A systematic review of the use of magnetic resonance imaging in non-conditional pacemakers and implantable defibrillators

Background Cardiac implantable electronic devices (CIEDs) were long considered a contraindication for magnetic resonance imaging (MRI). Modern devices are now MRI conditional, but still the majority of CIEDs in the population are legacy devices and are classified as unsafe for MRI. There is growing consensus that MRI is also safe in these patients. Purpose The purpose of this study was to perform an up to date systematic review of the evidence evaluating the use of MRI in patients with non-conditional CIEDs. Methods Searches of the PubMed, CINAHL and Embase databases were performed. Studies that assessed the rate of adverse outcomes after MRI in patients with non-conditional CIEDs were included. Studies were excluded if they did not disclose the conditionality of patients CIEDs. Case reports or case series were not included. Results 36 cohort studies were identified. No patient in these studies died during or immediately after MRI. Symptom associated with either torque or heating occurred in <1% of patients. Electrical resets occurred 1–2% of patients. There were no cases of non-conditional lead or generator failure. Inappropriate pacing occurred in <1% of patients. No ICD shocks occurred during MRI. Changes in CIED parameters occurred in 1–4% of patients. Conclusions This systematic review highlights the relative safety of the use of MRI in patients with non-conditional CIEDs. Demonstrated be the fact that no deaths or device shocks have been suffered as a consequence of MRI in any of these studies, and the extremely low incidence of device or lead related complications. Still strict selection and monitoring protocol should be used when imaging these patients. FUNDunding Acknowledgement Type of funding sources: None.

Is diversity harmful?—Mixed-brand cardiac implantable electronic devices undergoing magnetic resonance imaging

Summary Background Many patients with cardiac implantable electronic devices (CIED) undergo magnetic resonance imaging (MRI); however, a relevant proportion have a CIED system that has not been classified as MRI-conditional because of generators and leads from different brands (mixed-brand group). The available data concerning the outcome of these mixed patients undergoing MRI is limited. Methods A retrospective single center study, including all patients with CIEDs undergoing MRI between January 2013 until May 2020, was performed. Primary endpoints were defined as death or any adverse event necessitating hospitalization or CIED revision. Secondary endpoints were the occurrence of any sign for beginning device or lead failure or patient discomfort during MRI. Results A total of 227 MRI examinations, including 10 thoracic MRIs, were carried out in 158 patients, with 1–9 MRIs per patient. Of the patients 38 underwent 54 procedures in the mixed-brand group and 89 patients underwent 134 MRIs in the MRI-conditional group. Of the patients 31 were excluded since the MRI conditionality could not be determined. No primary endpoints occurred within the mixed-brand group but in 2.2% of the MRI-conditional group (p = 1.000), with 2 patients developing new atrial fibrillation during MRI, of whom one additionally had a transient CIED dysfunction. No secondary endpoints were met in the mixed-brand group compared to 3.4% in the MRI-conditional group (p = 0.554). No complications occurred in the excluded patients. Conclusion The complication rate of CIED patients undergoing MRI was low. Patients with a mixed CIED system showed no signs of increased risk of adverse events compared to patients with MRI-conditional CIED systems.

Assessing access to mri in patients with cardiac implantable electronic devices in australia

Funding Acknowledgements Type of funding sources: None. Background "Legacy" cardiac implantable electronic devices (CIEDs) have historically been considered non-MRI-conditional. However, a number of recent studies indicate that if certain protocols are followed, patients with such devices may undergo MRI without significant adverse outcomes. Nowadays, industry standards dictate that "modern" CIEDs are MRI compatible. Despite these developments, some patients with CIEDs are denied MRI. Paucity of access to this vital service has been shown to increase expense, lead to more invasive imaging and later diagnosis, and poorer patient outcomes. This study aims to identify if Australian public hospitals provide MRI services for patients with modern and legacy CIEDs, the characteristics of the services, and the barriers to implementing such a service. Methods This study surveyed all Australian Tertiary Referral Public Hospitals (n = 38), with a mixed qualitative and quantitative questionnaire. Results 35 of the 38 sites completed the survey. Figure 1A shows that the majority of hospitals (30/35, 85.7%) offer MRIs for modern MRI-conditional CIEDs. In contrast, Figure 1B shows that only a minority of hospitals (3/35, 8.6%) offer MRIs for legacy CIEDs. Protocols governing patient eligibility vary greatly among hospitals that scan modern devices. Locations either allow all CIEDs to be scanned, only non-dependent CIEDs, or only pacemaker CIEDs. 1.5 Tesla is the preferred strength to scan Modern CIEDs (59%), however a sizeable proportion scan at only 3.0 Tesla (10%) or both strengths (31%). A majority (80%) of staff in attendance of the scan were ACLS-trained (Advanced Cardiac Life Support), with no correlation to strength of MRI used. A range of different personnel attend the scan with varied patient monitoring strategies, and a majority (79%) offer thoracic as well as extra-thoracic scanning. The few hospitals that scan legacy devices only scan at 1.5 tesla, and follow individualised protocols. These sites offer more personnel in attendance for the scan than for modern CIED scans, with all staff ACLS-trained including a physician who can direct CIED programming of required. These sites have more involved patient monitoring, and all also offer thoracic and extra-thoracic MRI scanning. The predominant barrier identified was an absence of National Guidelines, followed by a lack of formal training or logistical device support. Conclusions The majority (85.7%) of Australian Tertiary Referral Public Hospitals have a MRI service for patients with modern CIEDs, but only 8.6% offer this service to patients with legacy CIEDs. This highlights the need for a national effort to guide the provision of MRI services for patients with CIEDs, and address the identified barriers.

