Comparative long-term outcomes after cardiac resynchronization therapy in right ventricular paced patients versus native wide left bundle branch block patients

Understanding the Application of Mechanical Dyssynchrony in Patients with Heart Failure Considered for CRT

Over the past two decades of CRT use, the failure rate has remained around 30-35%, despite several updates in the guidelines based on the understanding from multiple trials. This review article summarizes the role of mechanical dyssynchrony in the selection of heart failure patients for cardiac resynchronization therapy. Understanding the application of mechanical dyssynchrony has also evolved during these past two decades. There is no role of lone mechanical dyssynchrony in the patient selection for CRT. However, mechanical dyssynchrony can complement the electrocardiogram and clinical criteria and improve patient selection by reducing the failure rate. An oversimplified approach to mechanical dyssynchrony assessment, such as just estimating time-to-peak delays between segments, should not be used. Instead, methods that can identify the underlying pathophysiology of HF and are representative of a substrate to CRT should be applied.

Estimation of left ventricular activation sequence in patients with heart failure using two-dimensional speckle tracking echocardiography

Evaluation of longitudinal strain (LS) from two-dimensional echocardiography is useful for global and regional left ventricular (LV) dysfunction assessment. We determined whether the LS reflects contraction process in patients with asynchronous LV activation. We studied 144 patients with an ejection fraction ≤ 35%, who had left bundle branch block (LBBB, n = 42), right ventricular apical (RVA) pacing (n = 34), LV basal- or mid-lateral pacing (n = 23), and no conduction block (Narrow-QRS, n = 45). LS distribution maps were constructed using 3 standard apical views. The times from the QRS onset-to-early systolic positive peak (Q-EPpeak) and late systolic negative peak (Q-LNpeak) were measured to determine the beginning and end of contractions in each segment. Negative strain in LBBB initially appeared in the septum and basal-lateral contracted late. In RVA and LV pacing, the contracted area enlarged centrifugally from the pacing site. Narrow-QRS showed few regional differences in strain during the systolic period. The Q-EPpeak and Q-LNpeak exhibited similar sequences characterized by septum to basal-lateral via the apical regions in LBBB, apical to basal regions in RVA pacing, and lateral to a relatively large delayed contracted area between the apical- and basal-septum in LV pacing. Differences in Q-LNpeaks between the apical and basal segments in delayed contracted wall were 107 ± 30 ms in LBBB, 133 ± 46 ms in RVA pacing, and 37 ± 20 ms in LV pacing (p < 0.05, between QRS groups). Specific LV contraction processes were demonstrated by evaluating the LS distribution and time-to-peak strain. These evaluations may have potential to estimate the activation sequence in patients with asynchronous LV activation.

Upgrading right ventricular pacemakers to biventricular pacing or conduction system pacing: a systematic review and meta-analysis

Guidelines recommend patients undergoing a first pacemaker implant who have even mild left ventricular (LV) impairment should receive biventricular or conduction system pacing (CSP). There is no corresponding recommendation for patients who already have a pacemaker. We conducted a meta-analysis of randomized controlled trials (RCTs) and observational studies assessing device upgrades. The primary outcome was the echocardiographic change in LV ejection fraction (LVEF). Six RCTs (randomizing 161 patients) and 47 observational studies (2644 patients) assessing the efficacy of upgrade to biventricular pacing were eligible for analysis. Eight observational studies recruiting 217 patients of CSP upgrade were also eligible. Fourteen additional studies contributed data on complications (25 412 patients). Randomized controlled trials of biventricular pacing upgrade showed LVEF improvement of +8.4% from 35.5% and observational studies: +8.4% from 25.7%. Observational studies of left bundle branch area pacing upgrade showed +11.1% improvement from 39.0% and observational studies of His bundle pacing upgrade showed +12.7% improvement from 36.0%. New York Heart Association class decreased by -0.4, -0.8, -1.0, and -1.2, respectively. Randomized controlled trials of biventricular upgrade found improvement in Minnesota Heart Failure Score (-6.9 points) and peak oxygen uptake (+1.1 mL/kg/min). This was also seen in observational studies of biventricular upgrades (-19.67 points and +2.63 mL/kg/min, respectively). In studies of the biventricular upgrade, complication rates averaged 2% for pneumothorax, 1.4% for tamponade, and 3.7% for infection over 24 months of mean follow-up. Lead-related complications occurred in 3.3% of biventricular upgrades and 1.8% of CSP upgrades. Randomized controlled trials show significant physiological and symptomatic benefits of upgrading pacemakers to biventricular pacing. Observational studies show similar effects between biventricular pacing upgrade and CSP upgrade.

