVR were significantly associated with improved survival. Changes in LVEF and LVESV were superior to changes in LVEDV. A combination metric of an LVEF improvement ≥ 5% and LVESV reduction ≥ 10% was the best overall metric for model fit.

CONCLUSIONS

Changes in LVESV and LVEF are better predictors of long-term outcome following CRT compared to changes in LVEDV. Adding an assessment of LVEF to reduction in LVESV ≥ 10% provided the best overall definition for RVR in predicting CRT outcomes.

The Role of Cardiovascular Magnetic Resonance in Cardiac Resynchronization Therapy

Randomized, controlled trials have shown that cardiac resynchronization therapy (CRT) is beneficial in patients with heart failure, impaired left ventricular (LV) systolic function, and a wide QRS complex. Other studies have shown that targeting the LV pacing site can also improve patient outcomes. Cardiovascular magnetic resonance (CMR) is a radiation-free imaging modality that provides unparalleled spatial resolution. In addition, emerging data suggest that targeted LV lead deployment over viable myocardium improves the outcome of patients undergoing CRT. This review explores the role of CMR in the preoperative workup of patients undergoing CRT.

Gauging the response to cardiac resynchronization therapy: The important interplay between predictor variables and definition of a favorable outcome

AIMS

Selection of patients who are viable candidates for cardiac resynchronization therapy (CRT), prediction of the response to CRT as well as an optimal definition of a favorable response, all require further exploration. The purpose of this study was to evaluate the interplay between the prediction of the response to CRT and the definition of a favorable outcome.

METHODS

Seventy patients who received CRT were included. All patients met current guideline criteria for CRT. Forty-three echocardiographic parameters were evaluated before CRT and at 1, 3, 6, and 12 months. M-mode, 2D echocardiography, and Doppler imaging were used to quantify left ventricular (LV) systolic and diastolic function, mitral regurgitation, right ventricular systolic function, pulmonary artery pressure, and myocardial mechanical dyssynchrony. The following definitions of a favorable CRT response were used: left ventricular ejection fraction (LVEF) improvement more >5% acutely following CRT, LVEF improvement >20% at 12-month follow-up, and a LV end-systolic volume (LVESV) decrease >15% at 12-month follow-up.

RESULTS

For the LVEF improvement >5%, the best predictor was isovolumetric relaxation time (IVRT; P=.035). For improvement of LVEF >20%, the best predictors were left ventricular stroke index (LVSI; P=.044) and left ventricular fractional shortening (LVFS; P=.031). For the drop in left ventricular systolic volume (LVESV >15%), the best predictor was septal-to-lateral wall delay (ΔT) (P=.043, RR=1.023, 95% CI for RR=1.001-1.045).

CONCLUSION

The definition of a favorable CRT response influenced the optimal predictor variable(s). Standardization of defining a favorable response to CRT is needed to guide clinical decision making processes.

The Role of Cardiovascular Magnetic Resonance in Cardiac Resynchronization Therapy

Randomized, controlled trials have shown that cardiac resynchronization therapy (CRT) is beneficial in patients with heart failure, impaired left ventricular (LV) systolic function, and a wide QRS complex. Other studies have shown that targeting the LV pacing site can also improve patient outcomes. Cardiovascular magnetic resonance (CMR) is a radiation-free imaging modality that provides unparalleled spatial resolution. In addition, emerging data suggest that targeted LV lead deployment over viable myocardium improves the outcome of patients undergoing CRT. This review explores the role of CMR in the preoperative workup of patients undergoing CRT.

Long-Term Follow-Up of Isolated Epicardial Left Ventricular Lead Implant Using a Minithoracotomy Approach for Cardiac Resynchronization Therapy

BACKGROUND

Transvenous left ventricular (LV) lead placement for cardiac resynchronization therapy is unsuccessful in 5-10% of reported cases. These patients may benefit from isolated surgical placement of an epicardial LV lead via minithoracotomy approach.

AIM

To evaluate the success of this approach at long-term follow-up.

