Implantable defibrillator therapy: more than defibrillation...

During the past 25 years, the implantable cardioverter-defibrillator (ICD) has evolved from the treatment of last resort to the gold standard for patients at high risk for life­threatening ventricular tachyarrhythmias. Patients at high risk include those who survived life-threatening ventricular tachyarrhythmias, and patients with cardiac diseases who carry an increased risk for these tachyarrhythmias. We performed a clinical assessment during implantation and follow-up of our patients in Rotterdam. Part I Prognosis and follow-up of patients with an ICD In Chapter 1, the clinical benefit of ICD therapy, survival, and adverse events of patients who received an ICD at the Erasmus MC Rotterdam are described. Our data confirm the benefit from ICD implantation, especially for those patients with a poor left ventricular function. In Chapter 2, defibrillation efficacy testing is investigated. The role of a second defibrillation threshold test after implantation appears questionable. With the advances in ICD technology, defibrillation thresholds are low and stable, which changed the mode of death in ICD patients from instantaneous arrhythmic death to heart failure. Our data demonstrate that despite the advanced ICD technology, a subset of patients may require a second defibrillation efficacy test to confirm a poor prognosis. The feasibility of remote monitoring of ICD therapy is discussed in Chapter 3. The expanding indications for ICD therapy and the complexity of current devices have a high impact on follow-up policy. Currently, the quality of medical supervision only depends on scheduled regular follow-up visits, which is time consuming and expensive. Too long follow-up intervals may have the disadvantage of a delay in the awareness of changes of the clinical course of the underlying disease or in the technical status of the device. TransmiHet concept van de implantable cardioverter-defibrillator (ICD) heeft de afgelopen 25 jaar een grote ontwikkeling doorgemaakt. De eerste generatie defibrillatoren was uitsluitend in staat om ventrikelfibrilleren te herkennen en te onderbreken door middel van een elektrische shock. De volgende generaties defibrillatoren werden uitgerust met functies om verschillende ritmestoornissen te herkennen en te behandelen. Vanuit klinisch oogpunt is er een verschuiving opgetreden van secundaire preventie naar primaire preventie van plotse dood ten gevolge van ventriculaire ritmestoornissen. Dit proefschrift beschrijft zowel de klinische als technische aspecten van defibrillator therapie. Deel 1 Prognose en follow-up van ICD patiënten Hoofdstuk 1 beschrijft zowel het klinische voordeel als de potentiële complicaties van defibrillator therapie bij patiënten, bij wie een ICD in het Erasmus MC werd geïmplanteerd. De rol van het testen van de defibrillatie effectiviteit wordt in Hoofdstuk 2 behandeld. Door de technische vooruitgang kunnen ventriculaire ritmestoornissen effectief met lage energie gedefibrilleerd worden. Vanuit dit technisch oogpunt is een tweede defibrillatie test niet nodig, echter vanuit klinisch oogpunt kan deze test een slechte prognose bij een kleine groep patiënten bevestigen. Veranderingen in de klinische status van de ICD patiënt worden vaak pas vastgesteld bij het volgende poliklinisch bezoek. In Hoofdstuk 3 wordt de mogelijkheid van het op afstand waarnemen van zowel klinische als technische aspecten van defibrillator therapie beschreven. Het verzenden van opgeslagen data in de ICD heeft een potentiële meerwaarde voor de klinische follow-up van de patiënt. Ter illustratie wordt in Hoofdstuk 4 een voorbeeld van het op afstand waarnemen van ICD data gepresenteerd. Bij interpretatie van de ontvangen data werd een malfunctie van de ventriculaire elektrode vastgesteld. Deel 2 Onderscheiden van ritmestoornissen door de ICD Hoofdstuk 5 behandelt een voorbeeld van een opgeslagen registratie van een ventriculaire ritmestoornis, die na nauwkeurige analyse een ander ontstaansmechanisme heeft dan het op eerste oog doet lijken. In Hoofdstuk 6 wordt een nieuw tweekamer detectie algoritme, SMART, geëvalueerd. Na de vergelijking van de atriale en ventriculaire frequentie worden enkelkamer detectie criteria toegepast om een ritmestoornis te classificeren. Ventriculaire ritmestoornissen worden met behulp van dit algoritme betrouwbaar waargenomen. Ondanks een goede discriminatie tussen atriale en ventriculaire ritmestoornissen, worden atriale ritmestoornissen met een stabiele atrioventriculaire geleiding vooral verkeerd geclassificeerd. De ontwikkeling van detectie algoritmen om onterechte therapie ten gevolge van atriale ritmestoornissen te vermijden, wordt in Hoofdstuk 7 gepresenteerd. De classificatie van de ritmestoornis door de ICD is primair gebaseerd op de timing van ventriculaire signalen. De originele eenkamer detectie algoritmen zijn in de tweekamer ICD geïmplementeerd. De toevoeging van atriale informatie heeft tot betere en geavanceerde detectie algoritmen geleidt. Echter, onderzoeken die eenkamer met tweekamer detectie algoritmen vergeleken, lieten geen afname van onterechte therapie zien. Hoofdstuk 8 gaat over klinische variabelen die een verhoogd risico op onterechte therapie kunnen voorspellen. Uit onderzoek blijkt dat de aanwezigheid van atriale ritmestoornissen in het verleden en het voorkomen van trage ventriculaire ritmestoornissen, beide een verhoogd risico op onterechte therapie voorspellen. De beslissing om een tweekamer defibrillator bij patiënten met atriale ritmestoornissen te implanteren is een open vraag. Onterechte therapie werd namelijk in gelijke mate bij zowel eenkamer als tweekamer defibrillatoren waargenomen. Een gerandomiseerd onderzoek tussen eenkamer en tweekamer detectie algoritmen wordt in Hoofdstuk 9 gepresenteerd. De resultaten van dit onderzoek laten geen verschil zien in de discriminatie

