Multiparametric Rest and Dobutamine Stress Magnetic Resonance in Assessment of Myocardial Viability.

BACKGROUND: MR feature-tracking (FT) is a novel technique that quantitatively calculates myocardial strain and can assess myocardial viability. PURPOSE: To evaluate the feasibility of FT at rest and with low-dose dobutamine (LDD), visual assessment of contractility with LDD and left ventricle (LV) end-diastolic wall thickness (EDWT) in the assessment of viability in ischemic cardiomyopathy (ICM) patients compared to delayed gadolinium enhancement (DGE). STUDY TYPE: Prospective. SUBJECTS: Thirty ICM patients and 30 healthy volunteers. FIELD STRENGTH/SEQUENCES: A 1.5 T with balanced steady-state free precession (bSSFP) cine and phase-sensitive inversion prepared segmented gradient echo sequences. ASSESSMENT: LDD (5 µg/kg/min and 10 µg/kg/min) was administered in the patient group. LV was divided into 16 segments and MR-FT was derived from bSSFP cine images using dedicated software. Viable segments were defined as those with a dobutamine-induced increase in resting MR-FT values >20%, a dobutamine-induced increase in systolic wall thickening ≥2 mm by visual assessment, ≤50% fibrosis on DGE, and resting EDWT ≥5.5 mm. STATISTICAL TESTS: One-way analysis of variance (ANOVA), two-sampled t-test, paired samples t-test, and receiver operating characteristic (ROC) curve analysis. A P value < 0.05 was considered statistically significant. RESULTS: Resting peak global circumferential (Ecc) and radial (Err) strains were significantly impaired in patients compared to controls (-11.7 ± 7.9 vs. -20.1 ± 5.7 and 19.7 ± 13.9 vs. 32.7 ± 15.4, respectively). Segments with no DGE (n = 354) and ≤ 50% (n = 38) DGE showed significant improvement of both Ecc and Err with LDD while segments with >50% DGE (n = 88) showed no improvement. In comparison to viable and nonviable segments identified by reference-standard DGE, the sensitivity, specificity, and diagnostic accuracy of the four methods were: 74%, 92%, and 89%, respectively, for Ecc; 70%, 89%, and 86%, respectively, for Err; 67%, 88%, and 84% for visual assessment; and 39%, 90%, and 80% for EDWT. DATA CONCLUSION: Quantitative assessment of MR-FT, along with EDWT and qualitative visual assessment of myocardial contractility with LDD, are feasible alternative methods for the assessment of myocardial viability with moderate sensitivity and high specificity. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage: 2.

Plaque erosion masquerading as spontaneous coronary artery dissection: A case of sudden coronary death.

The three most common mechanisms of thrombosis in acute coronary syndrome (ACS) are plaque rupture, plaque erosion and calcified nodule. Plaque erosion occurs over an intact fibrous cap, commonly over pathological intimal thickening (PIT) rather than thin cap fibroatheroma (TCFA), and is more common among younger and female patients.1 A very rare mechanism of ACS is spontaneous coronary artery dissection (SCAD), resulting from the formation of an intramural hematoma and/or intimal disruption.2 We present a case of sudden coronary death with the appearance of SCAD on coronary computed tomography angiography (CCTA).

Vessel-specific plaque features on coronary computed tomography angiography among patients of varying atherosclerotic cardiovascular disease risk.

AIMS: The relationship between AtheroSclerotic CardioVascular Disease (ASCVD) risk and vessel-specific plaque evaluation using coronary computed tomography angiography (CCTA), focusing on plaque extent and composition, has not been examined. To evaluate differences in quantified plaque characteristics (using CCTA) between the three major coronary arteries [left anterior descending (LAD), right coronary (RCA), and left circumflex (LCx)] among subgroups of patients with varying ASCVD risk. METHODS AND RESULTS: Patients were included from a prospective, international registry of consecutive patients who underwent CCTA for evaluation of coronary artery disease. ASCVD risk groups were <7.5% (low), 7.5-20% (intermediate), and ≥20% (high). Among the ASCVD risk groups, the three coronary arteries were compared regarding quantified plaque volume and composition. Whole-heart plaque quantification was performed in 1340 patients (age 60 ± 9 years, 58% men). Across low, intermediate, and high ASCVD risk patients, the volume of plaque increased proportionally but was least in the LCx (7.4, 9.0, and 25.3 mm3, respectively) as compared with the RCA (19.3, 32.6, and 67.0 mm3, respectively, all P ≤ 0.006) and LAD (39.9, 60.8, and 93.3 mm3, respectively, all P < 0.001). In each ASCVD risk group, the composition of plaque in the LCx exhibited the least necrotic core and fibrofatty plaque (P < 0.05 vs. LAD and RCA). CONCLUSION: Among patients with varying risk of ASCVD, plaque in the LCx is decidedly less and is comprised of less non-calcified plaque supporting prior evidence of the lower rates of acute coronary events in this vessel.

