Efficacy on resynchronization and longitudinal contractile function comparing His-bundle pacing with conventional biventricular pacing: a substudy to the His-alternative study

AIMS

His-bundle pacing has emerged as a novel method to deliver cardiac resynchronization therapy (CRT). However, there are no data comparing conventional biventricular (BiV)-CRT with His-CRT with regard to effects on mechanical dyssynchrony and longitudinal contractile function.

METHODS AND RESULTS

Patients with symptomatic heart failure, left ventricular ejection fraction ≤ 35%, and left bundle branch block (LBBB) by strict ECG criteria were randomized 1:1 to His-CRT or BiV-CRT. Two-dimensional strain echocardiography was performed prior to CRT implantation and at 6 months after implantation. Differences in changes in mechanical dyssynchrony (standard deviation of time-to-peak in 12 midventricular and basal segments) and regional longitudinal strain in the six left ventricular walls were compared between the BiV-CRT and His-CRT groups.In the on-treatment analysis, 31 received BiV-CRT and 19 His-CRT. In both groups, mechanical dyssynchrony was significantly reduced after 6 months [BiV group from 120 ms (±45) to 63 ms (±22), P < 0.001, and His group from 116 ms (±54) to 49 ms (±11), P < 0.001] but no significant differences in changes could be demonstrated between groups [-9.0 ms (-36; 18), P = 0.50]. Global longitudinal strain (GLS) improved in both groups [BiV group from -9.1% (±2.7) to -10.7% (±2.6), P = 0.02, and His group from -8.6% (±2.1) to -11.1% (±2.0), P < 0.001], but no significant differences in changes could be demonstrated from baseline to follow-up [-0.9% (-2.4; -0.6), P = 0.25] between groups. There were no regional differences between groups.

CONCLUSION

In heart failure, patients with LBBB, BiV-CRT, and His-CRT have comparable effects with regard to improvements in mechanical dyssynchrony and longitudinal contractile function.

Mobitz type I 2nd degree atrioventricular (Wenckebach) block and cardiovascular death using 978,901 12 lead ECGs recordings

Background

Mobitz type I 2nd degree atrioventricular (AV) block (Wenckebach) is usually considered benign. Guidelines recommend permanent cardiac pacing for patients with Mobitz type II second degree AV block (Mobitz II), but for patients with Wenckebach, permanent pacing is only indicated if the AV block causes symptoms or if the conductions delay occurs below the bundle of His. However, these guidelines are based on evidence of modest quality and a consensus amongst experts (1).

Purpose

This study aims to investigate if Wenckebach really is benign by comparing the risk of cardiovascular death for patients with Wenckebach to patients with normal ECGs.

Methods

This retrospective cohort study included 978,901 ECGs obtained from general practitioners in Denmark from 01/02/2001 to 31/10/2014. Index date was the day of the ECG recording and the patients were followed until death or end of follow up at December 2019.

The association between Wenckebach and cardiovascular death was analyzed using: 1) multivariate Cox models adjusted for age and comorbidities, 2) cause-specific Cox models and 3) cumulative risk and cause-specific hazard function plots, compared to matched controls. Information about comorbidities, pacemaker, indications, and death was retrieved from Danish nationwide registries.

Results

From the 978,901 ECG recordings, we found 262 patients with Wenckebach, 131 patients with Mobitz II, and 229,056 patients with normal ECGs. In Wenckebach, Mobitz II, and normal ECG the median age was 76, 80, and 50 years, 76%, 63%, and 41% were male, 25%, 16%, and 3% had diabetes, 35%, 30%, and 8% had hypertension, respectively.

