Role of cardiac electronic implantable device in the stratification and management of embolic risk of silent atrial fibrillation: are all atrial fibrillations created equal?

Introduction: Ischemic strokes may be associated with atrial fibrillation (AF). AF detection is critical in ischemic stroke survivors, often recommending a switch from antiplatelet therapy to oral anticoagulants for secondary prevention.

Areas covered: Cardiac implantable electronic devices (CIED) with their long-term recording capability allows to document AF and to quantify the arrhythmia burden. Recent series in pacemaker and implantable cardioverter-defibrillator (ICD) recipients with no prior stroke showed that short episodes of AF increased stroke risk compared with those without AF recorded. Detection of AF by CIEDs represent a unique opportunity for promp prevention of embolic risk in silent AF. It will be attractive to identify AF before a stroke occurs.

Expert commentary: The purpose of this article is to review the role of CIED to detect AF, to quantify the role of AF burden, and to guide primary and secondary stroke prevention.     

The Implantable Cardioverter-Defibrillator: Clinical Results

To evaluate the effectiveness of the automatic implantable cardioverter-defibrillator (AICD), a 7-year experience, from 1983–1990, was reviewed. A total of 111 patients received an AICD device. Their ages ranged between 8 and 83 years. Mean age was 63.9 years. There were 91 men and 20 women. Eighty of the patients received the AICD following an out-of-hospital cardiac arrest, white 32 were suffering from intermittent symptomatic ventricular tachycardia. The underlying etiology in 97 patients (87%) was ischemic coronary artery disease, in 11 patients (10%) dilated cardiomyopathy, and in 3 patients (3%) idiopathic ventricular fibrillation. Mean ejection fraction was 33.2%. Implantation of the AICD was performed via a left thoracotomy in 39 patients, median sternotomy in 49 patients and subxiphoidsubcostal approach in 23 patients. In-hospital mortality occurred in one patient who suffered an acute myocardial infarction 4 hours postoperatively. Out-of-hospital mortality was observed in 19 patients. There were two arrhythmic deaths. Follow-up was available for 107 patients. Mean follow-up was 33.1 months. Sixty-six patients (62%) had AICD shocks. The initial appropriate shocks occurred during the first postimplantation year in 91% of the patients. In 53 of the survivors, initial AICD shocks took place within 4.4 ± 4.7 months from implantation. Thirteen of the 20 patients who died had received appropriate AICD shocks. In these patients, the time between implantation and first shock was 2.7 ± 3.6 months whereas the time between implantation and death was 11.3 ± 10.3 months (NS). We conclude that the AICD is effective in converting ventricular tachyarrhythmias and prolongs survival.     

Campylobacter fetus infection of an internal cardioverter defibrillator

Infection is a serious complication post implantation of an implantable cardiac defibrillator (ICD). We report a case of a 77-year-old man who had an ICD generator change complicated by a hematoma. The generator became infected at the time of Campylobacter fetus bacteremia. The ICD was removed and a new device was implanted without complication.     

Implantable defibrillator use for de novo ventricular tachyarrhythmias encountered after cardiac surgery

De novo postoperative life-threatening ventricular arrhythmias are poorly understood. Long-term benefits of, and need for, treatment is uncertain. To assess the therapeutic advantage of ICD to manage new-onset, life-threatening ventricular tachyarrhythmias after cardiac surgery. Patients included were those with an ICD implanted for de novo life-threatening ventricular tachyarrhythmias encountered 48 hours or more after cardiac surgery. Primary endpoints were total survival, time to first ICD therapy, and appropriateness of ICD therapy. Mean projected survival and projected time to first ICD therapy were calculated by the Kaplan-Meier method. Twenty-seven postoperative patients (left ventricular ejection fraction 0.22 +/- 0.07) were followed for 26 +/- 17.6 months. The index arrhythmia was sustained monomorphic ventricular tachycardia in 17 (63%) and ventricular fibrillation in 10 (37%). Electrophysiological study was positive in 22 (81%) of 27. Total survival and mean projected survival after ICD implant were 22 (81%) of 27 and 25.6 months, respectively, to end of follow-up. The majority received ICD therapy (21/27 [78%]), 20 (74%) of 27 receiving appropriate therapy. The mean time to first ICD therapy and mean projected time to first ICD therapy was 5.6 +/- 7.8 months and 10.5 months, respectively. De novo postoperative ventricular arrhythmias are associated with a high probability of late recurrence. The ICD is useful for these patients.     

