External cardioversion of atrial fibrillation and flutter in patients with cardiac implantable electrical devices.

BACKGROUND: Atrial fibrillation and flutter are often treated with external electrical cardioversion (ECV) in patients with potentially electrically sensitive cardiovascular implantable electronic devices (CIED). Long-term follow-up data on contemporary CIED undergoing ECV is sparse. The aim is to investigate shock-related complications and impact on CIEDs. METHODS: All ECV procedures from 2010 to 2020 in patients with CIED performed at a tertiary university hospital were identified in the Danish National Patient Registry. Changes in device measurements after ECV were retrospectively studied and procedure-related complications were identified by review of medical records. RESULTS: We analyzed 763 ECV procedures in 372 patients, median device implant time 1.9 years. The mean age of patients was 69.9 ± 9.9 years of which 73.4% were men. We identified two cases of device programming changes and four cases of premature battery depletion (≤3 years after device implant). Minor changes in device measurements were found for impedances, sensing, and pacing thresholds. No patients died due to ECV-related device dysfunctions within the first 12 months after cardioversions. CONCLUSION: External cardioversion in patients with contemporary pacemakers and implantable cardioverter-defibrillators seems safe in the majority of patients. Clinically important changes in device function following cardioversion were rarely observed but may be critical for device function. In an observational study, causality between cardioversion and device dysfunction cannot be established. For patient safety, we suggest that routine device interrogation after cardioversion still should be part of standard care.

Risk of Pacing-Induced Cardiomyopathy in Patients with High-Degree Atrioventricular Block-Impact of Right Ventricular Lead Position Confirmed by Computed Tomography.

Prospective studies applying fluoroscopy for assessment of right ventricular (RV) lead position have failed to show clear benefits from RV septal pacing. We investigated the impact of different RV lead positions verified by computed tomography (CT) on the risk of pacing-induced cardiomyopathy (PICM). We retrospectively included 153 patients who underwent routine fluoroscopy-guided pacemaker implantation between March 2012 and May 2020. All patients had normal pre-implant left ventricular ejection fraction (LVEF). Patients attended a follow-up visit including contrast-enhanced cardiac CT and transthoracic echocardiography. Patients were classified as septal or non-septal based on CT analysis. The primary endpoint was PICM (LVEF < 50% with ≥10% decrease after implantation). Based on CT, 48 (31.4%) leads were septal and 105 (68.6%) were non-septal. Over a median follow-up of 3.1 years, 16 patients (33.3%) in the septal group developed PICM compared to 31 (29.5%) in the non-septal group (p = 0.6). Overall, 13.1% deteriorated to LVEF ≤ 40%, 5.9% were upgraded to cardiac resynchronization therapy device, and 14.4% developed new-onset atrial fibrillation, with no significant differences between the groups. This study demonstrated a high risk of PICM despite normal pre-implant left ventricular systolic function with no significant difference between CT-verified RV septal or non-septal lead position.

Risk factors for cardiac implantable electronic device infections: a nationwide Danish study.

AIMS: Cardiac implantable electronic device (CIED) infection is a severe complication to modern management of cardiac arrhythmias. The CIED type and the type of surgery are recognized as risk factors for CIED infections, but knowledge of patient-related risk factors is scarce. This study aimed to identify lifelong patient-related risk factors for CIED infections. METHODS AND RESULTS: Consecutive Danish patients undergoing a CIED implantation or reoperation between January 1996 and April 2018 were included. The cohort consisted of 84 429 patients undergoing 108 494 CIED surgeries with a combined follow-up of 458 257 CIED-years. A total of 1556 CIED explantations were classified as either pocket (n = 1022) or systemic CIED infection (n = 534). Data were cross-linked with records from the Danish National Patient Registry and the Danish National Prescription Registry. Using multiple-record and multiple-event per subject proportional hazard analysis, specific patient-related risk factors were identified but with several variations amongst the subtypes of CIED infection. CIED reoperations were associated with the highest risk of pocket CIED infection but also CIED type, young age, and prior valvular surgery [hazard ratio (HR): 1.62, 95% confidence interval (CI): 1.29-2.04]. Severe renal insufficiency/dialysis (HR: 2.40, 95% CI: 1.65-3.49), dermatitis (HR: 2.80, 95% CI: 1.92-4.05), and prior valvular surgery (HR: 2.09, 95% CI: 1.59-2.75) were associated with the highest risk of systemic CIED infections. Congestive heart failure, ischaemic heart disease, malignancy, chronic obstructive pulmonary disease, and temporary pacing were not significant at multivariate analysis. CONCLUSION: Specific comorbidities and surgical procedures were associated with a higher risk of CIED infections but with variations amongst pocket and systemic CIED infection. Pocket CIED infections were associated with CIED reoperations, young age and more complex type of CIED, whereas systemic CIED infections were associated with risk factors predisposing to bacteraemia.

