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.

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.

Cancer risk among pacemaker recipients in Denmark, 1982-1996.

To address concerns about the potential carcinogenicity of pacemakers, we launched the first epidemiologic study of cancer incidence among pacemaker recipients. A nationwide cohort of 16,357 pacemaker recipients in Denmark from 1982 through 1996 was identified. The Danish Cancer Registry was used to identify all incident cancers within the cohort, with almost 75,000 person-years of observation. The cohort had a slight excess of cancer overall (SIR = 1.19, 95% confidence interval [95% CI, 1.1-1.2]). This was largely caused by an elevated SIR for multiple myeloma among men (SIR = 1.78,95% CI, 1.1-2.8), which increased to 2.60 (95% CI, 0.9-5.7) 5-9 years after implantation, and to a similarly increased SIR for kidney cancer among women (SIR = 2.05, 95% CI, 1.3-3.0), which increased to 3.39 (95% CI, 1.6-6.2) after a latency period of 5-9 years. An excess of urinary bladder cancer was also seen after 10 years. No excess risk was observed for breast cancer or sarcomas, although the SIRs for sarcomas tended to increase over time, based on small numbers. Our results are largely reassuring but, as pacemakers become more common and are implanted at earlier ages and as survival following implantation improves, the excesses of bladder cancer, multiple myeloma among men, and kidney cancer among women with long-term followup warrant further investigation.

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.

Twins with implanted pacemakers: Is there an increased mortality risk for the co-twin? A follow-up study based on the Danish Twin Registry and the Danish Pacemaker Register.

BACKGROUND: The main indications for implanting a cardiac pacemaker are either acquired atrio-ventricular block (AVB) or sick sinus syndrome (SSS). In general, the exact aetiology of these conditions is unknown. Genetic factors may play a role. Untreated AVB is associated with increased mortality but SSS seems to have a good prognosis. The present study was designed to assess whether first-degree relatives of these patients have an increased mortality risk. METHODS: We investigated the survival pattern of the co-twins of twins who have had a cardiac pacemaker implanted, by linking two nationwide registries in Denmark: the Danish Pacemaker Register and the Danish Twin Registry. For each "pacemaker-twin" four control-twins matched with respect to age, sex, and zygosity were selected among the twins who were alive at the time of the pacemaker implantation. A total of 159 twins with a pacemaker treated bradycardia of unknown aetiology were identified of which 73 had AVB and 64 had SSS. A total of 622 matched control-twins could be identified. The survival from age six of the co-twins of the "pacemaker-twins" was compared with that of the co-twins of the control-twins. The follow-up period ended January 1st, 2000. FINDINGS: The survival curves for the co-twins of the "pacemaker-twins" were virtually identical to those of the co-twins of the control-twins. This finding was consistent for both AVB and SSS and for monozygotic as well as dizygotic twins. CONCLUSION: No increased mortality risk could be demonstrated for first-degree relatives--including monozygotic twins--of patients with a cardiac pacemaker implanted due to either acquired AVB or SSS.

Risk of severe cardiac arrhythmia in male utility workers: a nationwide danish cohort study.

To address concern about the potential cardiovascular effects of occupational exposure to electromagnetic fields in the 50- to 60-Hz frequency band, the authors launched an epidemiologic study of the incidence of severe cardiac arrhythmia, as indicated by the need for a pacemaker, in a nationwide cohort of Danish utility workers. The cohort of 24,056 men employed at utility companies between 1900 and 1993 was linked to the nationwide, population-based Danish Pacemaker Register, and the numbers of persons who had undergone pacemaker implantation between 1982 and 2000 were compared with corresponding numbers in the general population. In addition, the data on the utility workers were fitted to a multiplicative Poisson regression model in relation to estimated levels of exposure to 50-Hz electromagnetic fields. Overall, based on 135 men with pacemakers (140 expected), there was no increased risk of severe cardiac arrhythmia among the utility employees; the risk estimate was 0.96 (95% confidence interval: 0.81, 1.14). No clear dose-response pattern emerged with increasing levels of exposure to electromagnetic fields or with duration of employment. These results are largely reassuring, since they do not support the hypothesis of a link between occupational exposure to electromagnetic fields and an excess risk of severe cardiovascular arrhythmia leading to permanent implantation of a pacemaker.