Very long term follow-up of cardiac resynchronization therapy: Clinical outcome and predictors of mortality

Targeted left ventricular lead positioning to the site of latest activation in cardiac resynchronization therapy: a systematic review and meta-analysis

AIMS

Several studies have evaluated the use of electrically- or imaging-guided left ventricular (LV) lead placement in cardiac resynchronization therapy (CRT) recipients. We aimed to assess evidence for a guided strategy that targets LV lead position to the site of latest LV activation.

METHODS AND RESULTS

A systematic review and meta-analysis was performed for randomized controlled trials (RCTs) until March 2023 that evaluated electrically- or imaging-guided LV lead positioning on clinical and echocardiographic outcomes. The primary endpoint was a composite of all-cause mortality and heart failure hospitalization, and secondary endpoints were quality of life, 6-min walk test (6MWT), QRS duration, LV end-systolic volume, and LV ejection fraction. We included eight RCTs that comprised 1323 patients. Six RCTs compared guided strategy (n = 638) to routine (n = 468), and two RCTs compared different guiding strategies head-to-head: electrically- (n = 111) vs. imaging-guided (n = 106). Compared to routine, a guided strategy did not significantly reduce the risk of the primary endpoint after 12-24 (RR 0.83, 95% CI 0.52-1.33) months. A guided strategy was associated with slight improvement in 6MWT distance after 6 months of follow-up of absolute 18 (95% CI 6-30) m between groups, but not in remaining secondary endpoints. None of the secondary endpoints differed between the guided strategies.

CONCLUSION

In this study, a CRT implantation strategy that targets the latest LV activation did not improve survival or reduce heart failure hospitalizations.

Ten-year follow-up of cardiac resynchronization therapy patients with non-ischemic dilated cardiomyopathy assessed by radionuclide angiography: a single-center cohort study

PURPOSE

Relatively few data are available on long-term survival and incidence of ventricular arrhythmias in cardiac resynchronization therapy (CRT) patients. We investigated long-term outcomes of CRT patients with non-ischemic dilated cardiomyopathy stratified as responders or non-responders according to radionuclide angiography.

METHODS

Fifty patients with non-ischemic dilated cardiomyopathy undergoing CRT were assessed by equilibrium Tc⁹⁹ radionuclide angiography with bicycle exercise at baseline and after 3 months. Intra- and interventricular dyssynchrony were derived by Fourier phase analysis. Patient clinical outcome was assessed after 10 years.

RESULTS

At 3 months, 50% of patients were identified as CRT responders according to an increase in LV ejection fraction ≥ 5%. During a follow-up of 109 ± 48 months, 30% of patients died and 6% underwent heart transplantation. Age and history of paroxysmal atrial fibrillation were found to be predictors of all-cause mortality. CRT responders showed lower risk of death from cardiac causes than non-responders. At follow-up, 38% of patients presented at least one episode of sustained ventricular tachycardia, with a similar percentage between responders and non-responders.

CONCLUSION

At long-term follow-up, non-ischemic CRT recipients identified as responders by radionuclide angiography were found to be at lower risk of worsening heart failure death than non-responders. Long-term risk for sustained ventricular arrhythmia was similar between CRT responders and non-responders.

Long-term outcomes in a randomized controlled trial of multimodality imaging-guided left ventricular lead placement in cardiac resynchronization therapy

AIMS

This study aims to investigate the long-term occurrence of the composite endpoint of heart failure (HF) hospitalization or all-cause death (primary endpoint) in patients randomized to cardiac resynchronization therapy (CRT) using individualized multimodality imaging-guided left ventricular (LV) lead placement compared with a routine fluoroscopic approach. Furthermore, this study aims to evaluate whether inter-lead electrical delay (IED) is associated with improved response rate of this endpoint.

METHODS AND RESULTS

We reviewed follow-up data until November 2020 for all 182 patients included in the ImagingCRT trial for the occurrence of HF hospitalization and all-cause death. During median (inter-quartile range) time to primary endpoint/censuring of 6.7 (3.3-7.9) years, the rate of the primary endpoint was 60% (n = 53) in the imaging group compared with 52% (n = 48) in the control group [hazard ratio (HR) 1.22, 95% confidence interval (CI) 0.83-1.81, P = 0.31]. Neither the risk of HF hospitalization (HR 1.11, 95% CI 0.62-1.99, P = 0.72) nor of all-cause death differed between treatment groups (HR 1.23, 95% CI 0.82-1.85, P = 0.32). The risk of the primary endpoint was significantly reduced among those with IED ≥100 ms when compared with those with IED <100 ms (HR 0.62, 95% CI 0.39-0.98, P = 0.04).

