Table 2.
Optimisation of placebo procedure and blinding using DITTO framework.
| Components | CTO PCI | Placebo intervention |
|---|---|---|
| Sedation | IV sedation + - Fentanyl | IV sedation + - Fentanyl |
| Before access | Skin preparation, positioning, draping, attachment of monitoring equipment | Skin preparation, positioning, draping, attachment of monitoring equipment |
| Anaesthesia | Local anaesthetic | Local anaesthetic |
| Access | Bilateral 7 Fr arterial access. Can be radial or femoral. | Bilateral 7 Fr arterial access. Can be radial or femoral. |
| Coronary angiogram | Bilateral coronary angiograms | Bilateral coronary angiograms |
| Radiation | Minimal number of views to delineate relevant coronary and CTO anatomy | Minimal number of views to delineate relevant coronary and CTO anatomy |
| Contrast | Minimal volume of contrast to delineate relevant coronary and CTO anatomy | Minimal volume of contrast to delineate relevant coronary and CTO anatomy |
| Guide catheter insertion | Guide catheter insertion. Operator determines best CTO PCI technique to achieve successful outcome. | N/A |
| Coronary CTO wiring, adjunctive device and balloon inflations and stent deployment | Coronary CTO technique including wiring, use of adjunctive devices, and DES implantation as per operator discretion to achieve best CTO PCI outcome. | N/A |
| Invasive and non-invasive physiological measurements | Measurements using dedicated catheters and wires. Administration of IV adenosine for hyperaemia indices. | IV infusion of Adenosine 140 μg/kg/min for 2 min prior to end of procedure to generate symptoms of chest tightness |
| Radiation | Minimal number of views, fluoroscopy, and cine runs to achieve successful CTO PCI | N/A |
| Contrast | Minimal volume of contrast to achieve successful CTO PCI | N/A |
| Closure of access | Removal of sheaths. TR band application if radial. Angioseal/FemoStop/Manual pressure for femoral access. | Removal of sheaths. TR band application if radial. Angioseal/FemoStop/Manual pressure for femoral access. |
| After access site closure | Apply dressing (optional) | Apply dressing (optional) |
| Placebo optimisation strategies | ||
| Visual masking | Vertical screen. | |
| Auditory masking | Headphones playing participants choice of music applied once in catheter laboratory until completion of procedure. Removed prior to transfer to recovery. | |
| Physical cues | IV adenosine administration 140 μg/kg/min for 2 min in both PCI (as part of physiological assessments) and placebo groups. | |
| Time masking | Participants to have no access to clocks/time/devices once attends to day-case unit (or equivalent). Participant will have access to time 2 h post-procedure. | |
| Restriction of interaction between blinded/unblinded trial persons | Operators, catheter laboratory personnel will not interact with participant after procedure. Recovery and ward team will be blinded to randomisation allocation. Nursing handover will state participant to be treated as if they have had CTO PCI as part of research trial. | |
| Omission of intervention details in patient notes | Standardised procedural reports will be provided to maintain blinding. Handwritten procedural report kept in site file/online secure site only to be accessed in an emergency. | |
| Communication with GP | Standardised discharge summary including contact details for trial team to be provided for GP to maintain blinding. | |