Relationship Between Coronary Artery Calcium and Atherosclerosis Progression Among Patients With Suspected Coronary Artery Disease.

BACKGROUND: Among symptomatic patients, it remains unclear whether a coronary artery calcium (CAC) score alone is sufficient or misses a sizeable burden and progressive risk associated with obstructive and nonobstructive atherosclerotic plaque. OBJECTIVES: Among patients with low to high CAC scores, our aims were to quantify co-occurring obstructive and nonobstructive noncalcified plaque and serial progression of atherosclerotic plaque volume. METHODS: A total of 698 symptomatic patients with suspected coronary artery disease (CAD) underwent serial coronary computed tomographic angiography (CTA) performed 3.5 to 4.0 years apart. Atherosclerotic plaque was quantified, including by compositional subgroups. Obstructive CAD was defined as ≥50% stenosis. Multivariate linear regression models were used to measure atherosclerotic plaque progression by CAC scores. Cox proportional hazard models estimated CAD event risk (median of 10.7 years of follow-up). RESULTS: Across baseline CAC scores from 0 to ≥400, total plaque volume ranged from 30.4 to 522.4 mm3 (P < 0.001) and the prevalence of obstructive CAD increased from 1.4% to 49.1% (P < 0.001). Of those with a 0 CAC score, 97.9% of total plaque was noncalcified. Among patients with baseline CAC <100, nonobstructive CAD was prevalent (40% and 89% in CAC scores of 0 and 1-99), with plaque largely being noncalcified. On the follow-up coronary CTA, volumetric plaque growth (P < 0.001) and the development of new or worsening stenosis (P < 0.001) occurred more among patients with baseline CAC ≥100. Progression varied compositionally by baseline CAC scores. Patients with no CAC had disproportionate growth in noncalcified plaque, and for every 1 mm3 increase in calcified plaque, there was a 5.5 mm3 increase in noncalcified plaque volume. By comparison, patients with CAC scores of ≥400 exhibited disproportionate growth in calcified plaque with a volumetric increase 15.7-fold that of noncalcified plaque. There was a graded increase in CAD event risk by the CAC with rates from 3.3% for no CAC to 21.9% for CAC ≥400 (P < 0.001). CONCLUSIONS: CAC imperfectly characterizes atherosclerotic disease burden, but its subgroups exhibit pathogenic patterns of early to advanced disease progression and stratify long-term prognostic risk.

Marked variation in atherosclerotic plaque progression between the major epicardial coronary arteries.

AIMS: Atherosclerosis develops progressively and worsens over time, yet event risk patterns vary in the left circumflex (LCx), right coronary artery (RCA) and left anterior descending (LAD). The aim of this analysis was to examine varying progressive disease alterations between the three major coronary arteries. METHODS AND RESULTS: Patients were included from a prospective, international registry of consecutive patients who underwent serial CCTA at a median interval of 3.3 years. Annual progression of quantitative total and compositional plaque volume were compared between the three coronary arteries (LCx, LAD, and RCA). Other analyses compared stenosis ≥50% and new high-risk plaque (HRP; ≥2 of the following: spotty calcification, positive remodelling, napkin-ring sign, and low-attenuation plaque) on follow-up. Generalized estimating equations and marginal Cox regression models were used to compare progression, with covariate adjustment by the baseline atherosclerotic cardiovascular disease risk score, statin use, and plaque burden. Quantitative plaque measurements were calculated in 1344 patients (age 60 ± 9 years, 57% men). Plaque progression occurred less often in the LCx (41.0%) as compared to the RCA (52.7%) and LAD (77.4%, P < 0.001). Odds for annual plaque burden increase ≥population mean were 1.98- and 1.43-fold as high in the LAD (P < 0.001) and RCA (P < 0.001) as compared to the LCx. Similarly, the LAD was associated with a 2.45 higher risk of progression to obstructive CAD (P < 0.001), as compared to the LCx; with no differences between the RCA and LCx (P = 0.13). New HRP lesions formed least often in the LCx (3.4%), followed by the RCA (8.1%) and most often in the LAD (10.1%; P < 0.001). CONCLUSIONS: Our findings reveal novel insights into varied patterns of atherosclerotic plaque progression within the LCx as compared to the other epicardial coronary arteries. These varied patterns reflect differing stages in the disease process or differing pathogenic milieu across the coronary arteries.