CONCLUSIONS

In this study, an individualized multimodality imaging-guided strategy targeting LV lead placement towards the latest mechanically activated non-scarred myocardial segment during CRT implantation did not reduce HF hospitalization or all-cause death when compared with routine LV lead placement during long-term follow-up. Targeting the latest electrical activation should be studied as an alternative individualized strategy for optimizing LV lead placement in CRT recipients.

Bipolar versus quadripolar left ventricular leads for cardiac resynchronization therapy: evidence to date

INTRODUCTION

In cardiac resynchronization therapy (CRT) devices, transvenous left ventricular (LV) leads are more prone to instability, high pacing thresholds, and phrenic nerve stimulation (PNS) that may necessitate lead revision, replacement in a suboptimal position, or deactivation of the lead. To overcome some of these challenges, quadripolar (QP) LV leads have been developed and accounted for over 90% of implanted LV leads 5 years after they were introduced.

AREAS COVERED

This review provides an overview of the current evidence of implanting QP leads in CRT as compared with traditional bipolar (BP) leads including details about feasibility, safety and lead performance, clinical outcome and cost-effectiveness.

EXPERT OPINION

Based on the current literature, implantation with a QP lead decreases revision rates but does not affect any clinical outcomes including mortality, hospitalization, symptoms, or echocardiographic parameters. Feasibility and stability do not differ between QP and BP leads. A QP lead should be preferred as first choice over a BP lead due to lower rates of PNS and lower pacing thresholds leading to less frequent lead revisions and battery replacements. In addition, this strategy may be cost saving despite a higher price of QP leads.

Ventricular arrhythmia risk is associated with myocardial scar but not with response to cardiac resynchronization therapy

AIMS

Sudden cardiac death (SCD) risk estimation in patients referred for cardiac resynchronization therapy (CRT) remains a challenge. By CRT-mediated improvement of left ventricular ejection fraction (LVEF), many patients loose indication for primary prevention implantable cardioverter-defibrillator (ICD). Increasing evidence shows the importance of myocardial scar for risk prediction. The aim of this study was to investigate the prognostic impact of myocardial scar depending on the echocardiographic response in patients undergoing CRT.

METHODS AND RESULTS

Patients with indication for CRT were prospectively enrolled. Decision about ICD or pacemaker implantation was based on clinical criteria. All patients underwent delayed-enhancement cardiac magnetic resonance imaging. Median follow-up duration was 45 (24-75) months. Primary outcome was a composite of sustained ventricular arrhythmia, appropriate ICD therapy, or SCD. A total of 218 patients with LVEF 25.5 ± 6.6% were analysed [158 (73%) male, 64.9 ± 10.7 years]. Myocardial scar was observed in 73 patients with ischaemic cardiomyopathy (ICM) (95% of ICM patients); in 62 with non-ischaemic cardiomyopathy (45% of these patients); and in all but 1 of 36 (17%) patients who reached the primary outcome. Myocardial scar was the only significant predictor of primary outcome [odds ratio 27.7 (3.8-202.7)], independent of echocardiographic CRT response. A total of 55 (25%) patients died from any cause or received heart transplant. For overall survival, only a combination of the absence of myocardial scar with CRT response was associated with favourable outcome.

CONCLUSION

Malignant arrhythmic events and SCD depend on the presence of myocardial scar but not on CRT response. All-cause mortality improved only with the combined absence of myocardial scar and CRT response.

Validation of Three European Risk Scores to Predict Long-Term Outcomes for Patients Receiving Cardiac Resynchronization Therapy in an Asian Population

To validate externally and recalibrate three European risk scores for all-cause mortality and transplantation in patients receiving cardiac resynchronization therapy (CRT) in an Asian population. Data were collected at our institution between January 2010 and December 2017. The primary endpoints were all-cause mortality and heart transplantation. Of the 506 patients who were followed for 2 years, 104 reached the primary endpoint. The Kaplan-Meier event-free survival analysis, stratified according to the three scores, yielded significant results (log-rank test, all P < 0.05), with a good fit between the predicted and observed event rates (Hosmer-Lemeshow goodness-of-fit test, all P > 0.05). The ScREEN score yielded the best discriminatory power for the primary endpoints compared with the VALID-CRT and EAARN scores. ScREEN was the best predictor of all-cause mortality and heart transplantation. Risk scores based on different populations should be selected cautiously. Graphical Abstract.

Transmural Myocardial Scar Assessed by Cardiac Computed Tomography: Predictor of Echocardiographic Versus Clinical Response to Cardiac Resynchronization Therapy?