Effect of implantable cardioverter-defibrillators in patients with non-ischaemic systolic heart failure and concurrent coronary atherosclerosis.

AIMS: Prophylactic implantable cardioverter-defibrillators (ICD) reduce mortality in patients with ischaemic heart failure (HF), whereas the effect of ICD in patients with non-ischaemic HF is less clear. We aimed to investigate the association between concomitant coronary atherosclerosis and mortality in patients with non-ischaemic HF and the effect of ICD implantation in these patients. METHODS AND RESULTS: Patients were included from DANISH (Danish Study to Assess the Efficacy of Implantable Cardioverter Defibrillators in Patients with Non-Ischaemic Systolic Heart Failure on Mortality), randomizing patients to ICD or control. Study inclusion criteria for HF were left ventricular ejection fraction ≤ 35% and increased levels (>200 pg/mL) of N-terminal pro-brain natriuretic peptide. Of the 1116 patients from DANISH, 838 (75%) patients had available data from coronary angiogram and were included in this subgroup analysis. We used Cox regression to assess the relationship between coronary atherosclerosis and mortality and the effect of ICD implantation. Of the included patients, 266 (32%) had coronary atherosclerosis. Of these, 216 (81%) had atherosclerosis without significant stenoses, and 50 (19%) had significant stenosis. Patients with atherosclerosis were significantly older {67 [interquartile range (IQR) 61-73] vs. 61 [IQR 54-68] years; P < 0.0001}, and more were men (77% vs. 70%; P = 0.03). During a median follow-up of 64.3 months (IQR 47-82), 174 (21%) of the patients died. The effect of ICD on all-cause mortality was not modified by coronary atherosclerosis [hazard ratio (HR) 0.94; 0.58-1.52; P = 0.79 vs. HR 0.82; 0.56-1.20; P = 0.30], P for interaction = 0.67. In univariable analysis, coronary atherosclerosis was a significant predictor of all-cause mortality [HR, 1.41; 95% confidence interval (CI), 1.04-1.91; P = 0.03]. However, this association disappeared when adjusting for cardiovascular risk factors (age, gender, diabetes, hypertension, smoking, and estimated glomerular filtration rate) (HR 1.05, 0.76-1.45, P = 0.76). CONCLUSIONS: In patients with non-ischaemic systolic heart failure, ICD implantation did not reduce all-cause mortality in patients either with or without concomitant coronary atherosclerosis. The concomitant presence of coronary atherosclerosis was associated with increased mortality. However, this association was explained by other risk factors.

Microbiological diagnosis in cardiac implantable electronic device infections detected by sonication and next-generation sequencing.

BACKGROUND: Device-related infection (DRI) is a severe complication of treatment with cardiac implantable electronic devices. Identification of the causative pathogen is essential for optimal treatment, but conventional methods often are inadequate. OBJECTIVE: The purpose of this study was to improve microbiological diagnosis in DRI using sonication and next-generation sequencing analysis. The primary objective was identification of causative pathogens. The secondary objective was estimation of the sensitivity of different microbiological methods in detecting the causative pathogen. METHODS: Consecutive patients with clinical signs of DRI between October 2016 and January 2019 from 3 tertiary centers in Denmark were included in the study. Patients underwent a diagnostic approach, including blood cultures and perioperative collection of microbiological samples (pocket swab, pocket tissue biopsies, generator, and leads). Conventional culturing was performed, and device components were sonicated and examined with an amplicon-based metagenomic analysis using next-generation sequencing. The results were compared with a reference standard-identified causative pathogen. RESULTS: In 110 patients with clinical signs of pocket (n = 50) or systemic DRI (n = 60), we collected 109 pocket swabs, 220 pocket tissue biopsies, 106 generators, 235 leads, and a minimum 1 set of blood cultures from 102 patients. Combining all findings, we identified the causative pathogen in 95% of cases, irrespective of DRI type. The usability of each microbiological method differed between DRI types. In pocket DRI, next-generation sequencing analysis of generators achieved sensitivity of 90%. For systemic DRI, blood cultures reached sensitivity of 93%. CONCLUSION: Using a strategy including sonication and next-generation sequencing, we identified the causative pathogen in 95% of DRI. Sensitivity of microbiological methods differed according to the type of DRI.

