A Prospective Evaluation of a Protocol for Magnetic Resonance Imaging of Patients With Implanted Cardiac Devices

作者：Nazarian Saman^*; Hansford Rozann; Roguin Ariel; Goldsher Dorith; Zviman Menekhem M; Lardo Albert C; Caffo Brian S; Frick Kevin D; Kraut Michael A; Kamel Ihab R; Calkins Hugh; Berger Ronald D; Bluemke David A; Halperin Henry R

来源：Annals of Internal Medicine, 2011, 155(7): 415-U39.

DOI：10.7326/0003-4819-155-7-201110040-00004

Background: Magnetic resonance imaging (MRI) is avoided in most patients with implanted cardiac devices because of safety concerns.
Objective: To define the safety of a protocol for MRI at the commonly used magnetic strength of 1.5 T in patients with implanted cardiac devices.
Design: Prospective nonrandomized trial. (ClinicalTrials.gov registration number: NCT01130896)
Setting: One center in the United States (94% of examinations) and one in Israel.
Patients: 438 patients with devices (54% with pacemakers and 46% with defibrillators) who underwent 555 MRI studies.
Intervention: Pacing mode was changed to asynchronous for pacemaker-dependent patients and to demand for others. Tachyarrhythmia functions were disabled. Blood pressure, electrocardiography, oximetry, and symptoms were monitored by a nurse with experience in cardiac life support and device programming who had immediate backup from an electrophysiologist.
Measurements: Activation or inhibition of pacing, symptoms, and device variables.
Results: In 3 patients (0.7% [95% CI, 0% to 1.5%]), the device reverted to a transient back-up programming mode without long-term effects. Right ventricular (RV) sensing (median change, 0 mV [interquartile range {IQR}, -0.7 to 0 V]) and atrial and right and left ventricular lead impedances (median change, -2 Omega [IQR, -13 to 0 Omega], -4 Omega [IQR, -16 to 0 Omega], and -11 Omega [IQR, -40 to 0 Omega], respectively) were reduced immediately after MRI. At long-term follow-up (61% of patients), decreased RV sensing (median, 0 mV, [IQR, -1.1 to 0.3 mV]), decreased RV lead impedance (median, -3 Omega, [IQR, -29 to 15 Omega]), increased RV capture threshold (median, 0 V, IQR, [0 to 0.2 Omega]), and decreased battery voltage (median, -0.01 V, IQR, -0.04 to 0 V) were noted. The observed changes did not require device revision or reprogramming.
Limitations: Not all available cardiac devices have been tested. Long-term in-person or telephone follow-up was unavailable in 43 patients (10%), and some data were missing. Those with missing long-term capture threshold data had higher baseline right atrial and right ventricular capture thresholds and were more likely to have undergone thoracic imaging. Defibrillation threshold testing and random assignment to a control group were not performed.
Conclusion: With appropriate precautions, MRI can be done safely in patients with selected cardiac devices. Because changes in device variables and programming may occur, electrophysiologic monitoring during MRI is essential.

• 出版日期2011-10-4