Clinical Edge

Summaries of Must-Read Clinical Literature, Guidelines, and FDA Actions

Is MRI Safe in Patients with Cardiac Devices?

N Engl J Med; 2017 Dec 28; Nazarian, et al

Magnetic resonance imaging (MRI) was safe in patients who had a legacy pacemaker or a legacy implantable cardioverter-defibrillator system, a recent study found. The prospective, nonrandomized study assessed the safety of MRI at a magnetic field strength of 1.5 Tesla in 1,509 patients who had a pacemaker (58%) or an implantable cardioverter-defibrillator (42%) that was not considered to be MRI-conditional. Overall, patients underwent 2,103 thoracic and nonthoracic MRI examinations that were deemed as clinically necessary. Researchers found:

  • No long-term clinically significant adverse events were reported.
  • The most common notable change in device parameters immediately after MRI was a decrease in P-wave amplitude (in 1% of patients).
  • At long-term follow-up, the most common notable changes from baseline were decreases in P-wave amplitude (in 4% of patients), increases in atrial capture threshold (4%), and increases in left ventricular capture threshold (3%).
  • The observed changes were not clinically significant, however, and did not require revision or reprogramming.

Citation:

Nazarian S, Hansford R, Rahsepar AA, et al. Safety of magnetic resonance imaging in patients with cardiac devices. N Engl J Med. 2017;377:2555-64. doi:10.1056/NEJMoa1604267.

Commentary:

People with cardiac pacemakers or ICDs often need MRIs, but are unable to get the MRI due to concern about the MRI interfering with the function of the pacemaker. This study shows that MRIs can be done in this group of patients. It is important to be aware that the patients did not just get an MRI without any input from the cardiologist. To avoid problems with electromagnetic interference causing inappropriate pacing, a specific protocol was used for all patients getting the MRIs. Asynchronous pacing mode were programmed, for instance, for pacing-dependent patients to avoid inappropriate inhibition of pacing. Other pacing modes were used for patients without pacing dependence. For patients whose devices were set to detect tachyarrhythmias, the devices were deactivated to avoid delivery of unneeded pacing or shocks. The main takeaway point of this article is that MRIs can be done in patients with pacers and ICDs, as long as appropriate expert consultation is available to manage the pacer settings and there is availability if needed of external pacing. — Neil Skolnik, MD

This Week's Must Reads

Combination model predicts imminent preeclampsia, Ciobanu A et al. Am J Obstet Gynecol. 2019 Feb 7. doi. org/10.1016/j.ajog.2019.01.235

Delayed cord clamping didn’t drop maternal hemoglobin in term cesarean deliveries, Purisch S. et al. Am J Obstet Gynecol. 2019 Jan;220(1):S37-38, Abstract 47

Dental device borrowed from sports world no help in pushing, Bergh E et al. Am J Obstet Gynecol. 2019 Jan;220(1):S39, Abstract 49

Enterovirus in at-risk children associated with later celiac disease, Kahrs CR et al. BMJ. 2019 Feb 13. doi: 10.1136/bmj.l231

Must Reads in Cardiology

Possible mechanism for fluoroquinolone-induced aortopathy uncovered, Guzzardi DG et al. J Thorac Cardiovasc Surg. 2019;157:109-19.

Are Automated Office BP Readings More Accurate?, JAMA Intern Med; ePub 2019 Feb 4; Roerecke, et al

BMI Measurements and Intensive BP Management , Am J Med; ePub 2019 Feb 2; Oxlund, et al

Intensive BP Control & Risk of Dementia, JAMA; ePub 2019 Jan 28; SPRINT MIND Investigators

Aspirin for Prevention of CV Events, JAMA; 2019 Jan 22; Zheng, Roddick