Intra- and interobserver reliability in measuring aortic root rotation with cardiac magnetic resonance imaging.

Background: The rotational position of the aortic root (AoR) is of substantial clinical interest as it has been associated with severe aortic complications, such as aortic dissections. We described a cardiac magnetic resonance (CMR)-based method for measuring AoR rotation and evaluated the reliability of measurements. Methods: CMR was used for measuring AoR rotation in 50 consecutive healthy subjects. Intra- and interobserver reliability were assessed by comparing repeated measurements by the same analyst and by three independent analysts. The angles of the non-coronary sinus (NCS), right coronary sinus (RCS), and left coronary sinus (LCS) were measured relative to the interatrial septum (IAS). The angle between IAS and posterior atrial wall was measured to examine the reliability of the IAS as a key anatomical landmark. Intra- and interobserver agreement were determined using intraclass correlation coefficients (ICCs). Results: Images of 47/50 (94%) subjects were analyzed; three were excluded due to insufficient image quality. The mean ± standard deviation (SD) AoR rotation angles of NCS, RCS, and LCS were 25.9°±12.9°, 37.5°±15.2°, and 97.0°±13.1°, respectively. For measurements of AoR rotation, both intraobserver [NCS: ICC =0.94, 95% confidence interval (CI): 0.88-0.96; RCS: ICC =0.93, 95% CI: 0.87-0.96; LCS: ICC =0.91, 95% CI: 0.84-0.95] and interobserver agreement (NCS: ICC =0.90, 95% CI: 0.84-0.94; RCS: ICC =0.86, 95% CI: 0.77-0.92; LCS: ICC =0.87, 95% CI: 0.80-0.92) were excellent. The IAS angle was 79.2°±8.9°; its intraobserver agreement was somewhat higher (ICC =0.94, 95% CI: 0.88-0.96) than the interobserver agreement (ICC =0.76, 95% CI: 0.63-0.85). Conclusions: The present study in healthy subjects reports a CMR-based approach for measuring AoR rotation. CMR allows to quantify AoR rotation with excellent intra- and interobserver agreement.

A Multimodality Myocardial Perfusion Phantom: Initial Quantitative Imaging Results.

This proof-of-concept study explores the multimodal application of a dedicated cardiac flow phantom for ground truth contrast measurements in dynamic myocardial perfusion imaging with CT, PET/CT, and MRI. A 3D-printed cardiac flow phantom and flow circuit mimics the shape of the left ventricular cavity (LVC) and three myocardial regions. The regions are filled with tissue-mimicking materials and the flow circuit regulates and measures contrast flow through LVC and myocardial regions. Normal tissue perfusion and perfusion deficits were simulated. Phantom measurements in PET/CT, CT, and MRI were evaluated with clinically used hardware and software. The reference arterial input flow was 4.0 L/min and myocardial flow 80 mL/min, corresponding to myocardial blood flow (MBF) of 1.6 mL/g/min. The phantom demonstrated successful completion of all processes involved in quantitative, multimodal myocardial perfusion imaging (MPI) applications. Contrast kinetics in time intensity curves were in line with expectations for a mimicked perfusion deficit (38 s vs. 32 s in normal tissue). Derived MBF in PET/CT and CT led to under- and overestimation of reference flow of 0.9 mL/g/min and 4.5 mL/g/min, respectively. Simulated perfusion deficit (0.8 mL/g/min) in CT resulted in MBF of 2.8 mL/g/min. We successfully performed initial, quantitative perfusion measurements with a dedicated phantom setup utilizing clinical hardware and software. These results showcase the multimodal phantom's potential.

Endothelial function after ST-elevation myocardial infarction in patients with high levels of high-sensitivity CRP and Lp-PLA2: A substudy of the RESPONSE randomized trial.

