PLWH with low-ASCVD score and healthy HIV- controls were enrolled in this retrospective, monocentric study. 53 PLWH with low-ASCVD score and 20 healthy controls were consecutively and retrospectively enrolled. Clinical history, anthropometric data, as well as cardiovascular and metabolic data were collected.
All HIV+ participants underwent contrast enhanced CCT for clinical purposes. Criteria for patient’s inclusion were: i) preserved glomerular filtration rate, ii) absence of contraindications to perform CCT and iii) completion of an iodine enhanced CCT scan after patient written consent acquisition. Exclusion criteria were: (i) known or suspected cardiac amyloidosis (causing interstitium expansion independently of myocardial fibrosis), (ii) hypertrophic cardiomyopathy, (iii) adult congenital heart disease. Demographics and anamnestic data, including information on HIV status and major cardiovascular risk factors were collected and registered. Vital status was ascertained by Social Security Death Index queries and medical record review. A previous history of heart failure (HF), defined according to current guidelines, was considered in presence of physician documentation: (i) documented symptoms (e.g. shortness of breath, fatigue, orthopnoea) and physical signs (e.g. edema, rales) consistent with HF; (ii) supporting clinical findings (e.g. pulmonary edema on chest X-ray), or (iii) therapy for HF (including diuretics, digitalis, angiotensin-converting enzyme inhibitors, or beta blockers).
The 18 control subjects enrolled consisted of outpatients referred to CCT for nonspecific thoracic pain, with no history of previous cardiovascular diseases, non-smokers nor under vasoactive therapy and with a previous documented negative ECG. Selection on individuals in the control group was conducted with age and gender matching criteria. All clinical investigations and laboratory exams were performed no more than 7 days before CCT. Review board and the local ethics committee provided approval for this investigation and informed consent was obtained from all patients.
CT image analysis
Pre- and post-contrast Hounsfield Unit (HU) were measured on CT images by the Picture Archiving and Communication System (PACS). The regions of interest (ROIs) were drawn firstly on the contrast image at the myocardial septum, in the equilibrium phase, and within the left ventricular chamber, the mean area was about 3 cm2 (range: 1.5–5 cm2). ROIs were then copied to the pre-contrast image. Mean attenuation at the ROI was recorded in HU and Myocardial ECV fraction was calculated using the following equation (1, 2) (see Equations in the Supplementary Files)
where the contrast agent (CA) partition coefficient (l) represents the ratio of the change (DHU) between myocardium and blood, and HCT is the hematocrit level. DHU was determined as DHU = HUpost - HUpre, where HUpost and HUpre are attenuation after and before administration of iodinated contrast material, respectively. CT examinations were performed with coronary angiography protocol with a 64-detector Dual-source CT scanner (Somatom Definition Siemens Medical Solution, Forehheimen, Germany). Cardiac scans (tube voltage, 120 kV; tube current time product, 190 mAs; section collimation, 64 detector rows, 1.2-mm section thickness; gantry rotation time, 330 ms) were acquired with prospective gating (65%-75% of R-R interval) and reconstructed into 3 mm-thick axial sections, using a B20f kernel. All patients underwent equilibrium CT, with a mean calculated effective dose of 2.18±0.26 mSv and a mean iohexol volume of 150.4 ± 20.4 mL.
HIV-1 RNA copy numbers were evaluated in plasma samples collected from whole blood obtained in EDTA-containing tubes and stored at -80˚C. Levels of HIV-RNA were measured with Versant kPCR (Siemens Healthcare Diagnostic Inc., Tarrytown, NY) with a detection limit of 37 copies/mL.
Categorical variables were summarized as absolute frequency (and/or percentage), and continuous variables were summarized as mean and Standard Deviation (±SD) or median and inter-quartile range (IQR: 25th and 75th percentile). Chi-square test (with a cell count are greater than 5) or Fisher exact test (with a cell count are equal to or less than 5) compared categorical variables. Mann-Whitney test compared continuous variables, since some continuous variables exhibited skewed distributions on visual inspection. Instead, the independent Student t-test were used to compare normally distributed variables. Besides, linear regression models were used for univariate and multivariate analysis to evaluate the correlation between quantitative ECV and other study parameters. Lastly, One-way analysis of variance (ANOVA) was used for multiple-group comparisons according to four categories, followed by Bonferroni test. When interpreting the results, a p-value of less than 0.05 was considered indicative of a significant difference. Statistical analyses were performed using statistical Program for the Social Sciences (SPSS, version 20) software package.