Iron overload in polytransfused patients without heart failure is associated with subclinical alterations of systolic left ventricular function using cardiovascular magnetic resonance tagging

Genetically predicted biomarkers of iron homeostasis and risk of non-ischemic cardiomyopathy: A mendelian randomization study

BACKGROUND AND AIMS

Both iron overload and iron deficiency have been associated with cardiovascular diseases in observational studies. Previous Mendelian Randomization (MR) studies discovered a protective effect of higher iron status on coronary atrial disease, while a neutral effect on all-cause heart failure. Using two-sample MR, we evaluated how genetically predicted systemic iron status affects the risk of non-ischemic cardiomyopathy and different phenotypes.

METHODS AND RESULTS

Two-sample MR analyses were performed to estimate the causal effect of four biomarkers of systemic iron status on diagnosed cardiomyopathy and its subtypes in 242,607 participants from the FinnGen research project. The level of transferrin saturation was significantly associated with an increased risk of cardiomyopathy (OR, 1.17; 95% CI, 1.13-1.38) when using nine separately selected genetic instruments. An increase in genetically determined serum iron (odds ratio [OR] per standard deviation [SD], 1.25; 95% confidence interval [CI], 1.13-1.38) and ferritin (OR, 1.49; 95% CI, 1.02-2.18) were associated with an increased risk of cardiomyopathy. Total iron binding capacity, a marker of reduced iron status, was inversely linked with cardiomyopathy (OR, 0.80; 95% CI, 0.65-0.98). The risk effect of iron status was more evident in hypertrophic cardiomyopathy and related heart failure.

CONCLUSIONS

These analyses support the causal effect of increased systemic iron status on a higher risk of non-ischemic cardiomyopathy. A screening test for cardiomyopathy should be considered in patients with evidence of iron overload. Future study is needed for exploring the mechanism of these causal variants on cardiomyopathy.

Cardiac Magnetic Resonance Strain in Beta Thalassemia Major Correlates with Cardiac Iron Overload

BACKGROUND

Beta thalassemia major (Beta-TM) is an inherited condition which presents at around two years of life. Patients with Beta-;TM may develop cardiac iron toxicity secondary to transfusion dependence. Cardiovascular magnetic resonance (CMR) T2*, a technique designed to quantify myocardial iron deposition, is a driving component of disease management. A decreased T2* value represents increasing cardiac iron overload. The clinical manifestation is a decline in ejection fraction (EF). However, there may be early subclinical changes in cardiac function that are not detected by changes in EF. CMR-derived strain assesses myocardial dysfunction prior to decline in EF. Our primary aim was to assess the correlation between CMR strain and T2* in the Beta-TM population.

METHODS

Circumferential and longitudinal strain was analyzed. Pearson's correlation was calculated for T2* values and strain in the Beta-TM population.

RESULTS

We identified 49 patients and 18 controls. Patients with severe disease (low T2*) were found to have decreased global circumferential strain (GCS) in comparison to other T2* groups. A correlation was identified between GCS and T2* (r = 0.5; p < 0.01).

CONCLUSION

CMR-derived strain can be a clinically useful tool to predict early myocardial dysfunction in Beta-TM.

Cardiac Magnetic Resonance at 3.0 T in Patients With C282Y Homozygous Hereditary Hemochromatosis: Superiority of Radial and Circumferential Strain Over Cardiac T2* Measurements at Baseline and at Post Venesection Follow-up

BACKGROUND

Iron-overload cardiomyopathy initially manifests with diastolic dysfunction and can progress to dilated cardiomyopathy if untreated. Previous studies have shown that patients with primary and secondary hemochromatosis can have subclinical left ventricle dysfunction with abnormalities on strain imaging. This study aimed to evaluate the relationship between cardiac T2* values and myocardial-wall strain in patients with hereditary hemochromatosis (HH) at the time of diagnosis and after a course of venesection treatment.

MATERIALS AND METHODS

Baseline cardiac magnetic resonance (CMR) at 3 T was performed in 19 patients with newly diagnosed HH with elevated serum ferritin levels and repeated after a course of treatment with venesection. Quantitative T2* mapping and strain analysis were performed offline using dedicated relaxometry fitting and feature-tracking software.

