Mihály K. de Bie

Inappropriate implantable cardioverter-defibrillator shocks: incidence, predictors, and impact on mortality.

OBJECTIVES The purpose of this study was to assess the incidence, predictors, and outcome of inappropriate shocks in implantable cardioverter-defibrillator (ICD) patients. BACKGROUND Despite the benefits of ICD therapy, inappropriate defibrillator shocks continue to be a significant drawback. The prognostic importance of inappropriate shocks outside the setting of a clinical trial remains unclear. METHODS From 1996 to 2006, all recipients of defibrillator devices equipped with intracardiac electrogram storage were included in the current analysis and clinically assessed at implantation. During follow-up, the occurrence of inappropriate ICD shocks and all-cause mortality was noted. RESULTS A total of 1,544 ICD patients (79% male, age 61 ± 13 years) were included in the analysis. During the follow-up period of 41 ± 18 months, 13% experienced ≥1 inappropriate shocks. The cumulative incidence steadily increased to 18% at 5-year follow-up. Independent predictors of the occurrence of inappropriate shocks included a history of atrial fibrillation (hazard ratio [HR]: 2.0, p < 0.01) and age younger than 70 years (HR: 1.8, p = 0.01). Experiencing a single inappropriate shock resulted in an increased risk of all-cause mortality (HR: 1.6, p = 0.01). Mortality risk increased with every subsequent shock, up to an HR of 3.7 after 5 inappropriate shocks. CONCLUSIONS In a large cohort of ICD patients, inappropriate shocks were common. The most important finding is the association between inappropriate shocks and mortality, independent of interim appropriate shocks.

Implantation-Related Complications of Implantable Cardioverter-Defibrillators and Cardiac Resynchronization Therapy Devices: A Systematic Review of Randomized Clinical Trials

The number of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy (CRT) implantations is increasing drastically worldwide, and hence, the number of implanting centers is also increasing. Despite abundant data on the beneficial effect of these devices, little is known regarding safety and complication rates. Eleven ICD and 7 CRT trials were systematically reviewed to provide data on the frequency of in-hospital mortality and complications related to the implantation. Average in-hospital mortality was 2.7% in trials using both thoracotomy and nonthoracotomy ICDs, 0.2% in trials using nonthoracotomy ICDs, and 0.3% in CRT trials. The pneumothorax rate was similar between the nonthoracotomy ICD and CRT trials (0.9%) Coronary sinus complications occurred in 2.0% of patients undergoing CRT. Lead dislodgement rates were higher in CRT trials (5.7%) than in nonthoracotomy ICD trials (1.8%).

Prevention of sudden cardiac death: rationale and design of the Implantable Cardioverter Defibrillators in Dialysis patients (ICD2) Trial – a prospective pilot study

ABSTRACT Objective: Sudden cardiac (arrhythmic) death (SCD) is the single largest cause of death in dialysis patients. Prophylactic Implantable Cardioverter Defibrillator (ICD) therapy reduces SCD and reduces all-cause mortality in several groups of patients at high risk for arrhythmic death. Whether this also applies to dialysis patients is unknown. Research design and methods: The Implantable Cardioverter Defibrillator in Dialysis patients (ICD2) trial is a prospective randomised controlled study. It has been designed to evaluate the efficacy and safety of prophylactic ICD therapy in reducing sudden cardiac death rates in dialysis patients aged 55–80 years. A total of 200 patients will be included. The primary endpoint of the study is sudden cardiac (arrhythmic) death. The mean follow-up time will be 4 years. Trial registration: ‘The Netherlands Trial Register’ – ISRCTN20479861 Conclusion: The ICD2 trial – a pilot study – will be the first study to evaluate the possible benefit of ICD therapy for the primary prevention of sudden cardiac death in dialysis patients.

Implantable cardioverter-defibrillator longevity under clinical circumstances: An analysis according to device type, generation, and manufacturer

BACKGROUND One of the major drawbacks of implantable cardioverter-defibrillator (ICD) treatment is the limited device service life. Thus far, data concerning ICD longevity under clinical circumstances are scarce. In this study, the ICD service life was assessed in a large cohort of ICD recipients. OBJECTIVE To assess the battery longevity of ICDs under clinical circumstances. METHODS All patients receiving an ICD in the Leiden University Medical Center were included in the analysis. During prospectively recorded follow-up visits, reasons for ICD replacement were assessed and categorized as battery depletion and non-battery depletion. Device longevity and battery longevity were calculated. The impact of device type, generation, manufacturer, the percentage of pacing, the pacing output, and the number of shocks on the battery longevity was assessed. RESULTS Since 1996, 4673 ICDs were implanted, of which 1479 ICDs (33%) were replaced. Mean device longevity was 5.0 ± 0.1 years. A total of 1072 (72%) ICDs were replaced because of battery depletion. Mean battery longevity of an ICD was 5.5 ± 0.1 years. When divided into different types, mean battery longevity was 5.5 ± 0.2 years for single-chamber ICDs, 5.8 ± 0.1 for dual-chamber ICDs, and 4.7 ± 0.1 years for cardiac resynchronization therapy-defibrillators (P <.001). Devices implanted after 2002 had a significantly better battery longevity as compared with devices implanted before 2002 (5.6 ± 0.1 years vs 4.9 ± 0.2 years; P <.001). In addition, large differences in battery longevity between manufacturers were noted (overall log-rank test, P <.001). CONCLUSIONS The majority of ICDs were replaced because of battery depletion. Large differences in longevity exist between different ICD types and manufacturers. Modern ICD generations demonstrated improved longevity.

