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4D flow cardiac magnetic resonance (CMR) imaging allows visualisation of blood flow in the cardiac chambers and great vessels. Post processing of the flow data allows determination of the residence time distribution (RTD), a novel means of assessing ventricular function, potentially providing additional information beyond ejection fraction. We evaluated the RTD measurement of efficiency of left and right ventricular (LV and RV) blood flow. 16 volunteers and 16 patients with systolic dysfunction (LVEF < 50%) underwent CMR studies including 4D flow. The RTDs were created computationally by seeding virtual 'particles' at the inlet plane in customised post-processing software, moving these particles with the measured blood velocity, recording and counting how many exited per unit of time. The efficiency of ventricular flow was determined from the RTDs based on the time constant (RTDc = - 1/B) of the exponential decay. The RTDc was compared to ejection fraction, T1 mapping and global longitudinal strain (GLS). There was a significant difference between groups in LV RTDc (healthy volunteers 1.2 ± 0.13 vs systolic dysfunction 2.2 ± 0.80, p < 0.001, C-statistic = 1.0) and RV RTDc (1.5 ± 0.15 vs 2.0 ± 0.57, p = 0.013, C-statistic = 0.799). The LV RTDc correlated significantly with LVEF (R = - 0.84, P < 0.001) and the RV RTDc had significant correlation with RVEF (R = - 0.402, p = 0.008). The correlation between LV RTDc and LVEF was similar to GLS and LVEF (0.926, p < 0.001). The ventricular residence time correlates with ejection fraction and can distinguish normal from abnormal systolic function. Further assessment of this method of assessment of chamber function is warranted.

Introduction: The aim of this study was to evaluate the incidence and severity of blunt cardiac injury (BCI) as determined by cardiac magnetic resonance imaging (CMR), and to compare this to currently used diagnostic methods in severely injured patients., Materials and Methods: We conducted a prospective, pilot cohort study of 42 major trauma patients from July 2013 to Jan 2015. The cohort underwent CMR within 7 days, enrolling 21 patients with evidence of chest injury and an elevated Troponin I compared to 21 patients without chest injury who acted as controls. Major adverse cardiac events (MACE) including ventricular arrhythmia, unexplained hypotension requiring inotropes, or a requirement for cardiac surgery were recorded., Results: 6/21 (28%) patients with chest injuries had abnormal CMR scans, while all 21 control patients had normal scans. CMR abnormalities included myocardial oedema, regional wall motion abnormalities, and myocardial haemorrhage. The left ventricle was the commonest site of injury (5/6), followed by the right ventricle (2/6) and tricuspid valve (1/6). MACE occurred in 5 patients. Sensitivity and specificity values for CMR at predicting MACE were 60% (15-95) and 81% (54-96), which compared favourably with other tests., Conclusion: In this pilot trial, CMR was found to give detailed anatomic information of myocardial injury in patients with suspected BCI, and may have a role in the diagnosis and management of patients with suspected BCI., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Introduction: Non-sustained ventricular tachycardia (NSVT) is a risk factor for sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM). We aimed to assess whether diffuse ventricular fibrosis on cardiac magnetic resonance (CMR) imaging could be a surrogate marker for ventricular arrhythmias in patients with HCM., Methods: A total of 100 patients with HCM (mean age 51 ± 13 years, septal wall thickness 20 ± 5 mm) underwent CMR with a 1.5 T scanner to determine the presence of ventricular late gadolinium enhancement (LGE) for focal fibrosis, and post-contrast T1 mapping for diffuse ventricular fibrosis. The presence of NSVT was determined by Holter monitoring and a subset of high risk patients received an implantable cardioverter-defibrillator (ICD)., Results: NSVT was detected in 23 of 100 patients with HCM. Focal ventricular fibrosis (by LGE) was observed in 87%, with no significant difference between patients with (96%) or without NSVT (86%, P = 0.19). However, LGE mass was greater in patients with (16.5 ± 19.1 g) versus without NSVT (7.6 ± 10.2 g, P < 0.01). NSVT was associated with a significant reduction in ventricular T1 relaxation time (422 ± 54 milliseconds) versus patients without NSVT (512 ± 115 milliseconds; P < 0.001). There was significant reduction in ventricular T1 relaxation time in patients with (430 ± 48 milliseconds) versus without aborted SCD (495 ± 113 milliseconds; P = 0.01) over a mean follow-up of 40 ± 10 months. On multivariate analysis post-contrast ventricular T1 relaxation time and septal wall thickness were the only predictors of NSVT., Conclusion: Post-contrast T1 relaxation time on CMR is associated with ventricular arrhythmias in patients with HCM. Diffuse ventricular fibrosis may be an important marker of arrhythmic risk in patients with HCM., (© 2016 Wiley Periodicals, Inc.)

Aims: In hypertrophic cardiomyopathy (HCM), attempts to associate genotype with phenotype have largely been unsuccessful. More recently, cardiac magnetic resonance (CMR) imaging has enhanced myocardial fibrosis characterization, while next-generation sequencing (NGS) can identify pathogenic HCM mutations. We used CMR and NGS to explore the link between genotype and fibrotic phenotype in HCM., Methods and Results: One hundred and thirty-nine patients with HCM and 25 healthy controls underwent CMR to quantify regional myocardial fibrosis with late gadolinium enhancement (LGE) and diffuse myocardial fibrosis with post-contrast T1 mapping. Collagen content of myectomy specimens from nine HCM patients was determined. Fifty-six HCM patients underwent NGS for 65 cardiomyopathy genes, including 36 HCM-associated genes. Post-contrast myocardial T1 time correlated histologically with myocardial collagen content (r = -0.70, P = 0.03). Compared with controls, HCM patients had more LGE (4.6 ± 6.1 vs. 0%, P < 0.001) and lower post-contrast T1 time (483 ± 83 vs. 545 ± 49 ms, P < 0.001). LGE negatively correlated with left-ventricular (LV) ejection fraction and outflow tract obstruction, whereas lower post-contrast T1 time, suggestive of more diffuse myocardial fibrosis, was associated with LV diastolic impairment and dyspnoea. Patients with identifiable HCM mutations had more LGE (7.9 ± 8.6 vs. 3.1 ± 4.3%, P = 0.03), but higher post-contrast T1 time (498 ± 81 vs. 451 ± 70 ms, P = 0.03) than patients without., Conclusion: In HCM, contrast-enhanced CMR with T1 mapping can non-invasively evaluate regional and diffuse patterns of myocardial fibrosis. These patterns of fibrosis occur independently of each other and exhibit distinct clinical associations. HCM patients with recognized genetic mutations have significantly more regional, but less diffuse myocardial fibrosis than those without., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.)