RESULTS

The majority (84%) of patients had normal baseline myocardial T2* values (mean 19.3 ms, range 8.9 to 31.2 ms), which improved significantly after venesection (mean 24.1 ms, range 11 to 38.1 ms) ( P =0.021). Mean global radial strain significantly improved from 25.0 (range: 15.6 to 32.9) to 28.3 (range: 19.8 to 35.8) ( P =0.001) and mean global circumferential strain improved, decreasing from -15.7 (range: -11.1 to -19.2) to -17.1 (range: -13.0 to -20.1) ( P =0.001).

CONCLUSION

Patients with HH may have normal T2* values in the presence of subclinical left ventricle dysfunction, which can be detected by abnormal radial and circumferential strain. As strain imaging improves following venesection in HH, it may serve as a useful biomarker to guide treatment.

Correlation between Myocardial Iron Overload Detected by CMRT2* and Left Ventricular Function Assessed by Tissue Doppler Imaging in Patients with Thalassemia Major

Background

Iron overload and cardiac dysfunctions are common complications in patients with thalassemia major (TM). Different imaging methods can be used to detect ventricular dysfunction in these patients. In this study, we aim to understand the value of tissue Doppler imaging (TDI) in the detection of myocardial dysfunction in patients with TM who have been diagnosed with iron overload using cardiovascular magnetic resonance CMRT2*.

Methods

In this cross-sectional study, fifty patients with TM diagnosed with iron overload who had no clinical signs and symptoms of cardiac dysfunction were chosen as a case group. The control group included fifty sex- and age-matched healthy participants without a history of cardiac and hematological diseases. TDI, pulsed wave Doppler (PWD), and standard echocardiography were performed to study the left ventricular function, and cardiac iron overload assessed by CMRT2*. Then, the patients with TM were divided into two subgroups and compared with each other. Group 1a includes individuals with T2* value <20 ms and group 1b T2* value >20 ms.

Results

There was no significant difference between the standard echocardiography results and PWD parameters of the case and control groups; however, CMRT2* findings and TDI parameters were different between the case and control groups. CMRT2* findings also were not correlated with PWD parameters. In group 1a, CMRT2* findings were negatively correlated with age, E', A', early deceleration time, and isovolumetric relaxation time and positively correlated with E/E' ratio. Finally, PWD and TDI parameters were significantly different between the two subgroups.

Conclusion

TDI can detect ventricular systolic and diastolic dysfunctions in earlier stages among patients with iron overload. It seems that TDI could detect abnormalities more accurately, and it is better to consider subclinical cardiac dysfunction in patients with even CMRT2* value of more than 20 ms and reevaluate them in future.

Dysregulation of iron metabolism in cardiovascular diseases: From iron deficiency to iron overload

Iron deficiency and iron overload are the most prevalent and opposite forms of dysregulated iron metabolism that affect approximately 30 percent of the world population, in particularly, elderly and patients with chronic diseases. Both iron deficiency and overload are frequently observed in a wide range of cardiovascular diseases, contributing to the onset and progression of these diseases. One of the devastating seqeulae for iron overload is the induction of ferroptosis, a newly defined form of regulated cell death which heavily impacts cardiac function through ferroptotic cell death in cardiomyocytes. In this review, we will aim to evaluate iron deficiency and iron overload in cardiovascular diseases. We will summarize current therapeutic strategies to tackle iron deficiency and iron overload, major pitfalls of current studies, and future perspectives.

How does iron deposition modify the myocardium? A feature-tracking cardiac magnetic resonance study

