Staphylococcus aureus bacteraemia, cardiac implantable electronic device, extraction, and the risk of recurrent infection; a retrospective population-based cohort study

BACKGROUND

Patients with cardiac implantable electronic device (CIED) and Staphylococcus aureus bacteraemia (SAB) are at risk of having CIED infection, pocket infection or endocarditis. To avoid treatment failures, guidelines recommend that the CIED should be extracted in all cases of SAB butrecent studies indicate low extraction rates and low risk of relapse. The aim of the study was to describe a Swedish population-based cohort of patients with CIED and SAB, the rate of extraction, and treatment failure measured as recurrent SAB.

METHODS

Patients identified to have SAB in the Karolinska Laboratory database, serving a population of 1.9 million, from January 2015 through December 2019 were matched to the Swedish ICD and Pacemaker Registry. Patients with CIED and SAB were included. Clinical data were collected from medical records.

RESULTS

A cohort of 274 patients was identified and 38 patients (14%)had the CIED extracted. Factors associated with extraction were lower age, lower Charlson comorbidity index, shorter time since CIED implantation, and non-nosocomial acquisition, but not mortality. No patient was put on lifelong antibiotic treatment. Sixteen patients (6%) had a recurrent SAB within one year, two in patients subjected to extraction (5%) and 14 in patients not subjected to CIED-extraction (6%). Three of the 14 patients were found to have definite endocarditis during the recurrent episode.

CONCLUSIONS

Despite a low extraction rate, there were few recurrences. We suggest that extraction of the CIED might be omitted if pocket infection, changes on the CIED, or definite endocarditis are not detected.

Implantable cardioverter defibrillator and cardiac resynchronization treatment in people with type 2 diabetes: a comparison with age- and sex matched controls from the general population

BACKGROUND

Increased risk of severe tachyarrhythmias is reported in patients with type 2 diabetes mellitus (T2DM). The aim of this study was to explore if treatment with cardiac implantable electronic device (CIED) such as implantable cardioverter defibrillator (ICD), cardiac resynchronization therapy- pacemaker and -defibrillator (CRT-P/CRT-D) differed in patients with vs. without T2DM. A secondary aim was to identify patient characteristics indicating an increased CIED treatment.

METHOD

416 162 adult patients with T2DM from the Swedish National Diabetes Registry and 2 081 087 controls from the Swedish population, matched for age, sex and living area, were included between 1/1/1998 and 31/12/2012 and followed until 31/12/2013. They were compared regarding prevalence of ventricular tachycardia (VT) at baseline and the risk of receiving a CIED during follow-up. Multivariable Cox regression analysis was performed to estimate the risk of CIED-treatment and factors identifying patients with such risk.

RESULTS

Ventricular fibrillation (VF) (0.1% vs 0.0004%) and (VT) (0.2% vs. 0.1%) were more frequent among patients with T2DM compared to controls. CIED-treatment was significantly increased in patients with T2DM both in unadjusted and adjusted analyses. HR and 95% CI, after adjustment for sex, age, marital status, income, education, country of birth, coronary artery disease and congestive heart failure, were 1.32 [1.21-1.45] for ICD, 1.74 [1.55-1.95] for CRT-P and 1.69 [1.43-1.99] for CRT-D. Blood-pressure and lipid lowering therapies were independent risk factors associated to receiving CIED, while female sex was protective.

CONCLUSIONS

Although the proportion of VT/VF was low, patients with T2DM had a higher prevalence of these conditions and increased risk for treatment with CIED compared to controls. This underlines the importance of recognizing that T2DM patients have an increased need of CIED.

Endocardial pacing compared to epicardial left ventricle pacing and right ventricle pacing: A single-center long-term experience in a pediatric population

BACKGROUND AND AIMS

Pediatric pacing is usually performed as epicardial pacing in small children in need of pacemaker therapy. Epicardial pacing compared with transvenous pacing for pediatric complete atrioventricular block (CAVB) has different strengths and weaknesses. The epicardial left ventricular wall position of the lead has been considered superior, in terms of contraction pattern, compared to a transvenous right ventricular stimulation. We aimed to compare QRS duration and cardiac function before and after the switch from epicardial to transvenous pacing in a pediatric population.

METHODS

Pediatric patients with congenital or acquired CAVB, who underwent a switch from epicardial-to transvenous pacing at our center from 2005 to 2021, were identified through the national ICD- and Pacemaker Registry. Data regarding clinical status, ECG, and echocardiography before and after the switch and at last follow-up were collected.

RESULTS

We included 15 children. The median age at the switch was 6.7 (4.4-11.7) years with a median weight of 21 (15-39) Kg. The median QRS duration with the transvenous systems was 136 (128-152) ms vs. a QRS duration during epicardial stimulation of 150 (144-170) ms with a median difference in QRS duration of 14 (6-20) ms. Children with a post-surgical AV block had a broader QRS duration, both with epicardial and endocardial stimulation. Before the switch, there was one patient with impaired left ventricular function (LVF) but with normal left ventricular end-diastolic diameters. After the switch, one patient developed symptomatic LV dysfunction with the recovery of LVF at the last follow-up after being implanted with a cardiac resynchronization therapy device.

CONCLUSIONS

Our report of pediatric patients after switching from epicardial to transvenous pacing shows how transvenous pacing is not inferior to epicardial pacing in terms of QRS duration and no significant deterioration of cardiac function was detectable.

Prognosis of CRT-treated and CRT-untreated unselected population with LBBB in Stockholm County

AIMS

Left bundle branch block (LBBB) might be the first finding of cardiovascular diseases but also the prerequisite for cardiac resynchronization therapy (CRT) in heart failure (HF) with reduced ejection fraction (HFrEF). The prognosis for patients with LBBB and the implications of CRT in an unselected real-world setting are the focus of our study.

METHODS AND RESULTS

A central electrocardiogram (ECG) database and national registers have been screened to identify patients with LBBB. Predictors of HF and the use of CRT were identified with Cox models. The hazard ratios (HRs) of death, cardiovascular death (CVD), and HF hospitalization (HFH) were estimated according to CRT use. Of 5359 patients with LBBB and QRS > 150 ms, median age 76 years, 36% were female. At the time of index ECG, 41% had a previous history of HF and 27% developed HF. Among 1053 patients with a class I indication for CRT, only 60% received CRT with a median delay of 137 days, and it was associated with a lower risk of death [HR: 0.45, 95% confidence interval (CI): 0.36-0.57], CVD (HR: 0.47, 95% CI: 0.35-0.63), and HFH (HR: 0.56, 95% CI: 0.48-0.66). The age of over 75 years and the diagnosis of dementia and chronic obstructive pulmonary disease were predictors of CRT non-use, while having a pacing/defibrillator device independently predicted CRT use.

