Strategy for safe performance of extrathoracic magnetic resonance imaging at 1.5 tesla in the presence of cardiac pacemakers in non-pacemaker-dependent patients: a prospective study with 115 examinations.
BACKGROUND
The purpose of the present study was to evaluate a strategy for safe performance of extrathoracic magnetic resonance imaging (MRI) in non-pacemaker-dependent patients with cardiac pacemakers.


RESULTS
Inclusion criteria were presence of a cardiac pacemaker and urgent clinical need for an MRI examination. Pacemaker-dependent patients and those requiring examinations of the thoracic region were excluded. The study group consisted of 82 pacemaker patients who underwent a total of 115 MRI examinations at 1.5T. To minimize radiofrequency-related lead heating, the specific absorption rate was limited to 1.5 W/kg. All pacemakers were reprogrammed before MRI: If heart rate was <60 bpm, the asynchronous mode was programmed to avoid magnetic resonance (MR)-induced inhibition; if heart rate was >60 bpm, sense-only mode was used to avoid MR-induced competitive pacing and potential proarrhythmia. Patients were monitored with ECG and pulse oximetry. All pacemakers were interrogated immediately before and after the MRI examination and after 3 months, including measurement of pacing capture threshold (PCT) and serum troponin I levels. All MR examinations were completed safely. Inhibition of pacemaker output or induction of arrhythmias was not observed. PCT increased significantly from pre- to post-MRI (P=0.017). In 2 of 195 leads, an increase in PCT was only detected at follow-up. In 4 of 114 examinations, troponin increased from a normal baseline value to above normal after MRI, and in 1 case (troponin pre-MRI 0.02 ng/mL, post-MRI 0.16 ng/mL), this increase was associated with a significant increase in PCT.


CONCLUSIONS
Extrathoracic MRI of non-pacemaker-dependent patients can be performed with an acceptable risk-benefit ratio under controlled conditions and by taking both MR- and pacemaker-related precautions.
Sommer
Torsten
T
University of Bonn, Department of Radiology, Bonn, Germany. t.sommer@uni-bonn.de
Naehle
Claas P
CP
Yang
Alexander
A
Zeijlemaker
Volkert
V
Hackenbroch
Matthias
M
Schmiedel
Alexandra
A
Meyer
Carsten
C
Strach
Katharina
K
Skowasch
Dirk
D
Vahlhaus
Christian
C
Litt
Harold
H
Schild
Hans
H
D000005:Abdomen / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D001921:Brain / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D004869:Equipment Safety / Q000295:instrumentation* / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006361:Heating; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D010388:Pelvis / Q000473:pathology; D011446:Prospective Studies; D011846:Radio Waves / Q000009:adverse effects; D018570:Risk Assessment; D019210:Troponin I / Q000097:blood
D019210:Troponin I