Cardiac device infections are associated with a significant mortality risk.

BACKGROUND Cardiac device infections (CDIs) are a serious complication associated with the implantation of cardiac rhythm devices. However, the effect of CDI on the subsequent risk of mortality is unknown. OBJECTIVE To assess the prognostic importance of CDI in recipients of implantable cardioverter-defibrillator and cardiac resynchronization therapy - defibrillator. METHODS All patients who received their initial implantable cardioverter-defibrillator/cardiac resynchronization therapy - defibrillator between January 2000 and September 2009 were included. During follow-up, the occurrence of CDI and all-cause mortality were noted. The prognostic importance of the first CDI on mortality was assessed by modeling CDI as a time-dependent covariate in the Cox proportional hazards model. RESULTS A total of 2476 patients (79% men; mean age 62 ± 13 years) were included in this analysis. During follow-up, CDI occurred in 64 (2.6%) patients. The 1-year mortality following first CDI was 16.9% (95% confidence interval 6.7%-27.1%). Experiencing the first CDI was associated with a 1.9-fold (hazard ratio 1.87; 95% confidence interval 1.07-3.26) increased risk of mortality compared to patients who did not experience CDI. After controlling for possible confounders, this increased to a 2.4-fold (hazard ratio 2.40; 95% confidence interval 1.35-4.28) increased risk of mortality. CONCLUSIONS In a large cohort of patients who receive implantable cardioverter-defibrillator/cardiac resynchronization therapy - defibrillator after their initial implant, the 3-year incidence of CDI was 2.6%. The occurrence of CDI was associated with substantial 1-year mortality, and patients experiencing CDI had a more than 2-fold increased risk of mortality compared with patients who remained free from CDI.

Incremental prognostic value of an abnormal baseline spatial QRS-T angle in chronic dialysis patients.

AIMS In order to improve the abysmal outcome of dialysis patients, it is critical to identify patients with a high mortality risk. The spatial QRS-T angle, which can be easily calculated from the 12 lead electrocardiogram (ECG), might be useful in the prognostication in dialysis patients. The objective of this study was to establish the prognostic value of the spatial QRS-T angle. METHODS AND RESULTS All patients who initiated dialysis therapy between 2002 and 2009 in the hospitals of Leiden (LUMC) and Amsterdam (AMC) at least 3 months on dialysis were included. The spatial QRS-T angle was calculated, from a routinely acquired ECG, and its relationship with mortality was assessed. An abnormal spatial QRS-T angle was defined as ≥ 130° in men and ≥ 116° in women. In total, 277 consecutive patients (172 male, mean age 56.3 ± 17.0) were included. An abnormal spatial QRS-T angle was associated with a higher risk of death from all causes [hazard ratio (HR) 2.33; 95% confidence interval (CI) 1.46-3.70] and especially a higher risk of sudden cardiac death (HR 2.99; 95% CI 1.04-8.60). Furthermore, an abnormal spatial QRS-T angle was of incremental prognostic value, when added to a risk model consisting of known risk factors. CONCLUSION In chronic dialysis patients the spatial QRS-T angle is a significant and independent predictor of all-cause and especially sudden cardiac death. It implies that this parameter can be used to identify high risk patients.

Suitability for subcutaneous defibrillator implantation: results based on data from routine clinical practice

Objective To assess the proportion of current implantable cardioverter defibrillator (ICD) recipients who would be suitable for a subcutaneous lead ICD (S-ICD). Design A retrospective cohort study. Setting Tertiary care facility in the Netherlands. Patients All patients who received a single- or dual-chamber ICD in the Leiden University Medical Center between 2002 and 2011. Patients with a pre-existent indication for cardiac pacing were excluded. Main outcome measure Suitability for an S-ICD defined as not reaching one of the following endpoints during follow-up: (1) an atrial and/or right ventricular pacing indication, (2) successful antitachycardia pacing without a subsequent shock or (3) an upgrade to a CRT-D device. Results During a median follow-up of 3.4 years (IQR 1.7–5.7 years), 463 patients (34% of the total population of 1345 patients) reached an endpoint. The cumulative incidence of ICD recipients suitable for an initial S-ICD implantation was 55.5% (95% CI 52.0% to 59.0%) after 5 years. Significant predictors for the unsuitability of an S-ICD were: secondary prevention, severe heart failure and prolonged QRS duration. Conclusions After 5 years of follow-up, approximately 55% of the patients would have been suitable for an S-ICD implantation. Several baseline clinical characteristics were demonstrated to be useful in the selection of patients suitable for an S-ICD implantation.