Comparison of de novo versus upgrade cardiac resynchronisation therapy on clinical effect and long-term outcome

BACKGROUND

The benefit of de novo cardiac resynchronisation therapy (CRT) implantation in selected patients with heart failure is well known. The number of upgrade procedures is increasing but data on clinical response and outcome are less well documented as compared to de novo implantation.

OBJECTIVES

To investigate the efficacy and outcome of CRT upgrade procedures in patients with existing cardiac implantable electronic devices (CIEDs).

METHODS

Baseline characteristics, change in New York Heart Association (NYHA) functional class, echocardiographic parameters, life-threatening ventricular tachyarrhythmias, all-cause mortality and mode of death were evaluated in CRT patients with the comparison between de novo and upgrade CRT procedures.

RESULTS

About 410 patients (CRT upgrade/de novo CRT, n = 97/313) were followed for 63.5 ± 38.1 months. Upgrade patients were older (75.5 ± 8.1 vs 69.9 ± 10.7 years; p < 0.001), had more often an ischaemic cause of heart failure (58.8% vs 45.4%; p = 0.021), a higher NYHA functional class (p = 0.004) and a higher comorbidity burden. Improvement in left ventricular ejection fraction (LVEF) was higher in the de novo CRT group (8.4 ± 9.9 vs 11.0 ± 10.3%; p = 0.035). Clinical response was similar between both groups (60.5 vs 62.5%; p = 0.793), as was mortality at 1 year (8.2 vs 5.8%; p = 0.351) and at last follow-up (33.0 vs 28.8%; p = 0.447). The proportion of cardiovascular related deaths was similar between both groups (46.9% vs 38.9%; p = 0.531).

CONCLUSIONS

Patients with CRT upgrade procedures have similar symptomatic improvements, as well as 1 year and long-term outcome as compared to patients with de novo CRT implantation.

Pacemaker Induced Cardiomyopathy: An Overview of Current Literature

Pacemaker induced cardiomyopathy (PICM) is commonly defined as a reduction in left ventricular (LV) function in the setting of right ventricular (RV) pacing. This condition may be associated with the onset of clinical heart failure in those affected. Recent studies have focused on potential methods of identifying patients at risk of this condition, in addition to hypothesizing the most efficacious ways to manage these patients. Newer pacing options, such as His bundle pacing, may avoid the onset of PICM entirely.

Upgrade from implantable cardioverter-defibrillator vs. de novo implantation of cardiac resynchronization therapy: long-term outcomes

AIMS

To assess and compare long-term mortality and predictors thereof in de novo cardiac resynchronization therapy defibrillators (CRT-D) vs. upgrade from an implantable cardioverter-defibrillator (ICD) to CRT-D.

METHODS AND RESULTS

Study population consisted of 595 consecutive patients with CRT-D implanted between 2002 and 2015 in a tertiary care, university hospital, in a densely inhabited, urban region of Poland [480 subjects (84.3%) with CRT-D de novo implantation; 115 patients (15.7%) upgraded from ICD to CRT-D]. In a median observation of 1692 days (range 457-3067), all-cause mortality for de novo CRT-D vs. CRT-D upgrade was 35.5% vs. 43.5%, respectively (P = 0.045). On multivariable regression analysis including all CRT recipients, the previously implanted ICD was an independent predictor for death [hazard ratio (HR) 1.58, 95% confidence interval (CI) 1.10-2.29, P = 0.02]. For those, who were upgraded from ICD to CRT-D, the independent predictors for all-cause death were as follows: creatinine level (HR 1.01, 95% CI 1.00-1.02, P = 0.01), left ventricular end-systolic diameter (HR 1.07, 95% CI 1.02-1.11, P = 0.002), New York Heart Association (NYHA) IV class at baseline (HR 2.36, 95% CI 1.00-5.53, P = 0.049) and cardiac device-related infective endocarditis during follow-up (HR 2.42, 95% CI 1.02-5.75, P = 0.046). A new CRT scale (Creatinine ≥150 μmol/L; Remodelling, left ventricular end-systolic ≥59 mm; Threshold for NYHA, NYHA = IV) showed high prediction for mortality in CRT-D upgrades (AUC 0.70, 95% CI 0.59-0.80, P = 0.0007).

