Coronary atherosclerosis and plaque rupture leads to acute coronary thrombosis and myocardial infarction. Current treatment involves re-establishing vessel patency, but no treatments have been developed to target post-infarction inflammatory pathways. Such treatments may reduce cardiomyocyte injury, attenuate adverse remodelling and improve clinical outcome. Inflammation within the infarcted myocardium is associated with chemotaxis of neutrophils and monocytes to the site of injury. Early reperfusion therapy amplifies this inflammatory cell influx. Neutrophil release a variety of pro-inflammatory factors, including human neutrophil elastase (HNE). HNE has a wide range of substrates. Preclinical studies have demonstrated that neutrophil depletion or inhibition of neutrophil elastase attenuates post-ischemic inflammatory reperfusion injury within the myocardium. Recruitment of monocytes into the infarcted myocardium is followed by maturation and differentiation into macrophages. Macrophages play a key role in orchestrating inflammation and repair. Therapeutic manipulation of this healing process will only come from understanding mechanisms and targeting reparative pathways. “Ultrasmall superparamagnetic iron oxide particles” (USPIOs) extravasate through capillaries and are phagocytosed by tissue inflammatory cells. These cells are predominately macrophages, but neutrophils have also been shown to take up USPIOs. USPIO-enhanced MRI can identify areas of inflammation in models inflammation in various tissues. Therefore we hypothesised that USPIO enhanced MRI could identify and assess cellular inflammation of the myocardium. During coronary artery bypass graft surgery (CABG), the myocardium receives an immediate ischaemic insult that is exacerbated by post-ischaemic reperfusion inflammatory responses leading to increased myocardial injury. CABG surgery can therefore be used as a clinical model of myocardial infarction and inflammation. We investigated this with blood markers of inflammation, MRI scanning and USPIO. Elafin inhibits the destructive and inflammatory HNE enzyme. Beyond this elafin inhibits inflammatory cytokines and modulates the innate and adaptive immune systems. In preclinical studies elafin treatment is associated with reduced myocardial injury. As such, elafin has a marked potential for the treatment of cardiovascular disease involving inflammation. Therefore, we hypothesised that elafin will reduce perioperative ischaemic myocardial injury and inflammation in patients undergoing elective coronary artery bypass graft surgery. We demonstrated for the first time that USPIOs are taken up by the infarct tissue in patients with recent myocardial infarction and by the peri-infarct myocardium to a lesser degree. This represents a novel non-invasive method to further study cardiac inflammation and therapeutic interventions. All patients undergoing CABG surgery demonstrated >10-fold elevation above the 99th centile of cardiac troponin by high sensitivity assay (hs-cTnI) indicating the current universal definition of type 5 myocardial infarction lacks specificity. A peak hs-cTnI at 6 hours following CABG surgery appears to be related to the surgical process and non-specific myocardial injury whilst a continuing increase at 24 hours suggests myocardial infarction. We would suggest hs-cTnI sampling at 6 and 24 hours post CABG surgery together with ECG assessment for the routine detection and diagnosis of type 5 MI. Differing levels of humoral makers inflammation post CABG surgery occurred, and did not correlate directly with the length of cardiopulmonary bypass time or hs-cTnI release. For the first time we identified differing levels of inflammatory cell infiltrate into the myocardium post CABG. This varied from none to levels similar to infarcted myocardial tissues. Elafin did not attenuate myocardial ischemia-reperfusion injury and inflammation. Post-hoc analysis identified reduced cTnI concentrations at 6 hours in Elafin treated patients and it is possible that a bigger dose would have conferred protection out to 48 hours. Elafin did not attenuate the cellular infiltration into the myocardium post CABG surgery, but did appear to reduce inflammation in renal tissue. USPIO enhanced CMR holds major promise in the non-invasive assessment of myocardial inflammation post surgery.

