Jens Brock Johansen

Worldwide experience with a totally subcutaneous implantable defibrillator: early results from the EFFORTLESS S-ICD Registry

Aims The totally subcutaneous implantable-defibrillator (S-ICD) is a new alternative to the conventional transvenous ICD system to minimize intravascular lead complications. There are limited data describing the long-term performance of the S-ICD. This paper presents the first large international patient population collected as part of the EFFORTLESS S-ICD Registry. Methods and results The EFFORTLESS S-ICD Registry is a non-randomized, standard of care, multicentre Registry designed to collect long-term, system-related, clinical, and patient reported outcome data from S-ICD implanted patients since June 2009. Follow-up data are systematically collected over 60-month post-implant including Quality of Life. The study population of 472 patients of which 241 (51%) were enrolled prospectively has a mean follow-up duration of 558 days (range 13–1342 days, median 498 days), 72% male, mean age of 49 ± 18 years (range 9–88 years), 42% mean left ventricular ejection fraction. Complication-free rates were 97 and 94%, at 30 and 360 days, respectively. Three hundred and seventeen spontaneous episodes were recorded in 85 patients during the follow-up period. Of these episodes, 169 (53%) received therapy, 93 being for Ventricular Tachycardia/Fibrillation (VT/VF). One patient died of recurrent VF and severe bradycardia. Regarding discrete VT/VF episodes, first shock conversion efficacy was 88% with 100% overall successful clinical conversion after a maximum of five shocks. The 360-day inappropriate shock rate was 7% with the vast majority occurring for oversensing (62/73 episodes), primarily of cardiac signals (94% of oversensed episodes). Conclusion The first large cohort of real-world data from an International patient S-ICD population demonstrates appropriate system performance with clinical event rates and inappropriate shock rates comparable with those reported for conventional ICDs. Clinical trial registration URL: http://www.clinicaltrials.gov. Unique identifier NCT01085435.

Complications after cardiac implantable electronic device implantations: an analysis of a complete, nationwide cohort in Denmark

Aims Complications after cardiac implantable electronic device (CIED) treatment, including permanent pacemakers (PMs), cardiac resynchronization therapy devices with defibrillators (CRT-Ds) or without (CRT-Ps), and implantable cardioverter defibrillators (ICDs), are associated with increased patient morbidity, healthcare costs, and possibly increased mortality. Methods and results Population-based cohort study in all Danish patients who underwent a CIED procedure from May 2010 to April 2011. Data on complications were gathered on review of all patient charts while baseline data were obtained from the Danish Pacemaker and ICD Register. Adjusted risk ratios (aRRs) with 95% confidence intervals were estimated using binary regression. The study population consisted of 5918 consecutive patients. A total of 562 patients (9.5%) experienced at least one complication. The risk of any complication was higher if the patient was a female (aRR 1.3; 1.1–1.6), underweight (aRR 1.5; 1.1–2.3), implanted in a centre with an annual volume <750 procedures (0–249 procedures: aRR 1.6; 1.1–2.2, 250–499: aRR 2.0; 1.6–2.7, 500–749: aRR 1.5; 1.2–1.8), received a dual-chamber ICD (aRR 2.0; 1.4–2.7) or CRT-D (aRR 2.6; 1.9–3.4), underwent system upgrade or lead revision (aRR 1.3; 1.0–1.7), had an operator with an annual volume <50 procedures (aRR 1.9; 1.4–2.6), or underwent an emergency, out-of-hours procedure (aRR 1.5; 1.0–2.3). Conclusion CIED complications are more frequent than generally acknowledged. Both patient- and procedure-related predictors may identify patients with a particularly high risk of complications. This information should be taken into account both in individual patient treatment and in the planning of future organization of CIED treatment.

Infection after pacemaker implantation: infection rates and risk factors associated with infection in a population-based cohort study of 46299 consecutive patients