Periprocedural complications and one-year outcomes after catheter ablation for treatment of atrial fibrillation in elderly patients: a nationwide Danish cohort study.

OBJECTIVES: To investigate complications within 30-days following first-time ablation for atrial fibrillation (AF), including a composite of cardiac tamponade, hematoma requiring intervention, stroke or death, in patients ≥ 75 years of age, compared to patients aged 65-74 years. In addition, one-year all-cause mortality and AF relapse were compared. METHODS & RESULTS: All patients receiving their first catheter ablation for AF between 2012 and 2016 were identified using Danish nationwide registries. Patients aged 65-74 years served as the reference group for patients ≥ 75 years. Relapse of AF within one year was defined as cardioversion following a three-month blanking period, re-ablation or confirmed relapse within follow-up. The composite complication outcome did not differ between the two age groups, with 39/1554 (2.8%) in patients 65-74 years of age, versus 5/199 (2.5%) in older patients (adjusted HR = 0.94), 95% CI: 0.37-2.39, P = 0.896). Patients ≥ 75 years or older had no increased hazard of death within 30 days after the procedure, with an incidence of 3/1554 (0.2%) in younger patients and 2/199 (1.0%) in patients ≥ 75 years of age (adjusted HR = 4.71, 95% CI: 0.78-28.40, P = 0.091). There was no difference in relapse of AF after one year between age groups (≥ 75 years adjusted HR = 1.00, 95% CI: 0.78-1.26, P = 0.969). CONCLUSION: In patients ≥ 75 years of age selected for catheter ablation for AF, the incidence of periprocedural complications, as well as one-year freedom from AF showed no statistical difference, when compared to patients 65-74 years of age.

Risk of atrial fibrillation after pacemaker implantation: A nationwide Danish registry-based follow-up study.

BACKGROUND: The overall risk of atrial fibrillation (AF) among patients with pacemaker (PM) in comparison to control cohort is unknown. PURPOSE: To investigate the risk of AF after implantation of a PM in an AF-naive population in comparison to an age- and sex-matched PM- and AF-free population cohort. METHODS: All patients with a dual chamber PM (DDD) implanted between 2000 and 2014 without a known history of AF were included (n = 17,428). To compare, a general population cohort without pacemaker and a cohort with loop recorder was identified. Outcome was the cumulative incidence of AF within the first 2 years from 3-months after device implantation. RESULTS: At the end of first 3-months after device implantation, 16,383 patients were free of AF and were included in the current study. In comparison to controls (n = 86,167), patients with PM had higher cumulative incidence of AF (5.2% vs 2.7%, P < 0.001)). Due to interaction with age, patients were divided into three age-groups) and the relative risk for the diagnosis of AF were: < 70 years (HR 4.46, 95% CI 3.65-5.44); 70-79 years (HR 2.60, 95% CI 2.27-2.98); and ≥ 80 years (HR 1.29, 95% CI 1.15-1.45). For comparison between PM and loop-recorder cohort (1:1 matching), 2202 patients were available in both groups. The incidence of AF within the first 2-years in the both groups was 7.9% vs. 8.4% (loop vs pacemaker). CONCLUSIONS: Patients with PM have an increased risk of being diagnosed with AF in comparison to general cohort likely due to continuous monitoring.

Index of contractile asymmetry improves patient selection for CRT: a proof-of-concept study.