During a mean follow-up of 11.2 years, cardiovascular death occurred in a total of 11,301 patients: 77 (29%) patients with Wenckebach, 40 (31%) patients with Mobitz II, and 11,184 (5%) patients with normal ECGs. In a matched cohort 262 Wenckebach patients were matched with 520 controls with normal ECGs. In the multivariate Cox model, Wenckebach was associated with cardiovascular death (HR: 2.14 [95% CI: 1.46–3.13], P&lt;0.001). Furthermore, in multivariate cause-specific Cox analysis with non-cardiovascular death and pacemaker as competing risk, Wenckebach was still associated with cardiovascular death (HR: 2.27 [95% CI: 1.37–3.75], P=0.001).

Furthermore, the results showed that 43% of the Wenckebach patients received pacemaker with a median time to pacemaker from ECG recording being 252 days. The vast majority of the Wenckebach patients who received pacemaker had a higher degree AV block than Wenckebach as indication for the implantation.

Conclusion

Wenckebach on routine ECG was associated with a significant higher hazard rate of cardiovascular death compared to matched controls with normal ECGs.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The Danish Heart Association

Type 2 diabetes is associated with higher risk of 3rd degree atrioventricular block: a Danish nationwide registry study

Background

Type 2 diabetes (T2DM) is suggested to affect the function of the cardiomyocytes and electrical pathways which could cause conduction abnormalities and cardiac arrhythmias, such as 3rd degree atrioventricular block. The association of T2DM and 3rd degree atrioventricular block has never been confirmed in large nationwide studies.

Purpose

To determine the association between T2DM and 3rd degree atrioventricular block.

Method

This nationwide nested case-control study design included patients older than 18 years, diagnosed with 3rd degree atrioventricular block between 1st of July 1995 and 31st of December 2018. Five controls from the risk set of each case of 3rd degree atrioventricular block were matched on age and sex to fit a Cox regression model with time-dependent exposure (T2DM) and time-dependent covariates and baseline hazard function stratified for age and sex. Subgroup analysis was conducted with Cox models for each subgroup.

Results

We identified 31.177 cases with 3rd degree atrioventricular block that were matched with 155.885 controls. The mean age was 78 years and 60% were males. Cases had higher prevalence of T2DM (20% vs 7.8%), hypertension (70% vs 43%) myocardial infarction (16% vs 6.6%), and heart failure (21% vs 5.9%) compared to the control group. In a Cox analysis T2DM was significantly associated with a higher rate of 3rd degree atrioventricular block [HR 2.61 (95% CI: 2.54–2.71)]. The association remained in several subgroup analyses of diseases suspected to be associated with 3rd degree atrioventricular block. There was a significant interaction with sex and age groups and comorbidities of interest including hypertension, atrial fibrillation, heart failure and myocardial infarction (Figure 1).

Conclusion

T2DM is associated with a higher rate of 3rd degree atrioventricular block. The findings were consistent across subgroups.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): This work was funded by the independent research foundation Skibsreder Per Henrik, R. og Hustrus Fond

Risk of lead explantation after first-time implantation of cardiac implantable electronic device as a function of comorbidity: a nationwide study

Background

The benefit of cardiac implantable electronic devices (CIEDs) is challenged by the risk of procedure-related complications and lead explantation. Whether patient comorbidity burden is associated with risk of lead explantation &lt;6 months of implantation is unknown.

Purpose

We assessed the risk of lead explantation and its association with comorbidity burden within 6 months after first-time CIED implantation.

Methods

The study population comprised patients ≥18 years old with first-time CIED implantation (i.e., pacemaker [PM], implantable cardioverter defibrillator [ICD], and cardiac resynchronisation therapy with defibrillator [CRT-D] or without [CRT-P]) using Danish nationwide registries including the Danish Pacemaker and ICD registry (1 January 2000 to 30 June 2018). Patients were followed from their first-time CIED implantation and 6 months forward. Patient comorbidity burden was categorised in four groups according to the Charlson Comorbidity Index (CCI) score: 0 (none), 1–2 (mild), 3–4 (moderate), and ≥5 (severe). Multivariable cause-specific Cox regression was performed to assess risk of lead explantation according to comorbidity burden, with death as competing risk. Comorbidity burden was adjusted for sex, age, type of CIED, and body mass index categories.