Aims Infection is a serious complication of pacemaker (PM) systems. Although the rate of infection has been debated, the figures are largely unknown. We therefore studied the incidence of PM infection and its associated risk factors in the Danish population. Methods and results Since 1982, all PM implantation and removal procedures performed in Denmark have been prospectively recorded in the Danish Pacemaker Register. All patients (n = 46299) who underwent implantation between 1982 and 2007 were included. The total length of surveillance was 236 888 PM-years. The incidence of infection was calculated according to the total number of PM-years. The incidence of surgical site infection (≤365 days after PM implantation) was compared with later infection in first implant and replacement procedures. Multiple-record and multiple-event-per-subject proportional hazards analyses were used to identify the independent risk factors of PM infection. Surgical site infection occurred in 192 cases after first implantation (incidence rate 4.82/1000 PM-years), and in 133 cases after replacement (12.12/1000 PM-years). Infections occurring more than 365 days after the first implantation occurred in 153 cases (1.02/1000 PM-years), and in 118 cases after replacement (3.26/1000 PM-years). Independent factors associated with an increased risk of PM infection were a greater number of PM operations (including replacements), male sex, younger age, implantation during the earliest part of the study period, and absence of antibiotics (P< 0.001). Conclusion The overall risk of infection after PM implantation was low. A greater number of operations augmented the risk of infection. This should be taken into account when considering revisions of PM systems.

Inappropriate shocks in the subcutaneous ICD: Incidence, predictors and management.

BACKGROUND The entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) eliminates the need for transvenous leads, and therefore has the potential to improve lead-longevity and reduce lead-related complications. The S-ICD has a morphology-based sensing algorithm of which inappropriate shocks have been reported. METHODS We analyzed the incidence, predictors and management of inappropriate shocks in the EFFORTLESS S-ICD Registry, which collects S-ICD implantation information and follow-up data from clinical centers in Europe and New Zealand. RESULTS During a follow-up of 21 ± 13 months, 48 out of 581 S-ICD patients (71% male, age 49 ± 18 years) experienced 101 inappropriate shocks (8.3%). The most common cause was cardiac signal oversensing (73%), such as T-wave oversensing. Eighteen shocks (18%) were due to supraventricular tachycardias (SVT), of which 15 occurred in the shock-only zone. Cox-proportional hazard modeling using time-dependent covariates demonstrated that patients with a history of atrial fibrillation (HR 2.4) and patients with hypertrophic cardiomyopathy (HR 4.6) had an increased risk for inappropriate shocks, while programming the primary vector for sensing (from xyphoid to V6) reduced the risk. Reprogramming or optimization of SVT treatment after the first clinical event of inappropriate shock was successful in preventing further inappropriate shocks for cardiac oversensing and SVT events. CONCLUSIONS Inappropriate shocks, mainly due to cardiac oversensing, occurred in 8.3% of the S-ICD patients. Patients with hypertrophic cardiomyopathy or a history of atrial fibrillation were at increased risk, warranting specific attention for sensing and programming in this population.

Evaluation oF FactORs impacTing cLinical outcome and cost EffectiveneSS of the S-ICD : Design and rationale of the EFFORTLESS S-ICD registry

Background: Leads in and on the heart of the transvenous implantable cardioverter defibrillator (ICD) form the Achilles’ heel of this system due to potential for peri‐ and postimplant complications. The S‐ICD is a newer generation of the ICD that does not require leads on the heart or in the vasculature. We present the rationale and study design of the Evaluation oF FactORs ImpacTing CLinical Outcome and Cost EffectiveneSS of the S‐ICD (EFFORTLESS S‐ICD) Registry which was designed to evaluate the long‐term performance of the S‐ICD including patient quality of life and long‐term resource utilization.

Risk factors for lead complications in cardiac pacing: a population-based cohort study of 28,860 Danish patients.

BACKGROUND Lead complications are the main reason for reoperation after implantation of pacemakers (PM) or cardiac resynchronization therapy (CRT-P) devices. OBJECTIVE This study sought to describe the incidence of lead complications causing reoperation after device implantation and to identify risk factors for lead complications. METHODS A nationwide, population-based, historic cohort study was performed based on data from the Danish Pacemaker Register, which includes all Danish patients who received their first PM or CRT-P device from 1997 to 2008. Follow-up occurred 3 months after implantation. RESULTS The study population consisted of 28,860 patients. The incidence of any lead complication was 3.6%, encompassing right atrial (RA; 2.3%), right ventricular (2.2%), and left ventricular (4.3%) lead complications. The lead complication risk declined during the first part of the study period and remained stable after 2002. Multivariate analysis identified the following significant risk factors: chronic heart failure as indication (adjusted odds ratio (aOR) 3.0; 95% confidence interval [CI] 2.1 to 4.3), implantation in a nonuniversity center (aOR 1.4; 95% CI 1.2 to 1.6), inexperienced operator with <25 implantations (aOR 1.6; 95% CI 1.3 to 2.0), single-lead RA device (aOR 1.4; 95% CI 1.1 to 1.8), dual-chamber pacing device (aOR 1.6; 95% CI 1.4 to 1.9), CRT-P device (aOR 3.3; 95% CI 2.4 to 4.4) and passive-fixation RA lead (aOR 2.2; 95% CI 1.7 to 2.9). CONCLUSION Lead complications causing reoperation remain a clinically important problem in device therapy. Mainly procedure-related factors were identified as independent risk factors for lead complications.

