MRI in Pediatric and Congenital Heart Disease Patients with CIEDs and Epicardial or Abandoned Leads

Abstract

Background:

Heart Rhythm Society guidelines outlining magnetic resonance imaging (MRI) in patients with cardiac implantable electronic devices (CIEDs) excluded children and epicardial or abandoned leads due to theoretical risks of harm. Research investigating these risks is lacking. The primary objective of our study is to determine the incidence of adverse events to patients or CIEDs from MRI imaging. The secondary objective is to describe CIED-related artifact on MRI images.

Methods:

A single-center retrospective review was performed on all patients with CIEDs who underwent 1.5 Tesla MRI between July 2007 and May 2019. We subdivided patients among four cohorts: 1) patients <18 years of age, 2) epicardial leads, 3) abandoned endocardial leads, 4) abandoned epicardial leads. Descriptive statistics pre- and post-MRI and at follow-up within 1.5 years were conducted.

Results:

Fifty-four MRIs were performed on 40 patients. Median age was 21.2 years (IQR 12.0–25.0). Eighteen (33%) MRIs contained abandoned leads; 20 (37%) contained epicardial leads. Three patients, one with abandoned epicardial leads and two with abandoned endocardial leads, experienced mild discomfort at the CIED site. One adult with endocardial leads experienced a pause in heartrate while programmed in a non-pacing mode. No clinically important changes to CIED parameters occurred. Nine MRIs (17%), especially those with functional cardiac imaging, were uninterpretable due to image artifact.

Conclusion:

In this study, pediatric and adult CHD patients with CIEDs, many with epicardial or abandoned leads, underwent MRIs without clinically significant complications. In some, CIED artifact reduced cardiac MRI image quality due to CIED position.

INTRODUCTION

Magnetic resonance imaging (MRI) in patients with cardiac implantable electronic devices (CIED) poses theoretical safety concerns such as CIED malfunction and damage to the CIED, leads, or heart at the lead-tissue interface.¹ Historically, MRIs were contraindicated for patients with CIEDs due to theoretical interactions between metal devices and MRI magnetic fields.² More recently, multiple large studies describe safely performing MRIs in adult patients with CIEDs.^3–5 As a result, in 2017, the Heart Rhythm Society approved MRI scanning in adult patients with CIEDs who did not have epicardial or abandoned leads. Patients with epicardial or abandoned leads were excluded from these guidelines due to a paucity of clinical research evaluating MRI safety in these patients.⁶

Because of conduction abnormalities that naturally occur or result from interventions, children and adults with congenital heart disease (CHD) often need CIEDs. For these patients, MRI is often the preferred imaging modality for evaluating anatomy, cardiac function, and myocardial viability due to the lack of radiation exposure and superior spatial resolution with MRI imaging.⁶ Abandoned and/or epicardial leads are common in this population due to complex cardiac anatomy, CIED implantation at a young age, and frequent generator and lead changes. A few studies have evaluated MRI scans in adult patients with CIEDs and epicardial or abandoned leads, including one larger study of nearly 100 MRI scans of adult patients with abandoned leads.^7–13 Additionally, our institution published a small series of eight pediatric and adult CHD patients undergoing eleven MRIs, most with epicardial leads.¹⁴ No clinically significant adverse events or changes in CIED parameters were identified.^7–11,14

The primary objective of our study was to determine if adverse events – defined as patient morbidity, arrhythmias, or clinically significant CIED parameter changes – occurred in pediatric and adult CHD patients with a CIED or abandoned leads undergoing an MRI at our institution. The secondary objective was to evaluate the effect of the CIED on MRI image quality.

METHODS

Patient Selection

This was a single-center retrospective review evaluating all pediatric and adult CHD patients with a permanent CIED or abandoned leads without a generator who underwent an MRI between July 2007 and May 2019. When patients underwent more than one MRI, each MRI was a separate datapoint. All patients and/or guardians provided informed consent before the MRI. Patients were analyzed as one entire group and subsequently divided into four subgroups (not mutually exclusive): 1) patients <18 years of age, 2) epicardial leads, 3) abandoned endocardial leads, 4) abandoned epicardial leads. These subgroups were chosen because each represents a unique population not well characterized in previously published cohorts of patients with CIEDs undergoing MRI scans. We elected to include eight patients with eleven MRIs who were included in a previous published study from our institution.¹⁴

Patient and CIED Monitoring

MRIs were performed using a General Electric Medical Systems (Milwaukee, WI, USA) Optima 450w 1.5 Tesla MRI scanner. Our protocol for selecting and monitoring patients and CIEDs during the MRI is illustrated in Figure 1. Patients were requested to inform physicians of any symptoms experienced during the procedure through an audio intercom system. None of the studies occurred under general anesthesia, and all patients were able to communicate during the MRI.