METHODS

Retrospective evaluation of all consecutive patients undergoing isolated epicardial LV lead placement after failed transvenous attempt over a 6-year period. Data collected on baseline parameters, procedural details, and outcome at follow-up (hospital stay, complications, mortality, and clinical response).

RESULTS

Forty-two patients underwent epicardial lead implant. Five died within 1 year (11.9%): two (4.8%) died within 30-days post op (one from intraoperative hemorrhage, the other from multiple organ failure); 39 (95.1%) were admitted to the high dependency unit and transferred to the ward <24 hours. Median hospital stay was 3.4 ± 1.9 days. The overall complication rate was 17.5% (n = 7): 15.0% (n = 6) short term and 2.5% (n = 1) long term; these included three (7.5%) LV noncapture events all treated with reprogramming. There were two (5.0%) wound infections requiring oral antibiotics and two (5.0%) device infections requiring intravenous antibiotics (one had device resiting, the other developed septic shock requiring intensive care admission). Assessment of clinical response was possible in 34 (81.0%) at follow-up: 21 (61.8%) were responders and 13 (28.2%) nonresponders with no significant differences between these groups; no clinical predictors of response were identified.

CONCLUSION

Isolated epicardial LV lead implant using minithoracotomy is relatively safe and effective at successful LV pacing. Response rate and postoperative recovery at long-term follow-up are reasonable in these high-risk patients.

Do we need to monitor the percentage of biventricular pacing day by day?

BACKGROUND

Incidence and clinical significance of transient, daily fluctuations of biventricular pacing percentage (CRT%) remain unknown. We assessed the value of daily remote monitoring in identifying prognostically critical burden of low CRT%.

METHODS AND RESULTS

Prospective, single-centre registry encompassed 304 consecutive heart failure patients with cardiac resynchronization therapy defibrillators (CRT-D). Patients with 24-h episodes of CRT% loss<95% were assigned to quartiles depending on cumulative time spent in low CRT%: quartile 1 (1-8days), 2 (9-20days), 3 (21-60days) and quartile 4 (>60days). During median follow-up of 35months 51,826 transmissions were analysed, including 15,029 in 208 (68.4%) patients with episodes of low CRT%. Overall, mean CRT%≥95% vs. <95% resulted in a 4-fold lower mortality (17.3 vs. 68.2%; p<0.001). Fifty-four percent of patients experienced episodes of CRT% loss, despite 85.6% having mean CRT%≥95%. Mortality was lowest in quartile 1 (7.7%), while longer periods of CRT% loss resulted in significantly higher death rates (25.0 vs. 34.6 vs. 57.7%; quartiles 2-4 respectively, p<0.001), despite mean CRT% still being ≥95% in quartiles 1-3. Cumulative low CRT% burden was the independent risk factor for death (HR 1.013; 95% CI 1.006-1.021; p<0.001). Mortality rose by 1.3 and 49% with every additional day and quartile of CRT% loss, respectively.

CONCLUSIONS

Daily remote monitoring allows one to detect 24-h episodes of CRT% loss<95% in over two-thirds of CRT-D recipients during median observation of 3years. Cumulative low CRT% burden (in days) independently predicts mortality before mean CRT% drop.

Short-term outcome of cardiac resynchronization therapy - a comparison between newly implanted and chronically right ventricle-paced patients

BACKGROUND

Cardiac resynchronization therapy (CRT) is considered as a standard adjunct therapy in symptomatic patients with congestive heart failure (CHF) who have a prolonged QRS. There is an increasing number of patients who do not receive de novo CRT devices but are upgraded from right ventricular (RV) pacing to biventricular stimulation. We wanted to evaluate the benefit of CRT in patients with chronic RV pacing in comparison to previously non-paced heart failure patients.

METHODS

One hundred and sixty-five patients who had their device newly implanted (group I) and 116 who were upgraded from previously implanted RV pacing systems (group II) at Mayo Clinic Hospital were retrospectively analyzed. Clinical and echocardiographic response to CRT was evaluated. Mean follow-up time was 290±250days.

