A review of the atrial upper rate algorithms of St. Jude Medical (Abbott) cardiac implantable electronic devices : Incidence of repetitive nonreentrant ventriculoatrial synchrony (RNRVAS)

Potential triggering of repetitive nonreentrant ventriculoatrial synchrony by loss of atrial capture

BACKGROUND

Data on the factors that trigger repetitive nonreentrant ventriculoatrial synchrony (RNRVAS) are limited. We hypothesize that loss of atrial capture may trigger RNRVAS. We aimed to use an atrial threshold test to observe the development of RNRVAS upon loss of atrial capture in patients with implantable cardiac electronic devices (CIED).

METHODS

Patients with DDD mode CIEDs [177 patients, 67.5 ± 14.8 (70) years; 70 women] were included. Atrial threshold test was done in DDD mode at a rate at least 10 beats above the basal heart rate, with an AV delay of 300 ms (range 250-350). A multivariable logistic regression model was used to assess the independent predictors of RNRVAS.

RESULTS

RNRVAS was observed in 69 of the 177 patients (39.0%) during atrial threshold test. In patients with VA conduction, incidence of RNRVAS increased to 76.7%. In univariate analysis, younger age (p = .038) and the presence of VA conduction (p < .001) were associated with an increased risk of RNRVAS, whereas complete AV block or any AV node conduction defect (p < .001) and the ventricular pacing ratio (p = .001) were inversely related to the risk of RNRVAS occurrence after loss of atrial capture. In multivariate analysis complete AV block (p = .009) and ventricular pacing ratio (p = .029) appeared as independent factors inversely related to the risk of RNRVAS development.

CONCLUSION

In this study, we demonstrated that loss of atrial capture results in RNRVAS in one-third of patients with a CIED in DDD mode, and in three-fourths of those with VA conduction under certain predisposing CIED settings.

A sudden change in pacing rate: Normal or malfunction?

A woman with a dual‐chamber pacemaker was examined for recurrent chest discomfort and palpitations at our hospital. The Holter monitor test recorded recurrent episodes of a sudden increase in pacing rate from 60 to 105 bpm, which corresponded to the symptoms. Orthodromic pacemaker‐mediated arrhythmia (OPMA), caused by ventricular lead dislodgement and atrial far‐field sensing, caused the recurrent episodes of a sudden change in pacing rate. The occurrence of OPMA may represent a rare but noteworthy pacemaker problem. To our knowledge, our study reports the first case of PMA that only occurs, and is maintained, in the DDI mode.

Novel Pacemaker-Mediated Arrhythmia Without Ventriculoatrial Conduction Can Induce Atrial Fibrillation

Cardiovascular implantable electronic devices can initiate and sustain pacemaker-mediated arrhythmias. Endless loop tachycardia and repetitive non-re-entrant ventriculoatrial synchrony (RNRVAS) are well-described examples of pacemaker-mediated arrhythmias. However, such arrhythmias only occur in the presence of ventriculoatrial conduction. We identified a novel pacemaker-mediated arrhythmia that closely mimics RNRVAS but in the absence of ventriculoatrial conduction. We identified these arrhythmias in 9 patients, all with a St. Jude Medical/Abbott device, recorded as inappropriate mode-switch episodes by a device algorithm that includes paced events in the atrial counter. This report describes the mechanism, discusses clinical implications, and outlines programming options to eliminate this pseudo-RNRVAS.

Is competitive atrial pacing a possible trigger for atrial fibrillation? Observations from the RATE registry

BACKGROUND

A high incidence of asymptomatic atrial tachycardia and atrial fibrillation (AT/AF) has been recognized in patients with cardiac implantable devices (CIED). The clinical significance of these AT/AF episodes remains unclear. Some "device-detected AT/AF" was previously shown to be triggered by competitive atrial pacing (CAP).

OBJECTIVE

To investigate and characterize a potential association between CAP and AT/AF in the largest series of observations to date.

METHODS

RATE, a multicenter registry, included 5379 patients with CIEDs followed for approximately 2 years. Electrograms (EGMs) from 1352 patients with AT/AF, CAP, or both were analyzed by experienced adjudicators to assess a causal relationship between AT/AF and CAP onset, duration, and morphology.