Inflammatory arthropathies and systemic rheumatic diseases (IASRDs) commonly involve the cardiovascular system, and are associated with high morbidity and mortality. Mechanisms of cardiovascular involvement in these clinical entities are not fully understood. Cardiovascular magnetic resonance (CMR) is the single imaging modality capable of assessing non-invasively cardiac function, strain, ischaemia, altered vascular function, perfusion, oedema/inflammation and fibrosis. Furthermore, magnetic resonance spectroscopy (MRS) can give further insights into the status of myocardial energetics and lipidosis. The pathophysiological mechanisms and phenotype of cardiovascular disease (CVD) in IASRDs need further clarification. CMR is an ideal tool for the early identification and monitoring of cardiac manifestations in patients with IASRDs. Hence, the aims of this D.Phil project were to (i) utilise CMR and MRS to study disease mechanisms in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc), and (ii) to assess the role of anti-cytokine therapies in abrogation of cardiovascular complications and effects on cardiovascular function in patients with RA, ankylosing spondylitis (AS) and psoriatic arthritis (PsA). First, we used CMR to assess myocardial structure and function in RA, SLE and SSc patients with no known cardiovascular symptoms. Patients and controls were stratified by the presence of traditional cardiovascular risk factors (CVRFs). Our data demonstrated no differences in overall left ventricular (LV) systolic function, size and mass between patients and matched controls. There were, however, impairments in regional function and myocardial deformation, which is most severe in RA, SLE and SSc patients with CVRFs. We also found evidence of impaired vascular function in RA, SLE and SSc, using pulse wave velocity (PWV) and aortic distensibility, and again, showed that patients with CVRFs demonstrated the most severe aberrations, while patients without CVRFs and controls with CVRFs had an intermediate phenotype. Abnormalities in vascular and regional function were most severe in patients with SSc. Also, we showed that impaired vascular function correlated with abnormal systolic myocardial strain and diastolic strain rate in all groups of IASRDs studied. These data have implications for the clinical care of patients with RA, SLE and SSc and show that there is extensive cardiovascular involvement in asymptomatic patients. These results also suggest that early identification and stratification of CVD in IASRDs, with non-invasive techniques like CMR, may permit earlier intervention, thus potentially reducing the effect of CVD on morbidity and mortality in IASRDs. Lastly, these data highlight the importance of early detection and aggressive management of co-existent traditional CVRFs, as they confer incremental risk of CVD in patients with IASRDs. Second, we used CMR for comprehensive phenotyping of tissue characteristics in patients with RA, SLE and SSc. Our data confirmed that subclinical myocardial changes are common in patients with IASRDs (even with apparently normal hearts), which can be detected using multiparametric CMR. In addition to focal areas of fibrosis (detected by late gadolinium enhancement [LGE]), there were also areas of focal myocardial oedema or inflammation (detected by T2-weighted imaging). Further, using more sensitive techniques such as native T1 mapping and extracellular volume (ECV) quantification, we were able to demonstrate even more areas of myocardial involvement in IASRD patients than conventional CMR techniques can reveal, with patients showing significantly larger areas of T1 abnormality and expanded ECV, which likely represent a combination of low grade inflammation and diffuse myocardial fibrosis that are well-described disease processes in this cohort. We also found that T1 and ECV measures were associated with subtle myocardial systolic and diastolic dysfunction. The results of this study suggest that CMR, particularly T1 and ECV quantification, can be used for early detection of subclinical myocardial involvement in IASRD patients, potentially serving as an early screening tool before overt LV dysfunction or irreversible myocardial damage occurs. Third, we utilised CMR to study myocardial perfusion in patients with RA, SLE and SSc. We found that myocardial perfusion was impaired in asymptomatic IASRD with no overt heart disease. Non-segmental, subendocardial perfusion defects consistent with microvascular dysfunction were present in 47%, 31% and 41% of RA, SLE and SSc patients, respectively. Furthermore, there was a significant correlation between MPRI and systolic and diastolic regional function in all groups of patients. In