Results

We identified 73,491 patients with first-time CIED implantation including 55,733 (75.8%) with PM, 11,351 (15.5%) with ICD, 2,989 (4.1%) with CRT-P, and 3,418 (4.7%) with CRT-D. In total, 1,049 (1.4%) patients underwent lead explantation. The median age of the study population was 75.1 years [25th-75th percentile 66.2–82.5 years], and 62.1% were male. Patients undergoing lead explantation had higher median CCI score, compared with those not undergoing lead explantation (2 [1–3] and 1 [0–3], respectively). The median age and distribution of sex were similar in both groups. In the multivariable Cox regression model (Figure 1), an increase in patient comorbidity burden was associated with higher hazard ratio [HR] of lead explantation, compared with CCI score 0 (CCI score 1–2: HR=1.38 [95% confidence interval [CI]: 1.12–1.69], CCI score 3–4: HR=1.61 [95% CI: 1.28–2.03], and CCI score ≥5: HR=1.60 [95% CI: 1.25–2.05]).

Conclusion

Risk of lead explantation within 6 months after first-time implantation of cardiac implantable electronic device was 1.4% and associated with higher comorbidity burden.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Independent Research Fund Denmark

Staphylococcus aureus bacteremia in Danish patients with cardiac implantable electronic devices: an explorative epidemiological study

Background

Device-related infection is the most common serious complication in patients with cardiac implantable electronic devices (CIED). Staphylococcus aureus accounts for up to 30% of CIED-related infections. There is a lack of scientific literature investigating risk of Staphylococcus aureus bacteremia (SAB) in CIED-patients.

Purpose

We aimed to describe the risk of SAB in Danish patients with a CIED through the years 2000–2018 compared to the background population.

Methods

Patients who received a CIED from 2000–2018 were identified from The Danish National Pacemaker and ICD Register. Patients were matched 1:5 on age and gender with the background population. We identified the primary endpoint of first time SAB from The National Danish Staphylococcus Aureus Bacteremia Database. The cumulative incidence of SAB was calculated using the Aalen-Johansen estimator, adding competing risk of death into account. Hazard ratios were estimated by Cox regression models adjusting for age and gender. Crude rates of relapse SAB, defined as a new SAB episode 14–180 days after first SAB, and device extractions were reported for all patients who survived 14 days from SAB diagnosis.

Results

We identified 79,324 CIED-patients (pacemaker (PM) = 61,227; Implantable Cardioverter Defibrillator (ICD) = 11,635; Cardiac resynchronization therapy, PM or ICD (CRT) = 6,364 and 396,590 matched controls (median age 75.5±13.3 years; 61% males). Age and gender distribution differed significantly by device type (age: PM 76.1±12.1; ICD 62.4±13.4; CRT 68.0±11.1; males: PM: 55.6%, ICD% 75.5: CRT: 80.9%). Across a mean follow-up of 5.9 (±4.6) years, we observed first episode of SAB in 1,430 (1.8%) CIED-patients, compared to 2,599 (0.7%) patients in the control population (p&lt;0.001).

The 10-year cumulative incidence of SAB was 1.0% for controls and 2.2% for CIED patients. The risk of SAB differed substantially by device type (Figure 1). Compared to controls and adjusted for age and gender, increasing hazard ratios for SAB were observed with more advanced devices: PM 1.12 (1.11–1.13); ICD 1.36 (1.33–1.39); CRT 1.55 (1.51–1.59). However, CIED-patients with SAB did not have higher 30-day mortality rates than the non-CIED control population with SAB (Controls 34.8%; PM 35.1%; ICD 28.1% CRT 26.1%, p=0.016). Out of all SAB patients who survived 14 days from SAB diagnosis (Controls=1,672; CIED=1,107), relapse SAB occurred in 52 (3.1%) controls and in 51 (4.6%) CIED-patients (PM 4.0%; ICD 5.8%; CRT 6.3%). Device extraction within 14 and 30 days from SAB diagnosis was undertaken in less than 30% of the CIED-patients (PM: 11.3/13.6%; ICD: 22.7/27.5%; CRT: 17.4/20.1%).