Figure 1:

Protocol for patient selection and MRI scan programming.

Immediately after the MRI (post-MRI), all CIEDs were programmed back to their initial settings. Device parameters including battery voltage, capture and sensing thresholds, and pacing impedance were collected immediately before and after the MRI and at follow-up.

Assessment of MRI Imaging Quality

MRI reports were reviewed to determine the degree to which CIED associated artifact affected MRI image quality. All cardiac MRIs were re-evaluated by pediatric cardiologists with expertise in cardiac MRI (J.S. and M.D.P.) to confirm the accuracy of the MRI report. If present, artifact was subdivided into three categories 1) no effect to image, 2) mild image degradation but no change to the diagnostic utility, and 3) artifact rendered the MRI scan diagnostically useless.

Statistical Analysis

Descriptive statistics of continuous patient and CIED variables were presented as median and interquartile ranges (IQR) due to distribution skew. Categorical variables were summarized as counts and percentages. Changes in CIED parameters were summarized as means with standard deviations (SD) for the following comparisons: 1) pre-MRI – post-MRI, 2) post-MRI – follow-up, and 3) pre-MRI – follow-up. Statistical tests comparing the difference in CIED parameters between the three time points were not performed due to small sample sizes. Because capture thresholds can routinely vary up to 0.5V between device interrogations in both epicardial and endocardial leads,^15,16 only changes in capture threshold > 0.5V across the three time points were considered clinically significant. We could not assess the relationship between adverse events and any potential risk factors because of the small number of adverse events identified in our study. Statistical summaries were performed in R, version 3.2.4.¹⁷

RESULTS

Patient and CIED Characteristics

There were 40 patients who underwent 54 MRIs during the study period (Table 1). The majority underwent one MRI. One patient had four MRIs, and another had six MRIs. The median patient age was 21.2 (IQR 12.0–25.0) years; 43% of the MRIs (50% of patients) were < 18 years of age. The youngest patient was 1.7 years old and 10.4 kg. Most MRIs were cardiac (29, 54%), and the remaining MRIs scanned the brain, spine, abdomen, pelvis, or extremity. The median time between MRI to follow-up device interrogation was 121.5 (IQR 49.7–159.5) days. Demographics and CIED characteristics of the entire cohort and the four subgroups (patients <18 years of age, epicardial leads, abandoned endocardial leads, abandoned epicardial leads) are in Tables 1 and 2, respectively.

Table 1:

Summary of patient demographics and characteristics of MRI scans.

	All	<18 years of age	Epicardial leads	Abandoned endocardial leads	Abandoned epicardial leads
Patients	40	20	19	5	7
MRIs	54	23	20	10	8
Age at MRI, yrs	21.2 [12.0–25.0]	11.5 [8.7–14.9]	12.4 [8.8–19.5]	21.9 [21.4–25.0]	18.4 [16.0–22.1]
Male	30 (56)	12 (60)	11 (61)	4 (80)	4 (57)
Body surface area, m2	1.62 [1.22–1.85]	1.15 [0.97–1.52]	1.18 [0.96–1.63]	1.63 [1.62–1.73]	1.82 [1.55–1.89]
MRIs per patient
One	32 (80)	16 (80)	16 (89)	4 (80)	6 (86)
Two	6 (15)	4 (20)	2 (11)	0 (0)	1 (14)
≥Four	2 (5)	0 (0)	0 (0)	1 (20)	0 (0)
Primary diagnosis
Complex CHD*	30 (55)	13 (57)	14 (70)	2 (20)	7 (88)
Simple CHD†	15 (28)	4 (17)	5 (25)	7 (70)	1 (12)
Arrhythmia‡	5 (9)	3 (13)	0 (0)	1 (10)	0 (0)
Hypertrophic cardiomyopathy	2 (4)	2 (9)	0 (0)	0 (0)	0 (0)
Long QT syndrome	2 (4)	1 (4)	1 (5)	0 (0)	0 (0)
Indication for pacing
SND or symptomatic bradycardia	32 (59)	11 (48)	13 (65)	6 (60)	4 (50)
Surgical heart block	5 (9)	3 (13)	4 (20)	0 (0)	2 (25)
Congenital heart block or progressive AV block	4 (8)	4 (18)	2 (10)	0 (0)	0 (0)
Anti-tachycardia pacing	3 (5)	1 (4)	0 (0)	1 (10)	0 (0)
Post-MI heart block	1 (2)	1 (4)	0 (0)	0 (0)	0 (0)
Not paced§	9 (17)	3 (13)	1 (5)	3 (30)	2 (25)
MRI types ¶
Cardiac	29	14	13	4	6
Brain	14	6	3	4	2
Upper Torso**	11	5	2	0	0
Lower Torso††	14	4	3	6	0
Extremity	3	1	2	0	0
Follow-up interrogation, d	121.5 [49.7,159.5]	112.0 [49.0–203.0]	135.0 [90.0–204.5]	137.0 [107.0–179.5]	116.0 [83.0–202.0]