RESULTS

Baseline characteristics did not differ between the two groups of patients. Clinical response rate was identical in Groups I and II (65 vs. 65%, respectively; P=0.98) and echocardiographic response rate was similar in both groups of patients (64 vs. 62%; P=0.80). Post-implant QRS increased in group I and was reduced in group II (5 (27.4) vs. -20.0 (33.9) ms; P<0.001). NYHA class improvement (-0.7 (0.6) vs. -0.7 (0.6), P=0.81), LV ejection fraction increase (9.2 (12.9) vs. 8.2 (9.9)%; P=0.55) and LV end-systolic volume reduction (-34.5 (50.7) vs. -25.7 (47.4)%; P=0.28) were comparable in both groups.

CONCLUSIONS

Chronically RV-paced patients who receive CRT have similar short-term benefits when compared with patients with new CRT implantations.

Multimodality imaging-guided left ventricular lead placement in cardiac resynchronization therapy: a randomized controlled trial

AIM

Left ventricular (LV) lead position at the latest mechanically activated non-scarred myocardial LV region confers improved response to cardiac resynchronization therapy (CRT). We conducted a double-blind, randomized controlled trial to evaluate the clinical benefit of multimodality imaging-guided LV lead placement in CRT.

METHODS AND RESULTS

Patients were allocated (1:1) to imaging-guided LV lead placement using cardiac computed tomography (CT) venography, ^99m Technetium myocardial perfusion imaging, and speckle-tracking echocardiography radial strain to target the optimal coronary sinus (CS) branch closest to the non-scarred myocardial segment with latest mechanical activation (imaging group, n = 89) or to routine LV lead implantation in a posterolateral region with late electrical activation (control group, n = 93). The primary endpoint was clinical non-response to CRT [≥1 of the following after 6 months: (1) death, (2) heart failure hospitalization, or (3) no improvement in New York Heart Association class and <10% increase in 6-min walk distance]. Secondary outcomes included LV remodelling and the combination of all-cause mortality and hospitalization owing to heart failure during 1.8 ± 0.9 years. Analysis was intention-to-treat. In the imaging group, fewer patients reached the primary endpoint (26% vs. 42%, P = 0.02). More patients in the imaging group had the LV lead placed in the optimal CS branch (83% vs. 65%, P = 0.01). There were no between-group differences in reverse LV remodelling or the combined endpoint of death or hospitalizations for heart failure.

CONCLUSIONS

Multimodality imaging-guided LV lead placement towards the CS branch closest to latest mechanically activated non-scarred myocardial LV segment reduces the proportion of clinical non-responders to CRT. Larger long-term multicentre studies are needed.

Clinical utility of speckle-tracking echocardiography in cardiac resynchronisation therapy

Cardiac resynchronisation therapy (CRT) can profoundly improve outcome in selected patients with heart failure; however, response is difficult to predict and can be absent in up to one in three patients. There has been a substantial amount of interest in the echocardiographic assessment of left ventricular dyssynchrony, with the ultimate aim of reliably identifying patients who will respond to CRT. The measurement of myocardial deformation (strain) has conventionally been assessed using tissue Doppler imaging (TDI), which is limited by its angle dependence and ability to measure in a single plane. Two-dimensional speckle-tracking echocardiography is a technique that provides measurements of strain in three planes, by tracking patterns of ultrasound interference ('speckles') in the myocardial wall throughout the cardiac cycle. Since its initial use over 15 years ago, it has emerged as a tool that provides more robust, reproducible and sensitive markers of dyssynchrony than TDI. This article reviews the use of two-dimensional and three-dimensional speckle-tracking echocardiography in the assessment of dyssynchrony, including the identification of echocardiographic parameters that may hold predictive potential for the response to CRT. It also reviews the application of these techniques in guiding optimal LV lead placement pre-implant, with promising results in clinical improvement post-CRT.

The Diagnostic Value of Neuropathy Symptom and Change Score, Neuropathy Impairment Score and Michigan Neuropathy Screening Instrument for Diabetic Peripheral Neuropathy

AIMS

This study aims to evaluate the diagnostic capabilities of neuropathy symptom and change (NSC) score, neuropathy impairment score (NIS) and Michigan neuropathy screening instrument (MNSI) in diagnosing diabetic peripheral neuropathy (DPN).