Conclusion

The occurrence of SAB was higher in CIED patients compared with controls and increased with more advanced devices. There was no difference in 30-day mortality after SAB between CIED patients and controls. Relapse SAB occurred in less than 7%, despite a low percentage of early device extractions.

Funding Acknowledgement

Type of funding sources: None.

Severity of chronic obstructive pulmonary disease and risk of one-year mortality after first-time implantation of implantable cardioverter defibrillator: a nationwide study

Background

Current guidelines, on implantable cardioverter defibrillator (ICD), recommend implantation in patients with an expected survival beyond one year. Information on risk of all-cause mortality among ICD recipients with chronic obstructive pulmonary disease (COPD) according to severity of COPD is lacking.

Purpose

We examined the association between the severity of COPD and risk of all-cause mortality within one year after first-time ICD implantation.

Methods

We identified patients ≥18 years old undergoing first-time ICD implantation with COPD using Danish nationwide registries (1 January 2000 to 31 December 2018). All patients were eligible for one-year follow-up. We used concomitant COPD-related pharmacotherapy six months prior to ICD implantation and COPD hospitalisations one year prior to ICD implantation to determine severity of COPD from mild to very severe according to Table 1. Multivariable Cox regression was used to assess risk of one-year all-cause mortality according to severity of COPD. Severity of COPD was adjusted for sex, age, year of implantation, primary prevention, type of ICD, history of atrial fibrillation, stroke, peripheral artery disease, diabetes, cancer, chronic renal disease, and dialysis.

Results

The study population included 1,536 patients with first-time ICD and COPD. The median age was 69.5 years [25th-75th percentile 63.5–74.3 years], and the majority of patients were males (79.4%). Of these, 896 (58.3%) received an ICD for primary prevention, and 485 (31.6%) had cardiac resynchronisation therapy device with defibrillator (CRT-D). In total, 1,348 (87.8%) patients were diagnosed with heart failure. Patients were grouped according to severity of COPD from mild to very severe: Group 1 (N=666), Group 2 (N=72), Group 3 (N=149), Group 4 (N=445), and Group 5 (N=204). Overall, 154/1,536 (10.0%) ICD recipients with COPD died within one year after first-time ICD implantation. No difference in sex and comorbidities was identified according to the five groups of COPD severity. However, ICD recipients with mild intermittent COPD (Group 1) were the youngest (68.3 years [61.8–73.0 years]). According to our multivariable cox regression in Figure 1, patients with very severe COPD (Group 5) were associated with increased risk of all-cause mortality within one year after first-time ICD implantation (adjusted hazard ratio [HR] 1.90 [95% confidence interval [CI]: 1.21–2.98]), compared with mild intermittent COPD (Group 1). The most common causes of death within one year after ICD implantation were attributed to cardiovascular diseases 95/154 (61.7%), respiratory diseases 15/154 (9.7%), and endocrine disorders 12/154 (7.8%).

Conclusion

In this nationwide study, very severe chronic obstructive pulmonary disease was associated with increased risk of all-cause mortality within one year after first-time implantation of implantable cardioverter defibrillator.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Independent Research Fund Denmark

Reduced longitudinal strain in the left ventricular inferior wall predicts malignant arrhythmia in non-ischemic heart failure. A DANISH substudy

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND

Small studies have suggested that poor regional myocardial function may be associated with malignant arrhythmias, in particular around the inferior-posterior region. We tested this hypothesis in a subgroup of patients from the DANISH trial.

