A new algorithm for the management of stable coronary artery disease incorporating CT coronary angiography and fractional flow reserve: how we can improve outcomes and reduce costs

In response to Kalff and colleagues, we firmly believe stress testing should be reserved for the diagnosis of ischaemia in patients with known coronary artery disease (CAD), and computed tomography coronary angiography (CTCA) is the investigation of choice for anatomical diagnosis of CAD in patients with suspected CAD. In this, we are supported by recent guidelines from the American Heart Association and others.1 Most heart attacks occur as a result of plaque rupture in coronary lesions of insufficient severity to cause ischaemia on stress testing, but that would be detected on CTCA.2 In view of the undoubted benefits of medical therapy in both primary3 and secondary prevention of CAD events, do Kalff et al seriously suggest that coronary atherosclerosis detected on CTCA should not be treated with proven anti-atherosclerotic therapy?

Regarding comments made by van Gaal and Allman, and Karamoskos, we believe the upfront use of CTCA in our proposed algorithm would substantially decrease downstream referrals for both stress testing and invasive angiography in patients with suspected CAD. The current practice of referrals for invasive angiography based on clinical assessment and functional tests results in a low yield of obstructive disease.4 Furthermore, we believe the responsible use of CTCA can be promoted by restricting its use to the anatomical diagnosis of CAD as a once-only investigation. Once the diagnosis is established, further functional testing can be pursued if clinically indicated. Multicentre studies designed to determine the optimal role of CTCA are underway and will provide important insights regarding our viewpoint.5

Van Gaal and Allman place considerable emphasis on the 5000-patient study of myocardial perfusion imaging.6 We point out, however, that this was an observational study. In contrast, the FAME study on which we base our views of fractional flow reserve (FFR) was a randomised study.7 In addition, we are bemused by their statement that “The review cited quotes a lower sensitivity and specificity of FFR compared with perfusion scintigraphy, and lists scintigraphy as the ‘clinical gold standard of ischaemia’”. To quote directly from the review article:

Regarding comments made by Better and colleagues, we believe both stress echocardiography and nuclear stress testing are overused in clinical practice. In most circumstances, a standard electrocardiographic stress test is sufficient to exclude significant ischaemia and thus to determine who should undergo invasive angiography. In circumstances requiring stress imaging, our preference is to perform stress echocardiography, as its accuracy is comparable to nuclear stress testing, with no additional radiation. Notably, in multilesion CAD, none of the stress testing modalities are sufficiently accurate to determine which lesions require intervention.9,10 Only FFR, a proven cost-effective investigation, can decide this.9,10

Rather than putting the cart before the horse, as suggested by Kalff et al, our algorithm provides a horse with the potential to win the Melbourne Cup.