CONCLUSION

In an unselected LBBB population, CRT is underused but of great value for HF patients. Therefore, it is crucial to find ways of better implementing and understanding CRT utilization and characteristics that influence the management of our patients.

Staphylococcus aureus bacteraemia, cardiac implantable electronic device, and the risk of endocarditis: a retrospective population-based cohort study

Patients with cardiac implantable electronic device (CIED) and Staphylococcus aureus bacteraemia (SAB) are at risk of having infective endocarditis (IE). The objectives were to describe a Swedish population-based cohort of patients with CIED and SAB, to identify risk factors, and to construct a predictive score for IE. Patients over 18 years old in the Stockholm Region identified to have SAB in the Karolinska Laboratory database from January 2015 through December 2019 were matched to the Swedish Pacemaker and Implantable Cardioverter-Defibrillator ICD Registry to identify the study cohort. Data were collected from study of medical records. A cohort of 274 patients with CIED and SAB was identified and in 38 episodes (14%) IE were diagnosed, 19 with changes on the CIED, and 35 with changes on the left side of the heart. The risk factors predisposition for IE, community acquisition, embolization, time to positivity of blood cultures, and growth in blood culture after start of therapy in blood cultures were independently associated to IE. A score to identify patients with IE was constructed, the CTEPP score, and the chosen cut-off generated a sensitivity of 97%, specificity of 25%, and a negative predictive value of 98%. The score was externally validated in a population-based cohort of patients with CIED and SAB from another Swedish region. We found that 14% of patients with CIED and SAB had definite IE diagnosed. The CTEPP-score can be used to predict the risk of IE and, when negative, the risk is negligible.

Women with atrial fibrillation undergoing pulmonary vein isolation are more symptomatic but improve more in health-related quality of life and symptom burden than men

Gender differences in symptoms and perceived health-related quality of life (HRQOL) in patients with atrial fibrillation (AF) referred to pulmonary vein isolation (PVI) have been reported previously. Women experience a lower HRQOL, faster heart rate, and more symptoms such as palpitation and dyspnea than men. Furthermore, they experience worse physical functioning independently of other heart diseases or age. This study evaluates referral patterns and symptoms, morbidity, functional impairment, and HRQOL from a gender perspective in patients with AF before and 6 months after PVI. The study includes 242 patients (121 men), mean age 62 ± 9 years, referred for PVI. Symptoms were assessed with the Symptom Checklist: Frequency and Severity (SCL), HRQOL with Short Form 36 (SF-36), and the functional impairment with Sickness Impact Profile (SIP). The patients' own experiences of the referral process and history of their disease were evaluated with a supplementary questionnaire. The results showed that women improved more than men in HRQOL, SIP, and SCL 6 months post PVI. There were no sex differences in proportion of paroxysmal and persistent AF or ablation outcome. At baseline, women scored higher than men in both scales of the SCL (p < 0.001), scored lower in all components in SF-36, and scored higher in five categories of the SIP. Women were not more reluctant to accept referral for ablation when offered. The conclusion is that women with AF undergoing PVI are more symptomatic but also improve more in HRQOL and in symptom burden than men.

Predictors of all-cause mortality for patients undergoing transvenous lead extraction

Background

Risk assessment of TLE patients may be challenging due to incomplete knowledge about possible risk factors for post-TLE outcomes. The aim of this study was to identify predictors of 30-days and 1-year all-cause mortality including the novel parameter frailty in a large retrospective series of patients undergoing TLE at a high-volume centre.

Methods

Medical journals of 893 consecutive patients undergoing TLE between January 1, 2010 and December 31, 2018 were retrogradely analysed. Univariate logistic regression and multivariate analyses were performed to identify risk factors.

Results

A total of 893 patients were identified. Local infection was the dominant indication (41.1%) and pacemaker was the most common device (49.4%). Mean age was 65±16 years and 73.0% were males. The median follow up was 3.9 years (IQR, 4.5 years). Within the systemic infection group, Staphylococcus aureus was the main microorganism in the positive blood cultures (44.4%) and 69.4% of the patients had vegetations. The 30-days and 1 year mortality rates were 2.5% and 9.7%, respectively. Per-procedural mortality occurred in 1 patient. Significant risk factors for 30-days all-cause mortality at univariate analysis were anaemia, systemic infection, clinical frailty scales (CFS) 5–7 and stage 5 chronic kidney disease (CKD). Age, CRT-P/D (vs ICD), reduced ejection fraction, anaemia, BMI &lt;25 kg/m2, CFS 4–7 and CKD stages 3–5 were identified as significant predictors of 1-year all-cause mortality. Within the systemic infection subgroup, leucocytosis and white blood cell count (WBC) 8.8–15x109/L were associated with significant 30-days and 1-year all-cause mortality and CRP 200–300 mg/L and low WBC count correlated with 1-year all-cause mortality. Local infection patients with CRP 100–150 mg/L had an elevated risk for 1-year all-cause mortality. Multivariate analysis identified CKD 5, CFS 5–7 and systemic infection for 30-days all-cause mortality and age, CKD 5, CFS 5–7, systemic infection and BMI &lt;25 kg/m2 for 1-year all-cause mortality as independent risk factors.

Conclusions

Patient-related characteristics, comorbidities and systemic infection independently predicted worse post-TLE prognosis. Several parameters need to be considered when assessing patients for TLE in order to risk stratify the patients and optimize the post-TLE care. Frailty is a novel parameter with significant influence on short and long-term outcome.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Internal funding

Predictors of all-cause mortality for patients undergoing transvenous lead extraction

Funding Acknowledgements

Type of funding sources: None.

Background

Risk assessment of TLE patients may be challenging due to incomplete knowledge about possible risk factors for post-TLE outcomes. The aim of this study was to identify predictors of 30-day and 1-year mortality in a large retrospective series of patients undergoing TLE at a high-volume centre.

Methods

Medical journals of 893 consecutive patients undergoing TLE between January 1, 2010 and December 31, 2018 were analysed. Univariate logistic regression analysis was performed to identify risk factors.