RA and SSc, there was also a correlation between myocardial perfusion reserve index (MPRI) and disease activity. SSc patients had the greatest burden of ECV expansion, and in this group ECV also correlated with MPRI. These data led us to hypothesise that myocardial ischaemia likely leads to impaired myocardial relaxation and diffuse fibrosis, which predate overt dysfunction in contractility. Fourth, we investigated the effect of TNF-alpha inhibitors on myocardial and vascular function and structure in RA, AS and PsA patients. We confirmed that anti-TNF therapy was associated with improvements in serum inflammatory parameters like CRP and ESR, as well as with improved clinical measures of disease activity. Anti-TNF therapy, however, was not related to a change in left ventricular size, mass and global systolic function. We found that inhibition of TNF-alpha activity does result in better myocardial strain and strain rate, likely reflecting an improvement in myocardial inflammatory burden. Moreover, these findings were also supported by improvements in T2 weighted measures, native T1 values and ECV calculations. There was, however, no significant change in myocardial perfusion following anti-TNF therapy. These results support the hypothesis that during episodes of disease activity, myocardial oedema is present in patients with IASRDS and that by reducing the systemic inflammatory response, improvements in myocardial and vascular function can be achieved. Finally, we used CMR and MRS in asymptomatic RA and SLE patients (with normal hearts on echocardiography) to investigate cardiac metabolic status in this cohort. We found that myocardial energetics were impaired in patients, despite preserved overall ejection fraction. Interestingly, abnormal myocardial energetics were associated with presence of LGE, decreased myocardial perfusion, expanded ECV, volume fraction of T1 >990ms (which represents >2 standard deviations above the mean T1 value at 1.5T) and left atrial size. We did not find any difference in myocardial and hepatic lipid content between patients and controls. These data clearly demonstrate that abnormalities in cardiac energetics are present in IASRD patients even before the development of overt cardiac dysfunction, and may be driven by microvascular function and fibrosis.

No description available.

Background Ultrasmall superparamagnetic particles of iron oxide (USPIO)- enhanced magnetic resonance imaging (MRI) can detect tissue-resident inflammatory macrophages and identify cellular inflammation. Clinical studies using this non-invasive technique are now emerging. Objectives The aims of this thesis were (i) to determine whether USPIO-enhanced MRI can detect and serially monitor myocardial inflammation after myocardial infarction (MI) using single and repeated USPIO administration, (ii) to report a range of normal R2* (1/T2*) values at 1.5 tesla (T) and 3 T in healthy myocardium and other tissues before and after USPIO administration, (iii) to determine whether USPIO-enhanced MRI can detect myocardial inflammation in acute myocarditis, and (iv) to determine whether USPIO-enhanced MRI can detect myocardial inflammation in patients with a prior cardiac transplant. Methods Thirty-one patients were recruited following acute MI and followed up for 3 months with repeated T2 and USPIO-enhanced T2* mapping 3 T MRI. Twenty healthy volunteers were recruited: 10 imaged each at 1.5 T and 3 T. T2 and USPIO-enhanced T2* mapping MRI was conducted. Fourteen patients with suspected acute myocarditis underwent T2 and USPIO-enhanced T2* mapping 3 T MRI, with further imaging at 3 months. Eleven patients with prior cardiac transplant underwent T2 and USPIO-enhanced T2* mapping 1.5 T MRI with further imaging at 3 months. Regions of interest within the myocardium, along with other tissues, were selected for analysis. Pre-contrast T2 values, and the change in R2* due to USPIO from baseline to 24 hours after USPIO were compared for each region of interest. Results In patients with MI, USPIO uptake in the infarct zone peaked at days 2-3, and greater USPIO uptake was detected in the infarct zone compared to remote myocardium in the first 2 weeks after myocardial infarction. In contrast, T2-defined myocardial oedema peaked at days 3-9 and remained increased in the infarct zone throughout the 3-month follow up period. Histology confirmed colocalisation of iron and macrophages within the infarcted, but not the non-infarcted, myocardium. In healthy volunteers, we reported a range of normal myocardial and tissue R2* values at baseline, and following USPIO. Tissues showing greatest USPIO enhancement were organs of the reticuloendothelial system: the liver, spleen and bone