Iron-overload cardiomyopathy is the principal cause of mortality in thalassemia. Via feature-tracking cardiac magnetic resonance (FT-CMR), we investigated alterations in cardiac deformation with the progression in myocardial iron overload (MIO). We enrolled 154 patients with thalassemia (50.64% male, mean age = 32.19 ± 9.79 years) referred for MIO assessment and 28 controls (50% male, mean age = 31.07 ± 4.35 years). Functional, strain, and T2* values were assessed in 4 study groups: no MIO (T2* > 20), mild-to-moderate MIO (T2* = 10-20), severe MIO (T2* < 10), and healthy controls. The recorded strain values were compared between the groups. The study groups were statistically significantly different vis-à-vis left ventricular (LV) global longitudinal strain (GLS) (F [3, 178] = 20.30), LV global radial strain (GRS) (F [3, 178] = 11.61), right ventricular (RV) GLS (F [3, 178]) = 5.32), RV global circumferential strain (GCS) (F [3, 178] = 26.02), and RVGRS (F [3, 178] = 16.86) (Ps < 0.005). The post hoc test revealed that LVGLS, RVGCS, and RVGRS were different between patients with thalassemia but without MIO and the control group (Ps < 0.001). A significant difference in LVGLS and LVGRS was detected between the T2* > 20 and 10 ≤ T2* ≤ 20 groups (Ps < 0.05). The multivariate logistic regression analysis depicted LVGRS as the most robust predictor of MIO (T2* ≤ 20) (odds ratio = 0.920, 95% CI 0.886 to 0.955), which predicted MIO with a cutoff point of 31.16% or less (sensitivity = 62% and specificity = 80.77%). Biventricular FT-CMR values are impaired in patients with thalassemia even without MIO. With MIO progression, LV strain values are the first ones to be undermined. Notably, functional CMR indices are jeopardized late, only after severe iron deposition.

Magnetic Resonance Myocardial Feature Tracking in Transfusion-Dependent Myelodysplastic Syndrome

BACKGROUND

Myocardial deformation with echocardiography allows early detection of systolic dysfunction and is related to myocardial iron overload (MIO) determined by T2* in hereditary anemias under transfusion support. Our aim was to analyze the diagnostic and prognostic usefulness of magnetic resonance feature tracking (MR-FT) myocardial strain in low-risk myelodysplastic syndromes (LR-MDS) patients.

METHODS

Prospective study in transfusion-dependent LR-MDS patients and healthy controls who underwent a cardiac MR-FT. We analyzed the relationships between strain MR-FT and iron overload parameters and its prognostic impact in cardiovascular events and/or death.

RESULTS

Thirty-one patients and thirteen controls were included. MIO (T2* < 20 ms) was detected in 9.7% of patients. Left ventricular global longitudinal strain (LV-GLS) by MR-FT was pathological (> −19.3%) in 32.3% of patients. Less negative strain values correlated with lower T2* (R = −0.37, p = 0.033) and native myocardial T1 (R = −0.39, p = 0.031) times. LV-GLS by MR-FT was significantly associated with higher incidence of the combined cardiovascular events and/or all-cause death (p = 0.047), with a cut-off value of −17.7% for predicting them (63% sensitivity and 81% specificity, area under the curve = 0.69). After adjusting analysis including demographic, biomarkers and imaging variables, a higher LV-GLS value by MR-FT remained as predictor of combined event in transfusion-dependent LR-MDS patients (hazard ratio, 0.4; confidence interval, 0.15–0.98; p = 0.045).

CONCLUSIONS

Longitudinal myocardial strain by MR-FT in LR-MDS patients is associated to MIO and correlates with adverse events in the follow-up, what could serve as a prognostic tool.

Prediction of long-term survival in patients with transfusion-dependent hemoglobinopathies: Insights from cardiac imaging and ferritin

AIMS

The current study evaluated the association of echocardiography, cardiac magnetic resonance (CMR), and ferritin data with 10-year survival in thalassemia patients.

METHODS

Demographics, ferritin, echocardiography, and CMR parameters of stable consecutive thalassemia patients were prospectively collected.

