It is Time for Coronary Computed Tomography Angiography to be Incorporated into the SUS

Cost-Benefit Analysis; Stable Angina; Coronary Artery Disease; Computed Tomography Angiography; Unified Health System; Diagnostic Imaging/methods

In the evaluation of patients with stable coronary artery disease (CAD), also called chronic coronary syndrome (CCS), complementary tests are used both for diagnostic and prognostic purposes.¹ , ² Anatomical (coronary angiography and coronary CT angiography) and functional (exercise testing, stress echocardiography, rest and stress myocardial perfusion imaging by scintigraphy, magnetic resonance, and positron emission tomography) tests are available. Coronary angiography, the gold standard, is invasive and therefore, indicated for clinically more severe patients, or those with poor prognostic findings in non-invasive testing, when myocardial revascularization is considered or planned.³

The choice for the most appropriate diagnostic test is an important and challenging issue for the cardiologist in the clinical evaluation of CCS. The first step in this decision-making process is the assessment of the pre-test probability (PTP) of CAD. As recommended by the current SCC guidelines,³ , ⁴ patients classified as having high PTP should receive medical therapy and undergo testing for prognostic information. The patients with low PTP should be assessed for an alternative diagnosis more likely than CAD. Patients with PTP calculated between 15-85% are in the intermediate range, where the complementary tests are more useful and important for CAD diagnosis.⁵ In addition to diagnostic accuracy and PTP, the selection of a non-invasive test depends on the clinical characteristics of patients, local expertise, and the availability of tests.⁴ In Brazil, it is estimated that up to 80% of the population depends exclusively on medical care provided by the public health system (SUS).⁶ In this context of managing economic resources, physicians and health managers should focus on the most cost-effective options for the diagnosis of CAD.

The article by Carmo et al.⁷ assesses just the intermediate and low-intermediate PTP (10-60%) scenario, via two different methods of cost-effectiveness analysis, using up-to-date concepts of health technologies (incremental cost-effectiveness ratio and the net benefit). The strategies with sequential tests were performed when the first test was positive. The results were presented according to the variation of PTP at different thresholds of willingness to pay for a correct diagnosis. Although coronary computed tomography angiography (CTA) is not yet available in SUS, it was the most cost-effective strategy in this study, either alone or in sequential testing, except in the lower thresholds of willingness to pay, in which was overwhelmed by stress echocardiogram (SE).⁷

Another interesting finding concerns the use of exercise testing (ET), which was placed in the background in international guidelines,⁴ but showed to be an excellent cost-effective option in lower PTPs and lower willingness to pay thresholds, especially when followed by SE in case the ET was positive.⁷ Given the large economic differences between regions in Brazil, in locations with less availability of resources and health financing, ET could remain the main diagnostic screening strategy for CAD.

Myocardial scintigraphy (MS), widely used in SUS, proved to be more expensive and less effective than CTA and SE in all scenarios evaluated, appearing as a negative spotlight in the diagnostic strategy in CAD. Furthermore, CTA was able to reveal non-obstructive CAD even in patients with moderate and severe myocardial ischemia in functional tests, such as 15% of those initially selected for the ISCHEMIA trial.⁸ Another advantage of CTA is the possibility of non-invasive quantification of the fractional flow reserve, capable of detecting flow-limiting obstructive coronary lesions, reducing the number of false-positive results.⁹ These findings highlight the usefulness of CTA in significantly reducing the number of CCS patients referred to coronary angiography and, therefore, decreasing the costs and possible complications of the invasive testing.

The main results of the analysis performed by the authors are based on the estimated CTA price in which SUS would pay for, that can be underestimated, since the ATC versus MS costs readily available online in many supplementary healthy services are comparable. This would lead to an important limitation of this manuscript if confirmed afterwards. Another gap is the intermediate-high PTP scenario (60-85%), not evaluated in this study, where MS could be able to show a better competitiveness, considering its good performance in confirming the diagnosis of functionally significant CAD in this higher PTP range.¹⁰

This article shows relevant evidence that may be applied by SUS health managers and physicians in the decision-making process of the diagnostic methods chosen for CAD. It might also be used as a future reference for local guidelines, that similarly to other international guidelines¹ , ¹¹ may consider the recommendation of ATC as a first-line diagnostic test for CAD, as an alternative to functional imaging. It should be noted, however, that functional testing remains irreplaceable in objectively assessing the degree of functional limitation and the patient’s response to therapy.³ , ⁴ Finally, there is still room for the rational use of all available methods in diagnosing obstructive CAD in clinical practice, but there is no longer any reason why CTA should not be incorporated into the SUS.

