Prospective evaluation of the utility of magnetic resonance imaging in patients with non-MRI-conditional pacemakers and defibrillators.

BACKGROUND: Magnetic resonance imaging (MRI) in patients with legacy cardiovascular implantable electronic devices (CIEDs) in situ is likely underutilized. We hypothesized the clinical benefit of MRI would outweigh the risks in legacy CIED patients. METHODS: This is a single-center retrospective study that evaluated and classified the utility of MRI using a prospectively maintained database. The outcomes were classified as aiding in diagnosis, treatment, or both for the patients attributable to the MRI. We then assessed the incidence of adverse effects (AE) when the MRI was performed. RESULTS: In 668, MRIs performed on 479 patients, only 13 (1.9%) MRIs did not aid in the diagnosis or treatment of the patient. Power-on reset events without clinical sequelae in three scans (0.45%) were the only AE. The probability of an adverse event happening without any benefit from the MRI scan was 1.1 × 10-4 . A maximum benefit in diagnosis using MRI was obtained in ruling out space-occupying lesions (121/185 scans, 65.4%). Scans performed in patients for elucidating answers to queries in treatment were most frequently done for disease staging at long term follow-up (167/470 scans, 35.5%). Conservative treatment (184/470 scans, 39%) followed by medication changes (153/470 scans, 28.7%) were the most common treatment decisions made. CONCLUSIONS: The utility of MRI in patients with non-MRI-conditional CIEDs far outweighs the risk of adverse events when imaging is done in the context of a multidisciplinary program that oversees patient safety.

Safety of thoracic magnetic resonance imaging for patients with pacemakers and defibrillators.

BACKGROUND: During magnetic resonance imaging (MRI), cardiac implantable electronic device (CIED) leads can be antennae to focus energy onto myocardium, leading to heating and arrhythmias. Clinical data on thoracic MRI safety for patients with legacy devices are limited. OBJECTIVE: The purpose of this study was to identify patients undergoing thoracic MRI with legacy devices, compare the incidence of adverse events of those patients with control patients undergoing brain MRI with legacy devices, and compare paired cardiac troponin T (cTnT) values. METHODS: In this single-center study, we reviewed a prospectively collected database of patients with CIED undergoing MRI from January 25, 2008, through February 28, 2017. RESULTS: Of 952 patients (1290 scans), 120 patients (12.6%) underwent 134 thoracic MRI scans with legacy CIEDs (median [range] age 61.98 [21.24-86.96] years; male 71.1%). Median (range; interquartile range [IQR]) age of leads across devices was 3.5 (1.6-7.1; 5.5) years; implantable cardioverter-defibrillators (ICDs) were oldest (median [range; IQR], 3.7 [1.1-8.0; 6.9] years). No difference was observed in incidence of adverse events between groups. Paired cTnT values were compared for 19 patients (19 scans) with no difference between pre- and postimaging values. No significant difference was present in device setting values before and after MRI (mean follow-up 72.5 days). Incidence of adverse events was no different after adjustment for ICD coil number. CONCLUSION: Thoracic MRI is relatively safe in an institutional multidisciplinary program. It does not represent greater risk than brain MRI for patients with legacy CIEDs.

Mortality After Magnetic Resonance Imaging of the Brain in Patients With Cardiovascular Implantable Devices.

BACKGROUND: Use of magnetic resonance imaging (MRI) brain is restricted in patients with cardiovascular implantable electronic devices (CIEDs). We proposed to determine whether mortality difference exists for patients with non-MRI-conditional CIEDs undergoing brain MRI compared with controls. METHODS AND RESULTS: Retrospective analysis of prospectively collected data was performed to compare all-cause mortality in patients with CIEDs undergoing brain MRI (CIED-MRI) with 3 control groups matched for age, sex, imaging year, and type of CIED: (1) no CIED, brain MRI (no-CIED-MRI); (2) CIED, brain computerized tomography (CT) scan (CIED-CT); and (3) no CIED, brain CT (no-CIED-CT). The primary outcome was a significant difference (P<0.05) between estimated mortality rates. Secondary outcomes were changes in device function before and after brain MRI. The estimated all-cause mortality at 5 years for the CIED-MRI group [mean age (±SD), 68.2 years (15.3 years); 61.2% men] was not significantly different from patients who underwent CT with or without a device (CIED-CT group: hazard ratio, 0.814; 95% confidence interval, 0.593-1.117; P=0.2; no-CIED-CT group: hazard ratio, 1.149; 95% confidence interval, 0.818-1.613; P=0.4). There was a significant increase in mortality between CIED-MRI and no-CIED-MRI groups (hazard ratio, 1.463; 95% confidence interval, 1.019-2.099; P=0.04). CONCLUSIONS: Brain MRI in patients with CIEDs does not carry an increased mortality risk compared with brain CT and can be performed with adherence to appropriate procedural protocols.

