Initial Clinical Experience with Cardiac Resynchronization Therapy Utilizing a Magnetic Navigation System

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Abstract
The placement of left ventricular (LV) leads during cardiac resynchronization therapy (CRT) involves many technical difficulties. These difficulties increase procedural times and decrease procedural success rates.A total of 50 patients with severe cardiomyopathy (mean LV ejection fraction was 21 +/- 6%) and a wide QRS underwent CRT implantation. Magnetic navigation (Stereotaxis, Inc.) was used to position a magnet-tipped 0.014'' guidewire (Cronus guidewire) within the coronary sinus (CS) vasculature. LV leads were placed in a lateral CS branch, either using a standard CS delivery sheath or using a "bare-wire" approach without a CS delivery sheath. The mean total procedure time was 98.1 +/- 29.1 minutes with a mean fluoroscopy time of 22.7 +/- 15.1 minutes. The mean LV lead positioning time was 10.4 +/- 7.6 minutes. The use of a delivery sheath was associated with longer procedure times 98 +/- 32 minutes vs 80 +/- 18 minutes (P = 0.029), fluoroscopy times 23 +/- 15 minutes vs 13 +/- 4 minutes (P = 0.0007) and LV lead positioning times 10 +/- 6 minutes vs 4 +/- 2 minutes (P = 0.015) when compared to a "bare-wire" approach. When compared with 52 nonmagnetic-assisted control CRT cases, magnetic navigation reduced total LV lead positioning times (10.4 +/- 7.6 minutes vs 18.6 +/- 18.9 minutes; P = 0.005). If more than one CS branch vessel was tested, magnetic navigation was associated with significantly shorter times for LV lead placement (16.2 +/- 7.7 minutes vs 36.4 +/- 23.4 minutes; P = 0.004).Magnetic navigation is a safe, feasible, and efficient tool for lateral LV lead placement during CRT. Magnetic navigation during CRT allows for control of the tip direction of the Cronus 0.014'' guidewire using either a standard CS delivery sheath or "bare-wire" approach. Although there are some important limitations to the 0.014'' Cronus magnetic navigation can decrease LV lead placement times compared with nonmagnetic-assisted control CRT cases, particularly if multiple CS branches are to be tested.