The objective of this post-market, clinical follow up (PMCF) study, is to confirm the long-term safety of the Tendril STS and Isoflex leads, implanted with the Assurity MRI™ or Endurity MRI™ pacemakers, in patients undergoing a clinically indicated 3T MRI (3 Tesla Magnetic Resonance Imaging) scan.

This prospective, non-randomized, observational study will be conducted at 35 centers worldwide where the study devices have 3T MR Conditional labeling; up to 110 patients will be enrolled, and will satisfy the recent PMCF requirement to maintain the CE mark.

Inclusion Criteria:

1. Subject must be willing and able to provide informed consent for study participation (legal guardian or legally authorized representative is NOT acceptable).
2. Subject must be implanted with a St. Jude Medical Tendril STS 2088 or Isoflex 1944/1948 lead, and Assurity MRI or Endurity MRI pacemaker.
3. Capture threshold is stable and < 2.5V @ 0.5ms at the time of enrollment.
4. Subject is clinically indicated for a 3T MRI scan without sedation NOTE: Antianxiety agents (e.g. minor tranquilizers, etc.) may be used as long as the patient can communicate with site personnel during the MRI scan
5. Subject is willing and able to comply with the prescribed follow-up tests and schedule of evaluations.

Exclusion Criteria:

1. The subject is currently participating in a clinical investigation that includes an active treatment arm that may confound the results of this study as determined by Abbott.
2. The subject is <18 years old (pediatric).
3. That subject has a life expectancy of less than 12 months due to any condition.
4. Pregnant or nursing subjects and those who plan pregnancy during the clinical investigation follow-up period.
5. Presence of other anatomic or comorbid conditions, or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the subject's ability to participate in the clinical investigation or to comply with follow-up requirements, or impact the scientific soundness of the clinical investigation results.
6. Any contraindication to MRI scan, including the presence of additional hardware (e.g. lead extenders, lead adapters, surgical staples, stents, dental braces, or abandoned leads).

Patients implanted with an SJM Tendril STS 2088 or Isoflex 1944/1948 lead, together with an Assurity MRI or Endurity MRI pacemaker, and who will undergo a 3T MRI scan are eligible to participate in this study. Subjects must meet all eligibility criteria and provide written informed consent prior to conducting any study procedures not considered standard of care.