Cardiac diseases are the main cause of death for both sexes worldwide. Treatment varies widely according to the sex of a patient, as there are differences in physiopathology, epidemiology, clinical presentation and management.
“Women who present with chest pain are at risk of underdiagnosis, and potential cardiac causes should always be considered.In women presenting with chest pain, it is recommended to obtain a history that emphasizes accompanying symptoms that are more common in women with acute coronary syndromes”.Considering the aforementioned pathophysiologic differences of IHD in women compared to men, as well as predominant plaque erosion, impaired coronary vasomotor function and microvascular dysfunction, it is crucial to identify in which scenarios the clinician should distinguish between women and men for an appropriate cardiovascular imaging approach [29][30][29,30]. In this sense, although CCTA shows sensitivity and specificity with respect to detecting coronary stenosis and coronary dissections, its diagnostic accuracy can be limited in women due to the smaller diameter of vessels [31]. On the contrary, CMR and positron emission tomography (PET) are valid options to evaluate microvascular dysfunction thanks to their capacity to measure myocardial blood flow (MBF) and CFR.Diagnostic Algorithm for IHD in Women Considering the Pretest Probability of the Disease in a Multimodal Cardiac Imaging Approach
In case of suspected stable IHD, several tables for calculations of pretest probabilities of presenting an obstructive CAD in symptomatic patients have been applied. The 2021 ACC guideline [28] includes one table that is particularly useful because, in addition to chest pain characteristics, age and sex, it considers calcium scoring, which allows for refining the calculation according to the amount of coronary calcium, mainly in the case of patients with intermediate-high pretest probabilities. Thus, in women with a suspected IHD, the first step should be to calculate the pretest probability of having an obstructive CAD. Accordingly, selection of the diagnostic test should also take into account the availability of tests, local expertise and patient characteristics and preferences (recommendation class I, level of evidence C, according to the 2019 ESC Guidelines for the Diagnosis and Management of Chronic Coronary Syndromes) [28]. According to the pretest probability of the disease:If an obstructive CAD is diagnosed, an appropriate management strategy should be applied that takes into consideration the extent and severity of ischemia and anatomic characteristics of coronaries, independent of sex. The possibility of a microvascular dysfunction and other causes of chest pain should also be considered. According to the 2019 ESC Guidelines for the Diagnosis and Management of Chronic Coronary Syndromes [33], a non-invasive functional imaging test for myocardial ischemia or CCTA is recommended as the initial test to diagnose CAD in symptomatic patients in whom obstructive CAD cannot be excluded by clinical assessment alone (recommendation class I, level of evidence B). Table 1 shows a comparison of advantages and disadvantages of the different imaging techniques.
In patients with a very low probability of obstructive CAD, diagnostic tests can be deferred, although according to clinical evaluation, other options may be considered [32], such as: an exercise test (without imaging) if the electrocardiogram (ECG) at rest is interpretable and the patient can exercise (although this is less useful for women, considering the lower sensitivity of the test compared to men and the possibility of false positives), or a coronary calcium scoring for a better refinement of risk (if not included in the pretest probability analysis). In patients with a low to intermediate probability and considering that CCTA has a very high negative predictive value, an anatomic approach with CCTA is the most effective option, independent of sex. In those with an intermediate to high probability, an ischemia-provoking test with imaging should be considered: stress-echocardiography, nuclear (either single-photon emission computed tomography -SPECT- or PET), or stress CMR. The type of applied stress will depend on functional capacity, ECG at rest and the type of test selected. In those patients with a very high pretest probability, there is no doubt that invasive coronary angiography (preferably with fractional flow reserve measurement) is the most effective option to choose, independent of sex.SPECT: single photon emission computed tomography; PET: positron emission tomography; MPI: myocardial perfusion imaging; CMR: cardiac magnetic resonance; CCTA: cardiac computed tomography angiography.Table 1. Advantages and disadvantages of imaging tests.
Imaging Test Advantages Disadvantages Stress echo No radiation, high availability, lower costs Poor acoustic windows, less reproducible SPECT MPI Good reproducibility, validated for ischemia detection. Uses stress-only protocols if possible Radiation exposure, need for attenuation correction for anterior defects in women PET MPI Validated for ischemia detection, MBF and CFR can be measured Radiation exposure, although less than SPECT MPI CMR Validated for ischemia detection, MBF and CFR can be measured. Standard measurement for ventricular function. No radiation Less availability, higher costs, claustrophobia, patients with implantable cardiac devices CCTA High negative predictive value. Measurement of calcium score in addition to coronary anatomy Radiation exposure
The use of solid-state cadmium zinc telluride (CZT) cameras has allowed for improved spatial resolution and increased camera sensitivity that has allowed for a lower required dose of the radiotracer and therefore, lower radiation exposure. The use of hybrid imaging (SPECT/CT) allows for attenuated-corrected images.