Trends and determinant factors in the use of cardiac resynchronization therapy devices in Japan: Analysis of the Japan cardiac device treatment registry database

A novel prediction model for survival in individual patients with cardiac resynchronization therapy with a defibrillator: Analysis of the new Japan cardiac device treatment registry database

Background

Accurate prediction for survival in individualized patients with cardiac resynchronization therapy with a defibrillator (CRT-D) is difficult.

Methods

We analyzed the New Japan cardiac device treatment registry (JCDTR) database to develop a survival prediction model for CRT-D recipients.

Results

Four hundred and eighty-two CRT-D recipients, at the implantation year 2018-2021, with a QRS width ≥120 ms and left ventricular ejection fraction (LVEF) ≤35% at baseline, were analyzed. During an average follow-up of 21 ± 10 months, death occurred in 66 of 482 CRT-D patients (14%). A prediction model estimating annual survival probability was developed using Cox regression with internal validation. With seven explanation predictors (age >75 years, serum creatinine >1.4 mg/dL, blood hemoglobin <12 g/dL, heart rate ≥90/min, LVEF, prior NSVT, and QRS width <150 ms), the model distinguished patients with and without all-cause death, with an optimism-corrected C-statistics of 0.766, 0.764, and 0.768, and calibration slope of 1.01, 1.00, and 1.00 at 1 year, 2 years, and 3 years. Additionally, we have devised the calculator of survival probability for individual CRT-D recipients.

Conclusions

Using routine available variables, we have developed a survival prediction model for individual CRT-D recipients.

Improved outcomes of cardiac resynchronization therapy with a defibrillator in systolic heart failure: Analysis of the Japan cardiac device treatment registry database

Background

Temporal change in outcomes of heart failure patients receiving cardiac resynchronization therapy with a defibrillator (CRT-D) is unknown.

Methods

We assess outcomes and underlying heart diseases of patients receiving CRT-D with analyzing database of the Japan cardiac device treatment registry (JCDTR) at the implantation year 2011-2015 and New JCDTR at the implantation year 2018-2021.

Results

Proportion of nonischemic heart diseases was about 70% in both the groups (JCDTR: 69%; New JCDTR: 72%). Cardiac sarcoidosis increased with the rate of 5% in the JCDTR to 9% in the New JCDTR group. During an average follow-up of 21 months, death from any cause occurred in 167 of 906 patients in the JCDTR group (18%) and 79 of 611 patients in the New JCDTR group (13%) (adjusted hazard ratio [aHR] in the New JCDTR group, 0.72; 95% confidence interval [CI]: 0.55-0.94; p = .017). The superiority was mainly driven by reduction in the risk of noncardiac death. With regard to appropriate and inappropriate implantable cardioverter-defibrillator (ICD) therapy, there was a significant reduction in the New JCDTR group versus the JCDTR group (aHR in the New JCDTR group, 0.76; 95% CI: 0.59-0.98; p = .032 for appropriate ICD therapy; aHR in the New JCDTR group, 0.24; 95% CI: 0.12-0.50; p < .0001 for inappropriate ICD therapy).

Conclusions

All-cause mortality was reduced in CRT-D patients implanted during 2018-2021 compared to those during 2011-2015, with a significant reduction in noncardiac death.

Cardiac resynchronization therapy with a defibrillator in non-ischemic and ischemic patients for primary and secondary prevention of sudden cardiac death: Analysis of the Japan cardiac device treatment registry database

Background

Panoramic studies in patients with cardiac resynchronization therapy with a defibrillator (CRT-D) focusing on the etiology and indication are scarce. Besides, a controversy exists regarding requirement of a defibrillator in non-ischemic patients for primary prevention with CRT.

Methods

Annual trends of de novo CRT-D implantations from 2011 to 2020 and outcomes of those between January 2011 and August 2015 were analyzed from the Japan cardiac device treatment registry (JCDTR) and New JCDTR database.