Trans-venous lead removal without the use of extraction sheaths, results of >250 removal procedures

AIMS The number of implanted cardiac rhythm devices has rapidly increased in the past decade. Subsequently, the need for lead extraction has also increased. Several techniques of lead removal have been documented from manual traction of the lead to lead extraction assisted with mechanical or laser sheaths. The goal of this study was to review our experience with lead removal using manual traction without the assistance of extraction sheaths. METHODS AND RESULTS In the Leiden University Medical Center all leads are removed using manual traction without the assistance of extraction sheaths. We have retrospectively reviewed all lead removal procedures performed between 2000 and 2009. Procedures were reviewed for indication, success, complication rates, and mortality. In total, 279 lead removal procedures were included. During these procedures 445 leads were removed. Time since lead implantation: 4.2 ± 4.7 years. During extraction 53(11.9%) leads fractured, of which >50% could still be completely removed using a femoral approach. A longer implantation duration [odds ratio (OR) 1.16 per year, 95% confidence interval (CI) 1.09-1.23] and passive fixation (OR 2.52, 95%CI 1.17-5.45) significantly associated with the chance of lead fracture during lead removal. Clinical success, using the primary approach of manual traction from the pectoral area, was obtained in 228 (84.8%) procedures. Major complications occurred in 2(0.7%) and minor in 13(4.7%) procedures. One patient died within 24 h after the procedure due to septic shock. There was no further mortality within the first month after the procedure. CONCLUSION Lead removal using manual traction, without the assistance of lead extraction sheaths, is clinically successful in ~85% of the lead extraction procedures. Concomitant morbidity and mortality are low. The highest clinical success (~95%) was observed in patients with leads implanted less than 2.6 years.

CT coronary angiography is feasible for the assessment of coronary artery disease in chronic dialysis patients, despite high average calcium scores.

Purpose Significant obstructive coronary artery disease (CAD) is common in asymptomatic dialysis patients. Identifying these high risk patients is warranted and may improve the prognosis of this vulnerable patient group. Routine catheterization of incident dialysis patients has been proposed, but is considered too invasive. CT-angiography may therefore be more appropriate. However, extensive coronary calcification, often present in this patient group, might hamper adequate lumen evaluation. The objective of this study was to assess the feasibility of CT-angiography in this patient group. Methods For this analysis all patients currently participating in the ICD2 trial (ISRCTN20479861), with no history of PCI or CABG were included. The major epicardial vessels were evaluated on a segment basis (segment 1–3, 5–8, 11 and 13) by a team consisting of an interventional and an imaging specialist. Segments were scored as not significant, significant and not interpretable. Results A total of 70 dialysis patients, with a mean age of 66±8 yrs and predominantly male (70%) were included. The median calcium score was 623 [79, 1619]. Over 90% of the analyzed segments were considered interpretable. The incidence of significant CAD on CT was 43% and was associated with cardiovascular events during follow-up. The incidence of cardiovascular events after 2-years follow-up: 36% vs. 0% in patients with no significant CAD (p<0.01). Conclusion Despite the high calcium scores CT-angiography is feasible for the evaluation of the extent of CAD in dialysis patients. Moreover the presence of significant CAD on CT was associated with events during follow-up.

Left Ventricular Diastolic Dysfunction in Dialysis Patients Assessed by Novel Speckle Tracking Strain Rate Analysis: Prevalence and Determinants

Background. Diastolic dysfunction is common among dialysis patients and is associated with increased morbidity and mortality. Novel echocardiographic speckle tracking strain analysis permits accurate assessment of left ventricular diastolic function, independent of loading conditions and taking all myocardial segments into account. The aim of the study was to evaluate the prevalence of diastolic dysfunction in chronic dialysis patients using this novel technique, and to identify its determinants among clinical and echocardiographic variables. Methods. Patients currently enrolled in the ICD2 study protocol were included for this analysis. Next to conventional echo measurements diastolic function was also assessed by global diastolic strain rate during isovolumic relaxation (SRIVR). Results. A total of 77 patients were included (age 67 ± 8 years, 74% male). When defined as E/SRIVR ≥236, the prevalence of diastolic dysfunction was higher compared to more conventional measurements (48% versus 39%). Left ventricular mass (OR 1.02, 95% CI 1.00–1.04, P = 0.014) and pulse wave velocity (OR 1.34, 95% CI 1.07–1.68, P = 0.01) were independent determinants of diastolic dysfunction. Conclusion. Diastolic dysfunction is highly prevalent among dialysis patients and might be underestimated using conventional measurements. Left ventricular mass and pulse wave velocity were the only determinants of diastolic dysfunction in these patients.