Chronic Experiences with a Single Lead Dual Chamber Implantable Cardioverter Defibrillator System

Novel two-lead cardiac resynchronization therapy system provides equivalent CRT responses with less complications than a conventional three-lead system: Results from the QP ExCELs lead registry

Introduction

The novel two‐lead cardiac resynchronization therapy (CRT)‐DX system utilizes a floating atrial dipole on the implantable cardioverter‐defibrillator lead, and when implanted with a left ventricular (LV) lead, offers a two‐lead CRT system with AV synchrony. This study compared complication rates and CRT response among subjects implanted with a two‐lead CRT‐DX system to those subjects implanted with a standard three‐lead CRT‐D system.

Methods and Results

A total of 240 subjects from the Sentus QP—Extended CRT Evaluation with Quadripolar Left Ventricular Leads postapproval study were selected to identify 120 matched pairs based on similar demographic characteristics using a Greedy algorithm. The complication‐free rate was evaluated as the primary endpoint. All‐cause mortality, heart failure hospitalizations, device diagnostic data, New York Heart Association (NYHA) class improvement, and defibrillator therapy were evaluated from clinical data, in‐office interrogations, and remote monitoring throughout the follow‐up period. Complication‐free survival favored the CRT‐DX group with 92.5% without a major complication compared to 85.0% in the CRT‐D cohort (P = .0495; 95% confidence interval: 0.1%‐14.9%) over a mean follow‐up of 1.3 and 1.4 years, respectively. Incidence of all‐cause mortality, heart failure hospitalizations, NYHA changes at 6 months postimplant, and percent of LV pacing during CRT therapy were similar in both device cohorts. Inappropriate shocks were more frequent in the CRT‐D cohort with 5.8% of subjects receiving an inappropriate shock vs 0.8% in the CRT‐DX cohort.

Conclusion

The results of this subanalysis demonstrate that the CRT‐DX system can provide similar CRT responses and significantly fewer complications when compared to a similar cohort with a conventional three‐lead CRT‐D system.

Implantable cardioverter defibrillator system with floating atrial sensing dipole: a single-center experience

BACKGROUND

The concept of a single-lead dual-chamber implantable cardioverter defibrillator (ICD) with floating sensing atrial dipole has been proven safe and functional. We report a single-center experience with this ICD system; the major focus of the work is on the recorded atrial activation and its stability on a medium term follow-up.

METHODS

Thirteen patients received a DX ICD (BIOTRONIK SE & Co, Berlin, Germany) with the Linox Smart S DX(ProMRI) ICD lead; the implantation data were reported. Daily P- and R-wave sensing amplitude was collected and followed up during 200 days; their coefficient of variance (CV) was calculated. In addition, all the atrial and ventricular high-rate episodes were analyzed.

RESULTS

The total x-ray exposure time was 3.9 ± 1.8 minutes. The overall mean sensing was 4.2 ± 1.9 mV for P wave and 12.9 ± 4.5 mV for R wave. The CV was significantly higher for the P-wave amplitude than for the R-wave one (0.25 ± 0.11 vs 0.08 ± 0.06; P < 0.001). A total of 27 high ventricular rate episodes were recorded and correctly discriminated by the device. Fifty-six high atrial rate episodes were recorded, 49 were true arrhythmic events.

CONCLUSIONS

The single-lead ICD system with floating atrial dipole provides reliable atrial sensing amplitude over time. The physician, without the implantation of an additional lead, has the atrial information that may be used for the discrimination of supraventricular tachyarrhythmia/ventricular tachycardia, for the early detection of atrial fibrillation episodes and for the evaluation of changes in the patient's heart status.

Comparison of a Novel, Single-Lead Atrial Sensing System With a Dual-Chamber Implantable Cardioverter-Defibrillator System in Patients Without Antibradycardia Pacing Indications

Background—

Supraventricular tachyarrhythmias are the main cause for inappropriate therapy by implantable cardioverter-defibrillators (ICDs). For better rhythm discrimination, an atrial electrogram is helpful and usually obtained from an additional atrial lead, even in the absence of sinus node or atrioventricular nodal disease. An A+-ICD system with integrated atrial sensing rings mounted 15 to 18 cm from the tip of an ICD lead may obviate the need to implant a separate atrial lead. The aim of the study was to compare the novel A+-ICD and a conventional dual-chamber (DR)-ICD.

Methods and Results—

Two hundred forty-nine patients with standard ICD indications but no requirement for antibradycardia pacing were randomized to receive an A+-ICD (n=124) or a DR-ICD (n=125). Implantation details, need for ICD system revision, long-term sensing, documented arrhythmia episodes, and the respective rhythm discrimination during follow-up were analyzed. The implantation time was significantly shorter in the A+-ICD group (67±30 vs 79±30 minutes, P =0.003). Mean P-wave amplitudes were 3.5±0.8 mV (A+-ICD) and 3.2±0.6 mV (DR-ICD) and remained stable during the follow-up period of 12 months. Surgical revision was necessary in 13 patients in the DR-ICD and 10 in the A+-ICD group. All 593 ventricular tachyarrhythmia episodes were correctly discriminated. Sensitivity and specificity of supraventricular tachyarrhythmia discrimination were not different between the study groups.

Conclusions—

The novel A+-ICD system can be implanted faster and is equivalent to a standard DR-ICD with regard to the detection of ventricular tachyarrhythmias and supraventricular tachyarrhythmias. It represents a useful alternative to obtain atrial sensing.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00324662.

Incidence and Significance of Far-Field R Wave Sensing in a VDD-Implantable Cardioverter Defibrillator

BACKGROUND

A VDD-implantable cardioverter-defibrillator (ICD) provides atrioventricular (AV) synchronous stimulation when necessary and incorporates the advantages of dual chamber arrhythmia discrimination algorithms both at potentially lower costs and less periprocedural complications than a DDD-ICD system. A prerequisite for correct dual chamber ICD function is reliable atrial sensing.

METHODS

We evaluated atrial near- and ventricular far-field sensing and its impact on the dual-chamber detection algorithm in 106 patients with a single-lead VDD-ICD during a 12-month follow-up period.

RESULTS

Six hundred and thirty-nine follow-ups were included. Mean near-field amplitude was 3.82 +/- 1.76 mV; mean far-field amplitude was 0.31 +/- 0.15 mV. 46% of patients had far-fields >0.35 mV and 35% of patients showed atrial EGM markers corresponding to a ventricular far-field in at least one follow-up. Six hundred and forty-five tachycardia episodes were evaluated. Due to far-field sensing, three of 66 episodes (4.5%) of sinus tachycardia were misclassified as ventricular tachycardia (VT), leading to antitachycardia therapies. Delayed detection of VT was seen in a 12 of 323 episodes (3.7%) in five of 62 patients (8%) having VT events (delay 6.4 +/- 6.0 seconds (range 2-24 seconds)). Stable far-field amplitudes <0.2 mV in a follow-up had a high negative predictive value for the occurrence of malfunction during tachycardia-conversely, high far-field amplitudes or a high incidence of far-field markers are only moderately correlated with malfunction.

CONCLUSIONS

Ventricular far-field sensing in a VDD-ICD is not uncommon, however, tachycardia detection by the dual chamber algorithm is not seriously impaired by far-field sensing.