BACKGROUND: Nearly one-third of heart failure (HF) patients do not respond to cardiac resynchronization therapy (CRT) despite having left bundle branch block (LBBB). The aim of the study was to investigate a novel method of quantifying left ventricular (LV) contractile asymmetry in HF. METHODS: Patients with HF and LBBB undergoing CRT (n = 89, 37.1% females, 68 ± 9 years, ischemic etiology in 61%, LV ejection fraction 27.1 ± 7.1%) were analyzed. LV longitudinal systolic strain rate values were extracted from curved anatomical M-mode plots of standard long-axis 2D-echocardiography images and cubic spline interpolation was used to generate a 3D-phantom. Index of contractile asymmetry (ICA) was calculated based on standard deviation of differences in strain rate of opposing walls. Average ICA was individually assessed pairwise in 12 opposing 30-degree LV sectors. Reduction in LV end-systolic volume (ESV) ≥15% after 6 months was considered as positive response to CRT. RESULTS: CRT response was found in 66 (74.2%) patients. Responders with both ischemic and non-ischemic cardiomyopathy had a higher and more extensive contractile asymmetry at baseline and achieved a greater ICA reduction after CRT than non-responders. Higher baseline ICA predicted higher degree and wider extent of ICA improvement. Also, both ICA at baseline and reduction of ICA correlated with the degree of ESV reduction after CRT. CONCLUSIONS: Quantification of asymmetrical LV activation in 3D by ICA provides valuable insights into LV contraction in case of LBBB and is a promising tool for improved patient selection for CRT.

Clinical impact of antithrombotic therapy in transvenous lead extraction complications: a sub-analysis from the ESC-EORP EHRA ELECTRa (European Lead Extraction ConTRolled) Registry.

AIMS: A sub-analysis of the ESC-EHRA European Lead Extraction ConTRolled (ELECTRa) Registry to evaluate the clinical impact of antithrombotic (AT) on transvenous lead extraction (TLE) safety and efficacy. METHODS AND RESULTS: ELECTRa outcomes were compared between patients without AT therapy (No AT Group) and with different pre-operative AT regimens, including antiplatelets (AP), anticoagulants (AC), or both (AP + AC). Out of 3510 pts, 2398 (68%) were under AT pre-operatively. AT patients were older with more comorbidities (P < 0.0001). AT subgroups, defined as AP, AC, or AP + AC, were 1096 (31.2%), 985 (28%), and 317 (9%), respectively. Regarding AP patients, 1413 (40%) were under AP, 1292 (91%) with a single AP, interrupted in 26% about 3.8 ± 3.7 days before TLE. In total, 1302 (37%) patients were under AC, 881 vitamin K antagonist (68%), 221 (17%) direct oral anticoagulants, 155 (12%) low weight molecular heparin, and 45 (3.5%) unfractionated heparin. AC was 'interrupted without bridging' in 696 (54%) and 'interrupted with bridging' in 504 (39%) about 3.3 ± 2.3 days before TLE, and 'continued' in 87 (7%). TLE success rate was high in all subgroups. Only overall in-hospital death (1.4%), but not the procedure-related one, was higher in the AT subgroups (P = 0.0500). Age >65 years and New York Heart Association Class III/IV, but not AT regimens, were independent predictors of death for any cause. Haematomas were more frequent in AT subgroups, especially in AC 'continued' (P = 0.025), whereas pulmonary embolism in the No-AT (P < 0.01). CONCLUSIONS: AT minimization is safe in patients undergoing TLE. AT does not seem to predict death but identifies a subset of fragile patients with a worse in-hospital TLE outcome.

Risk Models for Prediction of Implantable Cardioverter-Defibrillator Benefit: Insights From the DANISH Trial.

OBJECTIVES: This study aims to identify patients with nonischemic heart failure who are more likely to benefit from implantable cardioverter-defibrillator (ICD) implantation by use of established risk prediction models. BACKGROUND: It has been debated whether an ICD for primary prevention reduces mortality in patients with nonischemic heart failure. METHODS: The Seattle Heart Failure Model (SHFM) predicts all-cause mortality whereas the Seattle Proportional Risk Model (SPRM) predicts the proportion of sudden cardiac death (SCD) versus nonsudden death, with a higher score indicating a greater proportion of SCD. We report the effect of ICD implantation on all-cause mortality and SCD, according to median SPRM and SHFM scores in all 1,116 patients enrolled in the DANISH (Danish study to Assess the Efficacy of ICDs in Patients with Non-ischemic Systolic Heart Failure on mortality) trial. RESULTS: Among patients with an SPRM score above the median (n = 558), ICD implantation reduced all-cause mortality (hazard ratio [HR]: 0.63; 95% confidence interval [CI]: 0.43 to 0.94), whereas patients with lower SPRM scores (n = 558) had no effect (HR: 1.08; 95% CI: 0.78 to 1.49, p for interaction = 0.04). The corresponding numbers for SHFM score above and below the median were HR: 0.84; 95% CI: 0.62 to 1.13 and HR: 0.82; 95% CI: 0.53 to 1.28, respectively (p for interaction = 0.980). In 177 patients with upper SPRM/upper SHFM, ICD implantation reduced all-cause mortality (HR: 0.45; 95% CI: 0.25 to 0.80) when compared to 381 patients with lower SPRM/upper SHFM (HR: 1.09; 95% CI: 0.76 to 1.55) (p for interaction <0.001). CONCLUSIONS: Nonischemic heart failure patients with high predicted relative likelihood of SCD, as estimated by higher SPRM score, seemed to benefit from ICD implantation. (DANISH [Danish ICD Study in Patients With Ditaled Cardiomyopathy]; NCT00542945).

