MRI and implantable cardiac electronic devices.

PURPOSE OF REVIEW: To assess the current knowledge about the potential hazard from MRI in patients with devices such as pacemakers and implantable cardioverter defibrillators (ICDs).

RECENT FINDINGS: Most data concern 'MRI unsafe' devices, with only a few studies on 'MRI conditional' devices. No 'MRI safe' cardiac devices are currently available. Studies on 'MRI unsafe' devices tend to be small scale and reflect the experience of individual centres; few provide long-term follow-up data. Many newer devices are approved as 'MRI conditional' based on technical simulations or postmarket surveillance studies. With adequate measures taken before performing an MRI scan, reported complication rates are generally low, but there is a nonnegligible residual risk for power-on reset and lead heating. The presence of abandoned, older leads may affect the propensity for lead heating during MRI with newer devices, including those designated 'MRI conditional'. Very little research has been carried out on the hazard from MRI scans in patients with ICDs, but registry data indicate more events with ICDs than with pacemakers.

SUMMARY: The limited available data indicate a manageable but not negligible MRI-associated hazard in patients with implantable cardiac devices. Further controlled studies and large, independent registries, particularly in Europe, are needed to provide important safety information.