Age- and sex-related differences in coronary plaque high-risk features in patients with acute coronary syndrome assessed by computed tomography angiography

Age-andsex-relateddifferencesinthepathologicalfeaturesofacutecoronarysyndrome(ACS)culpritlesions(CLs)havebeenreported[1,2].Coronary computedtomography angiography (CCTA)has the potentialto detect high-risk coronary plaques by characterizing non-calcifiedcoronary atherosclerotic plaques (NCPs), including pure non-calcifiedplaques and non-calcified plaques associated with coronary calcium[3–6]. In this study, we investigated whether CCTA differentiated age-and sex-specific characteristics of ACS CLs by analyzing NCPs.From November 2006 to March 2013, we extracted 68 patients (53men, ages 65 ± 10 years) who were admitted to our hospital due toacute chest symptoms, underwent CCTA, and were finally diagnosedwith ACS [non-ST-segment elevation myocardial infarction (NSTEMI)or unstable angina]. Patients with unstable hemodynamic conditions,ongoing ST-segment elevation myocardial infarction, previous ACS,and previous coronary revascularizations were excluded. ACS wasdefined according to standard criteria [7], and the CCTA findings werenotreferredfortheACSdiagnosis.AlloftheACSpatientsunderwentin-vasive coronary angiography within 24 h following cardiac computedtomography(CT)examination.TheCLsweredeterminedbasedoninva-sivecoronaryangiographyandelectrocardiogramchanges,asdescribedpreviously[5].Ascontrols,atotalof80patients(61men,69±9 years)in whom CCTA revealed NCPs but who did not suffered ACS wereselected from our previous database [5]. Our hospital's ethical commit-tee approved this study, and written informed consent was obtainedfrom all patients.Followingaplain scantomeasurecoronarycalcium score accord-ing to the standard Agatston method, the data set for CCTA was ac-quired under retrospective electrocardiography (ECG), using a 64-slice(LightSpeed VCT; GE Healthcare, Waukesha, WI, USA) or 320-slice CTscanner (Aquilion One; Toshiba Medical Systems, Tokyo, Japan). For a64-slice CT scanner, a contrast-enhanced data set in helical mode wasacquired as described previously [3,5]. For a 320-slice CT scanner, acontrast-enhanced data set was acquired using a HeartNAVI® systemdeveloped by Toshiba Medical Company, providing the best number ofacquired heart beat data and temporal resolution optimized accordingto the heart rate during scanning. All reconstructed CT image data weretransferred to an offline workstation (Advantage Workstation Ver. 4.2,GE Healthcare) for post-processing and subsequent image analysis.Two blinded independent observers evaluated all coronary seg-ments N2-mm in diameter. Each NCP detected on CCTA was evaluatedwith the minimum CT density, vascular remodeling index (RI), andthe presence or absence of adjacent spotty calcium deposits, as in ourprevious studies [3,5]. We also determined the luminal enhancementof each reference segment. Additionally, the presence or absence of arim-like area of higher attenuation in NCPs (napkin-ring sign, NRS)was determined at each NCP [8].Coronary calcium score is expressed as the median value and inter-quartile range. Other measurements are expressed as mean ± SD. Tocompare continuous variables, the Student t test or Mann–Whitney Utest was used between two subgroups, and analysis of variance orKruskal–Wallis tests, including the Tukey–Kramer or Steel–Dwass testfor multiple comparisons, was used amongmore than three subgroups.Categorical variables are reported as number (%) and were comparedusing Pearson's chi-square test. Parameters of NCPs were tested usinga receiver-operator characteristic curve to assess their reliability asprognosticvariablesforpredictingACSCLs.Pvalueofb0.05wasconsid-ered statistically significant.We studied 27 patients diagnosed with NSTEMI and 41 with unsta-ble angina. Among them, 58 underwent CCTA with the 64-slice CTscanner and 10did with the 320-slicescanner. There was no differencein luminal enhancement of reference site lumens between 2 scanners:349 ± 39 vs. 338 ± 52 Hounsfield units (HU) (P = 0.48). The ACS