The purpose of the Micra Atrial TRacking Using A Ventricular AccELerometer 2 (MARVEL 2) study is to demonstrate safe and effective operation of the MARVEL 2 features for providing AV synchronous pacing in patients with normal sinus node function and AV block

The MARVEL 2 study is an acute, prospective, global, multi-center, software-download clinical study. The study is planned to be conducted in US, Europe, and Asia. The study is expected to be conducted at approximately 15-20 centers in up to 100 subjects to obtain at least 70 usable Holter datasets to meet the objectives of the study. The expected total study duration (from first subject enrollment to the exit of the last subject) is approximately 6-months; this represents the time necessary to enroll the target sample size of at least 70 subjects with usable Holter datasets. Software will be downloaded into patients implanted with a Micra device to allow the new algorithm performance to be measured in patients where a Micra device has already been chosen as most appropriate for the patient.

Most enrolled subjects will complete the study procedures during a single study visit. However, subjects enrolling in the study at the time of their Micra implant (anticipated to be approximately 10 subjects) will have the investigational algorithm downloaded following Micra implant, prior to hospital discharge, and approximately 1-month post-implant. This subset of subjects with de novo Micra implants will allow the MARVEL 2 features to be tested at multiple points in the device life cycle.

Since the download algorithm running in a Micra device significantly increases current drain, a 2-4 hour acute study is used to limit the reduction in device longevity.

Inclusion Criteria:

• Subject has been implanted with a Micra TPS (Model MC1VR01) with remaining device longevity of 6 years or more or is expected to be implanted with a Micra TPS.
• Subject has history of AV block*
• Subject is ≥ 18 years old and as per required local law.
• Subject (and/or witness as applicable per local regulations) provides signed and dated authorization and/or consent per institution and local requirements.
• Subject is willing and able to comply with the protocol. *This includes subjects with normal sinus function and persistent 3rd degree AV block and subjects with other forms of AV block.

Exclusion Criteria:

• Subject is currently enrolled or planning to participate in a potentially confounding drug or device trial during the study. Co-enrollment in concurrent trials is only allowed when documented pre-approval is obtained from the Medtronic Clinical Research Specialist.
• Subject is pregnant (if required by local law, women of child-bearing potential must undergo a pregnancy test within seven days prior to MARVEL 2 study procedures).
• Subject meets any exclusion criteria required by local law (age or other).

Echocardiogram core lab will be masked to the individual patient subjects and MARVEL 2 algorithm mode.