The number of patients with coronary artery disease and ischaemic heart failure -and those with terminal heart failure -is increasing despite improvements in medical and interventional therapies of ischaemic heart disease -and, over the next decades, it is projected to continue to increase further. Observer-independent, reproducible imaging techniques play a fundamental role in objective evaluation of both conventional (such as surgical or percutaneous) myocardial revascularization and novel therapeutic approaches to reduce myocardial ischaemia, improve contractility and prevent adverse myocardial remodelling. To be applicable to clinical practice, the clinical study design and data should best be rooted in everyday clinical practice. Accurate and reproducible assessment of left ventricular ejection fraction, left ventricular volumes, myocardial perfusion and function is one of the most important objectives of cardiac imaging. Current techniques used both in clinical studies and in everyday clinical practice include 2-and 3-dimensional echocardiography, magnetic resonance imaging, single-photon emission computed tomography and positron emission tomography; each of these has its strengths and limitations. We review present evidence on the role of single-photon emission computed tomography as a technique that may offer, through being observer-independent, the most objective evaluation of evolution of left ventricular perfusion, volumes and ejection fraction.

Introduction It has been suggested that infarct-related artery (IRA) atherosclerosis progression after stem cell transcoronary administration might represent a stem-cell mediated adverse effect. Aim To evaluate, using conventional (quantitative coronary angiography, QCA, intravascular ultrasound – IVUS) and novel (quantitative virtual histology – qVH) tools, evolution of IRA atherosclerosis following transcoronary stem cell transfer. Material and methods QCA, IVUS, VH-IVUS and qVH were performed in 22 consecutive patients (4 women) aged 59 years (data provided as median) undergoing a distal-to-stent infusion of 2.21 × 10 6 CD34 + CXCR4 + autologous bone marrow cells via a cell delivery-dedicated perfusion catheter at anterior AMI day 7. Imaging was repeated at 12 months. This was a substudy of Myocardial Regeneration by Intracoronary Infusion of Selected Population of Stem Cells in Acute Myocardial Infarction (REGENT) Trial (NCT00316381). Results 18.2% subjects showed absence of distal-to-stent angiographic/IVUS atherosclerotic lesion(s) at baseline and no new lesion(s) at 12-months. In the remaining cohort, there were 28 lesions by QCA (32 by IVUS) at baseline and no new lesion(s) at follow-up. Three fibroatheromas evolved (2 to calcified fibroatheroma and 1 to a fibrocalcific lesion); other plaques maintained their stable (low-risk) phenotypes. Diameter stenosis of QCA-identified lesions was 29.5 vs. 26.5% ( p = 0.012, baseline vs. 12-months). Gray-scale IVUS showed reduction in area stenosis (33.8 vs. 31.0%, p = 0.004) and plaque burden (66.27 vs. 64.56%, p = 0.009) at 12-months. Peak fibrotic plaque content increased from 70.41% to 75.0% ( p = 0.004). qVH peak confluent necrotic core area and minimal fibrous cap thickness remained stable (0.64 vs. 0.59 mm 2 , p = 0.290, and 0.15 vs. 0.16 mm, p = 0.646). Conclusions This study, using a range of classic and novel imaging techniques, indicates lack of any stimulatory effect of transcoronary stem cell transfer on coronary atherosclerosis. Whether, and to what extent, a moderate reduction in plaque burden and stenosis severity at 12-months results from optimized pharmacotherapy and/or stem cell transfer requires further elucidation.

Introduction: Infarct size (IS) is a fundamental determinant of left-ventricular (LV) remodelling (end-systolic and end-diastolic volume change, ΔESV, ΔEDV) and adverse clinical outcomes after myocardial infarction (MI). Our prior work found that myocardial uptake of transcoronary-delivered progenitor cells is governed by IS.Aim: To evaluate the relationship between IS, stem cell uptake, and the magnitude of LV remodelling in patients receiving transcoronary administration of progenitor cells shortly after MI.Material and methods: Thirty-one subjects (age 36-69 years) with primary percutaneous coronary intervention (pPCI)-treated anterior ST-elevation MI (peak CK-MB 584 [181-962] U/l, median [range]) and sustained left ventricle ejection fraction (LVEF) ≤ 45% were studied. On day 10 (median) 4.3 × 10 6 (median) autologous CD34+ cells (50% labelled with 99m Tc-extametazime) were administered via the infarct-related artery (left anterior descending). ΔESV, ΔEDV, and mid circumferential myocardial strain (mCS) were evaluated at 24 months.Results: Infarct mass (cMRI) was 57 g. Cell label myocardial uptake (whole-body γ-scans) was proportional to IS (r = 0.62), with a median 2.9% uptake in IS 1 st tercile (≤ 45 g), 5.2% in 2 nd (46-76 g), and 6.7% in 3 rd (> 76 g) (p = 0.0006). Cell uptake in proportion to IS attenuated the IS-ΔESV (p = 0.41) and IS-ΔEDV (p = 0.09) relationship. At 24 months, mCS improved in IS 2 nd tercile (p = 0.028) while it showed no significant change in smaller (p = 0.87) or larger infarcts (p = 0.58).Conclusions: This largest human study with labelled CD34+ cell transplantation shortly after MI suggests that cell uptake (proportional to IS) may attenuate the effect of IS on LV adverse remodelling. To boost this effect, further strategies should involve cell types and delivery techniques to maximize myocardial uptake.