The impact of cardiac SPECT in risk stratification for women with suspected coronary artery disease in a very high cardiovascular risk country

Background: Risk stratification has become increasingly important in the management of women with coronary artery disease (CAD). Population based cross-sectional study of cardiovascular risk (CVR) factors in Latvia revealed that women in age 25 -74 are in a very high CVR group: more than 60% of women have dyslipidemia, 30% have arterial hypertension (AH) and are overweight.
Purpose: To evaluate CVR factor profile in women with suspected CAD and performed cardiac single photon emission computed tomography
(SPECT) and to prove the need of perfusion imaging for women in a very high cardiovascular risk population.
Methods: Cardiac SPECT for women with suspected CAD and positive or non-informative exercise test was performed in a single center from
2018 till 2022. The patients were analyzed by risk factors and perfusion test result, divided into 2 groups: normal myocardial perfusion or true
myocardial perfusion defect.
Results: 466 patients without known CAD were analyzed. The mean age of cohort patients was 59.3±10.9 years. 28 (6.0%) patients had no CVR factors, 90 (19.3%) women had only 1, but the rest of them (348, 74.7%) had 2 or more CVR factors. Dyslipidemia was present in 358 (76.8%), AH in 282 (60.5%) and type 2 Diabetes mellitus (T2DM) in 27 (5.8%) patients. More than half of patients (n=303, 65.0%) were overweight (BMI>25.0 kg/m2). 65 (13.9%) women were current or ex-smokers. True myocardial perfusion defect was detected in 96 patients (20.6%). There was no statistically significant difference between CVR risk factor count and cardiac SPECT result (p=0.229), although there were patients with significant perfusion defect without any risk factor present.
However, significant correlation between risk factors and detection of obstructive coronary artery disease (CAD) after positive cardiac SPECT
was found (p<0.001). Totally in study was detected 71 patients with suspected ischemia with non-obstructive CAD (INOCA), but further investigation with
intracoronary physiology measurements – coronary flow reserve (CFR), index of microvascular resistance (IMR) and acetylcholine provocation test is required to define INOCA endotype.
Conclusions: The cardiac SPECT is an appropriate diagnostic method for women patients with suspected CAD. Even in patients with no CVR factors, but with positive or non-informative exercise test, the CAD is present, therefore they should be referred to cardiac SPECT in a very high CVR country. In patients with significant perfusion defect and absence of obstructive CAD, the performance of intracoronary physiology measurements is required.