Values are N, N (%), or median [IQR].

^*Simple CHD includes septal defects, coarctation of the aorta, and isolated atrioventricular septal defects.

^†Complex CHD includes any other congenital heart defect including Ebstein anomaly, single ventricle palliation, tetralogy of Fallot, transposition of the great arteries, and tricuspid atresia.

^‡Arrhythmia includes tachyarrhythmia, high-grade AV block, and SND.

^§Patients with abandoned leads only (4) or an implantable cardioverter-defibrillator without pacing need (5).

^¶Some MRI studies involved multiple body sites, so the sum of the MRI types is >54.

^**Upper torso includes MRIs of the chest or thoracic or cervical spine.

^††Lower torso includes MRIs of the abdomen, pelvis, or lumbar or sacral spine.

MRI indicates magnetic resonance imaging; yrs, years; N, number; IQR, interquartile range; CHD, congenital heart disease; SND, sinus node dysfunction; MI, myocardial infarction; d, days.

Table 2:

Summary of CIED characteristics

	All	<18 years of age	Epicardial leads	Abandoned endocardial leads	Abandoned epicardial leads
MRIs	54	23	20	10	8
CIED type
Pacemaker	43 (80)	19 (83)	19 (95)	6 (60)	6 (75)
ICD	7 (13)	3 (13)	1 (5)	2 (20)	0 (0)
No CIED*	4 (7)	1 (4)	0 (0)	2 (20)	2 (25)
CIED age at MRI, yrs	4.0 [2.3–6.0]	4.0 [3.0–6.0]	4.0 [2.0–6.3]	4.0 [3.3–5.0]	3.5 [2.3–4.0]
CIED lead age at MRI, yrs	6.0 [4.0–9.0]	6.0 [4.0–7.0]	6.0 [4.3–8.8]	5.0 [4.8–6.8]	8.0 [4.0–10.0]
CIED generator body position
Left chest	26 (48)	11 (48)	4 (20)	2 (20)	3 (38)
Left abdomen	15 (28)	11 (48)	15 (75)	0 (0)	3 (38)
Right chest	8 (15)	0 (0)	1 (5)	6 (60)	0 (0)
Unknown	1 (2)	0 (0)	0 (0)	0 (0)	0 (0)
Pacing dependent	14 (26)	7 (30)	9 (45)	0 (0)	3 (38)
MRIs with epicardial leads	20 (37) 19 patients	14 (61) 13 patients	20 (100) 19 patients	0 (0)	4 (50) 4 patients
MRIs with abandoned leads	18 (33) 12 patients	5 (22) 5 patients	4 (20) 4 patients	10 (100) 5 patients	8 (100) 7 patients
Endocardial	10 (19) 5 patients	1 (4) 1 patient	0 (0)	10 (100) 5 patients	0 (0)
Epicardial	8 (15) 7 patients	4 (17) 4 patients	4 (20) 4 patients	0 (0)	8 (100) 7 patients
MRI conditional CIED generator	14 (26)	3 (13)	2 (10)	4 (40)	3 (38)
MRI conditional system	10 (19)	2 (9)	0 (0)	4 (40)	0 (0)

Values are N, N (%), or median [IQR] unless otherwise indicated.

^*Patients with abandoned leads but no CIED.

CIED indicates cardiac implantable electronic device; N, number; IQR, interquartile range.