Is diversity harmful? - Mixed-brand cardiac implantable electronic devices undergoing magnetic resonance imaging

Funding Acknowledgements Type of funding sources: None. Introduction Many patients with cardiac implantable electronic devices (CIED) need to undergo magnetic resonance imaging (MRI). However, a significant proportion has a CIED system in place that has not been classified "MRI-conditional" because of generators and leads from different brands ("mixed-brand" group), although the individual components per se are MRI-conditional. There is only limited data available concerning the outcome of these patients with "mixed-brand" CIED systems undergoing MRI. Purpose To analyse complications or adverse effects in "mixed-brand" CIED patients undergoing MRI, compared to patients with a fully "MRI-conditional" CIED system. Methods A retrospective single-centre study was performed, including patients undergoing MRI between January 2013 until May 2020. Short- and long-term outcomes were compared between both groups. We defined the primary endpoint as death or any adverse event necessitating hospitalization or CIED revision in association with the MRI examination. Secondary endpoints were the occurrence of any surrogate for beginning device or lead failure or patient discomfort during MRI. Results A total of 227 MRI examinations, including 10 thoracic MRIs, were carried out in 158 patients, with a range of 1-9 MRIs per patient. Mean age was 73 years and 52 (32.9%) patients were female. We identified 38 patients undergoing 54 procedures in the "mixed-brand" group and 89 patients undergoing 134 MRI procedures in the "MRI-conditional" group. In 31 patients undergoing 39 MRI examinations the MRI-conditionality could not be determined. "Mixed-brand" patients were older than MRI-conditional patients (mean 77 vs. 72 years, p = 0.003). The primary endpoint occurred in 0% in the "mixed-brand" group and in 2.2% in the "MRI conditional" group (p = 1.000). Complications were as follows: Two patients had first diagnosed atrial fibrillation directly associated with the procedure, of whom one additionally had a transient CIED dysfunction. No patient in the "mixed-brand" group and three patients (3.4%) in the "MRI conditional" group met the secondary endpoints (p = 0.554). In patients with undeterminable MRI conditionality the complication rate was similar (0% for both the primary and secondary endpoints). Conclusion The complication rate of CIED patients undergoing MRI was low. There was no signal for increased risk of adverse events in patients with a CIED without MRI certification due to mixed brands systems compared to patients with "MRI-conditional" CIED systems.

Abstract 14089: Reduced Pain External Defibrillation (RPD) and MRI-conditional RPD: Reduced Pain ind Equivalent Efficiency Validation in Swine

Introduction: External defibrillators are used for cardioversion and resuscitation after sudden cardiac arrest (SCA). External defibrillators are also required for emergency MRI (acute stroke, spinal trauma). Low-power (9 Joule) ICD RPDs [1], and MRI-conditional external defibrillator prototypes exist [2]. An RPD external defibrillator was constructed, consisting of a Zoll defibrillator integrated with a tetanizing unit. The tetanizing waveform slowly compressed chest musculature prior to the strong biphasic defibrillating pulse, reducing chest contraction during the biphasic pulse, the major pain source. This RPD system (Fig. 1A-D) was evaluated for pain reduction and defibrillation effectiveness in swine. Method: The tetanizing unit consisted of a programmable generator that delivered a triangular 1-KHz pulse of 250-2000msec duration and 10-100 Volt peak amplitude, and subsequently triggered the conventional defibrillator to send out standard short (8msec) powerful (20-400 J) biphasic pulses. Forward limb motion (Fig. 1E), an established pain measure [3], was evaluated by measuring limb acceleration, acceleration rate and work (energy). 5 swine were arrested electrically and then defibrillated. RPD was repeated 15-20 times/swine, varying tetanizing parameters and biphasic energy. Results: Fig. 1F-H compare an RPD defibrillation and equivalent biphasic defibrillation, showing smaller accelerations and acceleration rates. Fig. 1J shows work results, at 30-200J biphasic energy, demonstrating an 83 + 15% limb work reduction with the RPD waveforms. Optimal tetanizing parameters were 15-25V amplitude and 500-750msec duration. Rhythm recovery for RPD and conventional defibrillation was identical. Conclusions: Reduced pain defibrillation may allow cardioversion without anesthesia and faster defibrillation after SCA. References: [1] Hunter DW 2016. [2] Schmidt EJ 2016. [3] Boriani G, 2005.