The CADScor system (Acarix A/S) is a medical device for acoustic detection of coronary artery disease (CAD). It is intended to be used before CT coronary angiography (CTCA) to rule out stable CAD in people aged 40 years and above who have symptoms suggestive of this condition. Heart sounds, murmurs and vibrations are recorded using the device and are converted into a CAD-score, in the range of 0 to 99. A CAD-score of 20 or below suggests a low probability of CAD and no further investigation is recommended. A CAD-score above 20 suggests a medium to high probability of CAD and further investigation is recommended, such as CTCA or invasive coronary angiography (ICA). The algorithm that is currently in use (version 3), combines acoustic measures with the patient's age, gender and blood pressure to generate a specific CAD-score.
The CADScor system consists of 2 units; the acoustic recording sensor and the docking station for charging and qualification of the sensor to make sure the sensor microphone is working properly. Single-use adhesive patches are also needed to connect the sensor to the patient's chest. The company claim the test can done in less than 10 minutes, including preparing the patient and readout of the CAD-score result.
The CADScor system provides a new method of detecting CAD acoustically by recording coronary murmurs caused by turbulent blood flow. Normally, coronary blood flow is laminar, but when stenosis happens, blood flow can become turbulent and this usually manifests as coronary murmurs. Coronary murmurs can therefore suggest the presence of haemodynamically important CAD. The company claim that no other acoustic CAD rule-out technology is currently available in the UK that has comparable sensitivity and specificity to the CADScor system. They also claim that the device could allow further testing to be ruled out for 40 to 50% of people. The test is non-invasive and does not use radiation, avoiding radiation exposure from CT scans in people for whom CTCA is ruled out. Apart from patient data that are entered into the CADScor device before the test, no external inputs are needed.
The current diagnosis of people presenting with suspected stable CAD is based on clinical assessment. NICE's guideline on the assessment and diagnosis of chest pain with recent onset states this should include a detailed clinical history and physical examination. The following factors should be taken into account: age, whether the person is male, cardiovascular risk (history of smoking, diabetes, hypertension, dyslipidaemia, family history of premature CAD), other cardiovascular disease, and history of established CAD. CTCA is recommended as the first diagnostic test for people in whom stable angina cannot be excluded by clinical assessment alone. The guideline also recommends taking a resting 12‑lead ECG as soon as possible in these patients. CTCA should be used if:
clinical assessment suggests typical or atypical angina or
clinical assessment suggests non-anginal chest pain but 12‑lead resting ECG has been done and indicates ST-T changes or Q waves.
If CTCA has shown CAD of uncertain functional importance or if it is non-diagnostic, patients should be offered non-invasive functional imaging for myocardial ischaemia. ICA may be offered as a third-line when the results of non-invasive functional imaging are inconclusive.
The CADScor system is proposed by the company to be used early on in the current care pathway as a CAD rule-out test before CTCA. It will be used in people over the age of 40 who present with symptoms suggestive of stable CAD, and in accordance with the manufacturer's instructions for use. It is intended to be used by trained health professionals, which may include nurses, physicians and catheterisation laboratory technicians. It could be used in both primary and secondary care settings. Product-specific training on how to use the device will be needed for healthcare professionals. Training sessions of up to 3 hours are provided by the company for all new primary users of the device. Training includes an instruction presentation followed by a CADScor practical test session.
The cost of the CADScor system is £4,460 per unit (excluding VAT). Assuming the technology has a lifespan of 2 years and is used to test 3 patients per day, 4 days a week for 41 weeks of the year, the company estimate a per-test cost of £49.12.
Per-patient costs for standard care tests are based on 2018/19 hospital resource group (HRG) tariffs, and are as follows:
CTCA: £196 (HRG code RD28Z, Complex CT Scan [including the cost of reporting]).
Calcium scoring: £71 (HRG code RD20A, CT scan, 1 area, no contrast [including the cost of reporting]).
ICA: £834 to £8,016 (HRG codes EY43A-F, standard cardiac catheterisation).