Anaemia is associated with severe RBC dysfunction and a reduced circulating NO pool: vascular and cardiac eNOS are crucial for the adaptation to anaemia.

Anaemia is frequently present in patients with acute myocardial infarction (AMI) and contributes to an adverse prognosis. We hypothesised that, besides reduced oxygen carrying capacity, anaemia is associated with (1) red blood cell (RBC) dysfunction and a reduced circulating nitric oxide (NO) pool, (2) compensatory enhancement of vascular and cardiac endothelial nitric oxide synthase (eNOS) activity, and (3) contribution of both, RBC dysfunction and reduced circulatory NO pool to left ventricular (LV) dysfunction and fatal outcome in AMI. In mouse models of subacute and chronic anaemia from repeated mild blood loss the circulating NO pool, RBC, cardiac and vascular function were analysed at baseline and in reperfused AMI. In anaemia, RBC function resulted in profound changes in membrane properties, enhanced turnover, haemolysis, dysregulation of intra-erythrocytotic redox state, and RBC-eNOS. RBC from anaemic mice and from anaemic patients with acute coronary syndrome impaired the recovery of contractile function of isolated mouse hearts following ischaemia/reperfusion. In anaemia, the circulating NO pool was reduced. The cardiac and vascular adaptation to anaemia was characterised by increased arterial eNOS expression and activity and an eNOS-dependent increase of end-diastolic left ventricular volume. Endothelial dysfunction induced through genetic or pharmacologic reduction of eNOS-activity abrogated the anaemia-induced cardio-circulatory compensation. Superimposed AMI was associated with decreased survival. In summary, moderate blood loss anaemia is associated with severe RBC dysfunction and reduced circulating NO pool. Vascular and cardiac eNOS are crucial for the cardio-circulatory adaptation to anaemia. RBC dysfunction together with eNOS dysfunction may contribute to adverse outcomes in AMI.

Consistency of left ventricular ejection fraction measurements in the early time course of STEMI.

BACKGROUND: Early after ST-segment elevation myocardial infarction (STEMI), initial LV reshaping and hypokinesia may affect analysis of LV function. Concomitant microvascular dysfunction may affect LV function as well. OBJECTIVE: To perform a comparative evaluation of left ventricular ejection fraction (LVEF) and stroke volume (SV) by different imaging modalities to assess LV function early after STEMI. METHODS: LVEF and SV were assessed using serial imaging within 24 h and 5 days after STEMI using cineventriculography (CVG), 2-dimensional echocardiography (2DE), 2D/3D cardiovascular magnetic resonance (CMR) (2D/3D) in 82 patients. RESULTS: 2D analyses of LVEF using CVG, 2DE and 2D CMR yielded uniform results within 24 h and 5 days of STEMI. SV assessment between CVG and 2DE was comparable, whereas values for SV were higher using 2D CMR (p < 0.01 all). This was due to higher LVEDV measurements. LVEF by 2D versus 3D CMR was comparable, 3D CMR yielded higher volumetric values. This was not influenced by infarct location or infarct size. CONCLUSIONS: 2D analysis of LVEF yielded robust results across all imaging techniques implying that CVG, 2DE, and 2D CMR can be used interchangeably early after STEMI. SV measurements differed substantially between imaging techniques due to higher intermodality-differences of absolute volumetric measurements.

Vasodilator Myocardial Perfusion Cardiac Magnetic Resonance Imaging Is Superior to Dobutamine Stress Echocardiography in the Detection of Relevant Coronary Artery Stenosis: A Systematic Review and Meta-Analysis on Their Diagnostic Accuracy.

Objectives: Guideline recommendations for patients with either a high or a low risk of obstructive coronary artery disease (CAD) are clear. However, the evidence for initial risk stratification in patients with an intermediate risk of CAD is still unclear, despite the availability of multiple non-invasive assessment strategies. The aim of this study was to synthesize the evidence for this population to provide more informed recommendations. Background: A meta-analysis was performed to systematically assess the diagnostic accuracy of vasodilator myocardial perfusion cardiovascular magnetic resonance imaging (pCMR) and dobutamine stress echocardiography (DSE) for the detection of relevant CAD. In contrast to previous work, this meta-analysis follows rigorous selection criteria in regards to the risk stratification and a narrowly prespecified definition of their invasive reference tests, resulting in unprecedentedly informative results for this reference group. Data Collection and Analysis: From the 5,634 studies identified, 1,306 relevant articles were selected after title screening and further abstract screening left 865 studies for full-text review. Of these, 47 studies fulfilled all inclusion criteria resulting in a total sample size of 4,742 patients. Results: pCMR studies showed a superior sensitivity [0.88 (95% confidence interval (CI): 0.85-0.90) vs. 0.72 (95% CI: 0.61-0.81)], diagnostic odds ratio (DOR) [38 (95% CI: 29-49) vs. 20 (95% CI: 9-46)] and an augmented post-test probability [negative likelihood ratio (LR) of 0.14 (95% CI: 0.12-0.18) vs. 0.31 (95% CI: 0.21, 0.46)] as compared to DSE. Specificity was statistically indifferent [0.84 (95% CI: 0.81-0.87) vs. 0.89 (95% CI: 0.83-0.93)]. Conclusion: The results of this systematic review and meta-analysis suggest that pCMR has a superior diagnostic test accuracy for relevant CAD compared to DSE. In patients with intermediate risk of CAD only pCMR can reliably rule out relevant stenosis. In this risk cohort, pCMR can be offered for initial risk stratification and guidance of further invasive treatment as it also rules in relevant CAD.

Cardiovascular Magnetic Resonance Relaxometry Predicts Regional Functional Outcome After Experimental Myocardial Infarction.

BACKGROUND: Cardiovascular magnetic resonance with gadolinium-based contrast agents has established as gold standard for tissue characterization after myocardial infarction (MI). Beyond accurate diagnosis, the value of cardiovascular magnetic resonance to predict the outcome after MI has yet to be substantiated. METHODS AND RESULTS: Recent cardiovascular magnetic resonance approaches were systematically compared for quantification of tissue injury and functional impairment after MI using murine models with permanent left anterior descending coronary artery ligation (n=14) or 50 minutes ischemia/reperfusion (n=13). Cardiovascular magnetic resonance included native/postcontrast T1 maps, T2 maps, and late gadolinium enhancement at days 1 and 21 post-MI. For regional correlation of parametric and functional measures, the left ventricle was analyzed over 200 sectors. For T1 mapping, we used retrospective triggering with variable flip angle analysis. Sectoral analysis of native T1 maps already revealed in the acute phase after MI substantial discrepancies in myocardial tissue texture between the 2 MI models (native T1 day 1: permanent ligation, 1280.0±162.6 ms; ischemia/reperfusion, 1115.0±140.5 ms; P<0.001; n=14/13), which were later associated with differential functional outcome (left ventricular ejection fraction day 21: permanent ligation, 24.5±7.0%; ischemia/reperfusion, 33.7±11.6%; P<0.05; n=14/13). At this early time, any other parameter was indicative for the subsequent worsening of left ventricular ejection fraction in permanent ligation mice. Linear regression of acute individual measures with contractile function in corresponding areas at day 21 demonstrated for early native T1 values the best correlation with the later functional impairment (R2 =0.94). CONCLUSIONS: The present T1 mapping approach permits accurate characterization of local tissue injury and holds the potential for sensitive and graduated prognosis of the functional outcome after MI without gadolinium-based contrast agents.