What is the preferred choice between a 1 gram hydrophilic wire and a 9 gram guide wire (GW) in the treatment of chronic total occlusions (CTO)?

Guidewire Selection for Chronic Total Occlusion Interventions

For chronic total occlusions (CTOs), a 1-gram hydrophilic wire is generally preferred over a 9-gram guide wire as the initial choice, particularly for tapered proximal caps or functional occlusions with visible channels, while reserving stiffer wires for specific challenging scenarios. 1

Guidewire Selection Algorithm Based on CTO Characteristics

Initial Wire Selection:

• Tapered proximal cap or functional occlusion with visible channel:

  • Start with polymer-jacketed, low penetration force (1-gram), tapered hydrophilic guidewire 1
  • These wires have higher crossability rates (82.1%) compared to stiffer wires 2

• Blunt proximal cap:

  • Begin with intermediate penetration force polymer-jacketed guidewire or composite core guidewire 1
  • The Pilot series has shown the highest success rate (36.2%) among brands 2

Wire Escalation Strategy:

1. Start with appropriate initial wire based on cap morphology
2. If resistance is encountered, escalate to intermediate penetration force wires
3. For highly resistant proximal caps or areas of resistance within the occlusion body, consider stiffer high penetration force (9-gram) guidewires 1
4. After crossing proximal cap (1-2mm), de-escalate to less penetrating guidewires to navigate through the CTO segment 1

Important Technical Considerations

Microcatheter Use:

• Always use a microcatheter to support the guidewire during CTO interventions 1
• Benefits of microcatheter use:
  • Improves precision of rotational and longitudinal guidewire movements
  • Allows dynamic alteration of wire penetration force by adjusting distance between guidewire tip and microcatheter
  • Facilitates rapid guidewire tip reshaping or exchange while preserving previous progress
  • Protects collateral channels from wire-induced trauma 1

Approach Selection:

• Antegrade wiring is the most widely used and generally preferred initial CTO crossing technique 1
• Consider retrograde approach for:
  • Proximal cap ambiguity
  • Flush aorto-ostial CTOs
  • Failed antegrade attempts 1

Procedural Success Factors

Predictors of Successful Wire Crossing:

• Lower J-CTO score (complexity score)
• Appropriate procedural technique
• Proper guidewire type selection
• Appropriate stiffness of the wire tip 2

Pitfalls to Avoid:

• Persisting with the same unsuccessful strategy ("getting stuck in failure mode")
• Using excessive force with stiff wires prematurely, increasing perforation risk
• Failure to use microcatheters for wire support
• Neglecting to change strategies when progress stalls 1

Complications and Safety Considerations

• Coronary perforation risk increases with stiffer guidewires
• Studies have reported perforation rates of 2-5% with hydrophilic guidewires 3, 4
• Pericardial tamponade requiring intervention occurs in 0.4-1.3% of CTO-PCI cases 1

Practical Implementation

• Begin with the least stiff wire that might work for the specific CTO morphology
• Have a systematic wire escalation strategy ready
• Be prepared to change crossing strategies if the initial approach fails
• Consider the J-CTO score to estimate procedural difficulty and guide wire selection 1, 2

The evidence clearly supports a tailored approach to guidewire selection in CTO interventions, with 1-gram hydrophilic wires being the preferred initial choice in most scenarios, while reserving 9-gram wires for specific challenging situations where greater penetration force is required.