Emerging electromagnetic interferences between implantable cardioverter-defibrillators and left ventricular assist devices: Authors' reply

Aims To investigate the prevalence of electromagnetic interference (EMI) between left ventricular assist devices (LVADs) and implantable cardioverter-defibrillators (ICDs)/pacemakers (PMs). ................................................................................................................................................................................................... Methods and results A retrospective single-centre study was conducted, including all patients undergoing HeartMate II (HMII) and HeartMate 3 (HM3) LVAD implantation (n = 106). Electromagnetic interference was determined by the inability to interrogate the ICD/PM. Overall, 85 (mean age 59 ± 8, 79% male) patients had an ICD/PM at the time of LVAD implantation; 46 patients with HMII and 40 patients with HM3. Among the 85 LVAD patients with an ICD’s/PM’s, 11 patients (13%) experienced EMI; 6 patients (15%) with an HMII and 5 patients (11%) with an HM3 (P = 0.59). Electromagnetic interference from the HMII LVADs was only present in patients with a St Jude/Abbott device; 6 of the 23 St Jude/Abbott devices. However, in the HM3 patients, EMI was mainly present in patients with Biotronik devices: 4 of the 18 with only one (1/25) patient with a Medtronic device. While initial interrogation of these devices was not successful, none of the 11 cases experienced pacing inhibition or inappropriate shocks. ................................................................................................................................................................................................... Conclusion In summary, the prevalence of EMI between ICDs in the older and newer type of LVAD’s remains rather high. While HMII patients experienced EMI with a St Jude/Abbott device (which was already known), HM3 LVAD patients experience EMI mainly with Biotronik devices. Prospective follow-up, preferably in large registries, is warranted to investigate the overall prevalence and impact of EMI in LVAD patient

Extreme interatrial conduction delay and regularization of atrial arrhythmias in a subgroup of patients with hypertrophic cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) patients may develop interatrial activation delay, indicated by a complete separation of the right and left atrial activation on the ECG. This study aimed to determine the prevalence of interatrial activation delay and the relation to atrial tachycardia (AT) cycle length (CL) in HCM patients. Methods: 159 HCM patients were included (mean age 52±14y). In group I (n=15, 9%) patients had atrial arrhythmias and progressive ATCL. In group II (n=22, 14%) patients had a stable ATCL. In group III (n=122, 77%) HCM patients without AT were included. P wave morphology and change in P wave duration (δP and Pmax) and changes in ATCL (δATCL) were analyzed. Mean follow-up was 8.7±4.7years. Results: In group I 33% (n=5) had separated P waves. In group II no P wave separation was identified (OR 1.50 [1.05-2.15], p=0.007). In group I patients were older compared to group III (62.6±15.1 vs. 50.2±14.0y, p=0.002) and had longer follow-up (13.4±2.2 vs. 7.8±4.6y, p<0.001). In group III Pmax and δP were significantly lower (105.1±22.0ms and 8.9±13.2ms, both p<0.0001). Group I patients had an increased LA size compared to group II (61.1±11.6 vs. 53.7±7.5mm, p=0.028) and higher E/A and E/E prime ratios (p=0.007; p=0.037, respectively). In group I 93.3% of the identified mutations were typical Dutch founder mutations of the MYBPC3 gene. Conclusion: In HCM patients a unique combination of separated P waves and regularization of ATs is associated with larger atria, higher LA pressures and myosin binding protein mutations

Poor health status and distress in cardiac patients: The role of device therapy vs. underlying heart disease