OBJECTIVES

Before cardiac resynchronization therapy (CRT) implantation, cardiac computed tomography (CT) can provide assessment of cardiac venous anatomy and visualize left ventricular (LV) myocardial scar. We hypothesized that localization and burden of transmural myocardial scar verified by cardiac CT are associated with echocardiographic and clinical response to CRT.

METHODS

We prospectively included 140 CRT recipients undergoing preimplant cardiac CT. We assessed transmural scar, defined as hypoperfusion involving more than one-half of the myocardial wall in each LV segment using a 17-segment model. Echocardiographic nonresponse was defined as less than 5% absolute improvement in LV ejection fraction at 6 months' follow-up. Clinical nonresponse was defined as 1 or more of the following at 6 months' follow-up: death, heart failure hospitalization, or no improvement in New York Heart Association class and less than 10% increase in 6-minute walk-test distance.

RESULTS

Higher burden of myocardial scar was associated with echocardiographic nonresponse (adjusted odds ratio, 3.02; 95% confidence interval, 1.03-8.91; P = 0.045). Scar concordant or adjacent to LV pacing site was associated with echocardiographic nonresponse (adjusted odds ratio, 8.2; 95% confidence interval, 1.51-44.27; P = 0.015). No association between scar and clinical nonresponse was demonstrated.

CONCLUSIONS

Higher scar burden and scar in proximity to the LV pacing site assessed by cardiac CT are associated with echocardiographic nonresponse to CRT. Burden and location of scar were not associated with clinical nonresponse. Further large-scale studies are needed to assess the potential association between myocardial scar detected by cardiac CT and clinical CRT outcome.

Electrically guided versus imaging-guided implant of the left ventricular lead in cardiac resynchronization therapy: a study protocol for a double-blinded randomized controlled clinical trial (ElectroCRT)

BACKGROUND

Cardiac resynchronization therapy (CRT) is an established treatment in patients with heart failure and prolonged QRS duration where a biventricular pacemaker is implanted to achieve faster activation and more synchronous contraction of the left ventricle (LV). Despite the convincing effect of CRT, 30-40% of patients do not respond. Among the most important correctable causes of non-response to CRT is non-optimal LV lead position.

METHODS

We will enroll 122 patients in this patient-blinded and assessor-blinded, randomized, clinical trial aiming to investigate if implanting the LV lead guided by electrical mapping towards the latest LV activation as compared with imaging-guided implantation, causes an excess increase in left ventricular (LV) ejection fraction (LVEF). The patients are randomly assigned to either the intervention group: preceded by cardiac computed tomography of the cardiac venous anatomy, the LV lead is placed according to the latest LV activation in the coronary sinus (CS) branches identified by systematic electrical mapping of the CS at implantation and post-implant optimization of the interventricular pacing delay; or patients are assigned to the control group: placement of the LV lead guided by cardiac imaging. The LV lead is targeted towards the latest mechanical LV activation as identified by echocardiography and outside myocardial scar as identified by myocardial perfusion (MP) imaging. The primary endpoint is change in LVEF at 6-month follow up (6MFU) as compared with baseline measured by two-dimensional echocardiography. Secondary endpoints include relative percentage reduction in LV end-systolic volume, all-cause mortality, hospitalization for heart failure, and a clinical combined endpoint of response to CRT at 6MFU defined as the patient being alive, not hospitalized for heart failure, and experiencing improvement in NYHA functional class or/and > 10% increase in 6-minute walk test.

DISCUSSION

We assume an absolute increase in LVEF of 12% in the intervention group versus 8% in the control group. If an excess increase in LVEF can be achieved by LV lead implantation guided by electrical mapping, this study supports the conduct of larger trials investigating the impact of this strategy for LV-lead implantation on clinical outcomes in patients treated with CRT.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02346097 . Registered on 12 January 2015. Patients were enrolled between 16 February 2015 and 13 December 2017.

What happens to non-responders in cardiac resynchronization therapy?

INTRODUCTION AND OBJECTIVES

Left ventricular reverse remodeling (LVRR) is strongly related to the long-term prognosis of patients undergoing cardiac resynchronization therapy (CRT). The aim of this study was to assess the long-term clinical outcome of patients without LVRR at six months after CRT implantation and to determine the prognostic impact of clinical response in this population.

METHODS

We analyzed 178 consecutive patients who underwent successful CRT device implantation (age 64±11 years; 69% male; 89% in New York Heart Association [NYHA] functional class III; 35% with ischemic cardiomyopathy). Clinical status and echocardiographic parameters were determined before and six months after CRT implantation. We identified those without criteria for LVRR (≥10% increase in left ventricular ejection fraction with ≥15% reduction in left ventricular end-systolic diameter compared to baseline). Clinical responders were defined by a sustained improvement of at least one NYHA functional class.

