Immediate and 12 months follow up of function and lead integrity after cranial MRI in 356 patients with conventional cardiac pacemakers

Background: Conventional cardiac pacemakers are still often
regarded as a contraindication to magnetic resonance imaging (MRI).
We conducted this study to support the hypothesis that it is safe
to scan patients with cardiac pacemakers in a 1.5 Tesla MRI, if
close supervision and monitoring as well as adequate pre- and
postscan programming is provided. Methods: We followed up 356
patients (age 61.3 +/- 9.1 yrs., 229 men) with single (n = 132) or
dual chamber (n = 224) cardiac pacemakers and urgent indication for
a cranial MRI for 12 months. The scans were performed at 1.5T.
During the scan patients were monitored with a 3-lead ECG and pulse
oximetry. Prior to the scan pacemakers were programmed according to
our own protocol. Results: All 356 scans were completed without
complications. No arrhythmias were induced, programmed parameters
remained unchanged. No pacemaker dysfunction was identified.
Follow-up examinations were performed immediately, 2 weeks, 2, 6,
and 12 months after the scan. There was no significant change of
pacing capture threshold (ventricular 0.9 +/- 0.4 V@0.4 ms, atrial
0.9 +/- 0.3 V@0.4 ms) immediately (ventricular 1.0 +/- 0.3 V@0.4
ms, atrial 0.9 +/- 0.4 V@0.4 ms) or at 12 months follow-up
examinations (ventricular 0.9 +/- 0.2 V@0.4 ms, atrial 0.9 +/- 0.3
V@0.4 ms). There was no significant change in sensing threshold
(8.0 +/- 4.0 mV vs. 8.1 +/- 4.2 mV ventricular lead, 2.0 +/- 0.9 mV
vs. 2.1 +/- 1.0 mV atrial lead) or lead impedance (ventricular 584
+/- 179 O vs. 578 +/- 188 O, atrial 534 +/- 176 O vs. 532 +/- 169
O) after 12 months. Conclusions: This supports the evidence that
patients with conventional pacemakers can safely undergo cranial
MRI in a 1.5T system with suitable preparation, supervision and
precautions. Long term follow-up did not reveal significant changes
in pacing capture nor sensing threshold.