Results

A total of 893 patients were identified. Local infection was the dominant TLE indication (40.5%), and pacemaker was the most common CIED (49.4%). Mean age was 65 + 16 years and 73.0% were males. The median follow up was 3.9 years (IQR, 2.0-6.4 years). Staphylococcus aureus was the most common microorganism found in blood cultures of the systemic infection group (39.9%). A total of 179 (69.4%) systemic infection patients had vegetations on echocardiography, where majority engaged the lead(s). The 30-day and 1 year mortality rates were 2.5% (86.4% had systemic infection) and 9.7% (64.4% had systemic infection), respectively. Per-procedural mortality occurred in 1 patient with systemic infection. Significant predictors of 30-day mortality were low haemoglobin, systemic infection as TLE-indication, clinical frailty scales (CFS) 5-7 and stage 5 chronic kidney disease (CKD). In case of 1-year mortality, age, CRT-P/D (vs ICD), reduced ejection fraction, anaemia, BMI &lt;25 kg/m2, CFS 4-7 and CKD stages 3-5 were identified as significant predictors. In the systemic infection subgroup, elevated white blood cell (WBC) count was associated with 30-day and 1 year mortality. Additionally CRP interval 200-300, low WBC count and WBC interval 8.8-15 correlated signigicantly with 1-year mortality within the systemic infection cohort. In the local infection subgroup, a significant correlation between CRP interval 100-150 and 1-year mortality was found.

Conclusions

Systemic infection as TLE-indication carries a high 30-days post-TLE all-cause mortality rate and is significantly correlated with short and long-term mortality, where elevated inflammatory parameters carried additional mortality risk in this subgroup. Anaemia, chronic kidney disease, CRT compared to ICD, reduced EF and patient-related features as high clinical frailty scale levels and BMI &lt;25 kg/m2 predicted worse prognosis in the entire TLE-cohort.

Endocardial pacing compared to epicardial left ventricle pacing and right ventricle pacing: a single center long term experience in a pediatric population

Introduction

Complete atrioventricular block (CAVB), either congenital or post heart surgery, are the main indications for cardiac pacing in the pediatric population.

Epicardial pacing is preferred in small infants or for specific cardiac anomalies and some studies highlight a superior contraction pattern when pacing epicardially from the left ventricular apex region [1–3]. Endocardial pacing is more frequently used in children with a weight &gt;20 kg and is less invasive [4].

Paced QRS duration seems to be independently associated with ventricular dysfunction irrespective of location or age at device implantation [5].

Purpose

Describe the echocardiographic and electrocardiographic changes after switch from epicardial to transvenous pacing in a pediatric population with CAVB.

Methods

Children (0–18 years), who underwent a switch from left- (LV) or right ventricle (RV) epicardial pacing to transvenous pacing at our center, were retrospectively studied. Clinical, ECG- and echocardiographic parameters before and after the switch of the PM-system were collected as well as the most recent FU data. Left ventricular end-diastolic diameter (LVDD) and fractional shortening (FS) values were transformed to a body surface-related and age-related z-score (z), respectively.

Results

Fifteen patients with CAVB who received an epicardial pacemaker (60% congenital, 40% post-cardiac surgery) were converted to a transvenous system at our center (2005–2021). The median age at the switch was 6.8 (2–13) years with a median weight of 21 (9–62) kg. The epicardial lead location was more frequently the RV wall (60%) than the LV wall (40%). The RV outflow tract and interventricular septum were the most common locations (73%) for the endocardial leads. The mean QRS duration during epicardial stimulation was 150 (IQR 26) ms vs. a median QRS duration with the transvenous system of 136 (IQR 19) ms and a median delta QRS duration of 13ms. A detailed comparison between RV and LV epicardial pacing are reported in Figure 1. Children with post-surgical AV block had a broader median QRS duration, both with epicardial and endocardial stimulation. Before the switch, there was only one abnormal observation of FS less than −2 z with normal LVDD. At the last available follow-up (mean time 7 years), all the children had normal LVDD and only one had FS less than −2 z.

Conclusions

Our report of pediatric patients after switch from epi to endo pacing, shows good results in terms of QRS duration with no significant echocardiographic or clinical evidence of deterioration of the cardiac function. Due to the small sample size the results could serve as a hypothesis generator, but larger prospective studies are needed to evaluate the electrocardiographic and echocardiographic impact of transvenous - compared to epicardial pacing.

Funding Acknowledgement

Type of funding sources: None. Comparison of QRS duration

Incidental finding of ”ghost” on echocardiography after transvenous lead extraction among systemic infection patients

Background

Ghosts are described as cylindrical and oscillating structures diagnosed after transvenous lead extraction (TLE) and may consist of thrombi, vegetations and fibrous sheaths. Presence of ghosts is found to be associated with poor outcomes.

Purpose

The aim of this study was to estimate the proportion of patients with ghosts and to describe the characteristic features of `'ghosts” seen post-TLE in a retrospective series of systemic infection patients.

Methods

Medical journals including echocardiography studies of systemic infection patients undergoing TLE between January 1, 2010 and December 31, 2018 were analysed.

Results

A total of 258 patients (72% males, mean age 71±12 years), underwent TLE due to systemic infection. Staphylococcus aureus was the dominant microorganism isolated in blood cultures (40%). Echocardiography identified ghosts as incidental findings in 15 (6%) patients, 1–23 day(s) (median, 5; mean, 7±6 days) post-TLE and ghosts remained up to 51 days post-TLE. Ghosts were described as tubular, echodense and mobile tissues with variety of dimensions (2–50 mm) on echocardiography, mostly localised in right atrium (40%). Ghosts were visually described by surgeons as vegetations on tricuspid valve, organised thrombotic material in superior/inferior vena cavae and more loose thrombotic materials in right atrium in 2 patients who underwent open heart surgery after TLE. Echocardiography could not certainly differentiate between non-infectious tissue and infectious vegetations, thereby endocarditis treatment was prolonged to at least 12 days (mean, 29±14 days) post-TLE in the ghost group.

Conclusion

Although this was a retrospective analysis and ghosts were incidental findings rather than differential diagnosis, which may have underestimated the proportion ghosts identified, ghosts were relatively common in this cohort. Presence of ghosts caused management challenges for clinicians. There is a great need for large multicentre studies enabling establishment of guidelines for diagnosis and management of this common post-TLE finding.