RESULTS

At six-month assessment after CRT, 109 (61%) patients showed LVRR. During a mean follow-up of 56±21 months, 47 (26%) patients died, with higher mortality in the group without LVRR (36% vs. 20%, p=0.023). Clinical response was greater in patients with LVRR (88% vs. 55%, p<0.001). In patients without LVRR, clinical response to CRT was the strongest independent predictor of survival (hazard ratio: 0.120; 95% confidence interval: 0.039-0.366; p<0.001).

CONCLUSION

Although patients without LVRR six months after CRT implantation had a worse prognosis, with higher all-cause mortality, clinical response can be an independent predictor of survival in this population.

Sex-specific mortality differences in heart failure patients with ischemia receiving cardiac resynchronization therapy

Background

Recent studies have reported prognosis differences between male and female heart failure patients following cardiac resynchronization therapy (CRT). However, the potential clinical factors that underpin these differences remain to be elucidated.

Methods

A meta-analysis was performed to investigate the factors that characterize sex-specific differences following CRT. This analysis involved searching the Medline (Pubmed source) and Embase databases in the period from January 1980 to September 2016.

Results

Fifty-eight studies involving 33445 patients (23.08% of whom were women) were analyzed as part of this study. Only patients receiving CRT with follow-up greater than six months were included in our analysis. Compared with males, females exhibited a reduction of 33% (hazard ratio, 0.67; 95% confidence interval, 0.62–0.73; P < 0.0001) and 42% (hazard ratio, 0.58; 95% confidence interval, 0.46–0.74; P = 0.003) in all-cause mortality and heart failure hospitalization or heart failure, respectively. Following a stratified analysis of all-cause mortality, we observed that ischemic causes (p = 0.03) were likely to account for most of the sex-specific differences in relation to CRT.

Conclusion

These data suggest that women have a reduced risk of all-cause mortality and heart failure hospitalization or heart failure following CRT. Based on the results from the stratified analysis, we observed more optimal outcomes for females with ischemic heart disease. Thus, ischemia are likely to play a role in sex-related differences associated with CRT in heart failure patients. Further studies are required to determine other indications and the potential mechanisms that might be associated with sex-specific CRT outcomes.

Cardiac Resynchronization Therapy: How to Decrease Nonresponders

Nonresponse to cardiac resynchronization therapy (CRT) is still a major issue in therapy expansion. The description of fast, simple, cost-effective methods to optimize CRT could help in adapting pacing intervals to individual patients. A better understanding of the importance of appropriate patient selection, left ventricular lead placement, and device programming, together with a multidisciplinary approach and an optimal follow-up of the patients, may reduce the percentage of nonresponders.

Long-Term Echocardiographic Outcome in Super-Responders to Cardiac Resynchronization Therapy and the Association With Mortality and Defibrillator Therapy

Super-response to cardiac resynchronization therapy (CRT) is associated with significant left ventricular (LV) reverse remodeling and improved clinical outcome. The study aimed to: (1) evaluate whether LV reverse remodeling remains sustained during long-term follow-up in super-responders and (2) analyze the association between the course of LV reverse remodeling and ventricular arrhythmias. Of all, primary prevention super-responders to CRT were selected. Super-response was defined as LV end-systolic volume reduction of ≥30% 6 months after device implantation. Cox regression analysis was performed to investigate the association of LV ejection fraction (LVEF) as time-dependent variable with implantable-cardioverter defibrillator (ICD) therapy and mortality. A total of 171 super-responders to CRT-defibrillator were included (mean age 67 ± 9 years; 66% men; 37% ischemic heart disease). Here of 129 patients received at least 1 echocardiographic evaluation after a median follow-up of 62 months (25th to 75th percentile, 38 to 87). LV end-diastolic volume, LV end-systolic volume, and LVEF after 6-month follow-up were comparable with those after 62-month follow-up (p = 0.90, p = 0.37, and p = 0.55, respectively). Changes in LVEF during follow-up in super-responders were independently associated with appropriate ICD therapy (hazard ratio 0.94, 95% CI 0.90 to 0.98; p = 0.005) and all-cause mortality (hazard ratio 0.95, 95% CI 0.91 to 1.00; p = 0.04). A 5% increase in LVEF was associated with a 1.37 times lower risk of appropriate ICD therapy and a 1.30 times lower risk of mortality. In conclusion, LV reverse remodeling in super-responders to CRT remains sustained during long-term follow-up. Changes in LVEF during follow-up were associated with mortality and ICD therapy.