Safety of magnetic resonance imaging in patients with legacy pacemakers and defibrillators and abandoned leads.

BACKGROUND: During magnetic resonance imaging (MRI), abandoned leads may act as antennae that result in tissue heating and arrhythmia induction. OBJECTIVE: The purpose of this study was to assess the safety of MRI in patients with abandoned leads, with the addition of cardiac troponin T (cTnT) assessment to screen for myocardial damage. METHODS: We reviewed our prospectively collected database of patients with cardiovascular implantable electronic devices (CIEDs) undergoing MRI between 2008 and 2017 at Mayo Clinic, Rochester, MN, and selected patients who had abandoned leads. We compared the adverse events in this population with an age, sex, and site of MRI-matched cohort of patients selected from this database. We evaluated paired (before/after) cTnT values using MRI in these patients. RESULTS: Of 952 patients, 80 (8.4%) underwent 97 MRI scans with CIEDs in situ with 90 abandoned leads in place during the scans. The median age was 66 years (interquartile range 22.3 years) 66.1 years (interquartile range, Q1,Q3: 53.6, 75.9) with 66.3% (53 patients) men. There was no clinical or electrical evidence of CIED dysfunction, arrhythmias, or pain. Paired samples for the measurement of cTnT values were available in 40 patients undergoing 44 MRI examinations. The mean difference between the pre- and postimaging values was -0.002 ± 0.006 ng/mL (interquartile range 0). There was no difference after adjustment for total number of leads per patient and total number of implantable cardioverter-defibrillator coils. CONCLUSION: There was no evidence of myocardial injury as measured by paired cTnT. The risk of MRI with abandoned leads appears low, suggesting a favorable risk-benefit profile in patients with CIEDs and abandoned leads who are considered for MRI.

Magnetic Resonance Imaging in Nondependent Pacemaker Patients with Pacemakers and Defibrillators with a Nearly Depleted Battery.

BACKGROUND: Magnetic resonance imaging (MRI) in patients with non-MRI-conditional cardiac implantable electronic devices (CIEDs) has been shown to be safe when performed under closely monitored protocols. However, the safety of MRI in patients with devices with a nearly depleted battery has not been reported. METHODS: Prospective data were collected between January 2008 and May 2015 in patients with non-MRI-conditional CIEDs undergoing clinically indicated MRI under institutional protocol. Patients who were pacemaker dependent were excluded. Patients whose devices were at elective replacement indicator (ERI) at the time of MRI or close to ERI (ERI or replacement for battery depletion within 3 months of scan) were identified through database review and analyzed for clinical events. RESULTS: MRI scans (n = 569) were performed in 442 patients. Of these, we identified 13 scans performed with a nearly depleted battery in nine patients. All scans with implantable cardioverter defibrillators (ICDs, n = 9) were uneventful. However, two scans with pacemakers close to ERI resulted in a power-on-reset (PoR) event. One scan with a pacemaker close to ERI that was programmed to DOO mode reached ERI during MRI and automatically changed to VVI mode. Additionally, one scan with a pacemaker at ERI did not allow programming. All pacemakers with events were implanted before 2005. CONCLUSION: Patients with pacemakers and ICDs with a nearly depleted battery can safely undergo MRI when patients are not pacemaker dependent. Attention should be paid because old devices can result in PoR or ERI during MRI, which may lead to oversensing and inhibition of pacing.

Cardiac troponin T in patients with cardiac implantable electronic devices undergoing magnetic resonance imaging.

