Advice
Clinical and technical evidence
Clinical and technical evidence
A literature search was carried out for this briefing in accordance with the interim process and methods statement for medtech innovation briefings. 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
Four studies are summarised in this briefing, which include a total of 1,134 people.
All studies are single-arm studies without a comparator. The evidence consists of 1 multicentre observational registry (Taggart et al. 2020), which has 1 secondary analysis from this data (Rosenfeld et al. 2021a), 1 prospective study (Wendt et al. 2019) and 1 retrospective observational study (Kim et al. 2020).
There is 1 secondary analysis that is not summarised below because it includes people with chronic and end-stage renal disease undergoing coronary artery bypass graft (CABG) surgery (Rosenfeld et al. 2021b).
The clinical evidence and its strengths and limitations are summarised in the overall assessment of the evidence.
Overall assessment of the evidence
The evidence for the technology is of low to moderate quality. None of the studies have a comparator and there is limited evidence in an NHS setting (1 centre). Some of the evidence is on VeriQ C, which is a previous version of the technology. The evidence suggests that MiraQ cardiac with transit time flowmetry (TTFM) and high-frequency ultrasound (HFUS) may improve the quality and efficacy of the CABG procedure. Comparative evidence on patient outcomes would be beneficial.
Taggart et al. (2020)
Key outcomes
HFUS was used to assess the ascending aorta in 79.3% (806 out of 1,016) of people, the in situ conduits in 65.1% (661 out of 1,016), the coronary targets in 47.5% (483 out of 1,016) and completed grafts in 59.3% (602 out of 1,016). People who had off-pump surgery had HFUS more frequently (88.3%) compared with people who had on-pump surgery (73.5%). The primary outcome of the study was any change in planned surgical procedure as a result of imaging with TTFM or HFUS, or from visual assessment. A surgical change was made in 256 people. Of these, in 77% (197 out of 256) this was a result of TTFM or HFUS. Of these, surgical changes were made to the aorta in 74 of 80 people (92.5%), to in situ conduits in 10 of 18 people (55.6%), to the proposed coronary target in 73 of 109 people (67.0%) and to grafts in 51 of 79 people (64.6%). In-hospital adverse event rates were 0.3% for myocardial infarction, 0.6% for mortality and 1.0% for cerebral events.
Strengths and limitations
The study suggests that TTFM and HFUS may improve the quality, safety and efficacy of CABG procedures. One of the centres was based in the UK. The main author has received research funding, speaking and travelling fees from the company. Seven out of the other 9 authors received travelling support or speaker fees from the company. A limitation of the study is that the outcomes were limited to in-hospital reporting and no further follow up was done.
Rosenfeld et al. (2021)
Key outcomes
This study focused on 3 sub-analyses, comparing on-pump (ONCAB, n=402) with off-pump procedures (OPCAB, n=614), arterial versus venous grafts, and grafts to different territories. There were more surgical changes to the ascending aorta in OPCAB (14.7%) compared with ONCAB (3.4%) procedures (odds ratio [OR] 4.03; 95% confidence interval [CI] 2.32 to 7.20). Strategy changes for in situ conduits occurred less in OPCAB (0.2%) versus ONCAB (2.8%) procedures (OR 0.09; 95% CI 0.01 to 0.56). Changes to coronary targets did not differ between groups (10.4% versus 10.9%; OR 0.95; 95% CI 0.62 to 1.46). However, when comparing only people that underwent HFUS scanning, there were more target location changes in OPCAB (28.6%) versus ONCAB (19.9%) procedures (OR 1.63; 95% CI 1.02 to 2.62). In all study participants, revisions were more common for arterial versus venous grafts (4.7% versus 2.4%; OR 2.05; 95% CI 1.29 to 3.37), and inferior versus anterior (5.1% versus 2.9%; OR 1.77; 95% CI 1.08 to 2.89) and lateral (5.1% versus 2.8%; OR 1.83; 95% CI 1.04 to 3.27) territory grafts.
Strengths and limitations
This study is a secondary analysis of Taggart et al. (2020). It suggests that compared with ONCAB, OPCAB procedures resulted in 4 times more changes related to the ascending aorta. An additional limitation to those mentioned above is that the study did not compare CABG procedures with or without the MiraQ cardiac TTFM and HFUS system because of the nature of the study.
Wendt et al. (2019)
Study size, design and location
A prospective study of 65 people undergoing CABG surgery in Germany.
Key outcomes
A surgical strategy change, based on imaging, was done in 10 procedures (15%). Changes related to the cannulation site (n=3), the target opening site (n=2) and the clamping site (n=1). In 3 cases, imaging was used to identify the left anterior descending artery, and in 1 case the imaging confirmed a calcified vessel and a procedure was done to treat the calcification. In 1 case, the graft was revised. Thirty-day mortality was 0% and no stroke was observed.
Strengths and limitations
This study suggests that MiraQ TTFM and HFUS was helpful in evaluating the clamping or cannulation site, the potential opening site of the vessel or the completed anastomosis. A limitation is that the main aim of the study was to evaluate MiraQ TTFM and HFUS in relation to postoperative troponin-I release.
Kim et al. (2020)
Study size, design and location
A retrospective observational study of 53 people undergoing CABG in Korea.
Key outcomes
In total, the quality of 141 distal anastomoses was evaluated, of which 123 with normal TTFM results also had good ultrasound findings. Abnormal TTFM findings, including low flow or high pulsatility index, were found in 18 distal anastomoses. The epicardial ultrasound identified that only 3 of these needed revisions. Revisions were not done for the other 15 distal anastomoses and at 1 year after surgery, all 15 of these were patent. The abnormal TTFM results were false positives for 15 of 18 distal anastomoses (83.3%). Epicardial ultrasound was also used to evaluate 32 target epicardial arteries in 30 people to identify the appropriate anastomosis sites. For 5 anastomoses, the target vessels were changed to adjacent vessels based on the ultrasound findings. The early and 1‑year overall graft patency rates were 100% (141 anastomoses) and 96.1% (122 of 127 anastomoses), respectively. The early mortality rate was 1.9% (1 of 53 people). Overall, postoperative complications included new-onset atrial fibrillation (n=13; 24.5%), respiratory complications (n=3; 5.7%), low cardiac output syndrome (n=2; 3.8%), and acute kidney injury (n=2; 3.8%).
Sustainability
The company claims the technology will reduce the use of single-use equipment related to the surgical procedure by reducing the need for repeat vascularisation (repeat CABG or percutaneous coronary intervention [PCI]) and the ionising radiation connected to PCI. Both the TTFM and HFUS probes can be used on multiple patients after cleaning and sterilisation. There is no published evidence to support these claims.
Recent and ongoing studies
Flow distribution in arterial composite grafts in patients with coronary heart disease undergoing coronary artery bypass grafting. ACTRN12622000774729. Status: not yet recruiting. Indication: coronary heart disease leading to coronary artery bypass grafting. Devices: MiraQ TTFM and HFUS. Estimated completion date: not reported. Country: Czech Republic.