Early versus late acute coronary syndrome risk patterns of coronary atherosclerotic plaque.

AIMS: The temporal instability of coronary atherosclerotic plaque preceding an incident acute coronary syndrome (ACS) is not well defined. We sought to examine differences in the volume and composition of coronary atherosclerosis between patients experiencing an early (≤90 days) versus late ACS (>90 days) after baseline coronary computed tomography angiography (CCTA). METHODS AND RESULTS: From a multicenter study, we enrolled patients who underwent a clinically indicated baseline CCTA and experienced ACS during follow-up. Separate core laboratories performed blinded adjudication of ACS events and quantification of CCTA including compositional plaque volumes by Hounsfield units (HU): calcified plaque >350 HU, fibrous plaque 131-350 HU, fibrofatty plaque 31-130 HU and necrotic core <30 HU. In 234 patients (mean age 62 ± 12 years, 36% women), early and late ACS occurred in 129 and 105 patients after a mean of 395 ± 622 days, respectively. Patients with early ACS had a greater maximal diameter stenosis and maximal cross-sectional plaque burden as compared to patients with late ACS (P < 0.05). Larger total, fibrous, fibrofatty, and necrotic core volumes were observed in the early ACS group (P < 0.05). Findings for total, fibrous, fibrofatty, and necrotic core volumes were reproduced in an external validation cohort (P < 0.05). CONCLUSIONS: Volumetric differences in composition of coronary atherosclerosis exist between ACS patients according to their timing antecedent to the acute event. These data support that a large burden of non-calcified plaque on CCTA is strongly associated with near-term plaque instability and ACS risk.

Strain analysis using feature tracking cardiac magnetic resonance (FT-CMR) in the assessment of myocardial viability in chronic ischemic patients.

The purpose of this study is to test the capability of a commercially available feature tracking-cardiac magnetic resonance (FT-CMR) strain analysis software module in differentiating between viable and non-viable myocardium in chronic ischemic patients. Thirty chronic ischemic patients and 10 healthy volunteers were enrolled. Cine images were used for peak circumferential and radial strains quantification using dedicated FT-CMR software. Global strain was compared between patients and controls. In patients, segmental strain was compared in viable and non-viable myocardium determined by late gadolinium enhancement (LGE); and in segments with wall abnormalities. Among 480 myocardial segments analyzed in patients, 76 segments were non-viable on LGE. The mean left ventricular ejection fraction (LVEF) of the patients (87% males, mean age 55 ± 12 years) was 40 ± 12% vs. 61 ± 5% for the controls (80% males, mean age 39 ± 11 years). Peak global circumferential strain (GCS) and global radial strain (GRS) were significantly impaired in patients compared to controls (-13.89 ± 4.12% vs. -19.84 ± 1.47%), p < 0.001 and (23.11 ± 6.59% vs. 31.72 ± 5.52%), p = 0.001. Segmental circumferential strain (SCS) and segmental radial strain (SRS) were significantly impaired in non-viable compared to viable segments (-9.47 ± 7.26% vs. -14.72 ± 7.5%), p < 0.001 and (15.67 ± 12.11% vs. 24.51 ± 16.22%), p < 0.001. Cut-off points of -9.36% for the SCS (AUC = 0.7, 95% CI = 0.63-0.77) and 19.5% for the SRS (AUC = 0.67, 95%CI = 0.61-0.73) were attained above which the segment is considered viable.SCS was able to discriminate between normokinetic, hypokinetic and akinetic segments (mean = 27.6 ± 17.13%, 18.66 ± 12.88% and 15.24 ± 10.70% respectively, p < 0.001). Circumferential and radial segmental strain analysis by FT-CMR was able to discriminate between viable and non-viable segments of the myocardium defined by LGE and between normokinetic, hypokinetic and akinetic segments, using routinely acquired cine images, and thus can provide a more objective metric for risk stratification in chronic ischemic patients.

Association of Statin Treatment With Progression of Coronary Atherosclerotic Plaque Composition.

