P2878Higher all-cause mortality in patients with implanted dual-chamber cardioverter-defibrillators for secondary prevention: an analysis from the Polish ICD Registry

Background

In the Polish ICD Registry population secondary prevention recipients account for over 27%. Despite the evolution of indications for secondary prevention implantable cardioverter defibrillators (ICDs), recommendations regarding the use of ICDs for secondary prevention of sudden cardiac death (SCD) rely on information from a small number of randomized controlled trials that were performed decades ago, with mixed results. Moreover, research on the outcomes after implantations for secondary prevention of ICDs is limited. While dual-chamber devices offer theoretical advantage over single-chamber devices, dual-chamber ICDs (DC-ICDs) were announced not superior to single-chamber (SC-ICDs) in some research.

Purpose

Therefore, the aim of the study was to evaluate the all-cause mortality among patients from the Polish ICD Registry receiving either a single- or a dual-chamber device for secondary prevention in contemporary clinical practice.

Methods

All patients enrolled in the Polish ICD Registry from 1995 to 2016 were identified. Patients were included in the study if they were designated as receiving an ICD for secondary prevention of SCD after documented tachycardic arrest, sustained ventricular tachycardia (VT), or syncope. Kaplan-Meier survival analysis was used to assess all-cause mortality.

Results

In the study population of 3596 ICD recipients (mean age 69±12 years, 81% male, SC-ICD 61%, DC-ICD 39%), during mean follow-up of 79±43 months all-cause mortality rate was higher in the dual-chamber group than in the single chamber group, with a significant difference between the two groups as depicted in Kaplan-Meier curve (p<0,05). The median survival time was 98 months versus 110 months for SC and DC-ICD, respectively.

Conclusions

This study is the first to describe the characteristics of a national cohort of patients receiving a secondary prevention ICD in such a long follow-up period in contemporary practice. Implantation of a dual-chamber ICD was associated with higher all-cause mortality compared with single chamber devices.

Recurrence of ventricular arrhythmias in patients with non-ischaemic dilated cardiomyopathy: evidence-based predictors

BACKGROUND

Ventricular arrhythmia (VA) is the most frequent cause of sudden death among patients with non-ischaemic dilated cardiomyopathy (DCM).

AIM

To identify the important VA risk factors in patients with DCM.

METHODS AND RESULTS

Eighty-five DCM patients (73 males, mean age 54 years) with DCM and implantable cardioverter defibrillators (ICD) were followed for 21+/-19 months after ICD implantation. The mean follow-up was 21 months. Data from 55 patients with VA recorded in the ICD memory and requiring ICD intervention during follow-up were compared with 30 patients without arrhythmia. Cox regression analysis identified the following univariate predictors of VA: alcoholic aetiology of DCM (0.05), diuretic treatment (0.003), history of cardiac arrest (0.03), right ventricular diastolic diameter (0.001). Both ACE inhibitor (ACEI) and statin treatments were associated with a tendency towards decreased risk of VA. Multivariate logistic analysis identified four predictors as significantly related to VA: alcoholic aetiology (HR 4.8, p=0.008), ACEI treatment (HR 0.4, p=0.01), diuretic treatment (HR 2.6, p=0.015), and statin treatment (HR 0.1, p=0.03).

CONCLUSIONS

The majority of patients with DCM and ICD have recurrences of VA. Alcoholic aetiology of DCM is associated with an increase in the incidence of arrhythmias. Treatment with ACEI and statins is associated with a reduction of arrhythmias.

[Long QT syndrome in the postpartum period]

The postpartum period can unmask LQTS. We described a case of 22-year-old woman with episode of lost of consciousness 6 months after delivery. Holter monitoring showed episodes of QTc prolongation, max. QTc - 618 ms, medium QTc - 538 ms with different morphology types of T wave. Beta-blocker (BB) therapy (metoprolol was initiated) and titrated up to 200 mg daily. The patient was out of symptoms. After 2 years during the second pregnancy she reduced BB to 50 mg/day. In the postpartum period, 3 months after delivery she had syncopal episodes. Holter monitoring showed polymorphic ventricular tachycardia. The cardioverter-defibrillator was implanted.

