HeartFlow FFRCT for estimating fractional flow reserve from coronary CT angiography

3 Current practice

In people with stable (non-acute) chest pain of recent onset, diagnostic tests aim to identify coronary artery disease by evaluating either coronary anatomy (narrowing) or function (flow/ischaemia). Tests can be classified as invasive or non-invasive. Fractional flow reserve (FFR) is currently measured invasively using a pressure wire placed across a narrowed artery during invasive coronary angiography (ICA).

The choice of diagnostic test is based on a number of factors such as patient characteristics, clinical features, test availability and access, local protocols and patient and clinician preferences.

The NICE guideline on chest pain of recent onset was updated in November 2016, but FFR was not considered as part of the update.

This guideline recommends 64-slice or above coronary CT angiography (CCTA) as a first-line diagnostic test. HeartFlow FFR_CT also needs 64-slice CCTA as a minimum.

Not all patients can have standard CT scanning. NICE diagnostics guidance on new-generation cardiac CT scanners includes recommendations on their use as a first-line imaging option in people with suspected or known coronary artery disease in whom imaging is difficult with earlier-generation CT scanners. This may include people with obesity, calcium scores above 400, arrhythmias, uncontrolled high heart rates, stents or previous bypass grafts.

There are several drivers of change in current practice around diagnostic testing for suspected coronary artery disease. These include the timing of the publication of the updated NICE guideline on chest pain of recent onset and its guidance on HeartFlow FFR_CT, as well as proposed CT replacement predictions in England described in the Clinical Imaging Board report (CT Equipment, Operations, Capacity and Planning in the NHS 2015).

Some trusts will already be equipped to comply with the new guidance, but for some a shift in practice may be needed. The challenges of this are set out in the British Society of Cardiovascular Imaging report (2015). The successful adoption of HeartFlow FFR_CT ultimately depends on the availability of adequate CCTA facilities and skills of the workforce.