Incidence of device-related infection in 97 750 patients: clinical data from the complete Danish device-cohort (1982-2018).

AIMS: Device-related infection (DRI) is a severe complication to cardiac implantable electronic devices (CIED) therapy. Device-related infection incidence and its risk factors differ between previous studies. We aimed to define the long-term incidence and incidence rates of DRI for different types of CIEDs in the complete Danish device-cohort and identify patient-, operation- and device-related risk factors for DRI. METHODS AND RESULTS: From the Danish Pacemaker (PM) and implantable cardioverter-defibrillator (ICD) Register, we included consecutive Danish patients undergoing CIED implantation or reoperation from January 1982 to April 2018, resulting in 97 750 patients, 128 045 operations and follow-up of in total 566 275 device years (DY). We identified 1827 DRI causing device removals. Device-related infection incidence during device lifetime was 1.19% (1.12-1.26) for PM, 1.91% (1.71-2.13) for ICD, 2.18% (1.78-2.64) for cardiac resynchronization therapy (CRT)-pacemakers (CRT-P), and 3.35% (2.92-3.83) for CRT-defibrillators (CRT-D). Incidence rates in de novo implantations were 2.04/1000 DY for PM, 3.84 for ICD, 4.38 for CRT-P, and 6.76 for CRT-D. Using multiple-record and multiple-event per subject proportional hazard analysis, we identified implantation of complex devices (ICD and CRT), reoperations, prior DRI, male sex, and younger age as significantly associated with higher DRI risk. CONCLUSION: Overall risk of infection was low in PM implantations but considerably higher in CRT systems and after reinterventions. These data support the importance of evaluating all patients considered for CIED therapy thoroughly, in order to identify potential modifiable risk factors and reduce the risk of early reoperations.

The Association of a classical left bundle Branch Block Contraction Pattern by vendor-independent strain echocardiography and outcome after cardiac resynchronization therapy.

BACKGROUND: The association of a Classical left bundle branch block (LBBB) contraction pattern and better outcome after cardiac resynchronization therapy (CRT) has only been studied using vendor-specific software for echocardiographic speckle-tracked longitudinal strain analysis. The purpose of this study was to assess whether a Classical LBBB contraction pattern on longitudinal strain analysis using vendor-independent software is associated with clinical outcome in CRT recipients with LBBB. METHODS: This was a retrospective cohort study including CRT recipients with LBBB, heart failure, and left ventricular (LV) ejection fraction ≤35%. Speckle-tracked echocardiographic longitudinal strain analysis was performed retrospectively on echocardiograms using vendor-independent software. The presence of a Classical LBBB contraction pattern was determined by consensus of two readers. The primary end point was a composite of time to death, heart transplantation or LV assist device implantation. Secondary outcome was ≥15% reduction in LV end-systolic volume. Intra- and inter-reader agreement of the longitudinal strain contraction pattern was assessed by calculating Cohen's κ. RESULTS: Of 283 included patients, 113 (40%) were women, mean age was 66 ± 11 years, and 136 (48%) had ischemic heart disease. A Classical LBBB contraction pattern was present in 196 (69%). The unadjusted hazard ratio for reaching the primary end point was 1.93 (95% confidence interval, 1.36-2.76, p < 0.001) when comparing patients without to patients with a Classical LBBB contraction pattern. Adjusted for ischemic heart disease and QRS duration < 150 milliseconds the hazard ratio was 1.65 (95% confidence interval, 1.12-2.43, p = 0.01). Of the 123 (43%) patients with a follow-up echocardiogram, 64 of 85 (75%) of patients with a Classical LBBB contraction pattern compared to 13 of 38 (34%) without, had ≥15% reduction in LV end-systolic volume (p < 0.001). Cohen's κ were 0.86 (95% confidence interval, 0.71-1.00) and 0.42 (95% confidence interval, 0.30-0.54) for intra- and inter-reader agreement, respectively. CONCLUSION: Using vendor-independent strain software, a Classical LBBB contraction pattern is associated with better outcome in CRT recipients with LBBB, but inter-reader agreement for the classification of contraction pattern is only moderate.