Left ventricular performance during triggered left ventricular pacing in patients with cardiac resynchronization therapy and left bundle branch block

PURPOSE

To assess the acute effect of triggered left ventricular pacing (tLVp) on left ventricular performance and contraction pattern in patients with heart failure, left bundle branch block (LBBB), and cardiac resynchronization therapy (CRT).

METHODS

Twenty-three patients with pre-implant QRS complex >150 ms, QRS complex narrowing under CRT, and sinus rhythm were included ≥3 months after CRT implantation. Echocardiographic assessment of left ventricular ejection fraction (LVEF), global peak systolic longitudinal strain (GLS), and contraction pattern by 2D strain was performed during intrinsic conduction, tLVp, and BiV pacing and compared as paired data. Echocardiographic analysis was done blinded with respect to pacing mode.

RESULTS

LVEF was significantly higher during BiV pacing (47 ± 11 %) compared with intrinsic conduction (43 ± 13 %, P = 0.001) and tLVp (44 ± 13 %, P = 0.001), while there was no difference between intrinsic conduction and tLVp (P = 0.28). GLS was higher during BiV (14 ± 3) than during intrinsic conduction (13 ± 3, P = 0.01) and tLVp (13 ± 3, P = 0.03). Difference in time-to-peak contraction between the basal septal and lateral walls was shorter during BiV pacing (-3 ± 44 ms) than during intrinsic conduction (129 ± 66, P < 0.001) and tLVp (118 ± 118 ms, P < 0.001), with no difference between tLVp and intrinsic conduction (P = 0.56). The electrocardiogram showed change in frontal axis from intrinsic conduction in only 2 (9 %) patients during tLVp and in 20 (87 %) patients during BiV pacing.

CONCLUSIONS

The acute effect of tLVp on LV systolic function and contraction pattern is significantly lower than the effect of BiV pacing and not different from intrinsic conduction in patients with LBBB and CRT.

Cardiac Resynchronization Therapy: How to Decrease Nonresponders

Nonresponse to cardiac resynchronization therapy (CRT) is still a major issue in therapy expansion. The description of fast, simple, cost-effective methods to optimize CRT could help in adapting pacing intervals to individual patients. A better understanding of the importance of appropriate patient selection, left ventricular lead placement, and device programming, together with a multidisciplinary approach and an optimal follow-up of the patients, may reduce the percentage of nonresponders.

Echocardiographic Predictors of Worse Outcome After Cardiac Resynchronization Therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) is the recommended treatment by leading global guidelines. However, 30%-40% of selected patients are non-responders.

OBJECTIVE

To develop an echocardiographic model to predict cardiac death or transplantation (Tx) 1 year after CRT.

METHOD

Observational, prospective study, with the inclusion of 116 patients, aged 64.89 ± 11.18 years, 69.8% male, 68,1% in NYHA FC III and 31,9% in FC IV, 71.55% with left bundle-branch block, and median ejection fraction (EF) of 29%. Evaluations were made in the pre‑implantation period and 6-12 months after that, and correlated with cardiac mortality/Tx at the end of follow-up. Cox and logistic regression analyses were performed with ROC and Kaplan-Meier curves. The model was internally validated by bootstrapping.

RESULTS

There were 29 (25%) deaths/Tx during follow-up of 34.09 ± 17.9 months. Cardiac mortality/Tx was 16.3%. In the multivariate Cox model, EF < 30%, grade III/IV diastolic dysfunction and grade III mitral regurgitation at 6‑12 months were independently related to increased cardiac mortality or Tx, with hazard ratios of 3.1, 4.63 and 7.11, respectively. The area under the ROC curve was 0.78.

CONCLUSION

EF lower than 30%, severe diastolic dysfunction and severe mitral regurgitation indicate poor prognosis 1 year after CRT. The combination of two of those variables indicate the need for other treatment options.

Development and Validation of Predictive Models of Cardiac Mortality and Transplantation in Resynchronization Therapy

Background

30-40% of cardiac resynchronization therapy cases do not achieve favorable outcomes.

Objective

This study aimed to develop predictive models for the combined endpoint of cardiac death and transplantation (Tx) at different stages of cardiac resynchronization therapy (CRT).

Methods

Prospective observational study of 116 patients aged 64.8 ± 11.1 years, 68.1% of whom had functional class (FC) III and 31.9% had ambulatory class IV. Clinical, electrocardiographic and echocardiographic variables were assessed by using Cox regression and Kaplan-Meier curves.