PURPOSE: Magnetic resonance imaging (MRI) has been safely performed in many patients with cardiac implantable electronic devices (CIEDs) using institution-specific protocols. A potential risk of MRI is myocardial heating and cardiac injury, which might be detectable with cardiac Troponin (cTn). We evaluated this in patients with CIEDs undergoing MRI. METHODS: Prospective data were collected from 2008 to the present in patients with CIEDs undergoing clinically indicated MRI performed under institutional protocol. Cardiac Troponin T (cTnT) levels were drawn both before and 24­36 h after the procedure. The collective data were retrospectively analyzed. RESULTS: MRI exams (n=512) were performed in 398 patients. Of these, there were 348 unique scans with cTnT recorded before and after MRI (median age 68, IQ 56­78; 62%men). cTnT did not significantly change for the group as a whole (0.00±0.056). There were 22 (6.3 %) exams with cTnT change ≥0.002 ng/mL following MRI (range 0.01­0.09 ng/mL). There were no clinically significant events in these patients directly attributable to MR. There were no significant changes in pacing threshold or impedance in the group with elevated cardiac biomarkers. CONCLUSION: There are very few situations where myocardial injury as detected by cTnT in patients undergoing MRI with CIEDs could be detected. No adverse clinical events or functional changes of the device were noted, even in those with increases in cTnT. Our experience supports that MRI can be performed safely for appropriately selected patients under close clinical observation. Proactive monitoring with the present iteration of cardiac biomarkers appears to be of limited utility, but prospective monitoring with high sensitivity assays may be able to detect subclinical myocardial damage.

"Power-on resets" in cardiac implantable electronic devices during magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging (MRI) has been safely performed in some patients with cardiac implantable electronic devices (CIEDs) under careful monitoring and prespecified conditions. Pacemaker-dependent patients are often excluded, partly because of the potential for "power-on reset" (PoR), which can lead to a change from asynchronous to inhibited pacing with consequent inhibition of pacing due to electromagnetic interference during MRI. OBJECTIVE: The purpose of this study was to review risk factors for PoR during MRI. METHODS: A prospective study was performed between January 2008 and May 2013 in patients with CIEDs undergoing clinically indicated MRI. Eligible patients were not pacemaker dependent. Devices were interrogated before and after MRI, programmed to an asynchronous mode or an inhibition mode with tachyarrhythmia therapies turned off, and reprogrammed to their original settings after MRI. RESULTS: MRI scans (n = 256) were performed in 198 patients with non-MRI-conditional CIEDs between 2008 and 2013 (median age 66 years; interquartile range 57-77 years; 59% men). PoR occurred during 9 MRI scans (3.5%) in 8 patients. PoR was more frequent with Medtronic devices than with other generator brands (n = 9/139 vs 0/117 [6% vs 0%]; P = .005). Devices with PoR were all released before 2002 and were implanted from 1999 to 2004. Effects of PoR included a decrease in heart rate during MRI (n = 4) and transient anomalous battery life indication (n = 1). All devices functioned normally after MRI. CONCLUSION: PoR occurs infrequently but can cause deleterious changes in pacing mode and heart rate. MRI should not be performed in pacemaker-dependent patients with older at-risk generators. Continuous monitoring during MRI is essential because unrecognized PoR may inhibit pacing or accelerate battery depletion due to high pacing output.

Multicenter study of the safety and effects of magnetic resonance imaging in patients with coronary sinus left ventricular pacing leads.

BACKGROUND: Magnetic resonance imaging (MRI) in patients with left ventricular (LV) leads may cause tissue or lead heating, dislodgment, venous damage, or lead dysfunction. OBJECTIVE: The purpose of this study was to determine the safety of MRI in patients with LV pacing leads. METHODS: Prospective data on patients with coronary sinus LV leads undergoing clinically indicated MRI at 3 institutions were collected. Patients were not pacemaker-dependent. Scans were performed under pacing nurse, technician, radiologist, and physicist supervision using continuous vital sign, pulse oximetry, and ECG monitoring and a 1.5-T scanner with specific absorption rate <1.5 W/kg. Devices were interrogated pre- and post-MRI, programmed to asynchronous or inhibition mode with tachyarrhythmia therapies off (if present), and reprogrammed to their original settings post-MRI. RESULTS: MRI scans (n = 42) were performed in 40 patients with non-MRI conditional LV leads between 2005 and 2013 (mean age 67 ± 9 years, n = 16 [40%] women, median lead implant duration 740 days with interquartile range 125-1173 days). MRIs were performed on the head/neck/spine (n = 35 [83%]), lower extremities (n = 4 [10%]), chest (n = 2 [5%]), and abdomen (n = 1 [2%]). There were no overall differences in pre- and post-MRI interrogation LV lead sensing (12.4 ± 6.2 mV vs 12.9 ± 6.7 mV, P = .38), impedance (724 ± 294 Ω vs 718 ± 312 Ω, P = .67), or threshold (1.4 ± 1.1 V vs 1.4 ± 1.0 V, P = .91). No individual LV lead changes required intervention. CONCLUSION: MRI scanning was performed safely in non-pacemaker-dependent patients with coronary sinus LV leads who were carefully monitored during imaging without clinically significant adverse effect on LV lead function.

Safety and outcomes of magnetic resonance imaging in patients with abandoned pacemaker and defibrillator leads.