Funding Acknowledgement

Type of funding sources: None. Table 1Figure 1

Prevalence of left bundle branch block and CRT treatment in a large regional unselected ECG database

Introduction

Heart failure is a clinical syndrome in which signs and symptoms are due to functional and/or structural abnormalities of the heart which prevent the necessary supply of oxygenated blood or do so at the expense of high filling pressures. It has a prevalence of 1–2% in the western world and increasing prevalence with increasing age. While the prognosis for coronary heart disease has improved significantly, the same does not apply for heart failure, perhaps because some effective treatment methods have not been sufficiently implemented in health care. One effective but underutilized heart failure treatment is the cardiac resynchronisation therapy (CRT), that coordinates the contraction of the left and right ventricles via a pacemaker (PM). CRT treatment is an evidence based treatment recommended by among other the ESC guidelines for heart failure. Clinical studies have suggested decreases in mortality, hospitalization, morbidity and improvements in quality of life for heart failure patients receiving a CRT.

Purpose

To find a new clinical pathway to improve CRT implementation and to evaluate if it might be optimized through ECG-based surveillance and thus improving prognosis.

Methods

In a population of approximately 2.5 million people in our region we investigated the University Hospital's ECG database between 2000 and 2018. During which time 432 108 adult patients with 1 482 489 ECG's presented to the hospital. We searched and found 5 511 unique patients with the following ECG criteria: QRS ≥150 ms at any time, LBBB and Non pace. According to the Pacemaker Registry we excluded 771 patients that had previously received a PM/CRT. We also identified patients with diagnosis of heart failure by using the ICD-10 codes (I42.0 and I50).

Results

Our final cohort consists of 4 740 patients. The median age was 75 (19–112) years, 34.5% were female and 14.9% were subsequently implanted with a CRT (60% with CRT-D). The median time to CRT implantation from the first ECG with LBBB was 244 (IQR 994) days. Of the 4 740 patients 20.6% had a previous hospitalistion for heart failure with a median delay from the hospitalisation to CRT implantation of 5 (IQR 5.4) years.

Conclusions

Our observational data from a large real-life regional ECG database show there is a considerable number of heart failure patients that could benefit from CRT treatment. Using an existing ECG database could be useful in finding patients with indication for CRT implantation. This could possibly influence morbidity and mortality in a regional heart failure population by minimizing the delay of CRT treatment.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Karolinska University Hospital Research Fund

Patients With Type 2 Diabetes Have an Increased Demand for Pacemaker Treatment: A Comparison With Age- and Sex-Matched Control Subjects From the General Population

OBJECTIVE

Patients with type 2 diabetes have an increased risk for cardiovascular disease, including arrhythmias. The prevalence of bradyarrhythmia and the subsequent need for treatment with pacemakers (PMs) is less well explored in a contemporary patient population. The current study explores 1) whether patients with type 2 diabetes have an increased demand for PM implantation compared with an age- and sex-matched control population without diabetes and 2) patient characteristics associated with an increased demand for receiving a PM.

RESEARCH DESIGN AND METHODS

In this population-matched registry study, a total of 416,247 patients with type 2 diabetes from the Swedish National Diabetes Registry and 2,081,235 age- and sex-matched control subjects selected from the general population were included between 1 January 1998 and 31 December 2012 and followed until 31 December 2013. Mean follow-up time was 7 years. Cox proportional hazards regression analyses were performed to estimate the demand of PM treatment and the factors identifying patients with such demand.

RESULTS

Type 2 diabetes was associated with an increased need of PM treatment (hazard ratio 1.65 [95% CI 1.60-1.69]; P < 0.0001), which remained (1.56 [1.51-1.60]; P < 0.0001) after adjustments for age, sex, educational level, marital status, country of birth, and coronary heart disease. Risk factors for receiving a PM included increasing age, HbA_1c, BMI, diabetes duration, and lipid- and blood pressure-lowering medication.

CONCLUSIONS

The need for PM treatment is higher in patients with type 2 diabetes than in matched population-based control subjects. Age, diabetes duration, and HbA_1c seem to be risk factors for PM treatment.

Rate, Time Course, and Predictors of Implantable Cardioverter Defibrillator Infections: An Analysis From the SIMPLE Trial

Background

The number of implantable cardioverter defibrillator (ICD) infections is increasing due to an increased number of ICD implants, higher-risk patients, and more frequent replacement procedures, which carry a higher risk of infection. Reducing the morbidity, mortality, and cost of ICD-related infections requires an understanding of the current rate of this complication and its predictors.

Methods

The Shock Implant Evaluation Trial (SIMPLE) trial randomized 2500 ICD recipients to defibrillation testing or not. Over an average of 3.1 years, patients were seen every 6 months and examined for evidence of ICD infection, which was defined as requiring device removal and/or intravenous antibiotics.

Results

Within 24 months, 21 patients (0.8%) developed infection. Fourteen patients (67%) with infection presented within 30 days, 20 patients by 12 months, and only 1 patient beyond 12 months. Univariate analysis demonstrated that patients with primary electrical disorders (3 patients, P = 0.009) and those with a secondary prevention indication (13 patients, P = 0.0009) were more likely to develop infection. Among the 2.2% of patients who developed an ICD wound hematoma, 10.4% developed an infection. Among the 8.3% of patients requiring an ICD reintervention, 1.9% developed an infection.

Conclusions

This cohort of ICD recipients at high-volume centres have a low risk of device-related infection. However; strategies to reduce wound hematoma and the need for ICD reintervention could further reduce the rate of infection.

Cardiac implantable electrical devices in patients with hypertrophic cardiomyopathy: single center implant data extracted from the Swedish pacemaker and ICD registry

Objectives: To investigate cardiac implantable electrical device (CIED) first implants in patients with hypertrophic cardiomyopathy (HCM) in a Swedish tertiary university hospital. Design: Clinical and technical data on pacemaker, implantable cardioverter defibrillator (ICD), and cardiac resynchronization therapy (CRT) first implants performed in HCM patients at the Karolinska University Hospital from 2005 to 2016 were extracted from the Swedish Pacemaker and ICD Registry. Echocardiographic data were obtained by review of hospital recordings. Results: The number of first pacemaker implants in HCM patients was 70 (1.5% of total pacemaker implants). The mean age of HCM pacemaker patients was 71 ± 10 years. Pacemaker implants were almost uniformly distributed between genders. Dual-chamber pacemakers with or without CRT properties were prevalent (6 and 93%, respectively). The number of first ICD implants in HCM patients was 99 (5.1% of total ICD implants). HCM patients receiving an ICD were 53 ± 15 years and prevalently men (70%). Sixty-five (66%) patients were implanted for primary prevention. Dual-chamber ICDs with or without CRT were 21 and 65%, respectively. Obstructive HCM was present in 47% pacemaker patients and 25% ICD patients with available pre-implant echo. Conclusions: This retrospective registry-based study provides a picture of CIED first implants in HCM patients in a Swedish tertiary university hospital. ICDs were the most commonly implanted devices, covering 59% of CIED implants. HCM patients receiving a pacemaker or an ICD had different epidemiological and clinical profiles.

