4.1 The company's claimed system benefits included reduced costs from fewer inconclusive or inaccurate diagnostic tests and avoidance of unnecessary staff and procedure costs. It claimed that this would lead to more effective use of invasive procedure suites.
4.2 The company confirmed that, with specific reference to the updated NICE guideline on chest pain, the proposed place in the diagnostic pathway for HeartFlow FFRCT (to inform management following a positive coronary CT angiography [CCTA] result) was unchanged.
4.3 Conservative estimates by the NICE resource impact assessment team suggest that by 2021/22, when fully implemented, HeartFlow FFRCT will potentially be used in around 40,000 patients a year. This would equate to national savings of at least £9.1 million a year.
4.4 During selection and routing, the committee asked for additional information on compliance with data protection legislation, and the reproducibility of HeartFlow FFRCT analysis, especially in the face of an increasing workload which might be expected to arise from adoption of the technology in the NHS. The external assessment centre (EAC) produced a technical report that concluded:
The company has a quality assurance process in place that fulfils data quality needs. This includes checks by different team members, and the separation of tasks to ensure that no single analyst is fully responsible for a diagnosis. After the procedure, a more experienced analyst reviews the process, focusing mainly on areas of stenosis. Expert clinician advice is also available should it be needed.
Although the analytical process is largely automated, any part of it can be manually changed by the analyst. This may affect the fractional flow reserve CT (FFRCT) estimate. Manual editing is part of the quality assurance process, negating the risk of spurious results generated from the automated analysis. Gaur et al. (2014) suggest that reproducibility is within acceptable 95% confidence interval limits of agreement. FFRCT reproducibility was found to be equivalent to invasive FFR reproducibility.
The reproducibility of outlining the coronary artery lumen, part of the FFRCT computation analysis, decreases in the distal portion of the vessel (Gage repeatability and reproducibility=29.4%). This could be a result of different factors including lower CT quality, lower CT resolution, smaller vessel diameter at the distal end and higher disease burden.
The company monitors FFRCT reproducibility by re-processing 5% of its case volume on a weekly basis. The company has confirmed that this has shown a reproducibility rate consistent with the literature (Gaur et al. 2014).
The company fulfils regulatory approval standards for data confidentiality and integrity protection for remote processing. It offers NHS customers the option to upload fully anonymised DICOM data to comply with UK data protection law.
4.5 The committee was satisfied with the EAC's conclusions on reproducibility (see section 4.4). It accepted that the company has protocols in place to manage an increased demand for HeartFlow FFRCT.
4.6 The committee considered the protection and oversight of data transferred during the administration of HeartFlow FFRCT to be an important factor in the device's adoption. The committee was satisfied, on the basis of the information available, that the company's data transfer protocols meet regulatory requirements. The committee noted that patients should be informed when sending personal data outside the European Economic Area with HeartFlow FFRCT, and that it may be necessary to obtain written consent.
4.7 The committee considered the availability of CCTA facilities. It understood that the cost model assumed access to CCTA facilities, but heard from experts that access to CCTA varies across the NHS despite recommendations in NICE's previous guideline on chest pain. Furthermore, because CT scanners are used for many purposes, a constraint currently exists with regard to both the availability of scanners and scanning time. The committee heard from experts that a sizable investment would be needed for the wider implementation of HeartFlow FFRCT, but acknowledged that this consideration was beyond the scope of the current assessment. It understood that adopting 64‑slice CCTA was ongoing in the NHS, in line with the recommendations in the previous NICE guideline on chest pain.