INTRODUCTION: Abandoned cardiovascular implantable electronic device (CIED) leads remain a contraindication to magnetic resonance imaging (MRI) studies, largely due to in vitro data showing endocardial heating secondary to the radiofrequency field. We tested the hypothesis that abandoned CIED leads do not pose an increased risk of clinical harm for patients undergoing MRI. METHODS: This single-center retrospective study examined the outcomes of patients who had device generators removed before MRI, rendering the device leads abandoned. Information was gathered through chart review. Data collected included lead model, pacing threshold before MRI, anatomic region examined, threshold data after generator reimplantation, and clinical patient outcome. RESULTS: Patients (n = 19, 11 men and eight women) ranged in age from 19 to 85 at the time of MRI. There was a mean of 1.63 abandoned leads at the time of imaging; none of the leads were MRI conditional. Of the three implantable cardioverter defibrillator (ICD) leads, two of three were dual coil. Most (31/35) of the scans performed were of the central nervous system, including head and spinal imaging. There were no adverse events associated with MRI in any of these patients with abandoned leads within 7 days of the scan. No lead malfunctions or clinically significant change in pacing thresholds were noted with generator reimplantation. CONCLUSION: The use of MRI in patients with abandoned cardiac device leads appears feasible when performed under careful monitoring, with no adverse events, although the experience is small. MRI did not affect the function of leads that were subsequently reconnected to a cardiac device.

Magnetic resonance imaging in patients with recently implanted pacemakers.

BACKGROUND: Recent studies have shown that magnetic resonance imaging (MRI) of patients with pacemakers can be safely performed under careful monitoring, but they excluded patients with recently implanted devices. Patients with recent implants may be at a greater risk for complications during MRI imaging due to lack of lead and wound maturity. METHODS: We implemented a clinical protocol for MRI imaging of patients with implanted cardiac devices, and prospectively collected data. For this study, we retrospectively analyzed two groups of patients: those with recently implanted (≤42 days) and nonrecently implanted (>42 days) leads at the time of MRI scanning. All devices were interrogated before and after scanning, and were reprogrammed during the scan as per protocol. RESULTS: Of the 219 scans (in 171 patients), eight included patients with recently implanted (range: 7-36 days) and 211 with only nonrecently implanted pacemaker leads. During the scan, there were no complications in the early or late group. In one patient imaged 79 days postimplant, frequent premature ventricular complexes were noted during the scan, requiring no action. No patient reported pain during or immediately after the procedure. No clinically significant changes in function were seen at subsequent follow up (average 104 days post-MRI). Compared to patients with nonrecently implanted leads, there was no difference in any parameter between the two groups. CONCLUSIONS: With a strong clinical indication and with careful monitoring, MRI imaging is feasible in patients with recently implanted pacemakers, although experience is limited.

Cardiac sympathetic reserve and response to cardiac resynchronization therapy.

BACKGROUND: The objective of the present study was to investigate the effect of cardiac resynchronization therapy (CRT) on cardiac autonomic function. METHODS AND RESULTS: This prospective study included 45 consecutive patients with heart failure who received CRT devices with defibrillator and 20 age-matched, healthy control subjects. At baseline and 3 months and 6 months after CRT, we assessed New York Heart Association (NYHA) class, 6-minute walk distance, plasma sympathetic biomarker nerve growth factor, echocardiography, heart rate variability and cardiac presynaptic sympathetic function determined by iodine 123 metaiodobenzylguanidine scintigraphy. After CRT, NYHA class improved by 1 class (P<0.001), and left ventricular ejection fraction increased by 8% (P<0.001). Along with improvement in the standard deviation of all normal-to-normal R-R intervals (85.63±31.66 ms versus 114.79±38.99 ms; P=0.004) and the standard deviation of the averaged normal-to-normal R-R intervals (82.62±23.03 ms versus 100.50±34.87 ms; P=0.004), the delayed heart/mediastinum (H/M) ratio increased (1.82 [0.58] versus 1.97 [0.59]; P=0.03), whereas the mean (SD) H/M washout rate was reduced (48% [19%] versus 37% [22%]; P=0.01). Twenty-two of 45 study patients responded to CRT, with a reduction of left ventricular end-systolic volume index >15%. Compared with nonresponders, responders had a higher delayed H/M ratio (2.11 versus 1.48; P=0.003) and lower H/M washout rate (37% versus 62%; P=0.003) at baseline. CONCLUSIONS: CRT improved sympathetic function. Cardiac sympathetic reserve may be a marker for the reversibility of failing myocardial function.