Magnetic-Guided Percutaneous Coronary Intervention Enabled by Two-Dimensional Guidewire Steering and Three-Dimensional Virtual Angioscopy: Initial Experiences in Daily Clinical Practice

Initial experience with a magnetic navigation system for invasive treatment in patients with non-ST-segment elevation acute coronary syndromes

BACKGROUND

Magnetic navigation system (MNS) assisted percutaneous coronary intervention (MPCI) has been demonstrated an advantage over conventional PCI (CPCI) in complex lesions and tortuous vessels. However, the benefits of MNS in clinical unstable and vulnerable lesions were little studied. The aim of this study is to evaluate the feasibility and benefits of MPCI versus CPCI in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS).

METHODS

Thirty-seven consecutive patients with NSTE-ACS undergoing MPCI were compared with 37 matched CPCI patients selected from the same concurrent database. Time to cross lesion, fluoroscopy time, and contrast usage to cross lesion were used as primary end-points.

RESULTS

Of the 37 culprit lesions in MPCI, 36 were crossed successfully giving a success rate of 97.3%. The procedure and the fluoroscopy time to cross the lesion were similar between the magnetic and conventional PCI groups (82.0 ± 67.9 seconds vs. 85.8 ± 59.2 seconds, P = 0.692, and 62.6 ± 57.6 seconds vs. 65.4 ± 49.5 seconds, P = 0.738, respectively). In Type A/B1 lesions, there seemed no difference in contrast use (2.7 ± 0.7 mL vs. 3.3 ± 0.9 mL, P = 0.284). But as lesion complexity increased from type B2 to C, significantly less contrast was needed in type B2 (5.1 ± 2.6 mL vs. 7.9 ± 4.0 mL, P = 0.019) and type C (9.8 ± 5.7 mL vs. 14.7 ± 7.4 mL, P = 0.030). No major adverse cardiac events were observed in either the MPCI or CPCI group.

CONCLUSIONS

MNS assisted technique appears to be feasible and effective in NSTE-ACS patients with more complex lesions; however, it probably offers little benefit in simple lesions like ACC/AHA type A/B1. 

The feasibility and safety of applying the Magnetic Navigation System to manage chronically occluded vessels: a single centre experience

AIMS

Applying the Magnetic Navigation System (MNS) to manage chronic total occlusions (CTOs). The MNS precisely directs a magnetised guidewire in vivo through two permanent external magnets.

METHODS AND RESULTS

The first 43 consecutive MNS treated CTOs were retrospectively evaluated. Computed tomography coronary angiography (CTCA) co-integration with the MNS provided a virtual road map through the occlusion. Unsuccessful MNS cases were managed with bailout conventional guidewire techniques. Experienced CTO and MNS operators had unrestricted access to CTO devices and equipments. The MNS crossing success increased from 40% to 56% over 52 months and averaged 44.2% (19/43 patients). In 58.3% (14/24) of failed MNS cases the conventional wire approach was successful, giving an overall procedural success rate of 76.6%. Of those conventionally treated, two patients required pericardiocentesis. On average, 1.8 ± 0.9 stents (lengths 44.7 ± 21.4 mm and diameter 2.8 ± 0.4 mm) were implanted. Procedural times were lengthy (125.0 ± 35.3 min) requiring high fluoroscopy dosage (11980.2 ± 6457.9 Gy/cm2) and contrast media usage (388.8 ± 170.2 ml). Operators persevered less with magnetic wires (20.9 ± 12.4 min vs. 27.7 ± 24.4 min), and preferentially used the least stiff wire as first choice (53.5%). CTCA co-integration did not influence procedural outcome. As with conventional wires, higher magnetic wire successes occurred in low calcified lesions, those with a central stump and without bridging collaterals.

CONCLUSIONS

In unselected CTOs, the magnetic wires are safe and feasible. Current modest success rates with a high procedural bailout rate implicate the need for improved magnetic guidewire technology comparable to available sophisticated conventional CTO wires. Randomised studies are needed to clarify the value of magnetic guided recanalisation.

A randomized comparison of the magnetic navigation system versus conventional percutaneous coronary intervention

OBJECTIVE

A randomized comparison of the magnetic navigation system (MNS) to conventional guidewire techniques in percutaneous coronary interventions.

BACKGROUND

The MNS precisely directs a magnetized guidewire in vivo through two permanent external magnets.

METHODS

A total of 111 consecutive patients were enrolled. Crossing success, crossing-/fluoroscopy times, and contrast usage were directly compared. Lesions were classified according to the AHA/ACC criteria. Three tertiles of vessel/lesion complexity [low (<5), medium (6-10) and high (>10)] were defined using 3D reconstructions and angiographic information.

RESULTS

The crossing success for magnetic and the conventional wires were 93.3 and 95.6%, respectively. Crossing and fluoroscopy times were longer with the magnetic wires (72.9 +/- 50.3 sec vs. 58.1 +/- 47.2 sec, P < 0.001 and 66.2 +/- 44.1 sec vs. 55.2 +/- 44.4 sec, P = 0.03, respectively). In vessels with low and medium complexity the magnetic wires had significantly longer times (P < 0.001) but for those with high scores (>10) a trend towards shorter times was observed. The MNS resulted in a small but significant reduction in contrast usage (2.3 +/- 3.5 ml vs. 4.5 +/- 4.4 ml, P < 0.001). Moreover by superimposing a virtual roadmap of the vessel on the live fluoroscopy image 48% of the lesions were crossed without requiring contrast agents with the MNS.

CONCLUSION

The MNS has comparable crossing success to conventional PCI. It is relatively slower but there is a trend to support a potential advantage in more complex vessels. By simultaneously employing a virtual roadmap there is a small but significant reduction in contrast usage.