[Atrial fibrillation in the long QT syndrome]

A case of a 58-year-old woman with occasionally diagnosed persistent atrial fibrillation (AF) is presented. The patient for many years experienced palpitations relived by oral propranolol treatment. After electrical cardioversion of AF to sinus rhythm prolongation of the QTc interval up to 520 ms became evident. Molecular screening of LQTS-related genes revealed the presence of R231S mutation in the KCNQ1 gene.

[QTc duration in the long QT syndrome type 2 - diagnostic dilemma]

We present a case of a 43-year old woman with a long QT syndrome (LQTS). Despite her family history of several sudden deaths in close relatives the patient was misdiagnosed, being treated many years for epilepsy. Finally, after another series of syncopal spells she was diagnosed with LQTS. Although QTc interval was normal on surface ECG, the presence of notched T-waves and QT prolongation up to 543 ms on Holter recording were helpful in establishing the correct diagnosis, which was later confirmed by genotyping revealing G601S mutation in the HERG gene. The patient refused an ICD and despite beta-blocker treatment died suddenly several months later.

Effects of shock polarity reversal on defibrillation threshold in an implantable cardioverter-defibrillator

BACKGROUND

An increased defibrillation threshold (DFT) may limit the efficacy of an implantable cardioverter-defibrillator (ICD) in termination of life-threatening ventricular arrhythmias. A search for methods of decreasing DFT has been ongoing since the introduction of ICD into clinical practice.

AIM

To assess the effects of various shock polarities on DFT.

METHODS

The study group consisted of 19 patients (8 females and 11 males, mean age 52+/-17 years) who received devices (Biotronik, Germany) with a single-coil defibrillation lead. In all patients the value of DFT was assessed using a normal shock polarity as well as using a reversed polarity shock, starting from the energy lower than that measured during normal DFT testing. The impedance of the defibrillation system using two different polarities was also measured. The effects of demographic and clinical parameters on defibrillation parameters were also examined.

RESULTS

When using normal shock polarity, the mean DFT value was 12+/-5 J (range 3.1-20 J) and impedance was 64+/-12 Omega. When shock polarity was reversed, the mean DFT value was 9.2+/-5.0 J (range 2-20 J) and impedance was 67+/-11 Omega. In 11 (58%) patients the polarity change caused a marked (by 37%) decrease in the mean DFT value - from 11.5+/-5.1 J to 7.2+/-3.8 J. In 5 patients DFT reduction was > or = 5 J. There was no relationship between demographic or clinical parameters and defibrillation efficacy using the two tested shock polarities.

CONCLUSIONS

The reversal of shock polarity reduces DFT in more than half of patients. In patients with a high DFT the use of reversed polarity of defibrillating impulse may reduce DFT, which widens the safety margin and makes implantation of additional leads unnecessary. Because clinical parameters have no value in predicting the effects of polarity changes on DFT, the efficacy of reversed polarity shock has to be assessed individually in each patient.

[Estimation of defibrillation threshold using abdominally implanted cardioverter-defibrillator with an additional defibrillation pole in a dual-coil lead endocardial defibrillation system]

Safety of patients treated with an implanted cardioverter-defibrillator (ICD) depends on defibrillator threshold (DFT). In patients with frequent ICD interventions the high DFT influences battery life-time. The aim of the study was to compare DFT in abdominally placed ICD with an active and passive can and dual-coil endocardial leads.

MATERIAL AND METHODS

The study involved 9 patients (4 F and 5 M, mean age 56 +/- 19 years) with previously implanted in abdominal position ICD with passive can and dual-coil defibrillation lead. In all patients DFT was measured using active and passive can ICD at the time of planed generator replacement.

RESULTS

Compared to the passive can, the abdominal active can ICD lowered DFT in 6 patients (66%), in 1 patients the DFT increased, whereas in 2 patients we observed no change in DFT. The mean DFT measured with the passive can ICD was 11.6 +/- 5.2J (5.1-20J) and with the active can was 9,3 +/- 4,5J (3-18J). The mean defibrillation resistance was 64 +/- 11W (48-84W) and 55 +/- 8W (47-70W) in passive and active can respectively. Active can ICD decreased the DFT by 20% (p = 0.049) and the defibrillation resistance by 23% (p = 0.012).

CONCLUSIONS

An abdominally positioned active can ICD with dual coil defibrillation leads allowed to lower DFT and defibrillation resistance in a majority of patients. It seems useful to replace previously implanted passive can ICDs with an active ones particularly in patients with high DFT.