Pacing therapy in children with isolated complete atrioventricular block: a retrospective study of pacing system survival and pacing-related complications in a national cohort

AIMS

To evaluate pacing system survival and complications to pacemaker (PM) therapy in children with isolated complete atrioventricular block (CAVB).

METHODS AND RESULTS

We performed a nationwide retrospective study of children diagnosed before 15 years of age with isolated CAVB and PM treatment. Between 1983 and 2012, 127 patients underwent PM-implantations at 3.2 (0-17) [median (range)] years and were followed for 11 (0.6-19) years. An endocardial or epicardial PM system was implanted in 72 and 55 patients, respectively. A total of 306 pacing leads (76% steroid-eluting) were implanted. Pacing system survival was significantly affected by age, with a higher risk of a new intervention for children aged <1 month at first implantation. Lead survival of the steroid-eluting leads at 5 and 10 years was 90 and 81%, respectively, with no difference between epicardial and endocardial systems. Complications leading to revision of the pacing system occurred in 24% of the patients. Patients aged <1 month at first PM implantation had a five-fold increased risk for a complication to occur. Dividing the cohort according to year of first procedure showed that those who had their first implantation ≥2002 had fewer complications and also lead- and pacing system survival was better in the later cohort.

CONCLUSION

Pacing system survival and complications to PM therapy in young patients with isolated CAVB were significantly affected by age, with low age at PM implantation constituting a risk factor. Endocardial and epicardial pacing systems showed no significant differences in performance.

Effectiveness of single- vs dual-coil implantable defibrillator leads: An observational analysis from the SIMPLE study

INTRODUCTION

Dual-coil leads (DC-leads) were the standard of choice since the first nonthoracotomy implantable cardioverter/defibrillator (ICD). We used contemporary data to determine if DC-leads offer any advantage over single-coil leads (SC-leads), in terms of defibrillation efficacy, safety, clinical outcome, and complication rates.

METHODS AND RESULTS

In the Shockless IMPLant Evaluation study, 2500 patients received a first implanted ICD and were randomized to implantation with or without defibrillation testing. Two thousand and four hundred seventy-five patients received SC-coil or DC-coil leads (SC-leads in 1025/2475 patients; 41.4%). In patients who underwent defibrillation testing (n = 1204), patients with both lead types were equally likely to achieve an adequate defibrillation safety margin (88.8% vs 91.2%; P = 0.16). There was no overall effect of lead type on the primary study endpoint of "failed appropriate shock or arrhythmic death" (adjusted HR 1.18; 95% CI, 0.86-1.62; P = 0.300), and on all-cause mortality (SC-leads: 5.34%/year; DC-leads: 5.48%/year; adjusted HR 1.16; 95% CI, 0.94-1.43; P = 0.168). However, among patients without prior heart failure (HF), and SC-leads had a significantly higher risk of failed appropriate shock or arrhythmic death (adjusted HR 7.02; 95% CI, 2.41-20.5). There were no differences in complication rates.

CONCLUSION

In this nonrandomized evaluation, there was no overall difference in defibrillation efficacy, safety, outcome, and complication rates between SC-leads and DC-leads. However, DC-leads were associated with a reduction in the composite of failed appropriate shock or arrhythmic death in the subgroup of non-HF patients. Considering riskier future lead extraction with DC-leads, SC-leads appears to be preferable in the majority of patients.

Wound haematoma following defibrillator implantation: incidence and predictors in the Shockless Implant Evaluation (SIMPLE) trial

Aims

Pocket haematoma is a common complication after defibrillator [implantable cardioverter defibrillator (ICD)] implantation, which is not only painful, but also increases the risk of device-related infection, and possibly embolic events. The present study seeks to evaluate the rate and predictors of clinically significant pocket haematoma.

Methods and results

This study included 2500 patients receiving an ICD in the SIMPLE trial. A clinically significant pocket haematoma was defined as a haematoma that required re-operation or interruption of oral anticoagulation (OAC) therapy. Clinically significant pocket haematoma occurred in 56 of 2500 patients (2.2%) of which 6 (10.7%) developed device-related infection. Patients who developed pocket haematoma were older (mean age 67.6 ± 8.8 years vs. 62.7 ± 11.6 years, P < 0.001), were more likely to have permanent atrial fibrillation (30.4 vs. 6.7%, P < 0.001) and a history of stroke (17.9 vs. 6.7%, P = 0.004), or were more likely to receive peri-operative OAC (50.0 vs. 28.4%, P < 0.001), unfractionated heparin (16.1 vs. 5.2%, P = 0.003), or low-molecular-weight heparin (37.5 vs. 17.5%, P < 0.001). Independent predictors of wound haematoma on multivariable analysis included the use of heparin bridging (OR 2.65, 95% CI 1.48-4.73, P = 0.001), sub-pectoral location of ICD (OR 2.00, 95% CI 1.12-3.57, P =0.020), previous stroke (OR 2.47, 95% CI 1.20-5.10, P = 0.015), an upgrade from permanent pacemaker (OR 2.52, 95% CI 1.07-5.94, P = 0.035), and older age (OR 1.03, 95% CI 1.00-1.06, P = 0.049).

Conclusion

Pocket haematoma remains an important complication of ICD implantation and is associated with a high risk of infection. Independent predictors of pocket haematoma include heparin bridging, prior stroke, sub-pectoral placement of ICD, older age, and upgrade from a pacemaker.

[Management of hypertrophic cardiomyopathy - the most common inherited heart disease]

Hypertrophic cardiomyopathy is the most common cardiogenetic disease affecting 1/500-1/1 000 individuals. Dyspnea is common but chest pain, dizziness or fainting may also cause considerable limitation for the patient. The diagnosis can be suspected from ECG. Echocardiography confirms hypertrophy of at least 15 mm, usually in the septum. If the obstruction of the outflow tract is severe, myectomy or alcohol ablation can relieve symptoms. Genetic evaluation of family members is advisable. To reduce symptoms, betablockers are used; verapamil or disopyramide are alternatives. Atrial fibrillation is often prevalent and requires special attention concerning anticoagulation and rhythm or rate control. An end-stage heart failure warrants advanced treatment options such as cardiac resynchronization therapy, ventricular assist devices or heart transplant. Sudden cardiac death is unpredictable and evaluation of risk markers is important to identify potential candidates for an implantable defibrillator.

