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.

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.

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.