RESULTS

In total, 75 patients (mean age 37 ± 11 years, 45% male) with thalassemia were included and dichotomized based on their survival status after a median follow-up period of 10.3 [9.6-10.9] years. Older age (HR: 1.071, p = 0.001), ferritin ≥2000 ng/ml (HR: 4.682, p = 0.007) and ≥1700 ng/ml (HR: 7.817, p = 0.002), elevated LV end-diastolic pressure (HR: 1.019, p = 0.044), TR Vmax >2.8 m/s (HR: 6.845, p = 0.005), and CMR T2∗ ≤20 msec (HR: 3.602, p = 0.043) and ≤34 msec (HR: 5.854, p = 0.026) were associated with increased all-cause mortality (primary endpoint). A baseline model including age was created and became more predictive of worse survival by adding TR Vmax >2.8 m/s instead of elevated LV end-diastolic pressure (C index 0.767 vs. 0.760, respectively), ferritin ≥1700 ng/ml instead of ≥2000 ng/ml (C index 0.890 vs. 0.807, respectively), or CMR T2∗≤34 msec instead of ≤20 msec (C index 0.845 vs. 0.839, respectively). Parameters associated with the combined endpoint of cardiac mortality/cardiac hospitalization (secondary endpoint) after adjusting for age were ferritin ≥1700 ng/ml (HR 3.770, p = 0.014), ratio E/A wave >2 (HR 3.565, p = 0.04), TR Vmax >2.8 m/s (HR 4.541, p = 0.049), CMR T2∗ ≤20 ms (HR 9.462, p = 0.001), and CMR T2∗ ≤34 ms (HR 11.735, p = 0.002). The model including age and T2∗ ≤34 ms instead of T2∗ ≤20 ms was more predictive of the secondary endpoint (C-index 0.844 vs 0.838, respectively).

CONCLUSIONS

In thalassemia patients, TR Vmax >2.8 m/s, ferritin ≥2000 ng/ml, and CMR T2∗ ≤20 ms were associated with worse long-term survival. In the current era of advanced chelation therapy, aiming for ferritin ≤1700 ng/ml and CMR T2∗ ≥34 ms may improve their prognosis.

How to diagnose heart failure with preserved ejection fraction: the HFA-PEFF diagnostic algorithm: a consensus recommendation from the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

Making a firm diagnosis of chronic heart failure with preserved ejection fraction (HFpEF) remains a challenge. We recommend a new stepwise diagnostic process, the 'HFA-PEFF diagnostic algorithm'. Step 1 (P=Pre-test assessment) is typically performed in the ambulatory setting and includes assessment for HF symptoms and signs, typical clinical demographics (obesity, hypertension, diabetes mellitus, elderly, atrial fibrillation), and diagnostic laboratory tests, electrocardiogram, and echocardiography. In the absence of overt non-cardiac causes of breathlessness, HFpEF can be suspected if there is a normal left ventricular ejection fraction, no significant heart valve disease or cardiac ischaemia, and at least one typical risk factor. Elevated natriuretic peptides support, but normal levels do not exclude a diagnosis of HFpEF. The second step (E: Echocardiography and Natriuretic Peptide Score) requires comprehensive echocardiography and is typically performed by a cardiologist. Measures include mitral annular early diastolic velocity (e'), left ventricular (LV) filling pressure estimated using E/e', left atrial volume index, LV mass index, LV relative wall thickness, tricuspid regurgitation velocity, LV global longitudinal systolic strain, and serum natriuretic peptide levels. Major (2 points) and Minor (1 point) criteria were defined from these measures. A score ≥5 points implies definite HFpEF; ≤1 point makes HFpEF unlikely. An intermediate score (2-4 points) implies diagnostic uncertainty, in which case Step 3 (F1: Functional testing) is recommended with echocardiographic or invasive haemodynamic exercise stress tests. Step 4 (F2: Final aetiology) is recommended to establish a possible specific cause of HFpEF or alternative explanations. Further research is needed for a better classification of HFpEF.

Biochemical and imaging markers in patients with thalassaemia

Beta-thalassaemia is a genetic disease with different clinical aspects, which can lead to heart failure with a multifactorial mechanism. Over the last years, growing interest has been reported for biomarkers that may help in the diagnosis, staging and prognosis of heart disease at an early stage, in patients with beta-thalassaemia. This review will highlight the current clinical value of cardiac biomarkers in patients with beta-thalassaemia and the ongoing research for a possible expanded future use.

Implications of SARSr-CoV 2 infection in thalassemias: Do patients fall into the "high clinical risk" category?