Clinical risk profile score predicts all cause mortality but not implantable cardioverter defibrillator intervention rate in a large unselected cohort of patients with congestive heart failure

BACKGROUND

Primary prophylactic implantable cardioverter defibrillator (ICD) therapy is indicated for patients with reduced left ventricular ejection fraction (LVEF). We aimed to determine if preoperative clinical risk profiling can predict long-term benefit, and if clinical risk scores can be applied and improved in a patient cohort outside the clinical trial setting.

METHODS

Using registry data, 789 patients with reduced LVEF who received ICDs for primary prevention during 2006-2011 were identified (age 64 ± 11 years, 82% men, 63% ischemic etiology, 52% cardiac resynchronization therapy with defibrillator). The patients were divided into three risk groups, based on the presence of baseline clinical risk factors (age >70, QRS duration >120 ms, New York Heart Association class III-IV, atrial fibrillation history, or creatinine >106 μmol/L). Endpoints were all-cause mortality and survival free of adequate ICD therapy.

RESULTS

Mean follow-up was 39 ± 18 months. Annual mortality was 7.6%, and increased with risk group (p < .001). Rates of appropriate antitachycardia pacing and shock therapy were not statistically different between the groups, and ranged from 11%-16% and 6%-14%, respectively. By combining the previous risk score with data on diabetes, a better independent prediction of mortality was achieved; mortality rates then ranged from 11% (low-risk) to 46% (high-risk) (p < .0001).

CONCLUSIONS

Implantable cardioverter defibrillator therapies occur across the spectrum of comorbidities in a population with systolic heart failure. However, all-cause mortality is considerably higher in the group of patients with accumulated risk factors, and using the proposed scoring system can be helpful for the evaluation and risk stratification of the patient prior to making a decision for a primary prophylactic ICD implantation.

Economic impact of longer battery life of cardiac resynchronization therapy defibrillators in Sweden

OBJECTIVE

The objective of this study was to quantify the impact that longer battery life of cardiac resynchronization therapy defibrillator (CRT-D) devices has on reducing the number of device replacements and associated costs of these replacements from a Swedish health care system perspective.

METHODS

An economic model based on real-world published data was developed to estimate cost savings and avoided device replacements for CRT-Ds with longer battery life compared with devices with industry-standard battery life expectancy. Base-case comparisons were performed among CRT-Ds of three manufacturers - Boston Scientific Corporation, St. Jude Medical, and Medtronic - over a 6-year time horizon, as per the available clinical data. As a sensitivity analysis, we evaluated CRT-Ds as well as single-chamber implantable cardioverter defibrillator (ICD-VR) and dual-chamber implantable cardioverter defibrillator (ICD-DR) devices over a longer 10-year period. All costs were in 2015 Swedish Krona (SEK) discounted at 3% per annum.

RESULTS

Base-case analysis results show that up to 603 replacements and up to SEK 60.4 million cumulative-associated costs could be avoided over 6 years by using devices with extended battery life. The pattern of savings over time suggests that savings are modest initially but increase rapidly beginning in the third year of follow-up with each year's cumulative savings two to three times the previous year. Evaluating CRT-D, ICD-VR, and ICD-DR devices together over a longer 10-year period, the sensitivity analysis showed 2,820 fewer replacement procedures and associated cost savings of SEK 249.3 million for all defibrillators with extended battery life.

CONCLUSION

Extended battery life is likely to reduce device replacements and associated complications and costs, which may result in important cost savings and a more efficient use of health care resources as well as a better quality of life for heart failure patients in Sweden.

Cardiac resynchronization therapy: results, challenges and perspectives for the future

Heart failure (HF) is considered as an epidemic and affects 2% of the population in the Western world. About 15-30% of patients with HF and reduced ejection fraction (HFrEF) also have prolonged QRS duration on the surface ECG, most commonly as a result of left-bundle branch block (LBBB). Increased QRS duration is a marker of a dyssynchronous activation, and subsequent contraction, pattern in the left ventricle (LV). When dyssynchrony is superimposed on the failing heart it further reduced systolic function and ultimately worsens outcome. During the past 15 years several randomized controlled clinical trials have documented that resynchronization of the dyssynchronous failing heart with a biventricular pacemaker - cardiac resynchronization therapy (CRT) - which can restore a more synchronous activation and contraction pattern. This translates in halted or reversed disease progression and improved clinical outcome, including reduced mortality. In this review, we will discuss several aspects of CRT including mechanisms of dyssynchrony and resynchronization in the failing heart, evidence of CRT efficacy derived from clinical trials and current challenges in CRT including patient selection and optimization of therapy delivery. Last, we will discuss future perspectives including the role of CRT to prevent adverse events in patients with an indication for antibradycardia pacing, the role of leadless pacing in the CRT setting as well as a new clinical arena where dyssynchrony and resynchronization may be important.

Effect of Cardiac Resynchronization Therapy on Left Atrial Size and Function as Expressed by Speckle Tracking 2-Dimensional Strain

Changes in left atrial (LA) strain in patients treated with cardiac resynchronization therapy (CRT) remain not entirely explored. We prospectively evaluated long-term changes in LA size and function and their relation with left ventricular (LV) reverse remodeling and noninvasive hemodynamic variables in patients treated with CRT by 2-dimensional speckle tracking echocardiography. Thirty patients (62 ± 11 years, 63% men) underwent 2-dimensional speckle tracking echocardiography before implant and after 12 months. LA area, global and regional LA strains, LV ejection fraction (LVEF) and longitudinal strain, mitral regurgitation (MR), and diastolic variables were evaluated. At 12 months, CRT responders (60%) exhibited an increase in LA strain (11.4 ± 6.5% vs 16.5 ± 7.9%, p <0.001) and a reduction in LA area (p = 0.002), which were associated with an improvement in MR, E/E' ratio, LVEF, and LV longitudinal strain. In nonresponders, a worsening in LA strain (11.4 ± 6.8% vs 8.7 ± 4.6%, p = 0.017) and LA area (p = 0.002) occurred in parallel with an increase in E/E', whereas LVEF and LV longitudinal strain were unchanged. In conclusion, over long-term follow-up, LA size and strain improved in CRT responders, while worsening in nonresponders. Changes in LV function, filling pressures, and MR seem to be related to LA reverse remodeling, giving a feedback loop.

