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 email@example.com.
Four studies are summarised in this briefing.
This includes 3 prospective comparative studies in adults and 1 retrospective single-arm study in children. A total of 125 people were included in the studies.
Two of the included full text papers compare using Carnation Ambulatory Monitor (CAM) with either Holter monitors or Zio XT. One study compared 4 external cardiac monitors and uses an implanted pacemaker to test for recording accuracy. These studies found that the CAM device led to equivalent or enhanced detection of atrial fibrillation. There was positive patient experience in wearing the device, particularly when compared with Holter monitor use. Two of the studies show CAM use over 24 hours to 48 hours. This could be considered as a limitation because the CAM device can be used for up to 2 weeks and may be more appropriate for longer term use where arrhythmias may not be detected within a 48-hour period. The evidence is also limited by having small sample sizes. In the single-arm study in children, the CAM device was being used in those under 10 kg, which is not recommended by the company. Only 1 study was done in the UK, which could limit the generalisability of the evidence to the NHS.
All patients acted as their own control and wore 4 external cardiac monitors (Zio XT, NUUBO vest, CAM, Novacor 'R' test 4) for 2 weeks each in randomised order. All patients also had dual chamber permanent pacemakers implanted, which detect arrhythmias to a high level of sensitivity and specificity.
CAM measures of atrial fibrillation burden were compared with the implanted pacemaker. The CAM device was found to correlate with the pacemaker (R-square value 0.9618). CAM more accurately identified the presence or absence of atrial fibrillation than the Novacor 'R' test 4 device (odds ratio 5.8; 95% confidence interval [CI] 1.1 to 32.1; p=0.042). Zio XT was also significantly more accurate than Novacor 'R' test 4 (odds ratio 12.3; 95% CI 1.4 to 110.3; p=0.02). CAM was significantly more comfortable during initial application than Novacor 'R' test 4 (p=0.024), but there was no significant different in comfort between the devices during the recording phase. All the devices were found to be more expensive than Novacor 'T' test 4 when both device and clinical care costs were considered.
This randomised study was done in the UK but was limited by having a small sample size. Most of the comparisons are with the Novacor 'R' test 4 device because it was viewed to be the most commonly used external cardiac monitor in the UK that can record for more than 48 hours. The study reviewed the 4 devices at separate intervals rather than at the same time which limits the comparability between devices. However, this was thought to be reasonable because of the risk of artefacts being generated on the recordings. People in the study had dual chamber permanent pacemakers implanted which is not generalisable to the atrial fibrillation population.
A total of 86.7 plus or minus 0.6 arrhythmias were detected using Zio XT and 121.7 plus or minus 2.1 for CAM (p<0.001). Of the arrhythmias identified, atrial tachycardia was most diagnosed, and was more frequently identified with CAM than Zio XT (22.3 plus or minus 0.6 compared with 8.7 plus or minus 3.2, p<0.001). ECG clarity was ranked as high in all 29 CAM reports (100%) and on 4.5 (16%) of the Zio XT reports (p<0.001). Higher ECG clarity was mostly because of the greater ability to see P-waves when using the CAM device. Patient experiences were comparable and positive for both devices.
This prospective study had a small sample size. The analysis was done using multiple reviewers with averaged rhythms decisions to compensate for subjectivity in individual reviewing opinions. Company analysis centres were also unaware of the research to prevent analysis bias.
The CAM patch identified rhythms in 23 people (46%) that changed management, compared with 6 in the Holter group (12%; p<0.01). All 6 Holter recordings with clinically significant arrhythmias were also found when using the CAM patch. The CAM patch ECG intervals PR, QRS and QT correlated well with the Holter ECG intervals having correlation coefficients of 0.93, 0.86, and 0.94, respectively. In terms of comfort, 48 people (96%) preferred wearing the CAM patch.
CAM patches worn for 48 hours. Five children wore a secondary CAM patch horizontally (leading to a total of 33 reports).
The mean age was 4.2 plus or minus 5 months and the mean weight was 5.3 plus or minus 2.4 kg. P-waves were identifiable in all 33 reports and led to changes in medical management in 30% of children. Horizontal patch placement led to smaller amplitude P-waves.
This study included children who weighed less than 10 kg. The company specify that their device is for use in children and adults weighing more than 10 kg. The retrospective study sample size was small and the monitoring time was limited to 48 hours, which may not be reflective of real-world use.
The company claims the technology will reduce the number of clinic visits needed. The device is also smaller than other patch monitors and the battrode can be recycled. The device packaging is made of paper and cardboard which can be recycled. There is no published evidence to support these claims.
Optimized Continuous 7-day Detection of Arrhythmias in Dialysis Population by a Patch With a High Resolution Differentiation of Atrial Activity. ClinicalTrials.gov identifier: NCT04071054. Status: unknown. Indication: arrhythmia, dialysis complications. Devices: CAM. Estimated study completion date: December 2020. Austria.
Comparative Study of the CarnationTM Ambulatory Monitoring Sternal ECG Patch System With a Conventional 24-Hour 7 Lead Holter Monitor Recorder. ClinicalTrials.gov identifier: NCT04241692. Status: enrolling by invitation. Indication: children with known or suspected cardiac arrhythmia. Devices: CAM, 7‑lead Holter Monitor recorder. Estimated study completion date: March 2023. US.