Magnetic resonance imaging at 1.5-T in patients with implantable cardioverter-defibrillators.
OBJECTIVE
Our aim was to establish and evaluate a strategy for safe performance of magnetic resonance imaging (MRI) at 1.5-T in patients with implantable cardioverter-defibrillators (ICDs).


BACKGROUND
Expanding indications for ICD placement and MRI becoming the imaging modality of choice for many indications has created a growing demand for MRI in ICD patients, which is still considered an absolute contraindication.


METHODS
Non-pacemaker-dependent ICD patients with a clinical need for MRI were included in the study. To minimize radiofrequency-related lead heating, the specific absorption rate was limited to 2 W/kg. ICDs were reprogrammed pre-MRI to avoid competitive pacing and potential pro-arrhythmia: 1) the lower rate limit was programmed as low as reasonably achievable; and 2) arrhythmia detection was programmed on, but therapy delivery was programmed off. Patients were monitored using electrocardiography and pulse oximetry. All ICDs were interrogated before and after the MRI examination and after 3 months, including measurement of pacing capture threshold, lead impedance, battery voltage, and serum troponin I.


RESULTS
Eighteen ICD patients underwent a total of 18 MRI examinations at 1.5-T; all examinations were completed safely. All ICDs could be interrogated and reprogrammed normally post-MRI. No significant changes of pacing capture threshold, lead impedance, and serum troponin I were observed. Battery voltage decreased significantly from pre- to post-MRI. In 2 MRI examinations, oversensing of radiofrequency noise as ventricular fibrillation occurred. However, no attempt at therapy delivery was made.


CONCLUSIONS
MRI of non-pacemaker-dependent ICD patients can be performed with an acceptable risk/benefit ratio under controlled conditions by taking both MRI- and pacemaker-related precautions. (Implantable Cardioverter Defibrillators and Magnetic Resonance Imaging of the Heart at 1.5-Tesla; NCT00356239).
Naehle
Claas P
CP
Department of Radiology, University of Bonn, Bonn, Germany. cp@naehle.net
Strach
Katharina
K
Thomas
Daniel
D
Meyer
Carsten
C
Linhart
Markus
M
Bitaraf
Sascha
S
Litt
Harold
H
Schwab
Jörg Otto
JO
Schild
Hans
H
Sommer
Torsten
T
D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004869:Equipment Safety / Q000295:instrumentation* / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012307:Risk Factors