RESULTS

In 225 patients, 1394 episodes of both AT/AF and CAP were present in the same tracing. CAP and AT/AF were strongly associated (P ≤ .02). AT/AF occurred during the course of the study in 71% of patients with CAP. In 62% of the episodes, expert adjudication concluded that CAP triggered AT/AF. The duration and morphology of triggered and spontaneous AT/AF episodes differed. Spontaneous AT/AF episodes were associated with constant EGM morphology, and were either long or extremely short. CAP-triggered AT/AF more often had variable and shorter cycle length EGMs. The incidence of short AT/AF events was higher among triggered episodes (25% vs 12.8%, P < .002).

CONCLUSION

Device-triggered AT/AF due to CAP is likely more common than previously recognized. This AT/AF entity differs from spontaneous AT/AF in duration and morphology. Clinical implications of spontaneous and device-triggered AT/AF may be different.

Proarrhythmic effects from competitive atrial pacing and potential programming solutions

BACKGROUND

Programmed long AV delays and intrinsic long first degree AV block may increase risk for competitive atrial pacing (CAP) in devices without CAP avoidance algorithms.

METHODS

Patients identified with CAP-induced mode switch episodes were followed clinically from September 2013 to August 2019. Attempts to avoid CAP included shortening of postventricular atrial refractory period (PVARP) or postventricular atrial blanking period (PVAB), or change to AAI or DDI modes. After observing associations with sensor-driven pacing, rate response was inactivated in a subset.

RESULTS

Among 23 patients identified with CAP (22 St Jude Medical [Abbott]; one Boston Scientific Corporation devices), atrial fibrillation (AF) was induced in 12 (52%), lasting 10 seconds to 28 hours and 32 minutes. In one patient with an ICD CAP-induced AF with rapid ventricular rates that triggered a shock, inducing ventricular fibrillation, syncope, and another shock. Changing AV delays and shortening of PVARP failed to resolve CAP. After noting that all had CAP during sensor-driven pacing, rate response was inactivated in seven, resolving further device-induced AF in the three of seven that had prior CAP-induced AF. In two patients with intact AV conduction, AAI(R) pacing resolved further documentation of CAP.

CONCLUSIONS

CAP predominantly occurs during sensor-driven atrial pacing that competes with intrinsic atrial events falling in PVARP. Inactivation of the activity sensor or change to atrial-based pacing modes (AAI/R) appears to effectively prevent induction of device-induced atrial proarrhythmia. Ultimately, a corrective algorithm is needed to avoid CAP-induced proarrhythmia.

Ventriculoatrial synchrony induced heart failure

OBJECTIVE AND IMPORTANCE

Endless loop tachycardia or pacemaker-mediated tachycardia, and atrioventricular desynchronization arrhythmia or repetitive non-reentrant ventriculoatrial synchrony (RNRVAS) are two forms of reverse impulse conduction - ventriculoatrial (VA) synchrony. Although VA synchrony can theoretically cause aggravation of heart failure, clinical cases describing severe consequential heart failure are lacking.

CLINICAL PRESENTATION AND INTERVENTION

We describe a case of a 60-year-old patient who underwent primary percutaneous coronary intervention and mitral valve surgery. Implantation of a two-chamber pacemaker was also performed during the same hospitalization due to development of third-degree atrioventricular block. Ten months later, he presented with a severe form of heart failure with a significant reduction of left ventricular ejection fraction (LVEF). The atrial lead was displaced and VA synchrony was registered (RNRVAS-like condition). The pacemaker was reprogrammed and VA synchrony induced heart failure was successfully resolved. Echocardiographic follow-up showed improvement in LVEF.

CONCLUSION

Ventriculoatrial conduction can be present even when the patient has a complete atrioventricular block. Atrial lead displacement and consequently loss of atrial capture with preserved sensing can be a predisposing factor for initiation of ventriculoatrial synchrony. Permanent ventriculoatrial synchrony may provoke aggravation of heart failure.