Health-related quality of life in hypertrophic cardiomyopathy patients with implantable defibrillators

Background

Health-related quality of life (HRQL) in hypertrophic cardiomyopathy (HCM) patients with implantable cardioverter-defibrillators (ICDs) is largely unknown. The aim was to assess HRQL, including comparisons between groups, using the questionnaire SF-36, and compare it to a Swedish age- and sex-matched population.

Methods and Results

Validated data on adult HCM patients with ICDs were used. The SF-36 response rate was 82.5 % and 245 patients (mean age 55.9 years, 70.2 % men) were analyzed using the Mann-Whitney U-test, t-test, Spearman correlation and effect size calculations. In all SF-36 domains the patients’ score was lower (p-value of <0.0001) than norms except for bodily pain. The general health domain showed the highest effect size (0.77) and the impact was more pronounced in the SF-36 physical component summary score (0.62) than the mental component summary score (0.46). Older age was correlated with lower scores on the physical component and higher scores on the mental component. Atrial fibrillation and/or systolic heart failure were associated with worse physical health. HRQL was similar in primary vs secondary prevention cases. Inappropriate ICD shock was associated with worse mental health while appropriate therapy trended toward better mental health.

Conclusion

HCM patients with ICDs suffer from poor HRQL regardless of age, sex, or primary vs secondary prevention indication. Atrial fibrillation and systolic heart failure are determinants of poor physical health. Inappropriate shocks, but not appropriate therapies, are associated with poorer mental health.

Apical versus Non-Apical Lead: Is ICD Lead Position Important for Successful Defibrillation?

INTRODUCTION

We aim to compare the acute and long-term success of defibrillation between non-apical and apical ICD lead position.

METHODS AND RESULTS

The position of the ventricular lead was recorded by the implanting physician for 2,475 of 2,500 subjects in the Shockless IMPLant Evaluation (SIMPLE) trial, and subjects were grouped accordingly as non-apical or apical. The success of intra-operative defibrillation testing and of subsequent clinical shocks were compared. Propensity scoring was used to adjust for the impact of differences in baseline variables between these groups. There were 541 leads that were implanted at a non-apical position (21.9%). Patients implanted with a non-apical lead had a higher rate of secondary prevention indication. Non-apical location resulted in a lower mean R-wave amplitude (14.0 vs. 15.2, P < 0.001), lower mean pacing impedance (662 ohm vs. 728 ohm, P < 0.001), and higher mean pacing threshold (0.70 V vs. 0.66 V, P = 0.01). Single-coil leads and cardiac resynchronization devices were used more often in non-apical implants. The success of intra-operative defibrillation was similar between propensity score matched groups (89%). Over a mean follow-up of 3 years, there were no significant differences in the yearly rates of appropriate shock (5.5% vs. 5.4%, P = 0.98), failed appropriate first shock (0.9% vs. 1.0%, P = 0.66), or the composite of failed shock or arrhythmic death (2.8% vs. 2.3% P = 0.35) according to lead location.

CONCLUSION

We did not detect any reduction in the ICD efficacy at the time of implant or during follow-up in patients receiving a non-apical RV lead.

Battery drain in daily practice and medium-term projections on longevity of cardioverter-defibrillators: an analysis from a remote monitoring database

AIMS

The longevity of generators is a crucial determinant of the cost-effectiveness of therapy with implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-D). We evaluated the trend of device-measured residual battery capacity and longevity projections over 5-year follow-up. We also investigated possible factors associated with battery drain.

METHODS AND RESULTS

Data from 4851 patients in the European LATITUDE(®) database who were followed up for a minimum of 3 years were analysed. The factors associated with battery drain (i.e. year-to-year decrease in residual battery capacity), and thus potentially impacting on device longevity, were mainly the pacing parameters in CRT-D devices and the number of shocks delivered and diverted in both ICD and CRT-D (all P < 0.01 on linear regression analysis). Over the first 5 years, the longevity estimates provided by devices showed low intra-patient variability and increased with time. The estimates exceeded 10 years for CRT-D and 13 and 12 years for single- and dual-chamber ICDs, respectively. In CRT-D patients, the expected patient age on replacement was 80 ± 12 years, and the expected probability of undergoing device replacement was 63 ± 13% for New York Heart Association (NYHA) II patients and 37 ± 16% for NYHA III patients. For comparison, the probabilities of replacing a CRT-D lasting 5 years were 78 ± 8 and 59 ± 13%, respectively (both P < 0.001).

CONCLUSION

Battery drain was mainly associated with pacing output in CRT-D devices and with the number of capacitor charges in both ICD and CRT-D devices. The longevity estimates provided by the devices were consistent and conservative. According to these estimates, among CRT-D recipients a low proportion of patients should require device replacement.

Risk Markers and Appropriate Implantable Defibrillator Therapy in Hypertrophic Cardiomyopathy

BACKGROUND

Risk stratification of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is mainly based on evaluations from patients at highly specialized centers.

AIM

To evaluate risk markers for appropriate implantable cardioverter defibrillator (ICD) therapy in an unselected, nationwide cohort of HCM.

METHODS

Patients with an ICD due to HCM were identified from the Swedish ICD Registry since its start in 1995, merged with Patient Register data, and medical records were retrieved. Risk markers for ventricular arrhythmias leading to appropriate ICD therapy were analyzed using Cox proportional hazard ratio (HR).

RESULTS

Of 321 patients (70.1% males), at least one appropriate therapy occurred in 77 (24.0%) during a mean follow-up of 5.4 years (5.3% per year; primary prevention 4.5%, secondary prevention 7.0%). Cumulative incidences at 1 year, 3 years, and 5 years were 8.1%, 15.3%, and 21.3%, respectively. Cardioversion effectively restored rhythm in 52% of the first episode and antitachycardia pacing was sufficient in the remaining. For the whole cohort, ejection fraction (EF) <50% (HR 2.63; P < 0.001) was associated with appropriate ICD therapy. In primary prevention, patients with established risk markers experienced appropriate therapy; atrial fibrillation (AF; HR 2.54; P = 0.010), EF < 50% (HR 2.78; P = 0.004), and nonsustained ventricular tachycardia (HR 1.80; P = 0.109) had the highest HR, and wall thickness ≥ 30 mm, syncope, exercise blood pressure response, or family history of SCD had weaker associations.

CONCLUSION

ICD therapy successfully terminates ventricular arrhythmias in HCM. In addition to conventional risk markers, a history of AF or EF < 50% may be considered in risk stratification.