Results

From 2011 to 2020, 8062 CRT-D recipients were registered, whose dominant indication was primary prevention of sudden cardiac death with a steady rate of about 70%. There was no significant temporal change of the proportion of non-ischemic patients being about 70% and 65% for primary and secondary prevention, respectively. Non-ischemic patients for primary prevention were associated with increased odds of appropriate ICD therapy [adjusted hazard ratio (aHR): 1.66; 95% confidence interval (CI): 1.01-2.75; p = .047] and reduced odds of any death (aHR: 0.66; 95% CI: 0.44-0.99; p = .046) as compared to ischemic patients.

Conclusions

Proportion of non-ischemic etiology was much higher than that of ischemic one in the CRT-D cohort. Based on the higher odds of appropriate ICD therapy, non-ischemic patients for primary prevention appear to be prudently selected in Japan.

Utilization and Efficacy of Cardiac Resynchronization Therapy in Patients With Chronic Heart Failure ― A Report From the CHART-2 Study ―

Background: Although cardiac resynchronization therapy (CRT) is effective for patients with chronic heart failure (CHF) with reduced left ventricular ejection fraction and wide QRS (≥120 ms), data on the use of or long-term outcomes after CRT implantation in Japan are limited.

Methods and Results: We examined proper CRT utilization and outcomes in 3,447 consecutive symptomatic CHF patients registered in the CHART-2 Study. We identified 167 potentially eligible patients and divided them into 4 groups according to the presence (+) or absence (−) of an indication for and implantation of CRT: Group A (reference group), (+)indication/(+)CRT; Group B, (+)indication/(−)CRT; Group C, (−)indication/(+)CRT; and Group D, (−)indication/(−)CRT. Based on the Japanese Circulation Society guidelines, 91 patients met the eligibility for CRT implantation, with 43 (47%) of them undergoing CRT implantation. After adjusting for confounders, age was significantly associated with no CRT use (odds ratio per 5-year increase 1.46; 95% confidence interval 1.11–2.05; P=0.012). Among the 4 groups, the cumulative incidence of cardiovascular death and CHF admission were highest in Group B and lowest in Group D (P=0.029).

Conclusions: In this study, only half the eligible CHF patients properly received CRT. Aging was a significant risk factor for no CRT use. Patients without CRT despite having an indication could be at higher risk of mortality and CHF admission.

The use of angiotensin II receptor blocker is associated with greater recovery of cardiac function than angiotensin-converting enzyme inhibitor in dilated cardiomyopathy

AIMS

Angiotensin-converting enzyme inhibitors (ACEis) or angiotensin II receptor blockers (ARBs) have been shown to be associated with recovery of cardiac function in patients with dilated cardiomyopathy (DCM). The aim of this study was to assess comparative effectiveness of ACEis vs. ARBs on recovery of left ventricular ejection fraction (LVEF) among patients with DCM.

METHODS AND RESULTS

We analysed the clinical personal records of DCM, a national database of the Japanese Ministry of Health, Labour and Welfare, from 2003 to 2014. Patients with LVEF < 40% and on either ACEis or ARBs were included. Eligible patients were divided into two groups according to the use of ACEis or ARBs. A one-to-one propensity case-matched analysis was used. The primary outcome was defined as LVEF ≥ 40% at 3 years of follow-up. Out of 4618 eligible patients, 2238 patients received ACEis and 2380 patients received ARBs. Propensity score matching yielded 1341 pairs. Mean age was 56.0 years, 2041 (76.1%) were male, median duration of heart failure was 1 year, and mean LVEF was 27.6%. The primary outcome was observed more frequently in ARB group than in ACEi group (59.8% vs. 54.1%; odds ratio 1.26; 95% confidence interval 1.08-1.47; P = 0.003). The per-protocol analysis showed similar results (62.0% vs. 54.0%; odds ratio 1.39; 95% confidence interval 1.17-1.66; P < 0.001). The change in LVEF from baseline to 3 years of follow-up was greater in ARB group than in ACEi group (15.8 ± 0.4% vs. 14.0 ± 0.4%, P = 0.003). The subgroup analysis showed that this effect was observed independently of systolic blood pressure, heart rate, LVEF, chronic kidney disease, and concomitant use of beta-blockers and mineralocorticoid receptor antagonists.

CONCLUSIONS

The use of ARBs was associated with LVEF recovery more frequently than ACEis among patients with DCM and reduced LVEF.