There were 43 MRI scans of patients with pacemakers, seven with implantable cardioverter-defibrillators (ICDs), and four with abandoned leads without a CIED (Table 2). Abandoned leads were present in 18 (33%) and epicardial leads in 20 (37%) of the MRIs. Table 3 lists the lead type and location of each epicardial and abandoned lead.

Table 3:

Number and model of intact epicardial leads and abandoned leads

Intact Epicardial Leads			Abandoned Leads
Lead Model	Atrial	Ventricular	Lead Model	Epicardial	Endocardial
Guidant 4047	1		Guidant 4469		1
Guidant 4469	1		Intermedies 438-10-45		6
Intermedies 439-04	1		Intermedies 439-04	1
Intermedies 439-07		1	Medtronic 4968 CapSure Epi	8
Intermedies 511111		1	St. Jude 1043K Epicardial	2
Medtronic 4968 CapSure Epi	13	9	St. Jude 511211		1
St. Jude 511211	1	2	St. Jude Tendril		1
St. Jude 511212		1	St. Jude Durata 7122		1
Model Unknown		1	ICD Lead - Model Unknown		1
Total	17	15	Total	11	11

Values are N.

Effect of MRI on Patients and CIEDs

In most of the MRIs (50/54, 93%; Table 4), patients did not experience symptoms. Of the four patients with symptoms, patients 1 and 2 experienced warmth in the left lateral chest during cardiac MRI that resolved after aborting the MRI. Patient 1 was 36 years old and had one abandoned endocardial lead without a CIED. Patient 2 was 21 years old and had a single-chamber non-MRI conditional pacemaker with one intact and one abandoned endocardial lead. Patient 2 underwent a previous MRI and four subsequent MRIs without any symptoms. Patient 3, who was 17 years of age and had a dual-chamber MRI conditional pacemaker with epicardial leads and two abandoned epicardial leads, experienced a tingling sensation near the cut, uncapped end of an abandoned lead during a magnetization transfer sequence of a brain MRI. This sequence was prematurely terminated, but the remainder of the MRI was completed without symptoms. Patient 4, who was 21 years old and had a non-MRI conditional pacemaker and endocardial lead system, experienced a pause in heart rhythm when programmed in a non-paced mode during a brain MRI. This patient had a repeat brain MRI a few weeks later with the device programmed in an asynchronous paced mode without pauses or symptoms.

Table 4:

Summary of events that occurred to patients or CIEDs after MRI studies

N=54 MRI Studies	N (%)
Symptoms during MRI
Warmth at left chest	2 (4)
Tingling sensation at left chest	1 (2)
Pause in heart rhythm when programmed in non-paced mode	1 (2)
CIED or lead removal required post-MRI	0 (0)
CIED or lead removal related to MRI at follow-up	0 (0)
Programming changes post-MRI (N=49) †
Change in Capture Threshold >0.5	0 (0)
Programming changes at follow-up (N=36) ‡
Change in Capture Threshold >0.5V	0 (0)

^†N=49 due to 4 patients not having a CIED generator and 1 patient whose post-MRI interrogation was not entered into the medical record.

^‡N=36 due to 4 patients not having a CIED generator and 14 patients who did not have a follow-up interrogation in the medical record.

In the four symptomatic patients, there were no clinically significant changes to device parameters pre- and post-MRI in the intact CIED components. We did not test the abandoned leads since there is no practical, non-invasive method for testing these. All patients who experienced symptoms had a non-MRI conditional CIED system (both leads and device). Thus, 91% (40/44) of the MRIs conducted in patients with non-MRI conditional systems were without adverse events. No patient reported symptoms after the MRI or at follow-up. There were no deaths attributable to the MRI or patients’ CIED.

Device parameters pre-MRI, post-MRI, and at follow-up interrogation were similar (Supplementary Table 1). There were minor differences in the capture threshold between the pre-MRI to post-MRI and post-MRI and the follow-up interrogations. However, none of these changes were greater than our predefined threshold of >0.5V (Table 4).

No patient in our study required CIED or lead revision immediately after the MRI (Table 4). One patient had a lead fracture one year after MRI. His CIED and leads were removed because the device was no longer required. Three other patients underwent changes to their CIED systems after follow-up interrogations. Two patients had pacemakers that were found to be at elective replacement indicator (ERI) prior to their MRIs, and subsequently had their generators replaced; of note, there were no changes in battery voltage in either of these two CIEDs between the pre- and post- MRI device interrogations. The third patient had a CIED upgrade unrelated to the MRI.