Cardioverter defibrillator implantation without induction of ventricular fibrillation: a single-blind, non-inferiority, randomised controlled trial (SIMPLE)

BACKGROUND

Defibrillation testing by induction and termination of ventricular fibrillation is widely done at the time of implantation of implantable cardioverter defibrillators (ICDs). We aimed to compare the efficacy and safety of ICD implantation without defibrillation testing versus the standard of ICD implantation with defibrillation testing.

METHODS

In this single-blind, randomised, multicentre, non-inferiority trial (Shockless IMPLant Evaluation [SIMPLE]), we recruited patients aged older than 18 years receiving their first ICD for standard indications at 85 hospitals in 18 countries worldwide. Exclusion criteria included pregnancy, awaiting transplantation, particpation in another randomised trial, unavailability for follow-up, or if it was expected that the ICD would have to be implanted on the right-hand side of the chest. Patients undergoing initial implantation of a Boston Scientific ICD were randomly assigned (1:1) using a computer-generated sequence to have either defibrillation testing (testing group) or not (no-testing group). We used random block sizes to conceal treatment allocation from the patients, and randomisation was stratified by clinical centre. Our primary efficacy analysis tested the intention-to-treat population for non-inferiority of no-testing versus testing by use of a composite outcome of arrhythmic death or failed appropriate shock (ie, a shock that did not terminate a spontaneous episode of ventricular tachycardia or fibrillation). The non-inferiority margin was a hazard ratio (HR) of 1·5 calculated from a proportional hazards model with no-testing versus testing as the only covariate; if the upper bound of the 95% CI was less than 1·5, we concluded that ICD insertion without testing was non-inferior to ICD with testing. We examined safety with two, 30 day, adverse event outcome clusters. The trial is registered with ClinicalTrials.gov, number NCT00800384.

FINDINGS

Between Jan 13, 2009, and April 4, 2011, of 2500 eligible patients, 1253 were randomly assigned to defibrillation testing and 1247 to no-testing, and followed up for a mean of 3·1 years (SD 1·0). The primary outcome of arrhythmic death or failed appropriate shock occurred in fewer patients (90 [7% per year]) in the no-testing group than patients who did receive it (104 [8% per year]; HR 0·86, 95% CI 0·65-1·14; pnon-inferiority <0·0001). The first safety composite outcome occurred in 69 (5·6%) of 1236 patients with no-testing and in 81 (6·5%) of 1242 patients with defibrillation testing, p=0·33. The second, pre-specified safety composite outcome, which included only events most likely to be directly caused by testing, occurred in 3·2% of patients with no-testing and in 4·5% with defibrillation testing, p=0·08. Heart failure needing intravenous treatment with inotropes or diuretics was the most common adverse event (in 20 [2%] of 1236 patients in the no-testing group vs 28 [2%] of 1242 patients in the testing group, p=0·25).

INTERPRETATION

Routine defibrillation testing at the time of ICD implantation is generally well tolerated, but does not improve shock efficacy or reduce arrhythmic death.

FUNDING

Boston Scientific and the Heart and Stroke Foundation (Ontario Provincial office).

Current use of implantable electrical devices in Sweden: data from the Swedish pacemaker and implantable cardioverter-defibrillator registry

AIMS

The National Swedish Pacemaker and Implantable Cardioverter-Defibrillator (ICD) Registry collects prospective data on all pacemaker and ICD implants in Sweden. We aimed to report the 2012 findings of the Registry concerning electrical devices implantation rates and changes over time, 1 year complications, long-term device longevity and patient survival.

METHODS AND RESULTS

Forty-four Swedish implanting centres continuously contribute implantation of pacemakers and ICDs to the Registry by direct data entry on a specific website. Clinical and technical information on 2012 first implants and postoperative complications were analysed and compared with previous years. Patient survival data were obtained from the Swedish population register database. In 2012, the mean pacemaker and ICD first implantation rates were 697 and 136 per million inhabitants, respectively. The number of cardiac resynchronization therapy (CRT) first implantations/million capita was 41 (CRT pacemakers) and 55 (CRT defibrillators), with only a slight increase in CRT-ICD rate compared with 2011. Most device implantations were performed in men. Complication rates for pacemaker and ICD procedures were 5.3 and 10.1% at 1 year, respectively. Device and lead longevity differed among manufacturers. Pacemaker patients were older at the time of first implant and had generally worse survival rate than ICD patients (63 vs. 82% after 5 years).

CONCLUSION

Pacemaker and ICD implantation rates seem to have reached a level phase in Sweden. Implantable cardioverter-defibrillator and CRT implantation rates are very low and do not reflect guideline indications. Gender differences in CRT and ICD implantations are pronounced. Device and patient survival rates are variable, and should be considered when deciding device type.

The HLA locus contains novel foetal susceptibility alleles for congenital heart block with significant paternal influence

OBJECTIVE

The main aim of this study was to identify foetal susceptibility genes on chromosome six for Ro/SSA autoantibody-mediated congenital heart block.

SUBJECTS AND DESIGN

Single nucleotide polymorphism (SNP) genotyping of individuals in the Swedish Congenital Heart Block (CHB) study population was performed. Low-resolution HLA-A, -Cw and -DRB1 allele typing was carried out in 86 families comprising 339 individuals (86 Ro/SSA autoantibody-positive mothers, 71 fathers, 87 CHB index cases and 95 unaffected siblings).

RESULTS

A case-control comparison between index cases and population-based out-of-study controls (n = 1710) revealed association of CHB with 15 SNPs in the 6p21.3 MHC locus at a chromosome-wide significance of P < 2.59 × 10(-6) (OR 2.21-3.12). In a family-based analysis of association of SNP markers as well as distinct MHC class I and II alleles with CHB, HLA-DRB1*04 and HLA-Cw*05 variants were significantly more frequently transmitted to affected individuals (P < 0.03 and P < 0.05, respectively), whilst HLA-DRB1*13 and HLA-Cw*06 variants were significantly less often transmitted to affected children (P < 0.04 and P < 0.03). We further observed marked association of increased paternal (but not maternal) HLA-DRB1*04 transmission to affected offspring (P < 0.02).

CONCLUSIONS

HLA-DRB1*04 and HLA-Cw*05 were identified as novel foetal HLA allele variants that confer susceptibility to CHB in response to Ro/SSA autoantibody exposure, whilst DRB1*13 and Cw*06 emerged as protective alleles. Additionally, we demonstrated a paternal contribution to foetal susceptibility to CHB for the first time.