METHODS

A total of 131 patients with type II diabetes received NSC, NIS and MNSI scoring systems. Electromyography/nerve conduction velocity (EMG/NCV) test was taken as gold standard. Correlations between EMG/NCV test and the 3 scorings, and their sensitivity, specificity, positive and negative predictive values, accuracy and kappa (x03BA;) value were analyzed.

RESULTS

The prevalence of DPN was 43.5% according to EMG/NCV findings. EMG/NCV test was significantly positive correlated with all the 3 scorings, highest with NIS scoring (r = 0.653, p < 0.001). Compared with EMG/NCV test, NSC score was most sensitive (85.96%) but least specific (77.03%); NIS score had lower sensitivity (59.65%) but best specificity (98.65%) and accuracy (81.68%). Both had high concordance with EMG/NCV test (x03BA; = 0.61). Sensitivity, specificity and accuracy of MNSI were highest (70.18, 98.65 and 80.15%) at the cutoff values of >1.0, >2.5 and >1.5, respectively (x03BA; = 0.58).

CONCLUSIONS

Both NSC and NIS were accurate and reliable diagnostic methods for DPN. The combined application of NSC and NIS was recommended in DPN diagnosis.

What We Can Learn from "Super-responders"

This review discusses the state of the art of knowledge to help decision making in patients who are candidates for cardiac resynchronization therapy (CRT) and to analyze the long-term total and cardiac mortality, sudden death, and CRT with a defibrillator intervention rate, as well as the evolution of echocardiographic parameters in patients with a left ventricular (LV) ejection fraction of greater than 50% after CRT implantation. Owing to normalization of LV function in super-responders, the need for a persistent defibrillator backup is also considered.

Current Technology to Maximize Cardiac Resynchronization Therapy Benefit for Patients With Symptomatic Heart Failure

The incidence of heart failure (HF) continues to increase, affecting millions of people in the United States each year. Cardiac resynchronization therapy (CRT) has been used and studied for patients with symptomatic HF for more than 20 years. The purpose of this article is to review technologies and developments to help maximize CRT for patients with symptomatic HF. Although most interventions to optimize CRT are physician directed, nurses also have an important role in the care and education of patients with symptomatic HF and can affect clinical outcomes. Therefore, nurses’ understanding of CRT and measures to maximize this lifesaving therapy is critical in HF management.

Cardiac resynchronization therapy update: evolving indications, expanding benefit?

Cardiac resynchronisation therapy (CRT) is an effective intervention for appropriately selected patients with heart failure, but exactly how it works is uncertain. Recent data suggest that much, or perhaps most, of the benefits of CRT are not delivered by re-coordinating left ventricular dyssynchrony. Atrio-ventricular resynchronization, reduction in mitral regurgitation and prevention of bradycardia are other potential mechanisms of benefit that will vary from one patient to the next and over time. Because there is no single therapeutic target, it is unlikely that any single measure will accurately predict benefit. The only clinical characteristic that appears to be a useful predictor of the benefits of CRT is a QRS duration of >140 ms. Many new approaches are being developed to try to improve the effectiveness of and extend the indications for CRT. These include smart pacing algorithms, better pacing-site targeting, new sensors, multipoint pacing, remote device monitoring and leadless endocardial pacing. Whether CRT is effective in patients with atrial fibrillation or whether adding a defibrillator function to CRT improves prognosis awaits further evidence.

Incidence, definition, diagnosis, and management of the cardiac resynchronization therapy nonresponder

PURPOSE OF REVIEW

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with mild-to-severe heart failure. However, up to 40% of CRT recipients are nonresponders. This review addresses important aspects with regard to the identification and management of CRT nonresponders.

RECENT FINDINGS

Mid-term clinical or echocardiographic nonresponse is associated with worse clinical outcomes during the extended follow-up. A number of predictors are indicative of CRT response, which include patient characteristics, electrical determinants, and imaging techniques from preimplant to postimplant period, and can be grouped as modifiable and nonmodifiable contributors to treatment response. Advanced age, male sex, ischemic cause, end-stage heart failure, inadequate electrical delay, and absence of mechanical dyssynchrony are regarded as unfavorable but nonmodifiable factors, for which considering underutilization of CRT by refining patient selection is reasonable. On the contrary, more efforts should be made to optimize patient management by correcting those modifiable factors, such as suboptimal medical therapy, uncontrolled atrial fibrillation, left ventricular lead dislodgement or inappropriate location, loss of biventricular capture, and lack of device optimization.