Pneumothorax in cardiac pacing: a population-based cohort study of 28 860 Danish patients

AIM To identify risk factors for pneumothorax treated with a chest tube after cardiac pacing device implantation in a population-based cohort. METHODS AND RESULTS A nationwide cohort study was performed based on data on 28 860 patients from the Danish Pacemaker Register, which included all Danish patients who received their first pacemaker (PM) or cardiac resynchronization device from 1997 to 2008. Multiple logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals for the association between risk factors and pneumothorax treated with a chest tube. The median age was 77 years (25th and 75th percentile: 69-84) and 55% were male (n = 15 785). A total of 190 patients (0.66%) were treated for pneumothorax, which was more often in women [aOR 1.9 (1.4-2.6)], and in patients with age >80 years [aOR 1.4 (1.0-1.9)], a prior history of chronic obstructive pulmonary disease [aOR 3.9 (1.6-9.5)], implantation of a dual-chamber PM [aOR 1.5 (1.0-2.2)], venous access with subclavian vein puncture [aOR 7.8 (4.9-12.5)], venous access with both subclavian vein puncture and cephalic vein cut-down [aOR 5.7 (3.0-10.8)], and implantation in a non-university centre [aOR 2.1 (1.6-2.9)]. CONCLUSION Pneumothorax treated with a chest tube remains a clinically important problem in device therapy. The cephalic vein cut-down technique should be applied whenever possible to avoid this complication.

Nationwide fluoroscopic screening of recalled riata defibrillator leads in Denmark

BACKGROUND The natural history of insulation defects with inside-out conductor externalization in recalled St Jude Medical Riata defibrillator leads is not well understood. OBJECTIVES To determine the prevalence of externalization in a nationwide screening. Secondary aims were to examine time dependence and location of externalization, association with electrical failure, and fluoroscopic diagnostic performance. METHODS All 299 patients with recalled Riata leads in Denmark were identified, and all except one underwent fluoroscopy and device interrogation. Externalizations were confirmed by multiple investigators. RESULTS The prevalence of externalization was 32 of 298 (11%) at a mean dwell time of 5.1 years. The prevalence was 21 of 98 (21%) for 8-F leads and 11 of 200 (6%) for 7-F leads; however, 8-F leads had longer dwell times. The degree of externalization was correlated with dwell time (Spearmans ρ = .37; P = .03). Externalization more often included the lead segment below the tricuspid annulus in dual coil leads than in single coil leads (69% vs 16%; P = .004). No association was observed between externalization and electrical function. Fluoroscopic diagnostic performance was good with positive and negative predictive values of 88% and 99%, respectively. CONCLUSIONS The prevalence of externalization in a nationwide screening is at the same level as reported in previous studies with similar lead dwell times. The degree of externalization is time dependent, and location seems to differ between single and dual coil leads. Long-term lead performance and association with electrical failure need further clarification. Fluoroscopy has a good diagnostic performance in clinical practice.

Neurohormonal Systems during Progression of Heart Failure: A Review

In the presence of a primary disorder in myocardial contractility and/or extraordinary hemodynamic pressure on the heart, ventricular performance depends on several compensating mechanisms. In the past, studies were mostly focused on the importance of the Frank-Starling mechanism and the hypertrophy and dilation of the heart in maintaining a circulation sufficient for metabolic intake during heart failure. Recently, however, the existence of neurohormonal systems has been demonstrated (the sympathetic nervous system, the renin-angiotensin system, atrial natriuretic peptide and several locally produced vasoactive substances), which change considerably according to the severity of the heart failure. While these compensatory mechanisms support the circulation in patients with acute heart failure, in whole or in part, neurohormonal activation over an extended period of time might be harmful to patients with chronic congestive heart failure since several neurohormonal factors might be inappropriately activated. This article will review the key neurohormonal systems and their importance in heart failure on the basis of the current literature.

The impact of co-morbidity burden on appropriate implantable cardioverter defibrillator therapy and all-cause mortality: insight from Danish nationwide clinical registers

In a nationwide cohort of primary (PP‐ICD) and secondary prevention (SP‐ICD) implantable cardioverter defibrillator (ICD) patients, we aimed to investigate the association between co‐morbidity burden and risk of appropriate ICD therapy and mortality.