What Are the Expectations for Cardiac Resynchronization Therapy? A Validation of Two Response Definitions

BACKGROUND

The definition of response to cardiac resynchronization therapy (CRT) varies across clinical trials. There are two main definitions, i.e., echocardiographic response and functional response. We assessed which definition was more reasonable.

METHODS

In this study of 260 patients who had undergone CRT, an echocardiographic response was defined as a reduction in a left ventricular end-systolic volume of greater than or equal to 15% or an improvement in left ventricular ejection fraction of greater than or equal to 5%. A functional response was defined as an improvement of at least one class category in the New York Heart Association functional classification. We assessed the response to CRT at 6 months after device implantation, based on each definition, and investigated the relationship between response and clinical outcomes.

RESULTS

The echocardiographic response rate was 74.2%. The functional response rate was 86.9%. Non-responder status, based on both definitions, was associated with higher all-cause mortality. Cardiac death was only associated with functional non-responder status (hazard ratio (HR) 2.65, 95% confidence interval (CI) 1.19-5.46, p = 0.0186) and heart failure hospitalization (HR 2.78, 95% CI, 1.29-5.26, p = 0.0111).

CONCLUSION

After CRT implantation, the functional response definition of CRT response is associated with a higher response rate and better clinical outcomes than that of the echocardiographic response definition, and therefore it is reasonable to use the functional definition to assess CRT response.

Current status and role of programmed ventricular stimulation in patients without sustained ventricular arrhythmias and reduced ejection fraction: Analysis of the Japan cardiac device treatment registry database

BACKGROUND

The aim of this study was to clarify the current status and role of programmed ventricular stimulation in patients without sustained ventricular arrhythmias and reduced left ventricular ejection fraction (LVEF).

METHODS

The follow-up data of the Japan cardiac device treatment registry (JCDTR) was analyzed in 746 patients with LVEF ≦35% and no prior history of sustained ventricular arrhythmias who underwent de novo implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy with a defibrillator (CRT-D) implantation between January 2011 and August 2015.

RESULTS

Electrophysiological study (EPS) with programmed ventricular stimulation had been performed before the device implant in 118 patients (15.8%, EPS group). During the mean follow-up of 21 ± 12 months, the rate of freedom from any death and appropriate defibrillator therapy was not significantly different between EPS group (n = 118) and No EPS group (n = 628). NYHA class II-IV, and QRS duration were negatively associated with performing EPS. Among patients in the EPS group, the rate of ventricular tachycardia (VT)/ventricular fibrillation (VF) induction was 48%. The inducibility was not a predictor of appropriate defibrillator therapy, whereas BNP ≧535 pg/mL and no use of amiodarone were significantly associated with a risk of the appropriate therapy.

CONCLUSION

EPS for induction of VT/VF had been performed in about 16% of patients with reduced LVEF before primary prevention ICD/CRT-D implantation. Elevated BNP levels and no use of amiodarone, but not inducibility of VT/VF, appeared to be associated with appropriate defibrillator therapy in these populations.

A Predictive Model for Super-Response to Cardiac Resynchronization Therapy: The QQ-LAE Score

Objectives

It is important to identify super-responders who can derive most benefits from cardiac resynchronization therapy (CRT). We aimed to establish a scoring model that can be used for predicting super-response to CRT.

Methods

We retrospectively reviewed 387 CRT patients. Multivariate logistic regression analysis was performed to identify predictors for super-response (defined as an absolute increase in left ventricular ejection fraction of ≥15% at 6-month follow-up) and to create a score model. Multivariate Cox proportional-hazard regression analysis was conducted to assess associations with the long-term endpoint (defined as cardiac death/heart transplant, heart failure (HF) hospitalization, or all-cause death) across the score categories at follow-up.

