ICD sees what you do not see: how does it beat you?

The utilization of atrial sensing dipole in single lead implantable cardioverter defibrillator for detection of new-onset atrial high-rate episodes or subclinical atrial fibrillation: A systematic review and meta-analysis

This meta-analysis aims to evaluate the performance of atrial sensing dipole in single lead implantable cardioverter defibrillator (VDD-ICD) recipients in particular diagnosing new-onset atrial high-rate episodes (AHREs) defined as rate threshold of 200 beats per minute, or subclinical atrial fibrillation (SCAF) defined as device-detected AF without symptoms. We comprehensively searched PubMed, Embase, and ClinicalTrials.gov. Studies comparing contemporary single- and dual-chamber ICD (VVI-/DDD-ICD) versus VDD-ICD were included. Restricted maximum likelihood method for random effect model and Mantel-Haenszel method for fixed effect model were used to estimate the effect size of new-onset AHREs, or SCAF detection in each group. Three prospective studies were identified and total of 991 participants were included. There were 330 (33.3%) in VDD-ICD and 661 (66.7%) in VVI-/DDD-ICD. Most (78%) participants were men. Median follow-up was from 365 days to 847 days. VDD-ICD has a higher likelihood of detecting AHREs or SCAF as compared to VVI-/DDD-ICD [(OR random effect : 2.6; 95% CI: 1.2, 5.8; p = .018); I-squared = 67.8%, p = .019]. This difference was more apparently seen in the comparison between VDD-ICD and VVI-ICD [(OR random effect: 3.8; 95% CI: 2.1, 6.6, p < .001), I-squared = 0.0%, p = .518]. The result is same as fixed effect. Rate of AHREs detection observed in VDD-ICD was not statistically different when compared to the only group with DDD-ICD from SENSE trial. In conclusion, this meta-analysis reveals that the use of floating atrial sensing dipole in VDD-ICD increases the detection of new-onset AHREs or SCAF when compared to VVI-ICD, with similar atrial sensing performance to DDD-ICD.

The Analog Blanking Period of Implantable Cardiac Rhythm Devices

BACKGROUND

Analog blanking periods (BPs) that hold down the display of electrograms (EGMs) in cardiac rhythm devices have received much less attention than the well-known digital BPs which do not influence the EGM display. In Biotronik devices (Biotronik GmbH, Berlin, Germany), when a paced event initiates an analog BP in one chamber (right atrium, right ventricle [RV], or left ventricle [LV]), an identical cross-chamber analog BP starts in the other two chambers.

METHODS

All clinical observations were recorded from patients with Biotronik devices. The effect of the atrial cross-chamber analog BP initiated by a ventricular paced event on the atrial EGM was studied in the records of seven patients with frequent paroxysmal atrial flutter to determine the effect of critically timed RV paced event (RVp) or LV paced event (LVp) upon the atrial EGM. The effect of atrial pacing triggering cross-chamber analog BPs in the RV and LV channels on the RV and LV EGMs was also investigated in cases of conducted supraventricular beats and ventricular premature complexes. The effect of a triggered LVp initiating a cross-chamber analog BP in the RV channel on the EGM of a sensed RV sensed event was evaluated in 10 cases. Simulation studies were also performed to verify the clinical observations.

RESULTS

Patients with atrial flutter showed intermittent truncation or deformity and even disappearance of the atrial signals due to an atrial cross-chamber analog BP initiated by RVp and/or LVp. Three patients demonstrated deformity of the signal shape of ventricular premature beats falling within a ventricular cross-chamber analog BP initiated by right atrial paced event (RAp). We found only one case of a supraventricular QRS complex trapped in a ventricular cross-chamber analog BP initiated by RAp. All the recordings of LVp triggering upon RVs revealed a variety of RV signal deformities occasionally with preservation of the terminal part of the RV signal. Simulation studies confirmed the effect of the analog BP on the atrial and the ventricular EGMs.

CONCLUSION

The analog BP of Biotronik devices may cause truncation or deformity of atrial and ventricular signals and the occasional disappearance of an atrial signal during atrial flutter. These effects must not be interpreted as device malfunction. In the clinical evaluation of the EGM curves, the effects of the analog BPs have to be carefully considered in order to avoid possible misinterpretation.