CONCLUSION

All-cause mortality in patients upgraded from ICD is significantly higher compared with de novo CRT-D implantations and reaches almost 45% within 4.5 years. A new CRT scale (Creatinine; Remodelling; Threshold for NYHA) has been proposed to help survival prediction following CRT upgrade.

Predictors of response to cardiac resynchronization therapy in patients with chronic right ventricular pacing

Background

The benefits of de novo cardiac resynchronization therapy (CRT) in patients with QRS-prolongation and impaired left-ventricular function (LVEF) are well established. Current guidelines also recommend CRT-upgrade in patients requiring permanent or frequent right ventricular pacing (RVP) with symptomatic heart failure and reduced LVEF. Whereas several predictors of response to de novo CRT-implantation such as female gender, QRS-duration, non-ischemic cardiomyopathy (NICM) are known due to large prospective trials, similar factors regarding CRT-upgrade are currently lacking.

Methods and results

We examine 114 patients 3–6 months after CRT-upgrade due to frequent RVP (> 50%) and symptomatic heart failure. Response to CRT was evaluated by improvement in NYHA class referring to the Minnesota Living With Heart Failure Questionnaire. Only cardiomyopathy type and use of Angiotensin-converting-enzyme (ACE) inhibitor had an impact on response to CRT-upgrade in a linear regression model. Patients with NICM presented a greater responder rate than patients with ischemic cardiomyopathy (ICM) (80.4 vs. 60.3%, p < 0.05). Other traditional response predictors in de novo CRT recipients (e.g. QRS-width, female gender) showed no effect on CRT-response in this cohort.

Conclusion

Only underlying heart disease (NICM vs. ICM) and the use of ACE inhibitor were significant predictors of response to CRT-upgrade. In contrast to de novo CRT-recipients, where pre-implant QRS-duration is a key predictor, QRS-duration during RV-pacing has no significant impact on CRT-response in this cohort.

Graphic abstract

Comparison of left ventricular lead upgrade vs continued medical care among patients eligible for cardiac resynchronization therapy at the time of defibrillator generator replacement: Predictors of left ventricular lead upgrade and associations with long-term outcomes

BACKGROUND

Randomized trials evaluating cardiac resynchronization therapy (CRT) have excluded patients with a pre-existing implantable cardioverter-defibrillator (ICD). The association of CRT upgrade with clinical outcomes in patients with a pre-existing ICD is unclear.

OBJECTIVE

The purpose of this study was to examine a CRT-eligible population to evaluate clinical outcomes associated with CRT upgrade compared to patients who did not undergo CRT.

METHODS

Using the National Cardiovascular Data Registry (NCDR) ICD Registry between April 2010 and December 2014, we created a hierarchical logistic regression model to identify predictors of CRT upgrade in a CRT-eligible ICD population. In the subpopulation of patients with Medicare-linked claims data, differential outcomes were determined with censoring at 3 years. The primary endpoint of this study was all-cause mortality, with secondary endpoints of rates of hospitalization and procedural complications.

RESULTS

CRT upgrade was performed in 75.5% of CRT-eligible patients with pre-existing ICD (n = 15,803). Presence of left bundle branch block conduction was the strongest predictor of CRT upgrade (odds ratio [OR] 4.56; 95% confidence interval [CI] 4.08-5.11; P <.0001). In both unadjusted and adjusted analyses, CRT upgrade was associated with a reduction in mortality at 3 years (unadjusted hazard ratio [HR] 0.80; 95% CI 0.70-0.92; P = .001; adjusted HR 0.84; 95% CI 0.72-0.98; P = .02, respectively). Compared to patients with ICD generator replacement only, patients who underwent CRT upgrade experienced no different 3-year rates of hospitalization (adjusted HR 1.01; 95% CI 0.91-1.12; P = .81) or 1-year periprocedural complication rates (adjusted HR 1.07; 95% CI 0.79-1.45; P = .66).

CONCLUSION

In a national registry of CRT-eligible patients with pre-existing ICD, upgrade to CRT was associated with lower rates of mortality than continued medical management.

Survival of patients with pacing-induced cardiomyopathy upgraded to CRT does not depend on defibrillation therapy

BACKGROUND

Permanent right ventricular pacing (RVP) results in cardiac dyssynchrony that may lead to heart failure and may be an indication for the use of cardiac resynchronization therapy (CRT). The study aimed to evaluate predictors of outcomes in patients with pacing-induced cardiomyopathy (PICM) if upgraded to CRT.