SUMMARY

Proper management and careful selection of CRT recipients will transform a proportion of treatment nonresponders into responders, which is vital to improve patients' outcome.

Echocardiographic assessment of right ventricular function in responders and non-responders to cardiac resynchronization therapy

INTRODUCTION

The aim of this study was to determine whether baseline right ventricular (RV) function assessed by standard echocardiography may indicate patients who will respond to cardiac resynchronization therapy (CRT).

MATERIAL AND METHODS

The data of 57 patients (54 men, 95%), aged 66.4 ±8.7 years with heart failure (HF) having a CRT device implanted were collected. All patients had left ventricular ejection fraction (LVEF) ≤ 35% and QRS complex duration ≥ 120 ms. Echocardiographic examination with tissue Doppler imaging techniques and complex RV evaluation were performed at baseline and three months after CRT onset.

RESULTS

Three months after CRT implantation, patients responding to CRT, defined as a reduction of left ventricle end-systolic volume (LVESV) of at least 10% (n = 34), compared to patients with a reduction of LVESV of less than 10% (n = 23), had at baseline a smaller right atrium diameter (47.85 ±11.33 mm vs. 52.65 ±8.69 mm; p = 0.028), higher TAPSE (14.56 ±2.57 mm vs. 13.04 ±2.93 mm; p = 0.030) and lower grade of tricuspid valve regurgitation (1.82 ±0.97 vs. 2.3 ±0.88; p = 0.033).

CONCLUSIONS

This study showed that there are differences in baseline right ventricular function between responders and non-responders to CRT. Yet in our study, none of the baseline RV parameters provided any value in identifying patients who would respond to CRT.

Prediction of response to cardiac resynchronization therapy using left ventricular pacing lead position and cardiovascular magnetic resonance derived wall motion patterns: a prospective cohort study

BACKGROUND

Despite marked benefits in many heart failure patients, a considerable proportion of patients treated with cardiac resynchronization therapy (CRT) fail to respond appropriately. Recently, a "U-shaped" (type II) wall motion pattern identified by cardiovascular magnetic resonance (CMR) has been associated with improved CRT response compared to a homogenous (type I) wall motion pattern. There is also evidence that a left ventricular (LV) lead localized to the latest contracting LV site predicts superior response, compared to an LV lead localized remotely from the latest contracting LV site.

METHODS

We prospectively evaluated patients undergoing CRT with pre-procedural CMR to determine the presence of type I and type II wall motion patterns and pre-procedural echocardiography to determine end systolic volume (ESV). We assessed the final LV lead position on post-procedural fluoroscopic images to determine whether the lead was positioned concordant to or remote from the latest contracting LV site. CRT response was defined as a ≥ 15% reduction in ESV on a 6 month follow-up echocardiogram.

RESULTS

The study included 33 patients meeting conventional indications for CRT with a mean New York Heart Association class of 2.8 ± 0.4 and mean LV ejection fraction of 28 ± 9%. Overall, 55% of patients were echocardiographic responders by ESV criteria. Patients with both a type II pattern and an LV lead concordant to the latest contracting site (T2CL) had a response rate of 92%, compared to a response rate of 33% for those without T2CL (p = 0.003). T2CL was the only independent predictor of response on multivariate analysis (odds ratio 18, 95% confidence interval 1.6-206; p = 0.018). T2CL resulted in significant incremental improvement in prediction of echocardiographic response (increase in the area under the receiver operator curve from 0.69 to 0.84; p = 0.038).

CONCLUSIONS

The presence of a type II wall motion pattern on CMR and a concordant LV lead predicts superior CRT response. Improving patient selection by evaluating wall motion pattern and targeting LV lead placement may ultimately improve the response rate to CRT.

