Ashok J. Shah

Implantable Defibrillators Improve Survival in End-Stage Renal Disease: Results from a Multi-Center Registry

Background: Small retrospective analyses suggest that end-stage renal disease (ESRD) patients do not obtain as much of a survival benefit from an implantable cardioverter-defibrillator (ICD) as non-ESRD patients do. We aimed to assess the survival effect of an ICD in ESRD patients with left ventricular dysfunction. Methods: Data from two registries identified ESRD patients with an ICD and ESRD patients with left ventricular dysfunction (defined as ejection fraction <0.35). Cox proportional hazards regression was performed, including certain predefined covariates to assess the effect of an ICD on survival. Results: Overall survival in the full cohort was a median of 4.7 years with 20 deaths in the ICD group and 29 deaths in the no-ICD group. The median survival in the ICD group was 8.0 years and 3.1 years in the no-ICD group. Crude analysis showed a better survival in the ICD group as compared to the no-ICD group (p = 0.016). The multivariable analysis confirmed that the ICD group had significantly less all-cause mortality compared to the no-ICD group (HR: 0.40; 95% CI: 0.19, 0.82; p = 0.013). Conclusion: An ICD is associated with a higher survival in ESRD patients with left ventricular dysfunction. This result merits further study in a larger cohort of patients.

Do Media Players Cause Interference with Pacemakers

Electrical devices generate electromagnetic fields that may interfere with pacemakers. Media players cause telemetry interference with pacemakers, but it is not known whether they cause direct interference with pacemakers. The purpose of this study was to examine the interaction between pacemakers and 3 different media players.

Reel syndrome—not a twiddler variant

We report three cases of an unusual form of “reel syndrome” characterized by isolated, reeling dislodgement of a single lead in patients with dual-chamber or biventricular devices. One of these patients presented with worsening heart failure due to loss of left ventricular pacing and the others were detected incidentally during scheduled device checks. We suspect that a ratchet mechanism was probably responsible for this and that this type of dislodgement is not a twiddler variant. We propose a simple solution for prevention.

Atrial Fibrillation in Patients with Implantable Defibrillators

Atrial fibrillation (AF) is common in patients who have implantable defibrillators and presents some unique challenges and opportunities. AF burden can be assessed more accurately, allowing for evaluation of therapy efficacy (drugs or ablation). It remains to be shown whether home monitoring of defibrillators to detect and treat AF more quickly can reduce cardiovascular and stroke end points. One major goal will be to reduce inappropriate shocks from atrial fibrillation. Otherwise, the goals of therapy remain the same-reduction of symptoms (including heart failure exacerbation and inappropriate implantable cardioverter defibrillator therapies) by controlling rate or rhythm and anticoagulation for stroke prophylaxis.

End -Stage Renal Disease and Sudden Cardiac Death

Patients with end-stage renal disease (ESRD) are at a high risk for sudden cardiac death (SCD). SCD is the most common cause of death in this population and, as in the general population, ventricular arrhythmias seem to be the most common cause of SCD. The increased risk of SCD in ESRD is likely due to factors that are unique to the metabolic derangements associated with this state, as well as the increased prevalence of traditional risk factors. Despite this, the evidence base for the assessment and management of SCD in these patients is limited. This article reviews the current data on underlying risk factors for SCD in patients with ESRD, the role of common medical and device-based therapies for the prevention and treatment of SCD, and the applicability of common methods of risk stratification to patients with ESRD.

Radiofrequency transseptal catheter electrode fracture.

Transseptal puncture is performed using a long needle advanced from the femoral approach. A radiofrequency catheter has been developed that delivers a short burst of radiofrequency energy and creates a micro puncture in the interatrial septum. We describe a case in which the distal radiofrequency electrode broke and became embedded in the interatrial septum. (PACE 2010; 33:e57–e58)

Inappropriate Implantable Cardioverter-Defibrillator Therapy

Although improvements in implantable cardioverter-defibrillator (ICD) therapy have taken place, many challenges do remain. Inappropriate delivery of therapy is a big problem that impacts the quality of life of ICD recipients. Although there is now a clear understanding that atrial arrhythmias are the main cause of inappropriate ICD therapies, physicians have not been very successful in preventing them. Additionally, although many tachycardia detection discriminators have been shown to be helpful, it is not clear that there is a particular combination that is ideal for all patients. Until such an algorithm is developed (which may not be possible), a detailed knowledge and use of all available programming options, guided by special characteristics of each unique patient, are the only foreseeable solutions. Finally, one must face the prospect that this problem cannot be vanquished, but only ameliorated.