METHODS

From two centers, 317 patients with non-ischemic heart failure (LVEF &lt; 35%) from the DANISH trial were evaluated by 2D-strain echocardiography. Regional strain was calculated as the average longitudinal strain in basal-, midventricular- and apical segments in each of the six left ventricular walls. Reduced regional function was defined as below-median regional strain. The endpoint was a composite of sudden cardiac death (SCD), sustained VT, admission with ventricular arrhythmia, and appropriate therapy from a primary prophylactic ICD. Time-to-first-event analysis was performed using Cox models.

RESULTS

Mean age at inclusion was 62 years (72% male), median LVEF was 25% (IQR 20-30) median inferior strain was -8.7% (IQR -12.3; -4.9). After a five-year follow-up, 43 events were observed. Reduced inferior strain was associated with the composite endpoint in univariate analysis with a HR 2.08(95% CI 1.11-3.90), P = 0.021. After multivariate adjustment for clinical and echocardiographic parameters, inferior strain remained an independent predictor with a HR 2.78(95% CI 1.39–5.56), P = 0.004. Strain measurements in no other region were associated with the endpoint in the multivariate analysis. In subgroup analysis of patients in the two lower age tertiles (&lt;68 of age) we found that reduced inferior- and posterior strain were associated with development of the composite endpoint after multivariate adjustment with HRs of 3.25(95% CI 1.41-7.53), P = 0.006 and 2.51(95% CI 1.14-5.53), P = 0.022.

CONCLUSIONS

Low inferior-posterior strain was associated with a 2-3-fold increase in risk of malignant arrhythmia and SCD in patients with non-ischemic heart failure. Abstract Figure.

The CADI-study: Compression after device implantation - To examine the effect of a compressive dressing after device implantation or replacement focusing on the patient"s bleeding, hematomas and pain

Funding Acknowledgements

University Hospital Rigshospitalet, Centre for Cardiac, Vascular, Pulmonary and Infectious Diseases, Denmark

Background

Bleeding and pocket hematomas are a known complication in pacemaker or implantable cardioverter defibrillator (ICD) implantations.  Hematomas are associated with increased risk of infection and pain.

Purpose

To investigate whether a compressive dressing applied for three hours can prevent bleeding, pocket hematomas and pain.

Method

The study was a pseudo-randomized intervention study including patients scheduled for implantation or box change of a pacemaker or an ICD. In alternating months patients either received a compressive dressing (intervention group) or not (control group). Patients were excluded by the implanting physician if there was a clinical indication for a compressive dressing due to seeping bleeding. Patients were followed at the catheterization lab, for three hours at the ward and until the first outpatient control visit (1-3 months). The outcomes were: Bleeding, pocket hematomas and pain. The bleedings were graded as active bleeding or seeping bleeding or hematomas. Hematomas were measured by degree 1 to 3 (3 largest) and size (in cm). Pain was rated by the patient by numerical rank scale (NRS) from 0 to 10 (10 worst). Descriptive statistics were used.

Results

A total of 191 patients were included, 95 patients in the intervention group. After inclusion 24 patients of the 96 patients in the control group were excluded by the implanting physician on clinical indication for a compressive dressing.

Before the intervention there were significantly more patients with bleeding (graded as: Seeping bleeding) in the intervention group (n = 25, (26.9%)) compared to the control group (n = 4, (5.6%), p &lt;0.001). No patients had developed pocket hematomas at the end of the procedure. Furthermore, the pain score was low in both groups (Total n = 19, NRS score ≤ 2.5).

Over the next three hours in the ward, there was no significant difference in the bleeding (graded as: Seeping bleeding) in the groups (intervention: n = 8 vs. control: n = 3, p = 0.55). Two patients in each group had developed a pocket hematoma after three hours (p = 0.36) and the intervention group experienced more pain (intervention: 1.7 (±2.4) vs. control: 1.1(±1.7), p= 0.02).

At the outpatient control 1-3 months after implantation, there was no significant difference between the groups related to bleeding, pocket hematomas and pain.

Conclusion

Compressive dressing did not significantly reduce bleeding or the number of pocket hematomas after pacemaker or ICD implantation. In addition patients reported a slight increase in pain scores related to the compressive dressing.