AimsImplantable cardioverter defibrillator (ICD) therapy, which includes the risk of shocks, is considered the primary culprit of reductions in patient reported outcomes (PROs; e.g. health status and distress), thereby negating the role of underlying disease severity. We examined the relative influence of living with an ICD vs. congestive heart failure (CHF) on PROs and compared (i) ICD patients without CHF (ICD only), (ii) CHF patients without an ICD (CHF-only), and (iii) CHF patients with an ICD (ICD + CHF).Methods and resultsSeparate cohorts of ICD and CHF patients (N = 435; 75% men) completed PROs at baseline, 6 and 12 months. Groups differed on physical health status only at baseline (F(2,415) = 7.15, P = 0.001) and on anxiety at 12 months (F(2,415) = 4.04, P = 0.01); ICD + CHF patients had the most impaired physical health status but the lowest anxiety level followed by the ICD only and CHF only patients. Congestive heart failure only patients had the most impaired mental health status and reported the highest level of anxiety as compared to the ICD only (P < 0.001) and ICD + CHF groups (P = 0.009), while the two latter groups did not differ. The effect sizes ranged from very small (0.03) to moderate-large (0.69). Groups did not differ in depression scores.ConclusionCongestive heart failure patients reported worse PROs as compared to ICD patients, although the magnitude of the differences was relatively small. This suggests that the well being of patients is not necessarily negatively influenced by the implantation of an ICD, and that underlying heart disease may have at least an equal if not greater influence on PROs

Remote monitoring of heart failure: benefits for therapeutic decision making

Introduction: Chronic heart failure is a cardiovascular disorder with high prevalence and incidence worldwide. The course of heart failure is characterized by periods of stability and instability. Decompensation of heart failure is associated with frequent and prolonged hospitalizations and it worsens the prognosis for the disease and increases cardiovascular mortality among affected patients. It is therefore important to monitor these patients carefully to reveal changes in their condition. Remote monitoring has been designed to facilitate an early detection of adverse events and to minimize regular follow-up visits for heart failure patients. Several new devices have been developed and introduced to the daily practice of cardiology departments worldwide. Areas covered: Currently, special tools and techniques are available to perform remote monitoring. Concurrently there are a number of modern cardiac implantable electronic devices that incorporate a remote monitoring function. All the techniques that have a remote monitoring function are discussed in this paper in detail. All the major studies on this subject have been selected for review of the recent data on remote monitoring of HF patients and demonstrate the role of remote monitoring in the therapeutic decision making for heart failure patients. Expert commentary: Remote monitoring represents a novel intensified follow-up strategy of heart failure management. Overall, theoretically, remote monitoring may play a crucial role in the early detection of heart failure progression and may improve the outcome of patients

Evaluation of recurrent ventricular tachyarrhythmias in patients who survived out-of-hospital cardiac arrest due to ventricular fibrillation: eligibility for subcutaneous implantable defibrillator therapy

Purpose: The subcutaneous implantable defibrillator (S-ICD) was developed to avoid complications related to transvenous leads. A trade-off with the S-ICD is the inability to deliver antitachycardia pacing (ATP). Data is scarce about the recurrence and characteristics of ventricular tachyarrhythmias (VTa) during a follow-up in survivors of out-of-hospital cardiac arrest due to ventricular fibrillation (OHCA-VF). The aim of the study is to determine the characteristics of VTa triggering ICD therapy in order to assess whether survivors of OHCA-VF are eligible candidates for the S-ICD. Methods: All OHCA-VF patients who received a transvenous ICD were identified, 378 patients, age 57 ± 14 years, predominantly male (76%) with ischemic heart disease (58%). Arrhythmic endpoints were appropriate ICD therapies for any ventricular arrhythmia. Results: Over a median follow-up of 4.5 years, 690 VTa in 91 patients (24%) were terminated by ICD therapy; 70% of patients had 300 ms were treated by ATP. The presence of a remote myocardial infarction (OR 2.07; 95% CI 1.08–3.97) and LVEF ≤ 0.35 (OR 2.09; 95% CI 1.09–4.00) were significantly associated with the occurrence of VTa with cycle length > 300 ms. Conclusion: S-ICD implantation may be reasonable in survivors of OHCA-VF who present without a remote myocardial infarction and LVEF > 35%

Prospective blinded evaluation of a novel sensing methodology designed to reduce inappropriate shocks by the subcutaneous implantable cardioverter-defibrillator

Background: Most inappropriate shocks from the subcutaneous implantable cardioverter-defibrillator (S-ICD) are caused by cardiac oversensing. A novel sensing methodology, SMART Pass (SP; Boston Scientific Corporation, Natick, MA), aims to reduce cardiac oversensing. Objective: The purpose of this study was to evaluate the effect of SP on shocks in ambulatory patients with S-ICD. Methods: Patients implanted in 2015–2016 and enrolled in a remote patient monitoring system were included and followed for 1 year. Shocks were adjudicated by 3 independent blinded reviewers as appropriate or inappropriate. Shock incidence was calculated for patients with SP programmed enabled or disabled at implantation, censoring patients when SP programming changed or at the last transmission. The SP setting (enabled vs disabled) was modeled as a time-dependent Cox regression variable. Results: The cohort consisted of 1984 patients, and a total of 880 shocks were adjudicated. At implantation, SP was enabled in 655 patients (33%) and disabled in 1329 patients (67%). SP reduced the risk for the first inappropriate shock by 50% (P <.001) and the risk for all inappropriate shocks by 68% (P <.001) in multivariate analysis adjusted for age and device programming. The incidence of inappropriate shocks was 4.3% in the SP enabled arm vs 9.7% in the SP disabled arm. The incidence of appropriate shocks was similar (5.2