Vectorcardiographic QRS area is associated with long-term outcome after cardiac resynchronization therapy.

BACKGROUND: Recent studies have suggested that vectorcardiographic measures predict left ventricular (LV) reverse remodeling and clinical outcome in patients receiving cardiac resynchronization therapy (CRT). OBJECTIVES: The objectives of this study were to compare predictive abilities of different vectorcardiographic measures (QRS area and sum absolute QRS-T integral) and transformation methods (Kors and inverse Dower) and to assess the independent association between the best predictor and outcomes in CRT recipients. METHODS: This retrospective study included CRT recipients with a digital baseline electrocardiogram, QRS duration ≥120 ms, and ejection fraction ≤35%. The end point was a composite of heart transplantation, LV assist device implantation, or all-cause death. Analyses were performed for the overall cohort and for a prespecified subgroup of patients with left bundle branch block (LBBB). RESULTS: Of 705 included patients with a mean age of 66.6 ± 11.5 years, 492 (70%) were men, 374 (53%) had ischemic heart disease, and 465 (66%) had LBBB. QRS area from vectorcardiograms derived via the Kors transformation demonstrated the best predictive value. In multivariable Cox regression, patients with a smaller QRS area (≤ 95 µVs) had an increased hazard in the overall cohort (adjusted hazard ratio 1.65; 95% CI 1.25-2.18 P < .001) and in the LBBB subgroup (adjusted hazard ratio 1.95; 95% CI 1.38-2.76 P < .001). QRS area was associated with outcome in patients with QRS duration <150 ms (unadjusted hazard ratio 3.85; 95% CI 2.02-7.37 P < .001) and in patients with QRS duration ≥150 ms (unadjusted hazard ratio 1.76; 95% CI 1.32-2.34 P < .001). CONCLUSION: Vectorcardiographic QRS area is associated with survival free from heart transplantation and LV assist device implantation in CRT recipients.

Failure to Treat Life-Threatening Ventricular Tachyarrhythmias in Contemporary Implantable Cardioverter-Defibrillators: Implications for Strategic Programming.

BACKGROUND: In clinical trials, manufacturer-specific, strategic programming of implantable cardioverter-defibrillators (ICDs), including faster detection rates, reduces unnecessary therapy but permits therapy for ventricular tachycardia/ventricular fibrillation (VF). Present consensus recommends a generic rate threshold between 185 and 200 beats per minute, which exceeds the rate tested in clinical trials for some manufacturers. In a case series, we sought to determine the relationship between programmed parameters and failure of modern ICDs to treat VF. METHODS AND RESULTS: We reviewed cases in which normally functioning ICDs failed to deliver timely therapy for VF from April 2015 to January 2017 at 4 institutions. Of 10 ambulatory patients, 5 died from untreated VF, 4 had cardiac arrests requiring external shocks, and 1 was rescued by a delayed ICD shock. VF did not satisfy programmed detection criteria in 9 patients (90%). Seven of these patients had slowest detection rates that were consistent with generic recommendations but not tested in a peer-reviewed trial for their manufacturer's ICDs. Manufacturer-specific factors interacted with fast detection rates to withhold therapy, including strict VF episode termination rules, enhancements to minimize T-wave oversensing, and features that restrict therapy to regular rhythms in ventricular tachycardia zones. Untreated VF despite recommended programming accounted for 56% of sudden deaths and 11% of all deaths during the study period. CONCLUSIONS: Complex and unanticipated interactions between manufacturer-specific features and generic programming can prevent therapy for VF. More data are needed to assess the risks and benefits of translating evidence-based detection parameters from one manufacturer to another.

Risk factors of cardiac device infection: Glove contamination during device procedures.