The results question routine compression after procedure, but should be validated in larger studies.

1261Geographical variations in the incidence of CIED infection and infection prevention strategies: Update from the global WRAP-IT study

Funding Acknowledgements

Medtronic, Inc.

Introduction

Cardiac Implantable Electronic Device (CIED) infections lead to significant morbidity, mortality, and use of health care resources. There is variation in infection prevention strategies among centers, and it is not clear whether there is also variation in infection rates across different geographies. Recently, WRAP-IT, the largest global randomized trial to evaluate an infection reduction strategy, randomized 6,983 patients to receive an antibacterial envelope (treatment) vs. no envelope (control). The results demonstrated a significant reduction in major CIED infection with the TYRX antibiotic envelope (12-mo infection rate for envelope vs. control 0.7% and 1.2%, respectively; HR, 0.60; 95% [CI], 0.36 to 0.98; P = 0.04).  The purpose of this analysis is to assess geographical variations in patient characteristics, procedural routines, and infection rates.

Methods

The WRAP-IT study enrolled patients undergoing a CIED pocket revision, generator replacement, or system upgrade or an initial implantation of a cardiac resynchronization therapy defibrillator and randomized them to receive the envelope or not, in addition to mandated pre-procedure intravenous antibiotic prophylaxis. To assess geographical variations in infection rates, the control group (per protocol) baseline demographics and procedural characteristics were identified. Major infection was defined as CIED infections resulting in system extraction or revision, long-term antibiotic therapy with infection recurrence, or death.

Results

A total of 3429 control patients were evaluated and followed for a mean of 20.9 ± 8.3 months; 2530 patients from 123 centers in North America, 777 patients from 46 centers in Europe, and 122 patients from 11 centers in Asia/South America. The 24-month Kaplan-Meier major infection rates were 1.2% in North America (30 pts), 2.5% in Europe (16 pts), and 4.3% Asia/South America (5 pts) (see Figure). These geographical variations in the incidence of major CIED infections were significant (overall P = 0.008, univariate). There were differences in baseline patient characteristics, including age, sex, medication use, NYHA Class, and number of previous devices across geographies. Differences also included procedural characteristics, such as device type, use of pocket wash, skin preparation, pre-operative antibiotic drug use, and procedure time.

Conclusion

Major CIED infection rates vary significantly across geographies. The effect of patient demographics and procedural characteristics on these findings will be assessed and presented at EHRA. Insights into geographical variability of CIED infections is important to mitigate infection risk, reduce morbidity and cost.

Abstract Figure. Major CIED Infection Rate by Geography

5968Adherence to driving restrictions among patients with an implantable cardioverter defibrillator: insights from a nationwide register-linked survey study

Background

Patients with an implantable cardioverter defibrillator (ICD) are restricted from driving following initial implantation or ICD shock. It is unclear how many patients are aware of, and adhere to, these restrictions.

Purpose

To investigate knowledge of, and adherence to, private and professional driving restrictions in a nationwide cohort of ICD patients.

Methods

A questionnaire was distributed to all living Danish residents ≥18 years who received a first-time ICD between 2013 and 2016 (n=3,913). During this period, Danish guidelines recommended 1 week driving restriction following ICD implantation for primary prevention, and 3 months following either ICD implantation for secondary prevention or appropriate ICD shock, and permanent restriction of professional driving and driving of large vehicles (>3.5 metric tons). Questionnaires were linked with relevant nationwide registries. Logistic regression was applied to identify factors associated with non-adherence.

Results

Of 2,741 questionnaire respondents, 92% (n=2,513) held a valid private driver's license at time of ICD implantation (85% male; 46% primary prevention indication; median age: 67 years (IQR: 59–73)). Of these, 7% (n=175) were actively using a professional driver's license for truck driving (n=73), bus driving (n=45), taxi driving (n=22), large vehicle driving for private use (n=54), or other purposes (n=32) (multiple purposes allowed).