BACKGROUND: The combination of high levels of high-sensitive C-reactive protein (hs-CRP) and lipoprotein-associated phospholipase-A2 (Lp-PLA2) was recently shown to correlate with increased cardiovascular risk. Endothelial dysfunction is also known to be a risk factor for cardiovascular events. AIM: To test among patients with previous ST-elevation myocardial infarction (STEMI) the hypothesis that high levels of both hs-CRP and Lp-PLA2 may be associated with impaired endothelium-dependent vasodilatation. METHODS: In this substudy of the RESPONSE randomized trial, we used reactive hyperemia peripheral artery tonometry (RH-PAT) 4 to 6weeks after STEMI and primary percutaneous coronary intervention (PPCI) to non-invasively assess endothelial function (RH-PAT index <1.67 identified endothelial dysfunction). Reliable measurements of RH-PAT, hs-CRP, and Lp-PLA2 were obtained in 68 patients, who were classified as high-risk if levels of both hs-CRP and Lp-PLA2 were in the upper tertile (≥3.84mg/L and >239µg/L, respectively). RESULTS: Patients were 57.4±9.7years and 53 (77.9%) were men. 11 (16%) patients were classified as high-risk and 57 (84%) as low-to-intermediate-risk. The RH-PAT index was 1.68±0.22 in high-risk and 1.95±0.63 in low-to-intermediate-risk patients (p=0.17). Endothelial dysfunction was present in 8 (72.7%) high-risk and 26 (45.6%) low-to-intermediate-risk patients (p=0.09). Framingham risk score, NT-proBNP and fibrinogen levels were higher in high-risk patients (p≤0.03). CONCLUSION: In this population of patients with recent STEMI and PPCI, we observed between patients with high hs-CRP and Lp-PLA levels and all other patients no more than numerical differences in endothelial function that did not reach a statistical significance. Nevertheless, further research in larger study populations may be warranted.

Assessment of the relation between initial culprit vessel patency in acute ST-elevation myocardial infarction and endothelial function.

AIMS: To assess whether better endothelial function increases the likelihood of patients with acute ST-elevation myocardial infarction (STEMI) having initially patent culprit vessels. Clinical data on the relation between endothelial function and culprit vessel patency in STEMI patients are scarce. METHODS AND RESULTS: In this prospective cohort study in 71 patients with STEMI, endothelial function was non-invasively assessed by use of the reactive hyperaemia peripheral artery tonometry (RH-PAT) method at four to six weeks after the primary percutaneous coronary intervention (PPCI). The RH-PAT index measured on average 1.90±0.58. In patients with patent culprit vessels before PPCI (n=33, 46.5%), endothelial function was significantly better than in patients with occluded vessels (n=38, 53.5%) (RH-PAT index 2.08±0.34 vs. 1.75±0.35; p<0.007). Compared to patients with normal endothelial function, the patients with severe endothelial dysfunction had a fivefold higher risk of presenting with an occluded culprit vessel (OR 5.1, 95% CI: 1.8-14.2). Logistic regression analysis revealed that this relation between endothelial function and vessel patency became even stronger after adjustment for potential confounders (adjusted OR 7.1, 95% CI: 2.1-23.6). CONCLUSIONS: In this series of patients with acute STEMI, better endothelial function was independently associated with a higher likelihood of presenting with an initially patent culprit vessel.

Evidence of myocardial scarring and microvascular obstruction on cardiac magnetic resonance imaging in a series of patients presenting with myocardial infarction without obstructed coronary arteries.

Patients with acute chest pain, electrocardiographic ST-elevation and significant elevation of cardiac troponin but without obstructive coronary artery disease represent a diagnostic and therapeutic dilemma. Cardiac magnetic resonance imaging (CMR) can elucidate underlying alternative causes of troponin elevation including detection of (minor) myocardial infarction (MI) by identifying myocardial scarring as delayed enhancement. Of 77 patients, who were admitted between March 2009 and December 2012 with electrocardiographic (ECG) and biochemical evidence of acute MI without obstructive coronary artery disease, 45 patients underwent CMR that showed in 11/77 (14%) late gadolinium enhancement (LGE), compatible with myocardial scarring. We analyzed clinical, echocardiographic, and CMR data of these patients. Elevated troponin I levels were observed in all patients (median 1.3 ng/l, IQR 0.44-187) with median peak creatinine phosphokinase of 485 U/l (IQR 234-618). Echocardiographic wall motion abnormalities were detected in 8/11 (73%) patients; in 75% of these segments, ECG abnormalities were observed in corresponding leads. CMR detected LGE in the inferior (4/11), the inferolateral (5/11), the inferoseptal (2/11), the anterior (3/11), apical (3/11) and in the lateral segments (2/11). In addition, in all but two patients, these segments matched ECG abnormalities in corresponding leads. CMR identified microvascular obstruction in 4/11 (36%) patients. Patients with clinical, ECG, and biochemical signs of acute MI but unobstructed coronary arteries may have CMR-detectable myocardial scars. Information on myocardial scarring may help to make the diagnosis and draw therapeutic consequences. This case series underlines the value of contrast-enhanced CMR for myocardial tissue characterization.