METHODS

One hundred fifteen patients, 75.0 years old (IQR 67.0-80.0), were upgraded to CRT due to the decline in left ventricle ejection fraction (LVEF) caused by the long-term RVP. A retrospective analysis was performed using data from hospital and outpatient clinic records and survival data from the National Health System.

RESULTS

The prior percentage of RVP was 100.0% (IQR 97.0-100.0), with a QRS duration of 180.0 ms (IQR 160.0-200.0). LVEF at the time of the upgrade procedure was 27.0% (IQR 21.0-32.75). The mean follow-up was 980 ± 522 days. The primary endpoint, death from any cause, was met by 26 (22%) patients. Age > 82 years (HR 5.96; 95% CI 2.24-15.89; P = .0004) and pre-CRT implantation LVEF < 20% (HR 5.63; 95%CI 2.19-14.47; P = .0003), but neither the cardioverter-defibrillator (ICD) implantation (HR 1.00; 95%CI 0.45-2.22; P = 1.00), nor the presence of atrial fibrillation (HR 1.22; 95%CI 0.56-2.64; P = .62), were independently associated with all-cause mortality.

CONCLUSION

Advanced age and an extremely low LVEF, but neither the presence of atrial fibrillation nor implanting an additional high voltage lead, influence the all-cause mortality in patients after long-term RVP, when upgraded to CRT.

Mortality and Heart Failure After Upgrade to Cardiac Resynchronization Therapy

Background

Cardiac resynchronization therapy (CRT) is effective in treating advanced heart failure (HF), but data describing benefits and long-term outcomes for upgrades from a preexisting device are limited. This study sought to compare long-term outcomes in de novo CRT implants with those eligible for CRT with a prior device.

Methods

This is a retrospective cohort study using data from a provincial registry (2002-2015). Patients were included if they had mild-moderate HF, left ventricular ejection fraction ≤ 35%, and QRS duration ≥ 130 ms. Patients were classified as de novo CRT or upgraded to CRT from a prior device. Outcomes were mortality and composite mortality and HF hospitalization.

Results

There were 342 patients included in the study. In a multivariate model, patients in the upgraded cohort (n = 233) had a higher 5-year mortality rate (adjusted hazard ratio, 2.86; 95% confidence interval, 1.59-5.15; P = 0.0005) compared with the de novo cohort (n = 109) and higher composite mortality and HF hospitalization (adjusted hazard ratio, 2.60; 95% confidence interval, 1.54-4.37; P = 0.0003).

Conclusions

Implantation of de novo CRTs was associated with lower mortality and HF hospitalization compared with upgraded CRTs from preexisting devices. It is unknown whether these differences are due to the timing of CRT implementation or other clinical factors. Further work in this area may be helpful to determine how to improve outcomes for these patients.

Incidence of heart failure after pacemaker implantation: a nationwide Danish Registry-based follow-up study

Aims

The objective of the current study is to investigate the risk of heart failure (HF) after implantation of a pacemaker (PM) with a right ventricular pacing (RVP) lead in comparison to a matched cohort without a PM and factors associated with this risk.

Methods and results

All patients without a known history of HF who had a PM implanted with an RVP lead between 2000 and 2014 (n = 27 704) were identified using Danish nationwide registries. An age- and gender-matched control cohort (matched 1:5, n = 138 520) without PM and HF was identified to compare the risk. Outcome was the cumulative incidence of HF including fatal HF within the first 2 years of PM implantation, with all-cause mortality and myocardial infarction (MI) as competing risks. Due to violation of proportional hazards, the follow-up period was divided into three time-intervals: <30 days, 30–180 days, and >180 days–2 years. The cumulative incidence of HF including fatal HF was observed in 2937 (10.6%) PM patients. Risks for the three time-intervals were <30 days [hazard ratio (HR) 5.98, 95% CI 5.19–6.90], 30–180 days (HR 1.84, 95% CI 1.71–1.98), and >180 days (HR 1.11, 95% CI 1.04–1.17). Among patients with a PM device, factors associated with increased risk of HF were male sex (HR 1.33, 95% CI 1.24–1.43), presence of chronic kidney disease (CKD) (HR 1.64, 95% CI 1.29–2.09), and prior MI (1.77, 95% 1.50–2.09).