Importance: The density of atherosclerotic plaque forms the basis for categorizing calcified and noncalcified morphology of plaques. Objective: To assess whether alterations in plaque across a range of density measurements provide a more detailed understanding of atherosclerotic disease progression. Design, Setting, and Participants: This cohort study enrolled 857 patients who underwent serial coronary computed tomography angiography 2 or more years apart and had quantitative measurements of coronary plaques throughout the entire coronary artery tree. The study was conducted from 2013 to 2016 at 13 sites in 7 countries. Main Outcomes and Measures: The main outcome was progression of plaque composition of individual coronary plaques. Six plaque composition types were defined on a voxel-level basis according to the plaque attenuation (expressed in Hounsfield units [HU]): low attenuation (-30 to 75 HU), fibro-fatty (76-130 HU), fibrous (131-350 HU), low-density calcium (351-700 HU), high-density calcium (701-1000 HU), and 1K (>1000 HU). The progression rates of these 6 compositional plaque types were evaluated according to the interaction between statin use and baseline plaque volume, adjusted for risk factors and time interval between scans. Plaque progression was also examined based on baseline calcium density. Analysis was performed among lesions matched at baseline and follow-up. Data analyses were conducted from August 2019 through March 2020. Results: In total, 2458 coronary lesions in 857 patients (mean [SD] age, 62.1 [8.7] years; 540 [63.0%] men; 548 [63.9%] received statin therapy) were included. Untreated coronary lesions increased in volume over time for all 6 compositional types. Statin therapy was associated with volume decreases in low-attenuation plaque (ß, -0.02; 95% CI, -0.03 to -0.01; P = .001) and fibro-fatty plaque (ß, -0.03; 95% CI, -0.04 to -0.02; P < .001) and greater progression of high-density calcium plaque (ß, 0.02; 95% CI, 0.01-0.03; P < .001) and 1K plaque (ß, 0.02; 95% CI, 0.01-0.03; P < .001). When analyses were restricted to lesions without low-attenuation plaque or fibro-fatty plaque at baseline, statin therapy was not associated with a change in overall calcified plaque volume (ß, -0.03; 95% CI, -0.08 to 0.02; P = .24) but was associated with a transformation toward more dense calcium. Interaction analysis between baseline plaque volume and calcium density showed that more dense coronary calcium was associated with less plaque progression. Conclusions and Relevance: The results suggest an association of statin use with greater rates of transformation of coronary atherosclerosis toward high-density calcium. A pattern of slower overall plaque progression was observed with increasing density. All findings support the concept of reduced atherosclerotic risk with increased densification of calcium.

Comparative differences in the atherosclerotic disease burden between the epicardial coronary arteries: quantitative plaque analysis on coronary computed tomography angiography.

AIMS: Anatomic series commonly report the extent and severity of coronary artery disease (CAD), regardless of location. The aim of this study was to evaluate differences in atherosclerotic plaque burden and composition across the major epicardial coronary arteries. METHODS AND RESULTS: A total of 1271 patients (age 60 ± 9 years; 57% men) with suspected CAD prospectively underwent coronary computed tomography angiography (CCTA). Atherosclerotic plaque volume was quantified with categorization by composition (necrotic core, fibrofatty, fibrous, and calcified) based on Hounsfield Unit density. Per-vessel measures were compared using generalized estimating equation models. On CCTA, total plaque volume was lowest in the LCx (10.0 ± 29.4 mm3), followed by the RCA (32.8 ± 82.7 mm3; P < 0.001), and LAD (58.6 ± 83.3 mm3; P < 0.001), even when correcting for vessel length or volume. The prevalence of ≥2 high-risk plaque features, such as positive remodelling or spotty calcification, occurred less in the LCx (3.8%) when compared with the LAD (21.4%) or RCA (10.9%, P < 0.001). In the LCx, the most stenotic lesion was categorized as largely calcified more often than in the RCA and LAD (55.3% vs. 39.4% vs. 32.7%; P < 0.001). Median diameter stenosis was also lowest in the LCx (16.2%) and highest in the LAD (21.3%; P < 0.001) and located more distal along the LCx when compared with the RCA and LAD (P < 0.001). CONCLUSION: Atherosclerotic plaque, irrespective of vessel volume, varied across the epicardial coronary arteries; with a significantly lower burden and different compositions in the LCx when compared with the LAD and RCA. These volumetric and compositional findings support a diverse milieu for atherosclerotic plaque development and may contribute to a varied acute coronary risk between the major epicardial coronary arteries.