CIED Effect on MRI Image Quality

Twenty (37%) MRIs contained artifact (Table 5). Of these, three had no effect on the MRI images, eight mildly affected the images without changing the clinical utility of the MRI, and nine contained sufficient artifact that the MRI was rendered diagnostically useless (Table 5). All significant artifact was caused by the generator and primarily affected functional cardiac MRI images. Of the uninterpretable MRIs, six involved pacemakers and three involved ICDs. Nearly all (19, 95%) MRIs with artifact were cardiac MRIs, and one (5%) was an abdominal MRI focusing on the liver with a pacemaker in the right abdomen.

Table 5:

Amount of artifact present in the MRI scans.

N=54 MRI Studies	N (%)
No artifact present	34 (63)
Artifact present	20 (37)
No effect on image	3 (5)
Mild image degradation but no change to the diagnostic utility	8 (15)
Artifact rendered MRI scan diagnostically useless	9 (17)

DISCUSSION

In the largest cohort of pediatric and adult CHD patients with CIEDs undergoing MRIs, we found that MRI scans had no clinically relevant adverse effects on patients or CIEDs. Many of these CIEDs contained epicardial and abandoned endocardial and/or epicardial leads. Half of the patients were <18 years of age, and 75% of patients had CHD. Both of these patient groups represent an understudied population often excluded from guidelines and larger studies. We found no identifiable differences in outcomes due to patient age, body surface area, or presence of CHD. Patients were asymptomatic during 93% of MRI studies, and only minor reports of discomfort were observed. Notably, two of the four patients reporting symptoms had MRIs without adverse events either before or after the MRI that was associated with symptoms. This suggests that symptoms were due, in part, to the MRI sequence and protocol rather than exclusively to CIED components. The patient who experienced a pause in non-paced mode successfully underwent an MRI in asynchronous pacing mode three weeks later, suggesting that asynchronous pacing mode may be a more suitable mode when it is uncertain if a patient is pacemaker dependent.

The 2017 Heart Rhythm Society guidelines permit patients with CIEDs to undergo multiple MRIs, as current evidence suggests the cumulative effects of MRI scans does not harm CIEDs.^6,18,19 Our study supports this guideline. No patient experienced clinically significant changes to CIED parameters after MRI exposure, including those who had two or more MRIs. One patient underwent six MRIs without adverse events.

Discomfort experienced by the four symptomatic patients was less likely related to cumulative MRI exposure, as suggested by one patient who experienced symptoms at the time of the second MRI but subsequently underwent two MRIs without symptoms or adverse effects to the CIED. We suspect that symptoms were more likely due to the presence of non-MRI conditional systems and their components. In fact, all patients reporting symptoms had non-MRI conditional systems. Because of our small sample size, we could not statistically compare outcome differences between MRI-conditional and non-MRI conditional CIEDs. We did find that most patients with non-MRI conditional CIED systems (91%) and all patients with MRI-conditional systems (10/10) were without symptoms at the time of the MRI.

Epicardial and Abandoned Leads

Epicardial lead pacing systems are an important and often necessary treatment modality in children because body size (<15–20kg) limits placement of standard endocardial leads.²⁰ Additionally, epicardial leads are commonly used in patients with CHD, especially in patients with intracardiac shunts, single ventricle physiology, and extracardiac Fontan palliation with no systemic venous access to the heart. In this study, we performed 20 MRIs on 19 patients with intact epicardial leads without significant adverse effects.

The Heart Rhythm Society published a consensus statement in 2017 for MRI imaging of CIEDs with endocardial leads that permits MRI imaging of patients with CIEDs and endocardial leads.⁶ These guidelines exclude patients with epicardial and abandoned leads due to a paucity of clinical data and theoretical concerns of harm from lead heating. The theoretical risks include thermal myocardial damage from lead tip heating, induction of current in CIED leads resulting in unintended changes in pacing, and arrhythmia induction.²¹ The writers recommend that the risks and benefits of scanning patients with these leads be weighed on a case-by-case basis.⁶

While we agree data are lacking regarding MRI and epicardial leads, there is increasing evidence that this practice may not cause significant patient harm. A recent meta-analysis evaluating the risk of MRI with non-MRI conditional CIED systems included 25 MRIs of epicardial leads. While the study authors did not analyze the patients with epicardial leads separately, the incidence of symptoms was low (0.3%), and there were no clinically significant device parameter changes in the entire cohort.²² This is consistent with our results in which no patient with intact epicardial leads experienced significant adverse effects from an MRI scan.