Comparison of defibrillation efficacy using implantable cardioverter-defibrillator with single- or dual-coil defibrillation leads and active can

INTRODUCTION

The reduction of defibrillation threshold (DFT) in patients treated with an implantable cardioverter-defibrillator increases patients' safety and prolongs ICD battery life.

AIM

To evaluate the possibility of reducing the defibrillation threshold in ICDs with an active can and an additional atrial defibrillation coil instead of the typical intracardiac single-coil lead.

METHOD

This study involved 138 patients (36 F and 102 M, mean age 54+/-15 years) including 62 subjects with dual-coil defibrillation lead (group A) and 76 ones with single-coil defibrillation lead (group B). No statistically significant differences with respect to age, left ventricular function, main disease or exacerbation of heart failure according to the NYHA functional class were observed between groups. The defibrillation threshold was measured using the DFT+ protocol.

RESULTS

No significant differences between groups were identified with respect to pacing and sensing parameters. The comparison of DFT values between the two studied groups revealed significant improvement (by 14% mean) of defibrillation efficacy in group A. In group A, the mean DFT was 9.8+/-4.6 J (3-20 J) and mean defibrillation resistance - 45+/-7 W (32-73 W), whereas in group B: 11.45+/-5.25 J (3-28 J) and 72+/-12.8 W (38-106 W), respectively. In 93% of patients from group A, DFT was below 15 J, in comparison to 81% of patients from group B (p=0.046). The odds ratio of a higher defibrillation threshold (ł15 J) in group A vs. group B was 0.3 (95% confidence interval: 0.09-0.98). The DFT reduction associated with modified ICD system use was independent of following clinical parameters: patient age, gender, main disease, end-diastolic left ventricular diameter, left ventricular ejection fraction, NYHA functional class and concomitant treatment with antiarrhythmic agents.

CONCLUSIONS

Modification of the electric field during defibrillation, achieved with the use of active-can ICDs with dual-coil defibrillation leads, allows a reduction of DFT by 14%. At the same time, it reduces the risk of a higher (> or =15 J) DFT by three times compared to patients with a standard single-coil defibrillation lead.

Clinical predictors of defibrillation threshold in patients with implantable cardioverter-defibrillators

BACKGROUND

Safety of patients with malignant ventricular arrhythmias, treated with implantable cardioverter defibrillators (ICD), depends on the possibility of immediate and effective intracardiac defibrillation. It is especially important in those patients in whom there is a risk of increased defibrillation threshold (DFT) of ventricular fibrillation (VF). Thus, it is important to know whether some clinical parameters may predict a high DFT.

AIM

To assess the relationship between DFT and clinical, demographic and anthropometric parameters, type and progression of underlying disease as well as antiarrhythmic therapy used in ICD recipients.

METHODS

The study group consisted of 168 patients (47 females, 121 males, mean age 55+/-15 years, range 15-82 years) who were selected to receive an ICD. DFT was systematically tested during ICD implantation in all patients. Various clinical, demographic, anthropometric and echocardiographic parameters were analysed as the function of DFT value, examining their accuracy in predicting a high (> or =15 J) or a low (<15 J) DFT, using logistic regression model.

RESULTS

Univariate analysis revealed that DFT value was significantly related to the following parameters: idiopathic VF, dilated cardiomyopathy, amiodarone therapy and the use of beta blockers. There was a significant correlation between DFT and LVEDD, height, LVEF and impedance of defibrillating system. Multivariate analysis showed that amiodarone therapy, height, impedance of defibrillating system and LVEDD were independently related to the DFT value. Parameters which predicted a high (> or =15 J) DFT, consisted of amiodarone therapy (p=0.005), height (p=0.01), LVEDD (p=0.01), LVEF (p=0.03), dilated cardiomyopathy (p=0.01) and body surface area (p=0.049). Amiodarone therapy occurred to be the only parameter which independently predicted a high DFT (odds ratio 2.78; 95% confidence interval 1.19-6.5).

CONCLUSIONS

Tall stature, enhanced LVEDD, decreased LVEF and amiodarone therapy increase the risk of a high DFT in ICD recipients. Chronic amiodarone therapy increases three times the risk of elevated DFT. In patients with already implanted ICD in whom amiodarone is started, reassessment of DFT following administration of a loading dose of the drug is required.