BACKGROUND: Infections in cardiac implantable electronic devices (CIEDs) constitute a serious complication. We sought to identify contamination of gloves before handling the device in primary and replacement CIED procedures. METHODS: Two groups of 30 patients underwent primary CIED implantation or replacement. Before the device entered the surgical field, surgeon and assistant imprinted their outer gloves on aerobe and anaerobe agar plates, and a wound swab was performed. Samples were cultured, and the presence of bacteria was identified, counted as the number of colony forming units, and characterized to the level of genus and species. RESULTS: Samples from 40 (67%) procedures revealed bacteria on surgeons' or assistants' gloves. Contamination occurred in 80% of replacements and 67% of primary implantations (risk difference, 13%; 95% confidence interval [CI], -8.8 to 35.5). Contamination of surgeons' and assistants' gloves occurred in 55% and 44% of procedures, respectively. Coagulase-negative Staphylococcus (CNS) occurred in 52%, and Propionibacterium spp (PS) occurred in 84% of positive cases. For every 15 minutes of procedure time, colony levels increased by 7.4% (95% CI, 1.4%-13.4%). CONCLUSIONS: Contamination of gloves is common during CIED procedures before handling the device. Therefore, devices are often handled with contaminated gloves. The most prevalent bacteria were PS and CNS, which are associated with clinical CIED infections. Changing outer gloves before handling the device might improve sterile state and lower infection risk.

Rationale, design, and baseline characteristics of the DANish randomized, controlled, multicenter study to assess the efficacy of Implantable cardioverter defibrillators in patients with non-ischemic Systolic Heart failure on mortality (DANISH).

BACKGROUND: The effect of an implantable cardioverter defibrillator (ICD) in patients with symptomatic systolic heart failure (HF) caused by coronary artery disease is well documented. However, the effect of primary prophylactic ICDs in patients with systolic HF not due to coronary artery disease is much weaker. In addition, HF management has improved, since the landmark ICD trials and a large proportion of patients now receive cardiac resynchronization therapy (CRT) where the effect of ICD treatment is unknown. METHODS: In the DANISH study, 1,116 patients with symptomatic systolic HF not caused by coronary artery disease have been randomized to receive an ICD or not, in addition to contemporary standard therapy. The primary outcome of the trial is time to all-cause death. Follow-up will continue until June 2016 with a median follow-up period of 5 years. Baseline characteristics show that enrolled patients are treated according to current guidelines. At baseline, 97% of patients received an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, 92% received a ß-blocker, 58% a mineralocorticoid receptor antagonist, and 58% were scheduled to receive CRT. Median age was 63 years (range, 21-84 years) at baseline, and 28% were women. CONCLUSION: DANISH will provide pertinent information about the effect on all-cause mortality of a primary prophylactic ICD in patients with symptomatic systolic HF not caused by coronary artery disease on contemporary standard therapy including CRT.

Single-coil and dual-coil defibrillator leads and association with clinical outcomes in a complete Danish nationwide ICD cohort.

BACKGROUND: The best choice of defibrillator lead in patients with routine implantable cardioverter-defibrillator (ICD) is not settled. Traditionally, most physicians prefer dual-coil leads but the use of single-coil leads is increasing. OBJECTIVE: The purpose of this study was to compare clinical outcomes in patients with single- and dual-coil leads. METHODS: All 4769 Danish patients 18 years or older with first-time ICD implants from 2007 to 2011 were included from the Danish Pacemaker and ICD Register. Defibrillator leads were 38.9% single-coil leads and 61.1% dual-coil leads. The primary end point was all-cause mortality. Secondary end points were lowest successful energy at implant defibrillation testing, first shock failure in spontaneous arrhythmias, structural lead failure, and lead extraction outcomes. RESULTS: Single-coil leads were associated with lower all-cause mortality with an adjusted hazard ratio of 0.85 (95% confidence interval 0.73-0.99; P = .04). This finding was robust in a supplementary propensity score-matched analysis. However, dual-coil leads were used in patients with slightly higher preimplant morbidity, making residual confounding by indication the most likely explanation for the observed association between lead type and mortality. The lowest successful defibrillation energy was higher using single-coil leads (23.2 ± 4.3 J vs 22.1 ± 3.9 J; P < .001). No significant differences were observed for other secondary end points showing high shock efficacies and low rates of lead failures and extraction complications. CONCLUSION: Shock efficacy is high for modern ICD systems. The choice between single-coil and dual-coil defibrillator leads is unlikely to have a clinically significant impact on patient outcomes in routine ICD implants.

Radiotherapy in patients with pacemakers and implantable cardioverter defibrillators: a literature review.

