ABC | Volume 114, Nº2, February 2020

Update Update of the Brazilian Guideline on Nuclear Cardiology – 2020 Arq Bras Cardiol. 2020; 114(2):325-429 9. Integrating Diagnostic Modalities in Cardiology – Tutorial Cases 9.1. Introduction Technological evolution has facilitated the development of excellent tools for both establishing diagnosis and estimating prognosis of CAD. These advances allow us to evaluate different aspects of anatomy and physiology of the heart non-invasively, with great accuracy. Most importantly, today we are able to rely on methods which help establish the best course of treatment in the most diverse clinical situations of patients with suspected or known diseases, whether they are symptomatic or asymptomatic. This wide range of alternatives presents an additional challenge to doctors, namely, that of defining the best strategy and the most rational complementary sequence of evaluation possible, regarding use of resources for diverse clinical situations, guaranteeing not only the highest accuracy in evaluation, but also the best benefits, considering healthcare costs. Doctors generally should seek to orient initial investigation with the aim of using the lowest number of diagnostic exams for an effective evaluation. However, in this era of multimodalities, it has become necessary to perform more than 1 exam in order to make the best therapeutic decision. Combined assessment of different phenomena of the heart is often necessary, for instance, to define physiological repercussions of an anatomical lesion. Two questions linked to the bases of medical semiology and to the essence of medicine ask, “Who is the patient?” and “What information is the doctor looking for?” In this approach, the application of good techniques, such as anamnesis and complete physical examination, has become clear in clinical medicine, enabling doctors to formulate their initial patient profiles and to establish the most probable diagnostic hypotheses. Joint estimation of the pre-test probability of the disease 233 and knowledge regarding the accuracy of a test to determine post-test probability of a true or false result (Bayes’ Theorem) are implicit and no less important. The application of this basic principle, associated with knowledge regarding what different diagnostic tools may offer, allows for the elaboration of better investigation strategies. Confirming or excluding the presence of CAD from the anatomical point of view or, alternatively, investigating the physiological repercussions of myocardial ischemia via stress tests have distinct implications for patient management. Whether to look for one response or another will depend on the patient at hand and the question the doctor wishes to answer. 9.2. Integrating Physiology (Exercise Testing and Nuclear Cardiology) and Anatomy (Calcium Score and Coronary Angiotomography) Exercise testing (ET), also known as ergometric test, stress or exercise tests, showing evidence of good performance (high workload) with normal results and MPS showing absence of ischemia do not represent absence of CAD indeed . In the presence of CAD, however, these findings are associated with better prognosis in relation to patients with ischemia, given that their use is extremely useful for risk stratification of patients with or without this disease. On the other hand, it is important to know that methodologies based on the anatomy of coronary arteries, such as coronary angio-CT, may also stratify risk, but the presence of atherosclerosis detected by this modality does not necessarily imply poor prognosis or, much less, mean that the patient will necessarily benefit from myocardial revascularization procedures. It may merely represent that prognosis is worse that that of an individual without atherosclerosis. It is, thus, worth reaffirming that it is necessary for doctors to possess global knowledge of their patients and also to delineate clearly the investigation strategy for the question they are seeking to answer. Basic knowledge regarding advantages and disadvantages of available procedures are implicit, making the absolute most of the technological evolutions that have occurred in recent years. Initially speaking, all modalities which have been covered may be used for diagnosis and prognosis. It is, however, evident that they all have strengths and limitations, which are not necessarily uniform for all patients; or be it, there are determined patient characteristics which may make one test superior or inferior to another (Table 25). Table 25 – Main advantages and disadvantages of exercise testing (ET), myocardial perfusion scintigraphy (MPS), and coronary angiotomography (angio-CT) for assessment of coronary artery disease (CAD) Advantages Disadvantages ET • Widely available • Relatively low complexity • Relatively low cost • Does not involve radiation • Requires ability to exercise • ECG may be uninterpretable • Limited accuracy • Does not detect initial CAD MPS • Localizes and quantifies ischemia • Evaluates perfusion and LV function associated with exercise • Evaluates ischemia in patients unable to exercise • Makes it possible to monitor treatment • Technological complexity • Uses radiation • Attenuation artifacts • Does not detect initial CAD Angio-CT • Excludes CAD with great accuracy • Detects CAD in its initial phase • Allows for anatomical evaluation (e.g., anomalous coronaries) • Quick exam • May overestimate obstructions • Limited use for known CAD • Limited for physiological aspects • Uses radiation ECG: electrocardiogram; LV: left ventricle. Source: Adapted from Vitola JV. 234 361