The Stereotaxis Niobe® magnetic navigation system received regulatory approval for human clinical use for interventional cardiology in 2003.
Magnetic navigation gives 3 dimensional (3D) directional control over the guide-wire tip during percutaneous coronary intervention (PCI) procedures.
Magnetic navigation has been shown to be feasible and effective (1-3), case reports suggest that it enables the performance of procedures that could not be successfully finished conventionally (4-6), and that the use of the system may lead to reductions in contrast use and procedure time (7-11) that can be expected to result in better patient outcomes, and an economical advantage (less consumables per procedure, more procedures per session). There are only a few centers that perform magnetic navigation for percutaneous coronary intervention The OLVG has performed the most procedures of any of these centers and has included all the patients in a registry.
The registry at the OLVG suggests that different subgroups derive different benefit.
Distal lesions (10) defined as lesions more distal than the first 2 coronary segments from the aorta (thus RCA segment, mid LAD or distal Cx).
Technical success did not differ significantly between magnetic and conventional PCI (88.5 vs 96.2%; p=0.14). Significantly shorter procedural and fluoroscopy time were observed for magnetic compared to conventional PCI (29.9±17.1 vs 42.9±21.1 min, p\<0.001; 8.2±7.7 vs 16.7±22.4 min, p=0.01 respectively). More contrast was used in de conventional PCI group (54 ml/patient; P=0.02). These advantages resulted in a mean saving of 1652 euro per patient (P\<0.0001).
Primary PCI (11) The technical success rate was high in both the MPCI and CPCI groups (95.4% vs 98%; P = NS). There was significantly less contrast usage in the MPCI compared to the CPCI group (167±80/patient vs 220±87/patient; P\<0.001). Procedural times were not significantly different for MPCI compared to CPCI (30.8±16.5 min vs 33.6±15.8 min, p=0.2) while fluoroscopy times were significantly better (8.1±5.0 min vs 14.6±26.5 min, p\<0.05).
Simple lesions (8) as defined by the elective treatment of a single discrete stenosis that would require a maximum of two stents and excluding multiple lesions in the target vessel, multi-vessel PCI, bifurcation lesions, acute and chronic total occlusions, or a previous failed conventional attempt for the same target lesion.
Procedural and fluoroscopy times were not significantly different for MPCI compared to CPCI (21.0±14.5 min vs 24.7±14.0 min; 4.9±4.8 min vs 7.3±10.3 min, p=NS). There was a significant reduction in median contrast use (60 ml/patient \[41-100\] vs 100 ml/patient \[64-130\]; P=0.006).
Summary Benefit appears to increase depending on the complexity of the vessel/lesion with distal lesions showing a significant benefit in terms of contrast use, procedure time and fluoroscopy time.
Simple lesions show that procedures are not negatively influenced in terms of time, or irradiation and there may be benefit in terms of contrast use.
Acute procedures where time is at a premium (primary PCI for a heart attack) are not slowed by the use of the system.
Furthermore, the investigators have published a clinical prediction rule for selection of patients that will most benefit from this technology. (12)
The use of this system may have a number of benefits
1. Reduction in the procedure time, irradiation and contrast use in the patient
2. Better procedures with wire passage that maintains the tip coaxial in the vessel to avoid inadvertent sidebranch cannulation or more accurate bend/sidebranch entry to produce less complications
The hypothesis that MPCI is better than CPCI should be investigated by a randomized controlled trial (Magnetic navigation wire placement vs conventional wire placement).
The investigators plan to randomize patients into magnetic and conventional groups.
Endpoints:
1. Primary endpoint Contrast use
2. Secondary:
Short-term procedural Procedure Fluoroscopy Procedure time Procedure success Short term contrast nephropathy
3. Long-term MACCE at 1 month and 12 months.
