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Management of coronary artery disease with cardiac CT beyond gatekeeping
  1. Filippo Cademartiri1,2,
  2. Stefano Nistri3,
  3. Giuseppe Tarantini4,
  4. Erica Maffei1
  1. 1 Department of Radiology & Research Center, Montreal Heart Institute/Universitè de Montreal, Montreal, Quebec, Canada
  2. 2 Department of Radiology, Erasmus Medical Center University, Rotterdam, The Netherlands
  3. 3 Cardiology Service, CMSR- Veneto Medica, Altavilla Vicentina, Italy
  4. 4 Department of Cardiology, University of Padua, Padua, Italy
  1. Correspondence to Professor Filippo Cademartiri, Department of Radiology, Montreal Heart Institute,Centre de Recherche, room S-2530, 5000 Rue Belanger, Montreal, Quebec, Canada H1T 1C8; filippocademartiri{at}gmail.com

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This journal reports an analysis of symptoms and quality of life (QOL) of patients enrolled in the Scottish COmputed Tomography of the HEART (SCOT-HEART).1

Last year the results of the two major trials on cardiovascular imaging strategies for the diagnosis of coronary artery disease (CAD) were published (ie, PROMISE/PROspective Multicenter Imaging Study for Evaluation of chest pain—performed in North America and SCOT-HEART—performed in Scotland).2–4 They were structured to analyse the impact of cardiac CT (CCT) on current standards of care.

The PROMISE trial ultimately showed a diagnostic and prognostic equivalence of anatomical strategy versus the North American standard of care; although more patients in the CCT group underwent cardiac catheterisation within 3 months after randomisation, the secondary end point of the frequency of catheterisation showing no obstructive CAD was significantly lower in the CCT group.

The SCOT-HEART investigated the incremental value of CCT on top of a European standard of care. The end point was certainty of the diagnosis of angina secondary to coronary heart disease at 6 weeks, while long-term outcomes were major adverse cardiovascular events. Most patients underwent stress ECG (85%) and a third underwent other stress imaging tests. CCT improved diagnosis, treatment and outcome of symptomatic stable patients with suspected CAD. The improvement was associated with better selection of patients for invasive coronary angiography, more appropriate changes in therapy, and a halving in the rates of fatal and non-fatal myocardial infarction.

In both studies the rates of events were lower than expected from previous studies.

Advantages of CCT in the management of CAD

CCT is the only non-invasive anatomical method that can provide robust information about obstructive CAD.5–8 The additional information provided by CCT is in the differentiation between normal coronary artery tree and non-obstructive CAD. This is an important and novel distinction to make when we think about CAD. Epicardial ischaemia is important in terms of diagnosis, treatment and outcome, but it is a complication of CAD. The possibility to stratify patients according to their disease (type, severity, extension and so forth) and not according to general epidemiological risk classifications or according to the degree of ischaemia is an innovation. This innovation affects the way we look at our patients and the way we should treat them. We already have strong evidence that obstructive disease is a dominant prognostic factor, but we know very little about what happens and which strategies we should adopt when coronary arteries show non-obstructive CAD. For decades, non-obstructive CAD and normal coronary arteries have been considered within the same category. A modern look should consider that when coronary arteries are normal, even patients with diabetes have the same risk of events as the general population. This is also a rather new vision, especially when trying to move towards a personalised approach to CAD.

Newer insights from SCOT-HEART

Williams et al 1 show that, beyond its gatekeeping effectiveness resulting in improved diagnosis, treatment and outcome, CCT is associated with a small attenuation of the improvements in symptoms and QOL due to the detection of moderate non-obstructive CAD. These finding raise a number of pathophysiological and clinical issues.

It is well known that the correlation between angiographic/anatomical and physiological stenoses severity is poor. Moreover, there are relevant disparities between different measures of stenosis significance which cannot be explained by available methodologies but which reflect differences in global coronary pathophysiology, and which can have implications and can offer opportunities for therapy targeting and for monitoring therapy responses. Indeed, a significant limitation of the study by Williams et al 1 resides in the lack of information on the psychological status of the patients and coronary microvascular function. Consistently, in this group of patients, a more personalised diagnostic approach may be needed. The present findings prompt the need of future studies investigating the role for different functional approaches in this intriguing subset. Importantly, these findings underscore the relevance of anxiety in determining the response in terms of symptoms and QOL.

It is conceivable that this behaviour is related to the perception of ischaemic heart disease as a black-or-white situation, which could have also been further supported by a ‘stenotic-centered’ communication by the attending physicians. The clinical approach to a non-obstructive stage of CAD, ranging from communication issues, to diagnostic evaluation and medical treatment is not really obvious, yet. Actually this clinical entity imposes questions and challenges.

While it is clear and understandable that the greatest improvements in symptoms are seen in those with normal exercise tolerance, normal coronary arteries and those who have preventative therapies cancelled, this study shows how QOL and symptoms are affected by diagnosis, by treatments and also by patients’ expectations. Probably, a step forward is needed with regard to education of patients to the fact that CAD is a complex condition, and not a black-or-white entity. This is even more important in the early stages of the clinical workup when less information is available.

We also need to consider that, as for any life-changing disease, the psychological reaction to rule-in or rule-out of obstructive CAD affects the perception of patients' QOL, on top of added or withdrawn medical treatment. Particularly in this respect, relevant room of improvement may be related to induction of appropriate lifestyle changes including targeted exercise prescription.

Conclusion

The SCOT-HEART trial represents a strong evidence in favour of the implementation of CCT in the clinical workup of stable chest pain; at least in the European context (figure 1). CCT appears to grant a different stratification of our patients and new opportunities for application and modulation of rehabilitative, pharmacological and interventional treatments.

Figure 1

Evolving role of CCT in the workup of patients with suspected anginal chest pain. The figure shows a possible simplified algorithm which implements the potential role of CCT in patients with suspected anginal chest pain. While it is straightforward when significant obstructive disease is present (>70% stenosis), the management becomes more articulated when different degrees of obstruction are detected. CAD, coronary artery disease; CHD, coronary heart disease; CCT, cardiac CT.

SCOT-HEART also sheds light into the most innovative and powerful information delivered by CCT. Maybe, the true Copernican revolution at this stage should consist in realising that anatomy and function should no longer be seen as opponent, but should be used appropriately at different stages of the disease and also of the patient-physician relationship. This study from SCOT-HEART revises the concept of CCT as a gatekeeper for invasive coronary angiography, addressing the need for a more personalised, patient-centred (not methodology-centred) approach to this complex situation.

References

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Footnotes

  • Contributors FC, SN, GT and EM made substantial contributions to the conception or design of the work, or the acquisition, analysis or interpretation of data; participated in drafting the work and revising it critically for important intellectual content; gave final approval for the published version and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.

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