Actuarial Incidence and Pattern of Occurrence of Shocks Following Implantation of the Automatic Implantable Cardioverter Defibrillator

The actuarial incidence and pattern of occurrence of shocks were analyzed in 65 patients after implantation of the automatic implantable cardioverter defibrillator. During a mean follow-up of 25 +/- 21 months only one patient died suddenly, and this patient had a nonfunctioning device at the time of death. The long-term actuarial risk of death from any cause in the patients who received appropriate shocks was not significantly different than for the entire group. The 1- and 4-year cumulative risk of receiving any shock was 51 +/- 7% and 81 +/- 11%; of receiving an appropriate shock was 33 +/- 7% and 64 +/- 10%; of receiving a spurious shock was 17 +/- 5% and 21 +/- 6%; and of receiving an "indeterminate" shock was 19 +/- 6% and 52 +/- 10%. In 14 patients who were followed for 24 months without receiving an appropriate shock, the actuarial risk of receiving an appropriate shock was 29 +/- 14% during the next 24 months. The mean number of shocks delivered during appropriate episodes was 1.6 +/- 0.9, which was significantly lower than the mean of 4.0 +/- 2.0 shocks during spurious episodes (P less than 0.02). The mean number of shocks during indeterminate episodes was 1.7 +/- 1.5. Our data confirms the efficacy of the implantable defibrillator in preventing sudden death. The majority of patients with this device receive appropriate shocks during long-term follow-up, and the cumulative incidence of appropriate shocks increases steadily for at least 4 years. In contrast, the cumulative incidence of spurious shocks plateaus at about 12 months. Our data suggests that many "indeterminate" shocks actually appear to be appropriate.     

Electroconvulsive therapy in patients with cardiac pacemakers and implantable cardioverter defibrillators

Electroconvulsive therapy (ECT) is used to treat major depressive illness, especially in elderly and medically frail patients. Not uncommonly, these patients have cardiac pacemakers or implantable cardioverter defibrillators (ICDs). Only a few case reports in the literature describe the use of ECT in such patients. Herein we review our ECT experience treating 26 pacemaker patients and 3 ICD patients. All patients obtained significant antidepressant benefits with ETC. Only one serious cardiac event occurred, a case of supraventricular tachycardia (SVT) requiring a stay on the cardiac intensive care unit. The SVT resolved and the patient went on to receive further uncomplicated ECT treatments. We conclude from this experience that with proper pre-ECT cardiac and pacemaker/defibrillator assessment, ECT can be safely and effectively administered to patients with an implanted cardiac device.     

Recurrent pericardial chest pain: a case of late right ventricular perforation after implantation of a transvenous active-fixation ICD lead

A 36-year-old woman with a history of recurrent syncopal episodes presumably due to ventricular tachyarrhythmia in mitral valve prolapse underwent implantation of a transvenous ICD system. During a 23-month follow-up, she developed recurrent pericardial chest pain with pericardial friction rub. The first episode of chest pain occurred without any detectable change in pacing or sensing parameters. The second episode was associated with an increase in pacing threshold and drop in intracardiac signal amplitude. Right ventricular perforation was suspected fluoroscopically and confirmed by right ventriculography. This case report emphasizes the key steps in the diagnosis of this rare complication of an ICD implantation.     

Implantable Cardioverter Defibrillator Therapy for Prevention of Sudden Cardiac Death in Children in The Netherlands

Introduction: Implantable cardioverter defibrillator (ICD) therapy is increasingly used in children. The purpose of this multicenter study is to evaluate mid‐term clinical outcome and to identify predictors for device discharge in pediatric ICD recipients. Methods and Results: From 1995 to 2006, 45 patients in The Netherlands under the age of 18 years received an ICD. Mean age at implantation was 10.8 ± 5.2 years. Primary prevention (N = 22) and secondary prevention (N = 23) were equally distributed. Underlying cardiac disorders were primary electrical disease (55%), cardiomyopathy (20%), and congenital heart disease (17%). The follow‐up was 44 ± 32.9 months. Three patients (7%) died and one patient (2%) underwent heart transplantation. ICD‐related complications occurred in eight patients (17%), seven of whom had lead‐related complications. Fourteen patients (31%) received appropriate ICD shocks; 12 patients (27%) received inappropriate ICD shocks. Fifty‐five percent of 22 ICD recipients under the age of 12 years received appropriate shocks, which was higher as compared with 9% of 23 older ICD recipients (P = 0.003). Although the incidence of appropriate shocks in the present study was larger in secondary prevention (9/23; 39%) as compared with primary prevention (5/22; 23%), this difference did not reach significance. Conclusions: In our population of patients, children <12 years of age had more appropriate shocks than patients 13–18 years. The complication rate is low, and is mainly lead related. (PACE 2010; 33:179–185)     

Can the Heart be Chronically Paced with Electrodes on the Pericardial Surface?