Infarct tissue characterization in implantable cardioverter-defibrillator recipients for primary versus secondary prevention following myocardial infarction: a study with contrast-enhancement cardiovascular magnetic resonance imaging.

Knowledge about potential differences in infarct tissue characteristics between patients with prior life-threatening ventricular arrhythmia versus patients receiving prophylactic implantable cardioverter-defibrillator (ICD) might help to improve the current risk stratification in myocardial infarction (MI) patients who are considered for ICD implantation. In a consecutive series of (ICD) recipients for primary and secondary prevention following MI, we used contrast-enhanced (CE) cardiovascular magnetic resonance (CMR) imaging to evaluate differences in infarct tissue characteristics. Cine-CMR measurements included left ventricular end-diastolic and end-systolic volumes (EDV, ESV), left ventricular ejection fraction (LVEF), wall motion score index (WMSI), and mass. CE-CMR images were analyzed for core, peri, and total infarct size, infarct localization (according to coronary artery territory), and transmural extent. In this study, 95 ICD recipients were included. In the primary prevention group (n = 66), LVEF was lower (23 ± 9% vs. 31 ± 14%; P < 0.01), ESV and WMSI were higher (223 ± 75 ml vs. 184 ± 97 ml, P = 0.04, and 1.89 ± 0.52 vs. 1.47 ± 0.68; P < 0.01), and anterior infarct localization was more frequent (P = 0.02) than in the secondary prevention group (n = 29). There were no differences in infarct tissue characteristics between patients treated for primary versus secondary prevention (P > 0.6 for all). During 21 ± 9 months of follow-up, 3 (5%) patients in the primary prevention group and 9 (31%) in the secondary prevention group experienced appropriate ICD therapy for treatment of ventricular arrhythmia (P < 0.01). There was no difference in infarct tissue characteristics between recipients of ICD for primary versus secondary prevention, while the secondary prevention group showed a higher frequency of applied ICD therapy for ventricular arrhythmia.

Relationship between infarct tissue characteristics and left ventricular remodeling in patients with versus without early revascularization for acute myocardial infarction as assessed with contrast-enhanced cardiovascular magnetic resonance imaging.

Left ventricular (LV) remodeling following myocardial infarction (MI) is the result of complex interactions between various factors, including presence or absence of early revascularization. The impact of early revascularization on the relationship between infarct tissue characteristics and LV remodeling is incompletely known. Therefore, we investigated in patients with versus without successful early revascularization for acute MI potential relations between infarct tissue characteristics and LV remodeling with contrast-enhanced (CE) cardiovascular magnetic resonance (CMR). Patients with versus without successful early revascularization underwent CE-CMR for tissue characterization and assessment of LV remodeling including end-diastolic and end-systolic volumes, LV ejection fraction, and wall motion score index (WMSI). CE-CMR images were analyzed for infarct tissue characteristics including core-, peri- and total-infarct size, transmural extent, and regional scar scores. In early revascularized patients (n = 46), a larger area of infarct tissue correlated significantly with larger LV dimensions and a more reduced LV function (r = 0.39-0.68; all P ≤ 0.01). Multivariate analyses identified peri-infarct size as the best predictor of LV remodeling parameters (R(2 )= 0.44-0.62). In patients without successful early revascularization (n = 47), there was no correlation between infarct area and remodeling parameters; only peri-infarct size versus WMSI (r = 0.33; P = 0.03) and transmural extent versus LVEF (r = -0.27; P = 0.07) tended to be related. A correlation between infarct tissue characteristics and LV remodeling was found only in patients with early successful revascularization. Peri-infarct size was found to be the best determinant of LV remodeling. Our findings stress the importance of taking into account infarct tissue characteristics and success of revascularization when LV remodeling is studied.

Cardiac imaging in a symptomatic patient with multiple coronary artery-left ventricular microfistulae.

We present the case of a 44-year-old woman with acute coronary syndrome and multiple coronary artery-left ventricular microfistulae at angiography. To evaluate the clinical significance of this observation and to obtain further insights into this rare disease, the patient was further examined with echocardiography and both magnetic resonance imaging and single-photon emission computed tomography, which showed considerable abnormalities.