Our study adds to the growing body of evidence that abandoned leads may not cause patient harm during MRI scans. Higgins performed MRIs on 31 abandoned leads in which patients’ pacemaker generators were removed prior to MRI scans. Twelve of 19 patients’ pacemakers were replaced after the scan.⁷ They reported no adverse events or significant changes in lead function parameters once the leads were reattached following the MRI scans.⁷ Additional published studies of MRIs with abandoned leads reported similar findings, including the aforementioned meta-analysis that included 100 abandoned leads and a different study of 97 MRIs with abandoned leads.^8,9,12,13,22 Likewise, the 18 MRIs in our study that contained abandoned leads were performed without clinically significant adverse events.

In our study, three of the symptomatic patients reported “heating” or “tingling”, and all three had abandoned leads. Unfortunately, lead parameter changes that might suggest tissue heating cannot be tested in abandoned leads. None of our patients had overt signs of tissue heating, and two of the three patients had subsequent MRI imaging without reported symptoms. We were not able to identify a difference between abandoned endocardial leads and abandoned epicardial leads. Until more definitive proof of the safety of MRI of abandoned leads is achieved, we limit MRI imaging of patients with abandoned leads to those who can communicate symptoms during the scan.

CIED Parameter Changes

While earlier studies with older generation CIEDs discovered that MRIs can alter CIED programming by inducing a device reset, magnet-mode response, or transient cessation of pacing,^5,9,19–21 more recent studies with improved patient screening and pre-MRI programming strategies similar to the strategies we employed, have limited these problems.^3–5 In our study, no patient had clinically significant threshold changes following MRI exposure. Although 13 CIEDs had minor threshold changes immediately after the MRI or at the follow-up appointment, these changes were within the usual clinical variation (<0.5V) observed in CIED generators.^15,16 Similarly, previous studies in adult CIED cohorts have identified pacing threshold changes after MRI scans within the range of normal variance between routine CIED interrogations.^5,10,23

Secondary Outcome: CIEDs and Image quality

Most MRIs (64%) in our study had no artifact present, and 83% of MRIs were clinically useful. Previous studies have identified multiple risk factors for developing CIED artifact in MRIs including CIED type, CIED manufacturer, patient body mass index, location of the CIED in relation to the field of view, and type of imaging sequence performed.^24–26 Some studies have found that pacemakers create little to no artifact and rarely affect the clinical utility of the scan, but ICDs may cause artifact in up to 44% of MRIs.^24,27 In contrast, our study found that pacemakers and ICDs limited the diagnostic utility of cardiac MRI scans equally. We attribute this finding to differences in body size between our patients and larger, adult patients in other studies – to this point, six of the nine patients (67%) with uninterpretable MRIs in our study were <18 years of age. In fact, most of the MRIs containing ICDs in our study were clinically useful, a finding similar to what is reported in the literature.^24,27,28

Limitations

The retrospective design and small sample size of our study limited our power to more definitively determine if MRI scans are safe in patients with CIEDs, particularly patients <18 years of age or with epicardial or abandoned leads. There is significant overlap between our four subgroups which, in conjunction with the smaller sample size, limits the data analysis. In addition, most (22/32, 69%) epicardial leads in this study were sew on button type (Medtronic 4968); their response to MRI may not be generalizable to other epicardial leads. Finally, there is a possibility of selection bias in our study. An electrophysiologist determined which patients could undergo an MRI, and we do not have data on patients who were prohibited from obtaining an MRI.

In this study, pediatric and adult CHD patients with CIEDs, many with epicardial or abandoned leads, underwent MRIs without clinically significant complications. Although CIED artifact reduced cardiac and abdominal MRI image quality, MRIs remained clinically useful in the majority of patients. Larger prospective studies using similar patient selection criteria and MRI scan programming protocols ought to be performed to confirm these findings, with the goal of liberalizing the restriction of this valuable imaging modality in this patient population.

Abbreviations:

MRI

Magnetic resonance imaging

CIED

Cardiac implantable electronic device

CHD

Congenital heart disease

SD

Standard deviation

IQR

Interquartile range

ICD

Implantable cardioverter-defibrillator

ERI

Elective replacement indicator

SAR

Specific absorption ratio

S/m

Siemens / meter