Can an MRI be performed while temporary epicardial pacing wires placed after coronary artery bypass grafting are still in place?

MRI Safety with Retained Temporary Epicardial Pacing Wires After CABG

MRI can be performed safely in patients with retained temporary epicardial pacing wires (TEPW) after CABG, though traditionally considered a contraindication. The 2018 ACC/AHA/HRS guidelines acknowledge that MRI may be performed safely in selected patients with abandoned leads under specialized protocols 1, and recent high-quality research strongly supports this practice.

Evidence Supporting MRI Safety

The most compelling evidence comes from a 2025 eight-year retrospective study of 54 patients with abandoned TEPW who underwent 104 MRI examinations 2. This study documented zero major adverse events and only one minor sensory event (during cervical spine MRI), demonstrating an exceptionally low risk profile. Importantly, this included 9 cardiac MRIs and 6 non-cardiac thoracic MRIs—the anatomical regions closest to the wires—without any adverse events.

Additional supporting research includes:

• A 2022 study showing MRIs in patients with modern functioning epicardial leads (implanted 2000 or later) had no detectable adverse events 3
• A 2021 prospective study of 51 CMR examinations in heart transplant patients with retained wires showing only one mild sensory event (2% rate) with preserved diagnostic image quality 4
• A 1997 study of 200 patients with retained epicardial pacing wires showing no arrhythmias or cardiac dysfunction during MRI 5

Critical Distinctions

Temporary epicardial pacing wires are fundamentally different from permanent pacemaker leads. The ESC guidelines exclude patients with epicardial and abandoned leads from their MRI protocols for permanent devices 6, but this reflects conservative positioning rather than evidence of harm. The Canadian guidelines note that "the risk of thermal-mediated cardiovascular injury is likely even lower for active or retained epicardial leads, especially those used for temporary pacing after cardiac surgery" 7.

Practical Implementation Algorithm

Pre-MRI Assessment:

1. Confirm wire presence and type via chest radiography
2. Identify manufacturer (most common: Medtronic Bipolar Coaxial 6495 2)
3. Exclude absolute contraindications:
   • Lead extenders present 7
   • Fractured leads 7
   • Wires implanted <6 weeks ago (though actual risk likely low 7)

Scanning Protocol:

1. Use 1.5T field strength when possible
2. Minimize energy deposition during imaging 2
3. Monitor patient continuously with ECG and physician observation 4
4. Ensure ACLS-trained personnel are immediately available 7
5. Follow manufacturer guidelines for specific wire types 2

Anatomical Considerations:

• Cardiac and thoracic MRIs are safe despite proximity to wires 2
• Brain (36%) and abdominal (28%) MRIs were most frequently performed without incident 2
• Image quality remains diagnostic across all sequences 4

Important Caveats

Duration of wire retention does not appear to increase risk. The 2025 study included patients with wires retained from 3 to 8,684 days (nearly 24 years) without correlation to adverse events 2. However, be aware that late complications including wire migration can occur years after surgery 8, 9, 10, though these are exceedingly rare and unrelated to MRI exposure.

Image artifacts are minimal. Unlike left-sided ICDs or CRT-D devices that can preclude analysis in up to 15% of cardiac MRIs 7, temporary epicardial wires were visible in 100% of HASTE and cine sequences without impairing diagnostic quality 4.

Risk-Benefit Framework

The primary risk is theoretical heating at wire tips, which has not materialized in clinical practice across hundreds of documented MRI examinations. The single documented adverse event was a transient pacing threshold elevation in a patient with a 29-year-old functioning epicardial lead 3—not a temporary wire scenario.

Do not withhold clinically indicated MRI from patients with retained TEPW 2. The evidence demonstrates safety is comparable to patients without retained wires when appropriate protocols are followed. Alternative imaging modalities should only be considered if they provide equivalent diagnostic information, not simply to avoid the theoretical MRI risk.

Obtain informed consent discussing the very low documented risk profile while acknowledging limited long-term data 7, 3. Document the clinical necessity for MRI and protocol adherence in the medical record.