1Klinikum Lippe-Detmold Universitätsklinik für Kardiologie, Angiologie, Intensivmedizin Detmold, Deutschland; 2Universitätsklinikum Münster Herz-MRT-Zentrum Münster, Deutschland
Background and Aims:
Many physicians are hesitant to perform magnetic resonance imaging (MRI) on patients with epicardial leads from cardiac implantable electronic devices (CIEDs) due to fear of heating that has been reported in in vitro studies. With increasing patient numbers, there is a clear need for trustable safety data.
Methods:
The electronic databases Medline and CINAHL were searched to identify relevant literature in Englisch language by applying the key terms “magnetic resonance imaging” AND “epicardial leads”. The primary outcome of interest in the selected studies were safety-relevant events, defined as (1) MACE. Secondary outcome measures included (2) major change in the CIED parameter, (3) device- or patient-related dysfunction, (4) signs of myocardial injury and/ or laboratory measurement of myocardial tissue damage with biomarker. The Newcastle-Ottawa Scale (NOS) for cohort studies was used to assess study quality and potential bias.
Results:
17 publications with a total of 351 epicardial leads (222 functional and 129 abandoned) and 425 MRI scans of different anatomical regions were included. No scan-related MACE was documented. Furthermore, no device dysfunction or severe arrhythmia was reported. Mainly transient device parameter changes were observed in 2.8% in the subgroup of patients with functional epicardial leads. As a possible correlate of myocardial injury, subjective sensations such as heating occurred mainly in the subgroup with abandoned epicardial leads (4.0%), but no change in myocardial biomarkers was observed.
Discussion:
Epicardial leads in MRI are a common problem, with an increasing trend as the population ages and CIEDs become more widespread. The removal of epicardial leads would always require thoracic surgery with associated risks. This is particularly relevant for the paediatric population since abandoned leads will remain in the body for the rest of the lives of children with implanted epicardial pacing systems. Interestingly, the well-known theoretical concerns of myocardial injury by potential heating of the electrode tip that are based on in vitro data are not supported by clinical results. The subjective feeling of heating as a correlate for tissue damage remains uncertain because heat sensation by the applied radiofrequency pulses is a common side effect of MRI. In general, heating-related issues in patients without CIED were reported in in literature up to 1.5 % of routine MRI scans, which is comparable to our present data (1.6 %) for functional epicardial leads. But 4.0 % occurred in abandoned epicardial leads, which have different physical properties. Another marker for cardiomyocyte death could be a deterioration of the measured CIED parameter. Parameter change was observed in 2.8 % in our population, compared to 1.5% of endocardial leads in a large previous meta-analysis. Those changes were transient in most of the cases who also reported follow-up data. After all, physicians should always be aware that safety protocol deviations carry a (at least theoretical) risk of serious adverse events, when performing off-label MRI scans in CIED patients.
Conclusion:
No severe adverse events occurred in 425 MRI scans in patients with functional and abandoned epicardial leads. Based on our data, clinically indicated and appropriately performed MRIs should not be strictly denied to these patients – if the clinical indication is sound and other alternative imaging modalities not appropriate.