marrow. Myocarditis was confirmed in 9 of the 14 suspected cases of myocarditis. There was greater myocardial oedema, but no demonstrable difference in USPIO enhancement, in inflamed myocardial regions in patients with myocarditis when compared to healthy myocardium. We recorded an improvement in cardiac function and reduced imaging measures of inflammation after 3 months. Ten patients with cardiac transplant were retained for analysis. Measures of myocardial oedema were greater in patients with cardiac transplant than healthy volunteers. There was no difference in the change in R2* due to USPIO between patients with transplantation and healthy volunteers. Imaging recordings did not change when repeated at 3 months. Conclusions Myocardial macrophage activity can be detected using USPIO-enhanced MRI in the first 2 weeks following acute MI. This observed pattern of cellular inflammation is distinct, and provides complementary information to, the more prolonged myocardial oedema detectable using T2 mapping. In patients with acute myocarditis, USPIO-enhanced MRI does not provide additional clinically relevant information to standard clinical MRI sequences. This suggests that tissue-resident macrophages do not provide a substantial contribution to the myocardial inflammation in this condition. Stable patients with cardiac transplantation have increased myocardial T2 values, consistent with resting myocardial oedema or fibrosis. In contrast, USPIO-enhanced MRI is normal and stable over time suggesting the absence of chronic macrophage-driven cellular inflammation. In conclusion, this imaging technique holds promise as a non-invasive method of assessing and monitoring macrophage-driven myocardial inflammation after myocardial infarction with potential application to diagnosis, risk stratification and assessment of novel anti-inflammatory therapeutic interventions. It remains to be determined whether USPIO-enhanced MRI may be able to identify myocardial inflammation in other myocardial inflammatory conditions including acute cardiac transplant rejection.

Dilated cardiomyopathy (DCM) is the second leading cause of heart failure. The pathophysiology in DCM is still poorly understood, partly because of currently limited research tools. We investigated whether cardiovascular magnetic resonance (CMR), using novel imaging techniques, could be used for in vivo assessment of some key pathophysiological mechanisms related to DCM. In addition, we evaluated whether the pathological findings on CMR would predict clinically relevant functional and morphological improvement of the left ventricular (LV) function - the LV reverse remodeling (LVRR). CMR together with endomyocardial biopsy, echocardiography, cardiopulmonary exercise testing and a thorough assessment of cardiac biomarkers was performed in 44 patients with new-onset DCM (<6 months of duration). The imaging was repeated after 12 months of clinical follow-up. Endomyocardial biopsy revealed myocardial inflammation in 34 % of the patients. LVRR at 12 months occurred in 45 % of the patients. Presence of late gadolinium enhancement (LGE) in the left ventricle was a sensitive but unspecific sign of myocardial inflammation because it was also a feature of hemodynamic stress related to the heart failure. The baseline extent of LGE was an independent predictor of future LVRR and also a predictor of adverse clinical...

Dilated cardiomyopathy (DCM) is the second leading cause of heart failure. The pathophysiology in DCM is still poorly understood, partly because of currently limited research tools. We investigated whether cardiovascular magnetic resonance (CMR), using novel imaging techniques, could be used for in vivo assessment of some key pathophysiological mechanisms related to DCM. In addition, we evaluated whether the pathological findings on CMR would predict clinically relevant functional and morphological improvement of the left ventricular (LV) function - the LV reverse remodeling (LVRR). CMR together with endomyocardial biopsy, echocardiography, cardiopulmonary exercise testing and a thorough assessment of cardiac biomarkers was performed in 44 patients with new-onset DCM (<6 months of duration). The imaging was repeated after 12 months of clinical follow-up. Endomyocardial biopsy revealed myocardial inflammation in 34 % of the patients. LVRR at 12 months occurred in 45 % of the patients. Presence of late gadolinium enhancement (LGE) in the left ventricle was a sensitive but unspecific sign of myocardial inflammation because it was also a feature of hemodynamic stress related to the heart failure. The baseline extent of LGE was an independent predictor of future LVRR and also a predictor of adverse clinical...