Conclusions

Pacemaker with an RVP lead is strongly associated with risk of HF specifically within the first 6 months. Patients with antecedent history of MI and CKD had substantially increased risk.

Long term outcomes in patients with chronic right ventricular pacing upgraded to cardiac resynchronization therapy

INTRODUCTION

In patients with chronic systolic heart failure and frequent right ventricular pacing (RVP), upgrade to cardiac resynchronization therapy (CRT) has become common practice despite a lack of randomized clinical trials. We aimed to evaluate long term outcomes in patients upgraded to CRT from chronic RVP compared with de novo CRT implants.

METHODS AND RESULTS

We reviewed medical charts on consecutive patients with a left ventricular ejection fraction (LVEF) ≤ 35% and a QRSd ≥ 120 ms undergoing CRT. Survival free of left ventricular assist device (LVAD) and a heart transplant was compared amongst patients on the basis of pre-CRT QRS morphology. Improvement in LVEF was also compared across groups. A total of 1260 patients met inclusion criteria of whom 233 were upgraded from chronic RVP. Over a mean follow up 6.5 ± 4.0 years there were 821 endpoints (27 LVAD, 30 heart transplants, and 764 deaths). In a multivariate Cox regression model, upgraded patients had worse outcomes (HR 1.3(1.1-1.7) P = .007) compared with those with native LBBB and similar outcomes to patients with non-LBBB(HR 0.96(0.76-1.21) P = .7). The survival curve for chronic RVP parallels native LBBB for approximately 2.5 years before dropping sharply. Patients with chronic RVP derive similar improvements in LVEF compared with those with LBBB and superior improvements compared with those with non-LBBB.

CONCLUSIONS

Despite achieving similar levels of LVEF improvement, patients with systolic heart failure with chronic RVP undergoing upgrade to CRT have inferior long term outcomes compared with patients with native LBBB. Long term outcomes with CRT in patients with chronic RVP, RBBB, and IVCD are similar.

Why Dyssynchrony Matters in Heart Failure?

Cardiac resynchronization therapy (CRT) is an electrical therapy to resolve an electrical problem. Any method to predict CRT response must specifically reflect the electrical substrate. Time-to-peak dyssynchrony is too unspecific for prediction of response because dyssynchrony by this approach may reflect the presence of scar or fibrosis even in the absence of conduction delay. New methods are based on the actual physiology of activation delay-induced heart failure (HF) and are superior to time-to-peak methods in predicting CRT response. Time-to-peak dyssynchrony may be used for prognosis in HF patients without signs of delayed ventricular activation and for monitoring CRT response.

Complications associated with cardiac resynchronization therapy upgrades versus de novo implantations

INTRODUCTION

A significant number of patients undergo upgrade to cardiac resynchronization therapy (CRT). These patients tend to differ from individuals undergoing de novo CRT implantations both in terms of their baseline demographics and the etiology underlying their heart failure. Areas covered: There are several factors that need to be considered when upgrading patients to CRT, such as, venous patency. Potentially, these conditions can cause issues which may result in procedures being more difficult than de novo implantations. This article discusses these issues and compares the rates of procedural-related complications for CRT upgrades and de novo implantations. It discusses the proportion of patients that are likely to respond to CRT with each intervention. Expert commentary: Understanding the relative risks of CRT upgrades versus de novo implantations is important to help operators select the correct initial device and counsel patients accordingly. Growing experience with image-guided implantations and endocardial pacing may prove to be particularly relevant to patients undergoing CRT upgrades.

De novo implantation vs. upgrade cardiac resynchronization therapy: a systematic review and meta-analysis