Results

The cardiac mortality/Tx rate was 16.3% during the follow-up period of 34.0 ± 17.9 months. Prior to implantation, right ventricular dysfunction (RVD), ejection fraction < 25% and use of high doses of diuretics (HDD) increased the risk of cardiac death and Tx by 3.9-, 4.8-, and 5.9-fold, respectively. In the first year after CRT, RVD, HDD and hospitalization due to congestive heart failure increased the risk of death at hazard ratios of 3.5, 5.3, and 12.5, respectively. In the second year after CRT, RVD and FC III/IV were significant risk factors of mortality in the multivariate Cox model. The accuracy rates of the models were 84.6% at preimplantation, 93% in the first year after CRT, and 90.5% in the second year after CRT. The models were validated by bootstrapping.

Conclusion

We developed predictive models of cardiac death and Tx at different stages of CRT based on the analysis of simple and easily obtainable clinical and echocardiographic variables. The models showed good accuracy and adjustment, were validated internally, and are useful in the selection, monitoring and counseling of patients indicated for CRT.

More Favorable Response to Cardiac Resynchronization Therapy in Women Than in Men

Background—

Data on sex difference in response to cardiac resynchronization therapy (CRT) remain controversial. We conducted a meta-analysis to summarize all published studies to determine whether sex-based differences in response to CRT exist.

Methods and Results—

We performed a literature search using MEDLINE (source PubMed; January 1966 to March 2014) and EMBASE (January 1980 to March 2014) with no restrictions. Pooled effect estimates were obtained by using random-effects meta-analysis. Seventy-two studies involving 33 434 patients were identified. Overall, female patients had better outcomes from CRT compared with male patients, with a significant 33% reduction in the risk of death from any cause (hazard ratio, 0.67; 95% confidence interval, 0.61–0.74; P <0.001), 20% reduction in death or hospitalization for heart failure (hazard ratio, 0.80; 95% confidence interval, 0.71–0.90; P <0.001), 41% reduction in cardiac death (hazard ratio, 0.59; 95% confidence interval, 0.42–0.84; P <0.001), and 41% reduction in ventricular arrhythmias or sudden cardiac death (hazard ratio, 0.59; 95% confidence interval, 0.49–0.70; P <0.001). These more favorable responses to CRT in women were consistently associated with greater echocardiographic evidence of reverse cardiac remodeling in women than in men.

Conclusions—

Women obtained greater reductions in the risk of death from any cause, cardiac cause, death or hospitalization for heart failure, and ventricular arrhythmias or sudden cardiac death with CRT therapy compared with men, with consistently greater echocardiographic evidence of reverse cardiac remodeling in women than in men. Further studies are needed to investigate the exact reasons for these results and determine whether indications for CRT in women should be different from men.

EAARN score, a predictive score for mortality in patients receiving cardiac resynchronization therapy based on pre-implantation risk factors

AIMS

The beneficial effects of CRT in patients with advanced heart failure, wide QRS, and low LVEF have been clearly established. Nevertheless, mortality remains high in some patients. The aims of our study were to identify the predictors of mortality in patients treated with CRT and to design a risk score for mortality.

METHODS AND RESULTS

A cohort of 608 consecutive patients treated with CRT from 2000 to 2011 in our centre was prospectively analysed. Baseline clinical and echocardiography variables were analysed and mortality data were collected. During a mean follow-up of 36.2 ± 29.2 months, 174 patients died: 123/174 (71%) due to cardiovascular causes, 25/174 (14%) non-cardiac causes, and 26/174 (15%) unknown aetiology. In a multivariate analysis the predictors of mortality were NYHA class IV [hazard ratio (HR) 2.54, 95% confidence interval (CI) 1.7-3.7, P < 0.001], glomerular filtration rate (GFR) <60 mL/min/1.73 m2 (HR 1.61, 95% CI 1.14-2.30, P = 0.008), AF (HR 1.67, 95% CI 1.19-2.3, P = 0.01), age ≥70 years (HR 1.44, (95% CI 1.04-2.00, P = 0.02), and LVEF <22% (HR 1.83, 95% CI 1.33-2.52, P ≤ 0.001). The EAARN score (EF, Age, AF, Renal dysfunction, NYHA class IV) summarizes the predictors. Each additional predictor increased the mortality: one predictor, HR 3.28 (95% CI 1.37-7.8, P = 0.008); two, HR 5.23 (95% CI 2.24-12.10, P < 0.001); three, HR 9.63 (95% CI 4.1-22.60, P < 0.001); and four or more, HR 14.38 (95% CI 5.8-35.65, P < 0.001).

CONCLUSION

The predictors of mortality have a significant add-on predictive effect on mortality. The EAARN score could be useful to stratify the prognosis of CRT patients.