Results

Among 387 patients, 109 (28.2%) met super-response. In multivariable analysis, 5 independent predictors (QQ-LAE) were identified: prior no fragmented QRS (odds ratio (OR) = 3.10 (1.39, 6.94)), QRS duration ≥170 ms (OR = 2.37 (1.35, 4.12)), left bundle branch block (OR = 2.57 (1.04, 6.37)), left atrial diameter <45 mm (OR = 3.27 (1.81, 5.89)), and left ventricular end-diastolic dimension <75 mm (OR = 4.11 (1.99, 8.48)). One point was attributed to each predictor, and three score categories were identified. The proportion of super-response after 6-month CRT implantation in patients with scores 0-3, 4, and 5 was 14.6%, 40.3%, and 64.1%, respectively (P < 0.001). Patients with score 5 had an 88% reduction in the risk of cardiac death/heart transplant (P=0.042), a 71% reduction in the risk of HF hospitalization (P=0.048), and an 89% reduction in the risk of all-cause mortality (P=0.028) compared to patients with scores 0-3.

Conclusions

The QQ-LAE score can be used for prediction of super-response to CRT and selection of most suitable patients in clinical practices.

Trends in the use of implantable cardioverter-defibrillator and cardiac resynchronization therapy device in advancing age: Analysis of the Japan cardiac device treatment registry database

BACKGROUND

Trends of de novo implantation of cardiac implantable electronic devices (CIEDs) including implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy with a defibrillator (CRT-D) or pacemaker (CRT-P) in advancing age are unknown.

METHODS

Analysis of data from the Japan cardiac device treatment registry (JCDTR) with an implantation date between January 2006 and December 2016 was performed focusing on advancing age of ≧75 years.

RESULTS

The cohort included 17 564 ICD, 9470 CRT-D and 1087 CRT-P recipients for de novo implantation. The rate of patients ≧75 years of age increased from 17.1% to 20.5% in ICD implantation (P = .052), from 19.7% to 30.0% in CRT-D implantation (P < .0001), and from 40.0% to 64.0% in CRT-P implantation (P = .17). There was an apparent increase in the percentage of nonischemic patients aged ≧75 years receiving ICD (10.9% in 2006 to 16.4% in 2016, P = .0008) and CRT-D (17.1% in 2006 to 27.8% in 2016, P = .0001). The implantation for primary prevention ICD (P = .059) and CRT-D (P = .012) was also associated with a temporal increase in the percentage of patients aged ≧75 years.

CONCLUSIONS

Proportion of patients ≧75 years of age for de novo CIED implantation gradually increased from 2006 to 2016, presumably because of the growing number of nonischemic cardiomyopathy and heart failure patients requiring primary prevention of sudden cardiac death.

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.

A novel risk model for mortality and hospitalization following cardiac resynchronization therapy in patients with non-ischemic cardiomyopathy: the alpha-score

Background

Non-ischemic cardiomyopathy (NICM) has been associated with a better left ventricle reverse remodeling response and improved clinical outcomes after cardiac resynchronization therapy (CRT). The aims of our study were to identify the predictors of mortality and heart failure hospitalization in patients treated with CRT and design a risk score for prognosis.

Methods

A cohort of 422 consecutive NICM patients with CRT was retrospectively enrolled between January 2010 and December 2017. The primary endpoint was all-cause mortality and heart transplantation.

Results

In a multivariate analysis, the predictors of all-cause death were left atrial diameter [Hazard ratio (HR): 1.056, 95% confidence interval (CI): 1.020–1.093, P = 0.002]; non-left bundle branch block [HR: 1.793, 95% CI: 1.131–2.844, P = 0.013]; high sensitivity C-reactive protein [HR: 1.081, 95% CI: 1.029–1.134 P = 0.002]; and N-terminal pro-B-type natriuretic peptide [HR: 1.018, 95% CI: 1.007–1.030, P = 0.002]; and New York Heart Association class IV [HR: 1.018, 95% CI: 1.007–1.030, P = 0.002]. The Alpha-score (Atrial diameter, non-LBBB, Pro-BNP, Hs-CRP, NYHA class IV) was derived from each independent risk factor. The novel score had good calibration (Hosmer-Lemeshow test, P > 0.05) and discrimination for both primary endpoints [c-statistics: 0.749 (95% CI: 0.694–0.804), P < 0.001] or heart failure hospitalization [c-statistics: 0.692 (95% CI: 0.639–0.745), P < 0.001].