Patients with conventional pacemakers or implanted defibrillators are often considered for cardiac resynchronization therapy (CRT). Our aim was to summarize the available evidences regarding the clinical benefits of upgrade procedures. A systematic literature search was performed from studies published between 2006 and 2017 in order to compare the outcome of CRT upgrade vs. de novo implantations. Outcome data on all-cause mortality, heart failure events, New York Heart Association (NYHA) Class, QRS narrowing and echocardiographic parameters were analysed. A total of 16 reports were analysed comprising 489,568 CRT recipients, of whom 468,205 patients underwent de novo and 21,363 upgrade procedures. All-cause mortality was similar after CRT upgrade compared to de novo implantations (RR 1.19, 95% CI 0.88-1.60, p = 0.27). The risk of heart failure was also similar in both groups (RR 0.96, 95% CI 0.70-1.32, p = 0.81). There was no significant difference in clinical response after CRT upgrade compared to de novo implantations in terms of improvement in left ventricular ejection fraction (ΔEF de novo - 6.85% vs. upgrade - 9.35%; p = 0.235), NYHA class (ΔNYHA de novo - 0.74 vs. upgrade - 0.70; p = 0.737) and QRS narrowing (ΔQRS de novo - 9.6 ms vs. upgrade - 29.5 ms; p = 0.485). Our systematic review and meta-analysis of currently available studies reports that CRT upgrade is associated with similar risk for all-cause mortality compared to de novo resynchronization therapy. Benefits on reverse remodelling and functional capacity improved similarly in both groups suggesting that CRT upgrade may be safely and effectively offered in routine practice.

CLINICAL TRIAL REGISTRATION

Prospero Database-CRD42016043747.

Comparison of De Novo versus Upgrade Cardiac Resynchronization Therapy; Focused on the Upgrade for Pacing-Induced Cardiomyopathy

PURPOSE

This study aimed to determine whether upgrade cardiac resynchronization therapy (CRT) shows better outcomes than de novo CRT. To do so, we compared the efficacy of CRT between de novo and upgrade groups, focusing particularly on the effect of upgrade CRT on patients with pacing-induced cardiomyopathy (PiCM).

MATERIALS AND METHODS

PiCM was defined as new-onset dilated cardiomyopathy following pacemaker implantation in patients with baseline normal ejection fraction ≥50%. Electro-mechanical reverse remodeling and clinical outcomes were compared among the de novo (n=62), PiCM upgrade (n=7), and non-PiCM upgrade (n=8) CRT groups.

RESULTS

The PiCM upgrade group showed significantly greater electro-mechanical reverse remodeling than the de novo CRT or non-PiCM upgrade groups at 6-month follow-up. The rate of super-responders was significantly higher in the PiCM upgrade group than the other CRT groups. The group factor of the PiCM upgrade was identified as an independent predictor of super-responder in multivariate analysis (odds ratio 10.4, 95% confidential interval 1.08-99.4, p=0.043). During the median follow-up of 15.8 months, the PiCM upgrade group showed the lowest rate of composite clinical outcomes, including cardiac death, heart transplantation, and heart failure-related rehospitalization (p=0.059).

CONCLUSION

The upgrade CRT for PiCM patients showed better performance in terms of electro-mechanical reverse remodeling than de novo implantation or upgrade CRT in non-PiCM patients.

Effects of Upgrade Versus De Novo Cardiac Resynchronization Therapy on Clinical Response and Long-Term Survival

Background—

Benefits of cardiac resynchronization therapy (CRT) on morbidity and mortality in selected patients are well known. Although the number of upgrade procedures from single- or dual-chamber devices to CRT is increasing, there are only sparse data on the outcomes of upgrade procedures compared with de novo CRT. This study aimed to evaluate clinical response and survival in patients receiving de novo versus upgrade CRT defibrillator therapy.

Methods and Results—

Prospectively collected outcome data were compared in patients undergoing de novo or upgrade CRT defibrillator implantation at 3 implant centers in Germany and Hungary. Clinical response was defined as an improvement by at least one New York Heart Association (NYHA) functional class. CRT implantation was performed in 552 consecutive patients of whom 375 underwent a de novo and 177 an upgrade procedure. Upgrade patients were more often implanted for secondary prevention, suffered more often from atrial fibrillation, chronic kidney disease, diabetes mellitus, and dyslipidemia, and had more often a non-LBBB (left bundle branch block) wide QRS complex, and lower left ventricular ejection fraction. Upgrade procedures were associated with a lower response rate compared to the de novo group (57% versus 69%, P univariate=0.008, P multivariate=0.021). During the follow-up of 37±28 months, survival was worse after upgrade compared with de novo CRT defibrillator implantations (hazard ratio, 1.65; 95% confidence interval, 1.22–2.24; P =0.001) even after careful adjustment for important baseline variables (adjusted hazard ratio, 1.68; 95% confidence interval, 1.20–2.34; P =0.002) and after propensity-score matching (propensity-adjusted hazard ratio, 1.79; 95% confidence interval, 1.08–2.95; P =0.023).

Conclusions—

Both clinical response and long-term survival were less favorable in patients undergoing CRT upgrade compared to de novo implantations.