Letters
Cardiovascular diseases
Volume 194 - Issue 12

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

Authors:  Victor Kalff, Stephen J Duffy and Andrew J Taylor

Med J Aust 2011; 194 (12): 666-669. || doi: 10.5694/j.1326-5377.2011.tb03164.x
Published online: 20 June 2011
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To the Editor: Harper and Ko recently suggested radically changing the way we investigate patients with stable coronary artery disease (CAD), stating that they should initially undergo computed tomography coronary angiography (CTCA), with subsequent stress testing if CTCA shows atherosclerosis.1 To save costs, they recommend excluding stress nuclear myocardial perfusion imaging (MPI) because it has similar accuracy to stress echocardiography and involves ionising radiation.

To suggest that the available evidence supports CTCA as the first-line investigation of stable CAD is premature, and likely to cause more therapeutic confusion than it resolves. Of particular concern is the assertion that all patients with any detectable atherosclerosis on CTCA should undergo intensive medical therapy for CAD. The clinical significance of mild atherosclerosis detected on CTCA in patients with chest pain that is unlikely to be of cardiac origin is uncertain, with no clinical studies demonstrating a benefit of medical management for CAD based on CTCA findings. Conversely, were such patients investigated first with a stress test, those with a negative test could be reassured that their chest pain is not cardiac and their intermediate-term prognosis is excellent. Importantly, the directive for unproven lifelong medical therapy for CAD is averted.

It is also incorrect to imply that different stress-testing modalities may be seen as equivalent because they have comparable diagnostic accuracies, because their strengths and weaknesses remain complementary. This allows referring physicians to choose the modality that most suits the individual patient. For example, stress echocardiography is more operator-dependent, with known limitations in patients with obesity, airways disease, arrhythmias, poorly controlled hypertension, and contraindications for β-blocker cessation. It also cannot be fused with CTCA images, as myocardial perfusion images can.2

While we agree that measurement of fractional flow reserve (FFR) is an extremely important advance in interventional cardiology, it has the limitation of underestimating ischaemia in patients with small-vessel disease (eg, patients with diabetes).3 We agree that demonstrating ischaemia is the critical component in the decision to perform either percutaneous coronary intervention or coronary artery bypass graft surgery — and until now the largest body of evidence has been accumulated with MPI.4 Moreover, demonstration of regional ischaemia on MPI associated with an angiographic stenosis obviates the need for FFR. Electrocardiographic stress testing alone cannot provide these localising data.

The advent of CTCA promises to reshape how we assess and manage CAD in the future, but today we should be guided by the clinical evidence, and be mindful not to put the cart before the horse.

Authors

  • Victor Kalff1
  • Stephen J Duffy1
  • Andrew J Taylor1
  • 1. Alfred Hospital, Melbourne, VIC.

Correspondence: Victor.Kalff@monash.edu

References

View this article on Wiley Online Library