An increasing number of patients with implantable cardiac rhythm devices undergo radiotherapy (RT) for cancer and are thereby exposed to the risk of device failure. Current safety recommendations seem to have limitations by not accounting for the risk of pacemakers and implantable cardioverter defibrillators malfunctioning at low radiation doses. Besides scant knowledge about optimal safety measures, only little is known about the exact prevalence of patients with devices undergoing RT. In this review, we provide a short overview of the principles of RT and present the current evidence on the predictors and mechanisms of device malfunctions during RT. We also summarize practical recommendations from recent publications and from the industry. Strongly associated with beam energy of photon RT, device malfunctions occur at ∼3% of RT courses, posing a substantial issue in clinical practice. Malfunctions described in the literature typically consist of transient software disturbances and only seldom manifest as a permanent damage of the device. Through close cooperation between cardiologists and oncologists, a tailored individualized approach might be necessary in this patient group in waiting time for updated international guidelines in the field.

Risk of device malfunction in cancer patients with implantable cardiac device undergoing radiotherapy: a population-based cohort study.

BACKGROUND: Pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) may develop malfunction during external beam radiotherapy (RT). We aimed to describe clinical practice in PM/ICD patients undergoing RT and to assess the rate and predictors of device malfunctions. METHODS: We reviewed medical records of all PM/ICD patients undergoing RT at four centers in Western Denmark during 2003-2012. Logistic regression was applied to identify predictors of PM/ICD malfunctions. RESULTS: Five hundred sixty patients were included. The annual rate of RT courses in PM/ICD patients increased by 199% from 1.45 treatments per 100,000 person-years in 2003 to 4.33 in 2012. Safety measures included supplementary evaluations of PM/ICD (38.3%), reprogramming (1.5%), relocation of the device (3.5%), and application of a magnet to the ICD during RT (10.8%). At device evaluations after the RT (n = 453), malfunctions were detected in 10 (2.5%) PMs and four (6.8%) ICDs. Electrical resets constituted 11 (78.6%) of the malfunctions, and no failures were life-threatening or warranted PM/ICD removal. Factors associated with device malfunctions in logistic regression analysis were beam energy ≥15 MV (odds ratio [OR] 5.73; 95% confidence interval [CI], 1.58-20.76) and location of tumor below the diaphragm (OR 4.31; 95% CI, 1.42-13.12). However, the effect of tumor location declined (OR 2.27; 95% CI, 0.65-7.95) after adjustment for beam energy. CONCLUSIONS: Although the rate of RT in PM/ICD patients is increasing, the damaging effects of RT on the devices seem to be usually transient. Our data suggest that high beam energy plays the pivotal role in inducing impairments in these devices.

Long pacing pulses reduce phrenic nerve stimulation in left ventricular pacing.

INTRODUCTION: Phrenic nerve stimulation is a major obstacle in cardiac resynchronization therapy (CRT). Activation characteristics of the heart and phrenic nerve are different with higher chronaxie for the heart. Therefore, longer pulse durations could be beneficial in preventing phrenic nerve stimulation during CRT due to a decreased threshold for the heart compared with the phrenic nerve. We investigated if long pulse durations decreased left ventricular (LV) thresholds relatively to phrenic nerve thresholds in humans. METHODS AND RESULTS: Eleven patients, with indication for CRT and phrenic nerve stimulation at the intended pacing site, underwent determination of thresholds for the heart and phrenic nerve at different pulse durations (0.3-2.9 milliseconds). The resulting strength duration curves were analyzed by determining chronaxie and rheobase. Comparisons for those parameters were made between the heart and phrenic nerve, and between the models of Weiss and Lapicque as well. In 9 of 11 cases, the thresholds decreased faster for the LV than for the phrenic nerve with increasing pulse duration. In 3 cases, the thresholds changed from unfavorable for LV stimulation to more than a factor 2 in favor of the LV. The greatest change occurred for pulse durations up to 1.5 milliseconds. The chronaxie of the heart was significantly higher than the chronaxie of the phrenic nerve (0.47 milliseconds vs. 0.22 milliseconds [P = 0.029, Lapicque] and 0.79 milliseconds vs. 0.27 milliseconds [P = 0.033, Weiss]). CONCLUSION: Long pulse durations lead to a decreased threshold of the heart relatively to the phrenic nerve and may prevent stimulation of the phrenic nerve in a clinical setting.