Background: MRI-conditional pacemaker system has been safely used in clinical practice worldwide. However, there are many patients with conventional pacemaker system need magnetic resonance imaging [MRI] evaluation with strong clinical indication that benefit of MRI outweighs the risks.

Objective: To investigate the safety of conventional pacemaker system and MRI-conditional pacemaker system in MRI scanning in term of the adverse occurrence such as a) a significant change in pacing capture threshold [PCT] of any leads, b) abnormal pacemaker function, and c) major adverse clinical event.

Materials and Methods: A retrospective study of consecutive pacemaker patients that underwent MRI at 1.5 Tesla and estimated specific absorption rate [SAR] of less than 2.0 W/kg, under institution safety protocol, between August 2012 and June 2014, was done.

Results: Sixteen patients (mean age 77.6 years old, 50% male) with a total of 32 leads and 16 pulse generators underwent MRI between August 2012 and June 2014 were included. Of all patients, eight (50%) were MRI-conditional pacemaker system, and five (31%) were pacemaker-dependent. The majority of MRI scanning position was brain (8, 50%), followed by spine (6, 37.5%) and others (2, 12.5%), which included upper abdomen and lower limb. Unintended cardiac stimulation induced by magnet occurred in one patient with conventional pacemaker system without significant clinical consequences. There was no other MRI-related complication during and after the scan. At six months follow-up, 12 patients had their pacemaker evaluated. There was no occurrence of significant change in PCT or abnormal pacemaker function found at six months follow-up.

Conclusion: Patients with conventional pacemaker system who have strong clinical indication for MRI may safely undergo the scan with close and continuous monitoring strategy.

Keywords: Permanent pacemaker and MRI, Safety of pacemaker patients and MRI