Effect of Cardiac Resynchronization Therapy on Inflammation in Congestive Heart Failure: A Review

Congestive heart failure is associated with increased levels of several inflammatory mediators, and animal studies have shown that infusion of a number of cytokines can induce heart failure. However, several drugs with proven efficacy in heart failure have failed to affect inflammatory mediators, and anti-inflammatory therapy in heart failure patients has thus far been disappointing. Hence, to what extent heart failure is caused by or responsible for the increased inflammatory burden in the patient is still unclear. Over the past couple of decades, resynchronization therapy with a biventricular pacemaker has emerged as an effective treatment in a subset of heart failure patients, reducing both morbidity and mortality. Such treatment has also been shown to affect the inflammation associated with heart failure. In this study, we review recent data on the association between heart failure and inflammation, and in particular how resynchronization therapy can affect the inflammatory process.

Narrow QRS systolic heart failure: is there a target for cardiac resynchronization?

Cardiac resynchronization therapy has revolutionized the management of systolic heart failure in patients with prolonged QRS during the past 20 years. Initially, the use of this treatment in patients with shorter QRS durations showed promising results, which have since been opposed by larger randomized controlled trials. Despite this, some questions remain, such as, whether correction of mechanical dyssynchrony is the therapeutic target by which biventricular pacing may confer benefit in this group, or are there other mechanisms that need consideration? In addition, novel techniques of cardiac resynchronization therapy delivery such as endocardial and multisite pacing may reduce potential detrimental effects of biventricular pacing, thereby improving the benefit/harm balance of this therapy in some patients.

Cardiac resynchronisation therapy in patients with chronic heart failure

Cardiac resynchronisation therapy (CRT) is common treatment for congestive heart failure (HF) with decreased LV function and wide QRS complex. Its foundations are set in the understanding of the pathophysiology of ventricular dyssynchrony. Over the last several decades, CRT has evolved through changes in implantation techniques, device and lead design, imaging modalities and our growing clinical experience. This review article will discuss the vast clinical experience that has led to current guidelines recommendations for CRT in patients with mild-to-severe HF. In addition, the article will also discuss recent evidence of benefits of CRT in patients beyond the guidelines. The article will also address the issue of non-responders, optimisation of CRT, postimplant evaluation and remote monitoring.

High sensitivity C-reactive protein and cardfiac resynchronization therapy in patients with advanced heart failure

Background

The data on the prognostic values of high sensitivity C-reactive protein (hsCRP) levels in patients with advanced symptomatic heart failure (HF) receiving cardiac resynchronization therapy (CRT) are scarce. The aim of present study was to investigate the association of serum hsCRP levels with left ventricle reverse remodeling after six months of CRT as well as long-term outcome.

Methods

A total of 232 CRT patients were included. The assessment of hsCRP values, clinical status and echocardiographic data were performed at baseline and after six months of CRT. Long-term follow-up included all-cause mortality and hospitalizations for HF.

Results

During the mean follow-up periods of 31.3 ± 31.5 months, elevated hsCRP (> 3 mg/L) prior to CRT was associated with a significant 2.39-fold increase (P = 0.006) in the risk of death or HF hospitalizations. At 6-month follow-up, patients who responded to CRT showed significant reductions or maintained low in hsCRP levels (–0.5 ± 4.1 mg/L reduction) compared with non-responders (1.7 ± 6.1 mg/L increase, P = 0.018). Compared with patients in whom 6-month hsCRP levels were reduced or remained low, patients in whom 6-month hsCRP levels were increased or maintained high experienced a significantly higher risk of subsequent death or HF hospitalizations (Log-rank P < 0.001). The echocardiographic improvement was also better among patients in whom 6-month hsCRP levels were reduced or remained low compared to those in whom 6-month hsCRP levels were raised or maintained high.

Conclusions

Our findings demonstrated that measurement of baseline and follow-up hsCRP levels may be useful as prognostic markers for timely potential risk stratification and subsequent appropriate treatment strategies in patients with advanced HF undergoing CRT.