Patient-assessed short-term positive response to cardiac resynchronization therapy is an independent predictor of long-term mortality

AIMS

Cardiac resynchronization therapy (CRT) has a well-documented positive effect on mortality and heart failure morbidity. The aim of this study was to assess the long-term survival and the predictive value of self-assessed functional status on the long-term prognosis of patients treated with CRT-pacemaker (CRT-P).

METHODS AND RESULTS

Data were retrospectively collected from medical records of 446 consecutive patients implanted with CRT-P at a large-volume Swedish tertiary care centre. Primary outcome was all-cause mortality, predictive variables were assessed by log-rank test and univariate cox regression. Three hundred and nine patients had reliable information available on early improvement after implantation and were included in the multivariate analyses. The cohort was followed for a median of 79 months and was similar in baseline characteristics compared with major controlled trials. During follow-up 204 patients died, yearly mortality was 11.7%. Early improvement of self-assessed functional status was a strong independent predictor of survival [hazard ratio, HR 0.59, confidence interval (CI) 0.40-0.87, P = 0.007], together with well-known predictors; NYHA III-IV vs I-II (HR 1.66, CI 1.09-2.536, P = 0.018), age (HR 1.05, CI 1.03-1.08, P < 0.001), male gender (HR 2.0, CI 1.11-3.45, P = 0.021), and loop diuretic use (HR 4.41, CI 1.08-18.02). Patients with early improvement of self-assessed functional status had better 2-year and 5-year survival (P < 0.001).

CONCLUSIONS

Real-life patient characteristics and predictors of outcome compare well with those in published prospective trials. Self-assessed functional status is a strong predictor of long-term survival, which may have implications for a more active follow-up of patients without spontaneous improvement.

Complete atrioventricular block does not reduce long-term mortality in patients with permanent atrial fibrillation treated with cardiac resynchronization therapy

AIMS

A maximum percentage of ventricular pacing is mandatory to obtain a good response to CRT. Atrioventricular junction (AVJ) ablation has been recommended to attain this objective in patients with AF.

THE AIMS OF OUR STUDY WERE

(i) to determine whether the presence of complete AVJ block (induced or spontaneous) improves survival in patients with permanent AF treated with CRT and (ii) to analyse the predictors of mortality in AF patients treated with CRT.

METHODS AND RESULTS

From a series of 608 patients treated with CRT in our centre from 2000 to 2011, a cohort of 155 patients with permanent AF was analysed. Patients in AF were divided into two groups, AF + AVJ block [76 (49%)] and AF non-AVJ block [79 (51%)]. Mean follow-up was 30 months (interquartile range 13-51 months). During the follow-up, 62 patients died. Overall and cardiovascular mortality were similar between both groups: hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.51-1.39, P = 0.51 and HR 0.94, 95% CI 0.52-1.68, P = 0.82. Multivariate analysis identified three independent predictors of mortality: basal NYHA functional class IV (HR 2.25, 95% CI 1.12-4.22, P = 0.03), glomerular filtration rate (HR 0.98, 95% CI 0.96-0.99, P = 0.03), and LVEF (HR 0.94, 95% CI 0.89-0.99, P = 0.02).

CONCLUSIONS

AVJ block did not improve survival for patients in AF treated with CRT. Basal NYHA functional class IV, poor renal function, and LVEF were the independent predictors of mortality.

Cardiac resynchronization therapy: a breakthrough in heart failure management

Heart failure is now considered an epidemic. In patients with heart failure, electrical and mechanical dyssynchrony, evident primarily as prolongation of the QRS-complex on the surface electrocardiogram, is associated with detrimental effects on the cardiovascular system at several levels. In the past 10 years, studies have demonstrated that by stimulating both cardiac ventricles simultaneously, or almost simultaneously [cardiac resynchronization therapy (CRT)], the adverse effects of dyssynchrony can be overcome. Here, we provide a comprehensive overview of different aspects of CRT including the rationale behind and evidence for efficacy of the therapy. Issues with regard to gender effects and patient follow-up as well as a number of unresolved concerns will also be discussed.

Outcomes of cardiac resynchronization therapy in patients with versus those without atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

Whether the benefits observed with cardiac resynchronization therapy (CRT) are similar in patients with versus those without atrial fibrillation (AF) is unclear. Furthermore, whether patients with AF receiving CRT should undergo atrioventricular nodal (AVN) ablation remains uncertain.

OBJECTIVE

The purpose of this study was to compare outcomes in patients with and those without AF receiving CRT and to evaluate the influence of AVN ablation on outcomes in patients with AF.

