Real-world experience on implantation and atrial signal detection of a SC ICD with atrial sensing capability: The MATRIX study

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): BIOTRONIK, Berlin, Germany

Introduction

A single-lead implantable cardioverter-defibrillator (ICD) with atrial sensing dipole (the DX ICD system) can potentially give additive information concerning atrial diagnostics in patients requiring only a single-chamber ICD. We therefore report the real-world experience from large DX registry on implantation, atrial signal quality and detection and the long-term stability of the atrial signal.

Methods

The prospective, single-arm MATRIX (Management and Detection of Atrial Tachyarrhythmias in Patients Implanted With BIOTRONIK DX Systems, NCT01774357) registry study effectively enrolled 2041 patients at 119 sites in 24 countries. All patients had a DX system implanted for a single-chamber ICD indication for primary or secondary prevention of sudden cardiac death. Patients were followed for 24 months including remote monitoring. Implantation and follow-up data are reported for the whole patient set. For the analyses on atrial sensing amplitude values, remotely transmitted device measurements of patients without history of long-standing persistent or permanent AF at baseline were used.

Results

The mean follow-up period was 677±173 days. Implantation took place at 15±22 days before enrollment. Baseline and implantation data are shown in the table. Implantation procedure and lead insertion were rated as "easy" or "very easy" in 91.0% and 96.3% of assessments, respectively. At implantation, the investigators rated the quality of the atrial sensing amplitude as "sufficient" in 97% of the assessed cases. At enrollment (12-month/24-month follow-up), the atrial signal quality and detection were rated as "good" or "excellent" in 92.3% (89.8%/89.9%) and 92.4% (90.1%/91.3%) of assessments, respectively. For 1841 patients (90.2%), remotely transmitted device information was received. The median (mean ± SD, IQR) transmission rate was 92.5% (85.4±18.2%, 81.4-97.3%). 1746 patients (85.5%) matched the inclusion criteria for the quantitative analyses on atrial sensing. 95.6% of available RA sensing amplitude values were ≥1 mV. Based on each patient’s overall median value, the median (mean ± SD, IQR) RA sensing amplitude was 4.6 mV (4.4±2.0 mV, 2.8-6.2 mV). The time course of patient median values stratified by month is shown in the figure.

Conclusion

The study followed 2041 patients implanted with the DX ICD system for two years. In the vast majority of cases, investigators rated implantation as (very) easy and the atrial signal over 24 months as good/excellent. According to daily, automatic Home Monitoring data, the overall mean P-wave amplitude remained stable throughout the whole follow-up. The MATRIX study demonstrated functionality and clinical utility of the DX concept in an unselected, real-life setting.

Capability of guideline-conform remote atrial high rate episode monitoring with a single-chamber implantable defibrillator with atrial sensing

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): BIOTRONIK, Berlin, Germany

Introduction

Device-detected atrial high-rate episodes (AHRE) and their burden progression are associated with an increased risk for thromboembolic events in correlation with CHA2DS2-VASc score and AHRE burden. To allow timely initiation of anticoagulation therapy for the prevention of stroke, the European guidelines on atrial fibrillation (AF) recommend the monitoring of AHRE progression along pre-specified strata (6min…<1h, 1h…<24, ≥24h). We sought to assess the capability of a single-lead implantable cardioverter defibrillator (ICD), that is equipped with an atrial dipole for atrial sensing, to remotely detect and monitor AHRE burden progression in patients with standard indication to single-chamber ICD.

Methods

From the MATRIX (Management and Detection of Atrial Tachyarrhythmias in Patients Implanted With BIOTRONIK DX Systems) registry, we analyzed remotely transmitted, and electrogram (IEGM) AHREs in a subset of patients with remote transmissions and without history of long-standing AF at baseline. For each patient, we selected the first occurring episode per duration stratum and the first subsequent occurrence when progressing to a stratum of any longer duration. After episode adjudication by an independent electrophysiologist, we assessed the classification performance of the device (positive predictive value [PPV]) and analyzed AHRE onset and progression pathways.

Results

Of the MATRIX cohort, 1,746 patients matched the inclusions criteria (see table for patient characteristics) and 1,451 had no AF history. Of the 258 patients with AHREs (14.8%), 450 out of 465 evaluated episodes were correctly classified as AHRE. Reasons for misclassification were artifact (13) and R-wave oversensing (2). PPV was 96.8% (95% confidence interval 94.7%-98.2%). Grouped by stratum, PPV was 93.9%, 99.5% and 100% for 6min…<1h, 1h…<24 and ≥24h, respectively. Ninety six of 240 patients (40.0%) with a first episode according to the pre-specified strata were progressing to a stratum of longer duration and 9 patients (3.8%) had further progression (see Figure). In 119 out of 1,451 patients without AF history (8.2%), the device detected AHRE and 81 of them (4.6% of analysis set) had a mid to high risk for stroke and were not on anticoagulation therapy. In 121 out of 295 patients with known history of paroxysmal and persistent AF (41.0%), the arrhythmia was confirmed by the device.

Discussion and Conclusion: The single-chamber ICD with atrial sensing capabilities correctly classified ≈97% of all adjudicated AHREs ≥6min. About 7% of patients had device-detected AHRE onset and/or progression and a mid to high stroke risk. These patients would potentially benefit the most from a guideline-conform AF monitoring strategy to timely initiate anticoagulation medication for stroke prevention.