During implantable defibrillator (ICD) operations, we measured acute and chronic transpericardial bipolar pacing thresholds through standard myocardial surface electrodes sewn on the pericardium for chronic ICD QRS rate-sensing use. We compared observations in 24 patients on day 0 with chronic measurements in seven patients at 27,4 ± 12.1 (median 31.7) months. The leads were used only for QRS rate-sensing, not for pacing, during the time between acute and chronic measurements. Acute transpericardial pacing threshold at 0.5-msec stimulus duration on day 0 was 4.5 ± 2.19 V (standard deviation), median 3.5 V, and at median time 964 days postimplantation was 3.8 ± 2.07 V, median 3.5 V. Mean acute pacing current threshold was 3.7 ± 1.90 mA, n = 23, and chronic was 2.7 ± 1.73 mA, n = 6. Acute bipolar impedance was 1,209 ± 383 ohms, median 1,138 ohms, and chronic was 1,550 ± 358 ohms, median 1,410 ohms, n = 7. Acute bipolar QRS amplitude was 12.3 ± 5.93 mV, median 12.1 mV, n = 24, and chronic was 13.5 ± 8.5 mV, median 17.2 mV, n = 7. None of the changes between the acute and chronic states was statistically significant, with the exception of bipolar impedance (P = 0.054). We concluded that: (1) transpericardial pacing threshold did not increase with time; (2) initial and chronic pacing impedances were high and current low; (3) QRS amplitudes were highly satisfactory for defibrillator rate-sensing; and (4) this approach to ICD implantation left the surgically virgin heart unscarred to make future transplantation easier, and enhanced safety when previous cardiac operations had been done.     

Ventriculoatrial Conduction Capability and Prevalence of 1:1 Retrograde Conduction During Inducible Sustained Monomorphic Ventricular Tacbycardia in 305 Implantable Cardioverter Defibrillator Recipients

Retrograde Conduction During Inducible Sustained Monomorphic Ventricular Tachycardia in 305 Implantable Cardioverter Defibrillator Recipients. Despite the advent of dual chamber ICDs, differentiation of VT (SMVT) with 1:1 VA conduction will remain a challenge. In this study, VA conduction capability and prevalence of inducible sustained monomorphic (SM) VT with 1:1 VA conduction was assessed in 305 ICD recipients. SMVT with a mean cycle length (CL) of 304 ± 61 ms was induced in 161 (53%) patients. Twenty-six percent of the patients maintained 1:1 VA conduction to CL ≤ 400 ms during incremental ventricular pacing, regardless of presenting tachyarrhythmia or presence of inducible SMVT. Among ten patients who had inducible SMVT with possible 1:1 VA conduction (based on SMVT CL comparable to the shortest CL associated with 1:1 retrograde conduction during ventricular pacing), all seven with available intracardiac tracings had documented 1 :1 VA conduction during the induced SMVT—representing 4.4% of the patients with inducible SMVT (95% CI 1.2%-7.6%), and 2.3% of the entire ICD cohort (95% CI 0.6%-4.0%). We conclude that about one-fifth of ICD recipients possess 1:1 VA conduction to CL ≤ 400 ms and that inducible SMVT with 1:1 VA conduction can be demonstrated in a small hut nonnegligible proportion of ICD recipients. These data are relevant to the design of tachyarrhythmia-discrimination algorithms for dual chamber ICDs.     

Successful use of a transvenous dual-chamber automatic implantable cardiac defibrillator after a classic Fontan operation for tricuspid atresia

We report the first successful totally percutaneous pacing and defibrillation of a single ventricle in a 52-year-old woman who had undergone a classic Fontan operation (atriopulmonary connection) for tricuspid atresia 21 years earlier. Left ventricular pacing and sensing was obtained with a bipolar lead in the lateral cardiac vein, and defibrillation was obtained with a coronary sinus coil lead and an "active can" in the retromammary position to optimize the current vector. This approach has significant potential benefits because it avoids a repeat thoracotomy, with its associated mortality and morbidity.     