METHODS

A systematic review and meta-analysis was performed. Outcomes included death, CRT nonresponse, and changes in left ventricular (LV) remodeling, quality of life (QoL), and 6-minute hall walk distance (6MWD).

RESULTS

Twenty-three observational studies were included and followed a total of 7,495 CRT recipients, 25.5% with AF, for a mean of 33 months. AF was associated with an increased risk of nonresponse to CRT (34.5% vs 26.7%; pooled relative risk [RR] 1.32; 95% confidence interval [CI] 1.12, 1.55; P = .001)) and all-cause mortality (10.8% vs 7.1% per year, pooled RR 1.50, 95% CI 1.08, 2.09; P = .015). The presence of AF was also associated with less improvement in QoL, 6-minute hall walk distance, and LV end-systolic volume but not LV ejection fraction. Among patients with AF, AVN ablation appeared favorable with a lower risk of clinical nonresponse (RR 0.40; 95% CI 0.28, 0.58; P <.001) and a reduced risk of death.

CONCLUSION

The benefits of CRT appear to be attenuated in patients with AF. The presence of AF is associated with an increased risk of clinical nonresponse and death than in patients without AF. AVN ablation may improve CRT outcomes in patients with AF.

Is "hyper response" to cardiac resynchronization therapy in patients with nonischemic cardiomyopathy a recovery, a remission, or a control?

BACKGROUND AND OBJECTIVES

Some patients treated by cardiac resynchronization therapy (CRT) recover "normal" left ventricular (LV) function and functional status. However, whether this "normalization" persists or reverts over time remains unknown. The aim of the present study was to evaluate the long-term outcomes of LV function in patients hyper responder to CRT.

METHODS

Eleven consecutive patients with nonischemic dilated cardiomyopathy, sinus rhythm, left bundle branch block (LBBB), New York Heart Association (NYHA) class III or IV, and optimal pharmacological treatment were hyper responder as they fulfilled concurrently the two following criteria: functional recovery (NYHA class I or II) and normalization of LV ejection fraction (LVEF).

RESULTS

After a mean follow-up of 65 ± 30 months between CRT implantation and last evaluation LVEF improved from 26 ± 9 to 59 ± 6% (P < 0.0001). One patient died from pulmonary embolism 31 months after implantation. Three patients exhibited LVEF ≤ 50% at their last follow-up visit (two at 40% and one at 45%). In eight patients, brief cessation of pacing was feasible (three were pacemaker-dependent). Mean QRS duration decreased from 181 ± 23 ms to 143 ± 22 ms (P = 0.006). In one patient, pacing was interrupted for 2 years and LVEF decreased markedly (from 65% to 31%) but returned to normal after a few months when pacing was resumed.

CONCLUSION

In hyper responder patients, "normalization" of LV function after CRT persists as long as pacing is maintained with an excellent survival.

What is treatment success in cardiac resynchronization therapy?

Cardiac resynchronization therapy (CRT) is an established treatment for symptomatic patients with heart failure, a prolonged QRS duration, and impaired left ventricular (LV) function. Identification of ‘responders’ and ‘non-responders’ to CRT has attracted considerable attention. The response to CRT can be measured in terms of symptomatic response or clinical outcome, or both. Alternatively, the response to CRT can be measured in terms of changes in surrogate measures of outcome, such as LV volumes, LV ejection fraction, invasive measures of cardiac performance, peak oxygen uptake, and neurohormones. This review explores whether these measures can be used in assessing the symptomatic and prognostic response to CRT. The role of these parameters to the management of individual patients is also discussed.

Echocardiography for cardiac resynchronization therapy selection: fatally flawed or misjudged?

After the publication of the PROSPECT (Predictors of Response to CRT) trial, the use of echocardiography for the assessment of mechanical dyssynchrony and as a possible aid for selecting patients for cardiac resynchronization therapy has been heavily criticized. Calls have been made to observe the current guidelines and implant according to the entry criteria of recent major trials. However, although this approach is currently to be recommended, the attempt to identify patients who will not receive the benefits of cardiac resynchronization therapy and whose clinical condition may be worsened should continue. Devices are not analogous to drugs: initial costs are higher, complications are significant, and the device cannot readily be withdrawn. Professional resources and the costs to society are high and wasted if devices are implanted inappropriately. Rather that discarding the attempt to identify the most suitable patients pre-operatively, further work is needed to refine the techniques and new clinical trials performed. A combination of methods that include finding the site of latest mechanical activation, myocardial scar localization, and assessing venous anatomy pre-operatively may help to identify those who will not derive any benefit or be potentially worsened.