Conclusion

The Alpha-score may enable improved discrimination and accurate prediction of long-term outcomes among NICM patients with CRT.

Design and results of aCRT MID-Q study: Adoption of adaptive CRT in patients with normal AV conduction and moderately wide left bundle branch block

BACKGROUND

Sub-analysis of the adaptive CRT (aCRT) trial demonstrated the potential benefits of the aCRT algorithm over conventional echo-guided bi-ventricular (BiV) pacing in patients with left bundle branch block (LBBB) with moderately wide QRS (120-149 ms) and normal atrioventricular (AV) conduction.

METHODS

Adoption of Adaptive CRT in Patients with Left Bundle Branch Block and Moderately Wide QRS (aCRT MID-Q, UMIN Clinical Trials Registry Number: 000022452) was a multicenter, prospective, randomized, double-blind study designed to investigate the superiority of the aCRT pacing algorithm compared to echo-guided BiV pacing in patients with moderately wide LBBB and normal AV conduction. The primary endpoint was the improvement in clinical composite score (CCS) at 6 months; the secondary endpoints were changes in left ventricular (LV) end-systolic volume, LV ejection fraction, New York Heart Association classification, 6-min walk distance, and quality of life from baseline to 6 months post-randomization; heart failure administration; all-cause mortality; and cardiac mortality within 12 months.

RESULTS

The trial was terminated prematurely after enrollment of 39 patients (aCRT arm; n = 17, echo-guided BiV arm; n = 22) because of lower than expected enrollment. In the intention-to-treat analysis, the improvement of CCS was achieved in 10 patients (59%) in the aCRT arm (n = 17) and 16 patients (73%) in the echo-guided BiV arm (n = 22, p = 0.36). For the secondary endpoint, only 6-min walk distance was significantly greater in the aCRT arm than in the echo-guided BiV arm, and no difference was observed in the echocardiographic parameters. Heart failure hospitalization-free survival was also not significantly different (p = 0.91). There was no death during the follow-up.

CONCLUSIONS

Improvement of CCS was similarly observed after aCRT and echo-guided BiV in CRT recipients with moderately wide LBBB and normal AV conduction. A prospective study is needed to explore the impact of CRT and pacing algorithm on Japanese patients with moderately wide LBBB.

Predictors of non-response to cardiac resynchronization therapy implantation in patients with class I indications: the markedly dilated left ventricular end-diastolic dimension and the presence of fragmented QRS

BACKGROUND

Cardiac resynchronization therapy (CRT) is a highly effective treatment in patients with a class I recommendation. However, a small proportion of the strictly selected patients still fail to respond. This study was designed to identify predictors of non-response in patients with class I indications for CRT and determine the non-response probability of the patients.

METHODS

A total of 296 consecutive patients with a class I recommendation received CRT from January 2009 to January 2017 were retrospectively analyzed. Multivariate logistic regression analysis was performed to identify predictors for non-response (defined as cardiac death, heart transplantation, or HF hospitalization during 1-year follow-up).

RESULTS

Among 296 patients, 30 (10.1%) met non-response. Multivariate analysis demonstrated that non-response to CRT was associated with a fragmented QRS (odd ratio (OR) = 2.86, 95% CI: 1.14-7.12; P = 0.025) and left ventricular end-diastolic dimension (LVEDD) ≥ 77 mm (OR = 3.02, 95% CI: 1.17-7.82; P = 0.022). Patients with both of the predictors had a non-response probability of 46.2% (95% CI: 19.1%-73.3%).

CONCLUSION

In patients with left bundle branch block and wider QRS duration, the proportion of non-response to CRT is not low in real world. The presence of the dilated LVEDD or fragmented QRS is a strong predictor of non-response to CRT. The probability of non-response in the patients with the two predictors was 46.2%.

Current Trends in Implantable Cardioverter-Defibrillator Therapy in Children - Results From the JCDTR Database

BACKGROUND

Implantable cardioverter defibrillators (ICDs) are being used with increasing frequency in children. Our aim was to examine the current trend of pediatric ICD implantation in Japan.

