PVC Response ''Atrial Pace'' Inducing Atrial Tachycardias

Switching PVC Response ''Atrial Pace'' in ST JUDE Medical or Abbott ICD (Implantable Cardioverter Defibrillator) or CRT-D (Cardiac Resynchronization Therapy) Devices to Off Mode Decreases the Burden of Atrial Tachycardia

Premature ventricular contractions (PVC) are common phenomenon and occasionally retrograde conduction from ventricle to atrium occurs and may cause pacemaker mediated tachycardia. In response certain Abbott (former St Jude Medical) pacemakers have a specific PVC response algorithm ''Atrial Pace''. In this algorithm the PVARP (Post Ventricular Atrial Refractory Period) is extended to 480ms but the initial 150ms of the PVARP is deemed absolute. If atrial sensed event occurs after absolute PVARP the PVARP terminates and atrial pace follows after 330ms alert period. Two case reports exists where patients atrial tachycardia were suspected to be induced by this algorithm. In Helsinki University Hospital an index patient with multiple atrial tachycardia episodes was recognized in late 2020 where the cause of the tachycardias was suspected to be the PVC response algorithm ''Atrial Pace''. After programming the algorithm from Atrial Pace to off mode the patient had none atrial tachycardias during 2021. After investigating all the patients with physiological ICD (Implantable Cardioverter Defibrillator) or CRT-D (Cardiac Resynchronization Therapy) device and analyzing remote monitoring transmissions from the year 2020 we found 25 patients with similar atrial tachycardia episodes possibly induced by the PVC response ''Atrial Pace''.

The device of the subjects participating to the study is interrogated and the PVC response algorithm is switched from ''Atrial Pace'' to ''Off'' mode. Subjects are also requested to fulfill the EQ-5D-3L and ICD8 questionaries before the change in the device programming and after the 12 months surveillance.

Number of atrial tachycardia episodes per participant which is initiated after PVC followed by atrial sensed event and atrial pace after 330ms delay.

Atrial tachycardia episode is considered as an episode which duration is >30s and atrial rate > 180 beats per minute.

The number of these episodes is compared between year 2020 and 12 months preceding the change in the programming setting and 12 months afterwards.

Number of any atrial tachycardia episodes and overall duration of atrial tachycardia episodes per participant.

Atrial tachycardia episode is considered as an episode which duration is >30s and atrial rate > 180 beats per minute.

The number of these episodes and overall duration of all atrial tachycardia episodes is compared between year 2020 and 12 months preceding the change in the programming setting and 12 months afterwards.

In EQ-5D-3L questionary the quality of life is measured in scale from 0 to 100 and in ICD8 questionary in scale from 0 to 32. The overall score in both of the questionaries is compared at two time points.

Inclusion Criteria: ST Jude Medical or Abbott physiological ICD or CRT-D device PVC response setting ''Atrial Pace'' Atrial tachycardia episode duration > 30s preceded by ventricular extrasystole and atrial pace in year 2020 or 2021 Exclusion Criteria: Permanent atrial fibrillation, duration ≥ 6 months before the enrollment to the study PVC response has been switched off before enrollment

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