Development of a universal dual-bolus injection scheme for the quantitative assessment of myocardial perfusion cardiovascular magnetic resonance

<p>Abstract</p> <p>Background</p> <p>The dual-bolus protocol enables accurate quantification of myocardial blood flow (MBF) by first-pass perfusion cardiovascular magnetic resonance (CMR). However, despite the advantages and increasing demand for the dual-bolus method for accurate quantification of MBF, thus far, it has not been widely used in the field of quantitative perfusion CMR. The main reasons for this are that the setup for the dual-bolus method is complex and requires a state-of-the-art injector and there is also a lack of post processing software. As a solution to one of these problems, we have devised a universal dual-bolus injection scheme for use in a clinical setting. The purpose of this study is to show the setup and feasibility of the universal dual-bolus injection scheme.</p> <p>Methods</p> <p>The universal dual-bolus injection scheme was tested using multiple combinations of different contrast agents, contrast agent dose, power injectors, perfusion sequences, and CMR scanners. This included 3 different contrast agents (Gd-DO3A-butrol, Gd-DTPA and Gd-DOTA), 4 different doses (0.025 mmol/kg, 0.05 mmol/kg, 0.075 mmol/kg and 0.1 mmol/kg), 2 different types of injectors (with and without "pause" function), 5 different sequences (turbo field echo (TFE), balanced TFE, k-space and time (k-t) accelerated TFE, k-t accelerated balanced TFE, turbo fast low-angle shot) and 3 different CMR scanners from 2 different manufacturers. The relation between the time width of dilute contrast agent bolus curve and cardiac output was obtained to determine the optimal predefined pause duration between dilute and neat contrast agent injection.</p> <p>Results</p> <p>161 dual-bolus perfusion scans were performed. Three non-injector-related technical errors were observed (1.9%). No injector-related errors were observed. The dual-bolus scheme worked well in all the combinations of parameters if the optimal predefined pause was used. Linear regression analysis showed that the optimal duration for the predefined pause is 25s to separate the dilute and neat contrast agent bolus curves if 0.1 mmol/kg dose of Gd-DO3A-butrol is used.</p> <p>Conclusion</p> <p>The universal dual-bolus injection scheme does not require sophisticated double-head power injector function and is a feasible technique to obtain reasonable arterial input function curves for absolute MBF quantification.</p

Natural History of Patients with Ischemia and No Obstructive Coronary Artery Disease: The CIAO-ISCHEMIA Study

Background: Ischemia with no obstructive coronary artery disease (INOCA) is common and has an adverse prognosis. We set out to describe the natural history of symptoms and ischemia in INOCA. Methods: CIAO-ISCHEMIA (Changes in Ischemia and Angina over One year in ISCHEMIA trial screen failures with INOCA) was an international cohort study conducted from 2014-2019 involving angina assessments (Seattle Angina Questionnaire [SAQ]) and stress echocardiograms 1-year apart. This was an ancillary study that included patients with history of angina who were not randomized in the ISCHEMIA trial. Stress-induced wall motion abnormalities were determined by an echocardiographic core laboratory blinded to symptoms, coronary artery disease (CAD) status and test timing. Medical therapy was at the discretion of treating physicians. The primary outcome was the correlation between changes in SAQ Angina Frequency score and change in echocardiographic ischemia. We also analyzed predictors of 1-year changes in both angina and ischemia, and compared CIAO participants with ISCHEMIA participants with obstructive CAD who had stress echocardiography before enrollment, as CIAO participants did. Results: INOCA participants in CIAO were more often female (66% of 208 vs. 26% of 865 ISCHEMIA participants with obstructive CAD, p\u3c0.001), but the magnitude of ischemia was similar (median 4 ischemic segments [IQR 3-5] both groups). Ischemia and angina were not significantly correlated at enrollment in CIAO (p=0.46) or ISCHEMIA stress echocardiography participants (p=0.35). At 1 year, the stress echocardiogram was normal in half of CIAO participants and 23% had moderate or severe ischemia (≥3 ischemic segments). Angina improved in 43% and worsened in 14%. Change in ischemia over one year was not significantly correlated with change in angina (rho=0.029). Conclusions: Improvement in ischemia and improvement in angina were common in INOCA, but not correlated. Our INOCA cohort had a similar degree of inducible wall motion abnormalities to concurrently enrolled ISCHEMIA participants with obstructive CAD. Our results highlight the complex nature of INOCA pathophysiology and the multifactorial nature of angina