Distinct clinical features in the recipients of the implantable cardioverter defibrillator in Taiwan: a multicenter registry study

Little information about the ICD is available from the Asian Pacific region. The purpose of this study was to characterize the clinical features in ICD patients in Taiwan and to compare these features with those in patients in the Western populations, mainly the Canadian Implantable Defibrillator Study (CIDS), the Antiarrhythmics versus Implantable Defibrillator (AVID) trial, and the Cardiac Arrest Study Hamburg (CASH) trial. From February 1995 to October 2001, 101 ICDs were implanted in 92 patients (78 [84%] men) in 12 hospitals. Clinical presentations included sudden cardiac death due to VF/VT in 35 (38%) patients, syncopal VT in 25 (27%), drug refractory nonsyncopal VT in 27 (29%), and unexplained syncope with inducible sustained VT/VF in 5 (6%). The mean age was significantly younger than that in CIDS or AVID (59 +/- 16 vs 63 +/- 9 years in CIDS, P = 0.02; vs 65 +/- 11 years in AVID, P < 0.001), but was comparable to that in CASH (59 +/- 16 vs 58 +/- 11 years in CASH, P = 0.75). The mean LVEF was significantly higher than that in CIDS or AVID (48 +/- 19% vs 34 +/- 15% in CIDS, P < 0.001; vs 32 +/- 13% in AVID, P < 0.001), but was comparable to that in CASH (48 +/- 19 vs 46 +/- 19% in CIDS, P = 0.83). The ICD patients in the current study also showed a higher incidence of normal heart (23 vs 4% in CIDS, P < 0.001; vs 3% in AVID, P < 0.001; vs 9% in CASH, P < 0.001) and cardiomyopathy (41% vs 10% in CIDS, P < 0.001; vs 15% in AVID, P < 0.001; vs 11% in CASH, P < 0.001), but a lower incidence of coronary artery disease (29% vs 83% in CIDS, P < 0.001; vs 82% in AVID, P < 0.001; vs 73% in CASH, P < 0.001). During a mean follow-up of 28 +/- 24 months, 13 (14%) patients died. Older age was the only factor associated with poorer survival after ICD implantation. Forty-seven (51%) patients received appropriate ICD discharges during follow-up. History of prior myocardial infarction was the only factor associated with an earlier first appropriate ICD discharge and LVEF < 0.35 the only factor associated with subsequent poorer survival after the first ICD discharge. In conclusion, this study demonstrated many distinct clinical features in our ICD population that were different from those in the Western populations.     

The basic pacing rate in CRT patients: the higher the better?

Background  To maximize the hemodynamic benefit of cardiac resynchronization therapy (CRT), echocardiographic AV interval optimization is routinely performed, complemented by VV interval optimization especially in non-responders. Programming of the basic pacing rate, however, is largely empirical in these patients. Therefore, the present study aimed to systematically evaluate the impact of basic pacing rate on hemodynamic parameters in CRT patients with sinus bradycardia. Methods and results  We included 70 consecutive patients with moderate to severe heart failure, LV ejection fraction ≤35%, left bundle branch block or a QRS duration >120 ms combined with echocardiographic evidence of ventricular dyssynchrony. All patients were on optimal heart failure medication, with CRT-ICD devices implanted at least 6 months before inclusion into the study. All patients were in sinus rhythm with a spontaneous heart rate <40 bpm. In all patients, cardiac output (CO) and stroke volume (SV) were determined using electrical velocimetry (EV) (Aesculon, Osypka Medical, Berlin, Germany). EV provides a new algorithm to calculate CO based on variations in thoracic electrical bioimpedance, which has been recently validated. Hemodynamic measurements were performed at four different pacing rates ranging from 40 to 70 bpm. A stepwise increase in CO was encountered with increasing heart rates, reaching statistical significance when comparing 70 with 40 bpm. SV remained unchanged throughout all pacing rates. Conclusions  In the range between 40 and 70 bpm, an increase in basic pacing rate enhances CO without reducing SV. According to this pilot study, a basic pacing rate between 60 and 70 bpm would appear reasonable. Dr. F. Voss and Dr. R. Becker contributed equally to this work.