Only 42% of primary prevention patients, 63% of secondary prevention patients, and 72% of patients who experienced an appropriate ICD shock, recalled being informed of any driving restrictions. Only 45% of professional drivers recalled being informed about specific professional driving restrictions (Figure). Most patients (93%, n=2,344) resumed private driving after ICD implantation, more than 30% during the driving restriction period: 34% of primary prevention patients resumed driving within 1 week, 43% of secondary prevention patients resumed driving within 3 months, and 30% of patients who experienced an appropriate ICD shock resumed driving within 3 months. Professional driving was resumed by 35%. Patients who resumed driving within the restricted periods were less likely to report having received information about driving restrictions (all p<0.001) (Figure).

In a multiple logistic regression model, non-adherence was predicted by reporting non-receipt of information about driving restrictions (OR: 3.34, CI: 2.27–4.03), as well as male sex (OR: 1.53, CI: 1.17–2.01), age ≥60 years (OR: 1.20, CI: 1.02–1.64), receipt of a secondary prevention ICD (OR: 2.2, CI: 1.80–2.62), and being the only driver in the household (OR: 1.29, CI: 1.05–1.57).

Conclusion

In this nationwide survey study, many ICD patients were unaware of the driving restrictions, and many ICD patients, including professional drivers, resumed driving within the restricted periods. More focus on communicating driving restrictions might improve adherence.

Acknowledgement/Funding

Danish Heart Foundation, Arvid Nilsson Foundation, Fraenkels Mindefond

Importance of beta-blocker dose in prevention of ventricular tachyarrhythmias, heart failure hospitalizations, and death in primary prevention implantable cardioverter-defibrillator recipients: a Danish nationwide cohort study

Aims

There is a paucity of studies investigating a dose-dependent association between beta-blocker therapy and risk of outcome. In a nationwide cohort of primary prevention implantable cardioverter-defibrillator (ICD) patients, we aimed to investigate the dose-dependent association between beta-blocker therapy and risk of ventricular tachyarrhythmias (VT/VF), heart failure (HF) hospitalizations, and death.

Methods and results

Information on ICD implantation, endpoints, comorbidities, beta-blocker usage, type, and dose were obtained through Danish nationwide registers. The two major beta-blockers carvedilol and metoprolol were examined in three dose levels; low (metoprolol ≤ 25 mg; carvedilol ≤ 12.5 mg), intermediate (metoprolol 26-199 mg; carvedilol 12.6-49.9 mg), and high (metoprolol ≥ 200 mg; carvedilol ≥ 50 mg). Time to events was investigated utilizing multivariate Cox models with beta-blocker as a time-dependent variable. From 2007 to 2012, 2935 first-time ICD devices were implanted. During follow-up, 399 patients experienced VT/VF, 728 HF hospitalizations and 361 died. As compared with patients not on beta-blockers, low, intermediate, and high dose had significantly reduced risk of HF hospitalizations {hazard ratio (HR) = 0.68 [0.54-0.87], P = 0.002; HR = 0.53 [0.42-0.66], P < 0.001; HR = 0.43 [0.34-0.54], P < 0.001} and death (HR = 0.47 [0.35-0.64], P < 0.001; HR = 0.29 [0.22-0.39], P = 0.001; HR = 0.24 [0.18-0.33], P < 0.001). For the endpoint of VT/VF, only intermediate and high dose beta-blocker was associated with significantly reduced risk (HR = 0.58 [0.43-0.79], P < 0.001; HR = 0.53 [0.39-0.72], P < 0.001). No significant difference was found between comparable doses of carvedilol and metoprolol on any endpoint (P = 0.06-0.94).

Conclusion

In primary prevention ICD patients, beta-blocker therapy was associated with significantly reduced risk of all endpoints, as compared with patients not on beta-blocker, with the suggestion of a dose-dependent effect. No detectable difference was found between comparable doses of carvedilol and metoprolol.