Demographic, multi-morbidity and genetic impact on myocardial involvement and its recovery from COVID-19: protocol design of COVID-HEART—a UK, multicentre, observational study

Abstract: Background: Although coronavirus disease 2019 (COVID-19) is primarily a respiratory illness, myocardial injury is increasingly reported and associated with adverse outcomes. However, the pathophysiology, extent of myocardial injury and clinical significance remains unclear. Methods: COVID-HEART is a UK, multicentre, prospective, observational, longitudinal cohort study of patients with confirmed COVID-19 and elevated troponin (sex-specific &gt; 99th centile). Baseline assessment will be whilst recovering in-hospital or recently discharged, and include cardiovascular magnetic resonance (CMR) imaging, quality of life (QoL) assessments, electrocardiogram (ECG), serum biomarkers and genetics. Assessment at 6-months includes repeat CMR, QoL assessments and 6-min walk test (6MWT). The CMR protocol includes cine imaging, T1/T2 mapping, aortic distensibility, late gadolinium enhancement (LGE), and adenosine stress myocardial perfusion imaging in selected patients. The main objectives of the study are to: (1) characterise the extent and nature of myocardial involvement in COVID-19 patients with an elevated troponin, (2) assess how cardiac involvement and clinical outcome associate with recognised risk factors for mortality (age, sex, ethnicity and comorbidities) and genetic factors, (3) evaluate if differences in myocardial recovery at 6 months are dependent on demographics, genetics and comorbidities, (4) understand the impact of recovery status at 6 months on patient-reported QoL and functional capacity. Discussion: COVID-HEART will provide detailed characterisation of cardiac involvement, and its repair and recovery in relation to comorbidity, genetics, patient-reported QoL measures and functional capacity

The clinical significance of a common, functional, X-linked angiotensin II type 2-receptor gene polymorphism (-1332 G/A) in patients with cardiovascular disease

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Comparison of ESC and NICE guidelines for patients with suspected coronary artery disease:Evaluation of the pre-test probability risk scores in clinical practice

The European Society of Cardiology (ESC) and UK National Institute for Health and Care Excellence (NICE) have recently published guidelines for investigating patients with suspected coronary artery disease (CAD). Both provide a risk score (RS) to assess the pre-test probability for CAD to guide clinicians to undertake the most effective investigation. The aim of the study was to establish whether there is a difference between the two RS models. We retrospectively reviewed records of 479 patients who presented to a UK district general hospital with chest pain between August 2011 and April 2013. The RS was calculated using ESC and NICE guidelines and compared. From the 479 patients, 277 (58%) were male and the mean age was 60 years. The mean RS was greater using NICE guidelines compared with ESC (66.3 vs 47.9%, 18.4% difference; p<0.0001). The difference in mean RS was smaller in patients with typical chest pain (13.0%). When we divided the cohort based on NICE criteria into ‘high’- and ‘low’-risk groups, the difference in the mean RS was 24.3% in the ‘high’-risk group (p<0.001) compared with 2.8% in the ‘low’-risk group. The UK NICE risk score model overestimates risk compared with the ESC model

Normal range of human left ventricular volumes and mass using steady state free precession MRI in the radial long axis orientation

Background: The radial long-axis orientation for the measurement of left ventricular (LV) volume and mass has been shown to have advantages over the short-axis orientation. Previous work has highlighted the need for technique specific normal ranges. The purpose of this study was therefore to establish normal ranges of LV volume and mass for the radial long-axis orientation. Materials and methods: Forty normal subjects (20 males, average age 32.3, age range 19–58; 20 females, average age 37.4, age range 21–54) were examined utilising a steady state free precession (SSFP) pulse sequence. Two observers analysed the images independently using in-house validated software. Results: The normal ranges for LV end-diastolic volume measurements after adjustment to body surface area (BSA) were 62–120 ml for males and 58–103 ml for females. LV mass indexed to BSA ranged from 50–86 g for males and 36–72 g for females. The normal range for ejection fraction was 49–73 % for males and 54–73 % for females. Conclusion: A gender specific normal range using SSFP in the radial long-axis orientation was established