METHODS AND RESULTS

Data was extracted from the Japanese Cardiac Device Treatment Registry (JCDTR), a nation-wide registry started in 2006. All patients aged less than 18 years who had an ICD implantation registered between 2006 and 2016 were included in the analysis. A total of 201 patients were included, with a median age of 16 years (range 1-18). The underlying cardiac diagnosis was primary electrical disease (67%), cardiomyopathy (26%) and congenital heart disease (4%), with idiopathic ventricular fibrillation (29%) and long QT syndrome (21%) being the 2 most common diagnoses. Implantation indication was primary prevention in only 30 patients (15%). There were 27 patients (13%) aged ≤12 years, with a larger proportion of patients with cardiomyopathy (33%). The indication in younger children was secondary prevention in all cases. Younger children may be under-represented in our study given the nature of the database as it is a predominantly adult cardiology database.

CONCLUSIONS

In the past decade, ICD implantation has been performed in approximately 20 children per year in Japan, mostly for secondary prevention. There was no increase in the trend nor a change in age distribution.

Prognostic significance of nonsustained ventricular tachycardia in patients receiving cardiac resynchronization therapy for primary prevention: Analysis of the Japan cardiac device treatment registry database

Background

Whether nonsustained ventricular tachycardia (NSVT) is a marker of increased risk of sustained ventricular tachyarrhythmias (VTAs) remains to be established in patients receiving cardiac resynchronization therapy with a defibrillator (CRT‐D) for primary prevention.

Methods

Among the follow‐up data of the Japan cardiac device treatment registry (JCDTR) with an implantation date between January 2011 and August 2015, information regarding a history of NSVT before the CRT‐D implantation for primary prevention had been registered in 269 patients. Outcomes were compared between two groups with and without NSVT: NSVT group (n = 179) and No NSVT group (n = 90).

Results

There was no significant difference with regard to age, gender, and NYHA class between the two groups. Left ventricular ejection fraction (LVEF) was 25.6% in the NSVT group and 28.0% in the No NSVT group (P = .046). The rate of appropriate therapy at 24 months was 26.0% and 18.4% in the NSVT and No NSVT groups (P = .22), respectively. Survival free from heart failure death was reduced in the NSVT group, as compared with the No NSVT group, with the rate of 90.2% vs 97.2% at 24 months (P = .030). A multivariate analysis identified a history of NSVT, anemia, and no use of angiotensin‐converting enzyme inhibitor (ACEI) or angiotensin‐receptor blocker (ARB) as predictors of heart failure death.

Conclusions

NSVT appears to be a surrogate marker of severe heart failure rather than a substrate for subsequent sustained VTAs in patients with CRT‐D for primary prevention.

Survival and Heart Failure Hospitalization in Patients With Cardiac Resynchronization Therapy With or Without a Defibrillator for Primary Prevention in Japan - Analysis of the Japan Cardiac Device Treatment Registry Database

BACKGROUND

Randomized control trials comparing the effectiveness of cardiac resynchronization therapy devices, with (CRT-D) or without (CRT-P) a defibrillator, are scarce in heart failure patients with no prior sustained ventricular tachyarrhythmias.

METHODS AND RESULTS

The Japan Cardiac Device Treatment Registry (JCDTR) has data for 2714 CRT-D and 555 CRT-P recipients for primary prevention with an implantation date between January 2011 and August 2015. Of these patients, follow-up data were available for 717. Over the mean follow-up period of 21 months, Kaplan-Meier curves of survival free of combined events for all-cause death or heart failure hospitalization (whichever came first) diverged between the CRT-D (n=620) and CRT-P (n=97) groups with a rate of 22% vs. 42%, respectively, at 24 months (P=0.0011). However, this apparent benefit of CRT-D over CRT-P was no longer significant after adjustment for covariates. With regard to mortality, including heart failure death or sudden cardiac death, there was no significant difference between the 2 groups.

CONCLUSIONS

In patients without sustained ventricular tachyarrhythmias enrolled in the JCDTR, there was no significant difference in mortality between the CRT-D and CRT-P groups, despite a lower trend in CRT-D recipients. This study was limited by large clinical and demographic differences between the 2 groups.

Cardiac resynchronization therapy in ischemic and non-ischemic cardiomyopathy

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