Referências

• ¹
  Gottlieb I, Bittencourt MS, Rochitte CE, Cavalcante JL. Coronary Computed Tomography Angiography Takes the Center Stage and Here is Why. Arq Bras Cardiol. 2019;112(1):104-6. DOI: 10.5935/abc.201900
• ²
  Newby DE, Adamson PD, Berry C, Boon NA, Dweck MR, Flather M, et al. Coronary CT Angiography and 5-Year Risk of Myocardial Infarction. N Engl J Med. 2018;379(10):924-33. doi: 10.1056/NEJMoa1805971.
• ³
  Cesar LA, Ferreira JF, Armaganijan D, Gowdak LH, Mansur AP, Bodanese LC, et al. Guideline for stable coronary artery disease. Arq Bras Cardiol. 2014;103(2 Suppl 2):1-56. doi: 10.5935/abc.2014s004.
• ⁴
  Knuuti J, Wijns W, Saraste A, Capodanno D, Barbato E, Funck-Brentano C, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J. 2020;41(3):407-77. doi: 10.1093/eurheartj/ehz425.
• ⁵
  Fihn SD, Gardin JM, Abrams J, Berra K, Blankenship JC, Dallas AP, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2012;60(24):e44-e164. doi: 10.1016/j.jacc.2012.07.013
• ⁶
  Selig FA. Outlook and Perspectives in Diagnosis and Treatment of Congenital Heart Diseases in Brazil. Arq Bras Cardiol. 2020;115(6):1176-7. doi: 10.36660/abc.20200680.
• ⁷
  Carmo PB, Magliano CAS, Rey HCV, Camargo GC, Trocado LFL, Gottlieb I. Análise da Custo-Efetividade da Angiotomografia Coronariana no SUS, em Comparação com Outros Métodos Não Invasivos na Suspeita de DAC Estável. Arq Bras Cardiol. 2022; 118(3):578-585.
• ⁸
  Maron DJ, Hochman JS, Reynolds HR, Bangalore S, O’Brien SM, Boden WE, et al. Initial Invasive or Conservative Strategy for Stable Coronary Disease. N Engl J Med. 2020;382(15):1395-407. doi: 10.1056/NEJMoa1915922.
• ⁹
  Morais TC, Assunção-Jr AN, Dantas Júnior RN, Silva CFGD, Paula CB, Torres RA, et al. Diagnostic Performance of a Machine Learning-Based CT-Derived FFR in Detecting Flow-Limiting Stenosis. Arq Bras Cardiol. 2021;116(6):1091-8. doi: 10.36660/abc.20190329.
• ¹⁰
  Knuuti J, Ballo H, Juarez-Orozco LE, Saraste A, Kolh P, Rutjes AWS, et al. The performance of non-invasive tests to rule-in and rule-out significant coronary artery stenosis in patients with stable angina: a meta-analysis focused on post-test disease probability. Eur Heart J. 2018;39(35):3322-30. doi: 10.1093/eurheartj/ehy267.
• ¹¹
  Moss AJ, Williams MC, Newby DE, Nicol ED. The Updated NICE Guidelines: Cardiac CT as the First-Line Test for Coronary Artery Disease. Curr Cardiovasc Imaging Rep. 2017;10(5):15. doi: 10.1007/s12410-017-9412-6.

• Short Editorial related to the article: Cost-Effectiveness Analysis of CCTA in SUS, as Compared to Other Non-Invasive Imaging Modalities in Suspected Obstructive CAD

Publication Dates

• Publication in this collection
  18 Mar 2022
• Date of issue
  Mar 2022