Clinical and technical evidence

Advice

Published evidence
Overall assessment of the evidence
Recent and ongoing studies

Clinical and technical evidence

A literature search was carried out for this briefing in accordance with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting mibs@nice.org.uk.

Published evidence

Three studies are summarised in this briefing including a total of 183 lesions in 173 patients who had clinical indication for percutaneous coronary intervention (PCI). These studies have been assessed as most relevant from a wider evidence base.

Table 1 summarises the clinical evidence as well as its strengths and limitations.

Overall assessment of the evidence

The evidence suggests that Optowire may be associated with less pressure drift when measuring fractional flow reserve (FFR). This may mean that FFR is measured more accurately.

The studies in this briefing are non-comparative, single-centre, cohort studies (2 full publications and 1 conference abstract) with a small number of patients. A common feature across these studies was that FFR measurements were used for clinical decision making about whether stenting a stenosis was necessary. Two of the studies showed the feasibility of measuring FFR in a side-branch lesion after main vessel stenting; a procedure which is often difficult to do. No comparison with other guide wires means it is unknown how much reduced drift improves accuracy in FFR measurements. It is also unclear how the studies got the pressure drift threshold and FFR cut‑off points. A variation in FFR cut‑off points is seen across the studies. Results should be interpreted with caution because the impact of this variation is uncertain. Other outcomes assessed include the usability, safety and accuracy of the device.

These studies were not done in the UK and it is likely that clinical practice at the study sites may vary. Therefore the generalisability of the evidence to the NHS may be limited.

There are several published abstracts and conference posters for optical sensor guide wires that were not included in the evidence summary because they give limited additional information.

Table 1 Summary of selected studies

Hiroyuki et al. (2017)
Study size, design and location	A cohort study to decide whether to treat a jailed (covered) side-branch lesion after main vessel stenting in 35 patients (37 lesions) with coronary bifurcation in a heart centre in Japan.
Intervention	Jailed pressure wire technique using Optowire.
Key outcomes	FFR was successfully measured in the SB in all cases. Pre- and post-procedure FFR values in the SB was 0.83±0.12 and 0.84±0.13 respectively in 84% of lesions. Based on an FFR cut-off of more than 0.75, these lesions had no further intervention. In 16% of lesions when FFR measured 0.75 or less, kissing balloon technique was used for further treatment of these lesions. None of the 37 lesions showed PD of more than 3 mmHg.
Strengths and limitations	The study addressed a clearly defined population and considered specific outcomes. This is a conference abstract with limited details about the study such as patient recruitment, baseline characteristics of patients, inclusion criteria and study design.
Kawase et al. (2017)
Study size, design and location	A prospective study of 90 patients (95 consecutive lesions) who had clinical indications for elective PCI of native coronary artery in a heart centre in Japan.
Intervention	Coronary catheterisation based on FFR measurements using Optowire and coronary angiography for anatomic lesion measurement.
Key outcomes	Pre- and post-procedure FFR values were 0.63±0.16 and 0.85±0.07 respectively. PD assessment was performed at the discretion of the operator. PD was seen in 71% of cases. For the measurements with PD, the mean FFR change by PD correction was 0.01 (range −0.02 to 0.08). The decision changed from FFR of 0.80 or less, to above 0.80 in 7% of measurements and the other way around in 1%. The authors noted that PD correction contributed a significant positive bias (0.00960, 95% CI 0.00589 to 0.01331). The grey zone for FFR was defined as 0.75 to 0.80. When FFR values were between 0.78 and 0.82, classification changed in 53% of lesions. Absolute PD of less than 4 mmHg was seen in 66% of cases. Large PDs were seen in 4% of cases.
Strengths and limitations	Statistical analysis was used to assess the relationship between readout and PD-corrected FFR values. This potentially ruled out confounding factors. The authors noted that there was no established validation of FFR correction by PD and no consensus regarding an acceptable PD threshold.
Omori et al. (2019)
Study size, design and location	A retrospective cohort study of 48 patients (51 consecutive lesions) who had the jailed pressure wire technique for PCI of CBL during main vessel stenting. Japan.
Intervention	Jailed pressure wire technique using Optowire.
Key outcomes	The primary endpoint was safety defined by rate of complication. No complication associated with the jailed pressure wire technique was reported. The study also reports successfully measuring FFR and retrieving pressure wires in all cases. It was not possible to assess drift retrospectively in 2 cases because of missing data records. FFR was measured without significant final drift in 95.9% of cases. FFR measurements helped interventionists change their decision to perform FKBD in 49% of the cases. There were 24 SB lesions deferred despite having over 50% angiographical stenosis based on the FFR value of 0.84. There was 1 SB lesion that had additional treatment without significant angiographical stenting.
Strengths and limitations	There was an institutional consensus and defined criteria about what cases to include and exclude. This potentially reduced selection bias. The source of funding was not mentioned. However, 1 of the authors is a consultant for the company and other authors noted no conflict of interest.
Abbreviations: CBL, coronary bifurcation lesions; CI, confidence interval; PCI, percutaneous coronary intervention; FFR, fractional flow reserve; FKBD, final kissing balloon dilatation; PD, pressure drift; SB, side branch.

Recent and ongoing studies

The drift-reduction for improved FFR using fiberoptic technology (DRIFT) study (OPSENS). ClinicalTrials.gov identifier: NCT03848650. Condition: left anterior descending coronary artery stenosis. Status: recruiting. Estimated completion date: January 2021. Location: US.
Assessing the accuracy of the Optowire Deux in a wire to wire comparison (ACCURACY). ClinicalTrials.gov identifier: NCT01751906. Condition: coronary artery disease. Status: recruiting. Estimated primary completion date: January 2020. Location: Canada.