Identification of Genetic Markers for Treatment Success in Heart Failure Patients

Background—

Cardiac resynchronization therapy (CRT) can improve ventricular size, shape, and mass and reduce mitral regurgitation by reverse remodeling of the failing ventricle. About 30% of patients do not respond to this therapy for unknown reasons. In this study, we aimed at the identification and classification of CRT responder by the use of genetic variants and clinical parameters.

Methods and Results—

Of 1421 CRT patients, 207 subjects were consecutively selected, and CRT responder and nonresponder were matched for their baseline parameters before CRT. Treatment success of CRT was defined as a decrease in left ventricular end-systolic volume >15% at follow-up echocardiography compared with left ventricular end-systolic volume at baseline. All other changes classified the patient as CRT nonresponder. A genetic association study was performed, which identified 4 genetic variants to be associated with the CRT responder phenotype at the allelic ( P <0.035) and genotypic ( P <0.031) level: rs3766031 ( ATPIB1 ), rs5443 ( GNB3 ), rs5522 ( NR3C2 ), and rs7325635 ( TNFSF11 ). Machine learning algorithms were used for the classification of CRT patients into responder and nonresponder status, including combinations of the identified genetic variants and clinical parameters.

Conclusions—

We demonstrated that rule induction algorithms can successfully be applied for the classification of heart failure patients in CRT responder and nonresponder status using clinical and genetic parameters. Our analysis included information on alleles and genotypes of 4 genetic loci, rs3766031 ( ATPIB1 ), rs5443 ( GNB3 ), rs5522 ( NR3C2 ), and rs7325635 ( TNFSF11 ), pathophysiologically associated with remodeling of the failing ventricle.

Clinical Long-Term Response to Cardiac Resynchronization Therapy Is Independent of Persisting Echocardiographic Markers of Dyssynchrony

BACKGROUND

The aim of the study was to prove the concept that correction of established parameters of dyssynchrony is a requirement for favorable long-term outcome in patients with cardiac resynchronization therapy (CRT), whereas patients with persisting dyssynchrony should have a less favorable response.

METHODS

After CRT implantation and optimization of dyssynchrony parameters, we evaluated whether correction or persistence of dyssynchrony predicted long-term outcome. Primary endpoint was a combination of cardiac mortality/heart transplantation and hospitalization due to worsening heart failure, and secondary endpoint was NYHA class.

RESULTS

One hundred twenty-eight consecutive patients (mean age 68 ± 10 years) undergoing CRT with a mean left ventricular ejection fraction of 27±9% were followed for 27 ± 19 months. All cause mortality was 17.2%, cardiac mortality was 7.8% and 3.1% had to undergo heart transplantation. Rehospitalization due to worsening heart failure was observed in 14.8%. NYHA class before CRT implantation was 2.8 ± 0.8 and improved during follow-up to 2.0 ± 0.8 (P < 0.001). A clinical response was observed in 76% (n = 97) and an echocardiographic response was documented in 66% (n = 85). After individually optimized AV and VV intervals with echocardiography, atrioventricular dyssynchrony was still present in 7.2%, interventricular dyssynchrony in 13.3% and intraventricular dyssynchrony in 16.4%. Despite persistent atrioventricular, interventricular and intraventricular dyssynchrony at long-term follow-up, the combined primary and secondary endpoints did not differ compared to the group without mechanical dyssynchrony (P = ns). QRS duration with biventricular stimulation did not differ between responders vs. nonresponders.

CONCLUSION

After successful CRT implantation, clinical long-term response is independent of correction of dyssynchrony measured by echocardiographic parameters and QRS width.

Multisite left ventricular pacing in cardiac resynchronization therapy

Cardiac resynchronization therapy is an effective treatment for selected patients with heart failure and left bundle branch block dyssynchrony. Unfortunately, about a third of patients, so-called nonresponders, do not display any symptomatic or structural improvements after the treatment. In another 5% of patients, the left ventricular lead cannot be implanted due to technical limitations. Novel quadripolar pacing lead and associated multisite pacing technology has the potential to help improve both of these problems. The technology and applications of these leads are reviewed and the novel technique of multisite pacing from two poles of one quadripolar lead is discussed. This technology may improve response to cardiac resynchronization therapy for some patients.