The ProMRI clinical trial is multicenter, prospective, single-arm, nonrandomized trial evaluating the safety and efficacy of the BIOTRONIK ProMRI pacemaker system in patients who underwent head and lower lumbar spine MRI scanning.1 The majority of cardiac rhythm device patients (50-75%) are expected to require MRI scanning at some point in their lives, although MRIs are contraindicated with the majority of implantable pacemakers and all defibrillator systems today in the U.S.2 MR conditional implantable cardiac rhythm management systems are emerging as the new standard of care globally.3 All of the BIOTRONIK family of cardiac rhythm management systems (pacemakers, implantable cardioverter-defibrillators, and cardiac resynchronization systems with and without defibrillation) are MR conditional in Europe. There are two BIOTRONIK MR conditional pacemakers available in the U.S.
A 67-year-old male patient was seen as part of this study on January 28, 2013, upon referral from another cardiologist. The patient had symptoms of tiredness, fatigue, and decreased energy and exercise capacity for about one year. Prior to that, the patient reported going regularly to a health club where he exercised without problem. When he presented, he said that he would run out of energy on the treadmill or recumbent bicycle — things he used to do regularly. He would modulate his activity, but even at low levels of exertion, he eventually became too fatigued to continue. Since his physical condition was good, he did not understand why he could not exercise at his previous level. He noticed that he was walking and climbing steps more slowly than he used to, and when going about ordinary activities such as going to the store, he was slower and more easily fatigued than he previously had been. His sleep habits, appetite, and weight maintenance remained good. He was working part-time as a teacher, but physical exertion at school (such as walking in the halls or standing) had become difficult for him. He had recently tried to go on a hunting trip, but was unable to do so because of exhaustion. The referring physician had discovered the patient had episodes of paroxysmal atrial fibrillation (AF), but had not prescribed any pharmacological therapy out of concern these might exacerbate the patient’s symptoms.
As part of his workup, a Holter monitor was conducted, which confirmed chronotropic incompetence. The echocardiogram documented normal left ventricular function with a left ventricular ejection fraction of 63%. His past history was significant with very rare episodes of paroxysmal AF and hypertension. His past surgical history was significant for an extensive traumatic injury to the face. In December 2009, he had been in a four-wheeler vehicular accident resulting in multiple facial fractures, requiring three surgical interventions for their correction and repair. He subsequently had a large area of central midline facial numbness and lost his sense of smell. The accident did not result in any change to his vision.
On February 15, 2013, the patient underwent implantation of a dual-chamber Entovis ProMRI pacemaker (BIOTRONIK, Inc.). The implant surgery was uneventful, and good pacing and sensing parameter values were obtained. All of the patient’s symptoms had resolved within the first month after implant and he was able to resume all his usual activity. Following implantation, the patient gave informed consent to participate in the ProMRI scanning trial. He underwent the MRI scan per the study protocol on April 25, 2013. As an incidental finding of this MRI, a soft tissue mass in the olfactory groove was detected (2 cm x 8 mm). It was recommended that the MRI be repeated but with contrast. The contrast MRI was carried out on May 13, 2013. At that time, a meningioma (measuring 1.3 x 2.0 x 1 cm) located in the olfactory groove could be determined. There was no edema in the frontal lobes and with no impingement on the optic nerve. These findings were discussed with the patient, as were the original incidental findings.
Because of his history of extensive facial trauma and loss of smell with the four-wheeler accident as well as subsequent corrective surgeries, the patient decided to pursue no further workup, evaluation, or further treatment at that time. Over the intervening period of a couple of years, his symptoms have remained stable. No visual disturbances have developed. On May 26, 2015, he underwent a follow-up MRI scan. The olfactory groove meningioma had changed only minimally, now measuring 1.3 x 2.0 x 1.6 cm. No other abnormalities were seen. As there had been no change in his symptoms, the patient once again opted to continue monitoring the growth of the meningioma over time but with no treatment.
Incidental findings on MRI scans are not uncommon.4 In the ProMRI trial, incidental findings on MRI scans occurred in 7.4% of patients in phase A and 13.9% in phase B. None of these incidental findings were of a serious nature. Meningiomas are a common incidental finding in MRI scans,5 with olfactory groove meningiomas accounting for about 10% of all meningiomas.6 While trauma has been put forward as a possible mechanism for the meningiomas, this mechanism has been called into question by many authors. If not for the ProMRI study, it is unknown when or if this patient would have presented with symptoms, and if the patient would have been able to get an MRI with a non-MR conditional pacing system. This case shows that we cannot always determine which pacemaker patients will need an MRI scan during the life of their device.
Use of an MR conditional pacemaker in this case provided not only symptomatic relief of the patient’s bradycardia and chronotropic incompetence, but also allowed the patient to undergo imaging for the long-term follow-up of his olfactory groove meningioma.
Disclosure: The author has no conflicts of interest to report regarding the content herein. Outside the submitted work, Dr. Bailey reports receiving non-financial support as well as personal fees from BIOTRONIK for research funding (trial investigator) and a speakers’ bureau.
- Bailey WM, Rosenthal L, Fananapazir L, et al. Clinical safety of the ProMRI pacemaker system in patients subjected to head and lower lumbar 1.5-T magnetic resonance imaging scanning conditions. Heart Rhythm. 2015;12(6):1183-1191.
- Kalin R, Stanton M. Current clinical issues for MRI scanning of pacemaker and defibrillator patients. Pacing Clinical Electrophysiol. 2005;28:326-328.
- Nordbeck P, Ertl G, Ritter O. Magnetic resonance imaging safety in pacemaker and implantable cardioverter defibrillator patients: how far have we come? Eur Heart J. 2015;36(24):1505-1511.
- Semaan HB, Bieszczad JE, Bieszczad JE, et al. Incidental Extra-Spinal Findings at Lumbar Spine Magnetic Resonance Imaging: A Retrospective Study. Spine. Jun 12 2015.
- Abeloos L, Lefranc F. [What should be done in the event of incidental meningioma?]. Neuro-Chirurgie. 2011;57(2):78-81.
- Types of meningiomas. Johns Hopkins Medicine. 2015. Available online at http://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/brain_tumor/center/meningioma/types.html. Accessed July 6, 2015.