We're all flying blind regarding coronavirus, but it's fair to think if thalassemic patients are particularly vulnerable to SARS-COV-2  infection or are at potential higher risk of complications from COVID-19 than normal population, specially when they become older. The frustrating thing is that, right now,  this virus is still new. It only came to the attention of the World Health Organization at the end of December. Very few cases in thalassemia have so far been reported; is this due to lack of testing or a true lack of infection/susceptibility? However, we believe that more data should be collected to better characterise the impact of SARS-CoV-2 infection in patients with thalassemias. Therefore, a multicenter registry and the collection of comprehensive data from both positive COVID-19 thalassemia major and non-transfusion dependent thalassemia are necessary to clarify debated issues. In the meantime an early and vigilant monitoring along with high quality supportive care are needed in thalassemic patients at high risk for SARS-CoV-2 infection.

Cardiovascular magnetic resonance native T2 and T2* quantitative values for cardiomyopathies and heart transplantations: a systematic review and meta-analysis

BACKGROUND

The clinical application of cardiovascular magnetic resonance (CMR) T2 and T2* mapping is currently limited as ranges for healthy and cardiac diseases are poorly defined. In this meta-analysis we aimed to determine the weighted mean of T2 and T2* mapping values in patients with myocardial infarction (MI), heart transplantation, non-ischemic cardiomyopathies (NICM) and hypertension, and the standardized mean difference (SMD) of each population with healthy controls. Additionally, the variation of mapping outcomes between studies was investigated.

METHODS

The PRISMA guidelines were followed after literature searches on PubMed and Embase. Studies reporting CMR T2 or T2* values measured in patients were included. The SMD was calculated using a random effects model and a meta-regression analysis was performed for populations with sufficient published data.

RESULTS

One hundred fifty-four studies, including 13,804 patient and 4392 control measurements, were included. T2 values were higher in patients with MI, heart transplantation, sarcoidosis, systemic lupus erythematosus, amyloidosis, hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) and myocarditis (SMD of 2.17, 1.05, 0.87, 1.39, 1.62, 1.95, 1.90 and 1.33, respectively, P <  0.01) compared with controls. T2 values in iron overload patients (SMD = - 0.54, P = 0.30) and Anderson-Fabry disease patients (SMD = 0.52, P = 0.17) did both not differ from controls. T2* values were lower in patients with MI and iron overload (SMD of - 1.99 and - 2.39, respectively, P <  0.01) compared with controls. T2* values in HCM patients (SMD = - 0.61, P = 0.22), DCM patients (SMD = - 0.54, P = 0.06) and hypertension patients (SMD = - 1.46, P = 0.10) did not differ from controls. Multiple CMR acquisition and patient demographic factors were assessed as significant covariates, thereby influencing the mapping outcomes and causing variation between studies.

CONCLUSIONS

The clinical utility of T2 and T2* mapping to distinguish affected myocardium in patients with cardiomyopathies or heart transplantation from healthy myocardium seemed to be confirmed based on this meta-analysis. Nevertheless, variation of mapping values between studies complicates comparison with external values and therefore require local healthy reference values to clinically interpret quantitative values. Furthermore, disease differentiation seems limited, since changes in T2 and T2* values of most cardiomyopathies are similar.

Comparison of global strain values of myocardium in beta-thalassemia major patients with iron load using specific feature tracking in cardiac magnetic resonance imaging

Thalassemia defined a spectrum of diseases characterized by reduced or absent production of one of the globin chains of hemoglobin. High iron deposition in the myocardium may cause functional impairment even before any changes in left ventricular (LV) ejection fraction. These impairments may appear as changes in strain values. Early detection of myocardial dysfunction is essential for improving survival and preventing further complications. Therefore, this study aims to evaluate the cardiac strain patterns by Feature Tracking -Cardiac Magnetic Resonance Imaging (FT-CMR) method and their correlation with T2* values as a new parameter in determining myocardial iron overload (MIO). In this retrospective investigation, ninety-one patients with B-thalassemia major included from May 2016 to July 2019. Twenty-three healthy subjects, also incorporated as a control group. CMR used to evaluate ventricular volumes, LVEF, and the amount of myocardial T2*. Moreover, Global Longitudinal Strain (GLS), Global Circumferential Strain (GCS), and Global Radial Strain (GRS) were measured and analyzed in both rights and left ventricles. Correlations of cardiac T2* with GLS, GCS, and GRS were evaluated. The optimal cutoff value of GLS for prediction of cardiac T2* < 20 ms (as an indicator of inadequate chelation) calculated as well. There were significant correlations between cardiac T2* with LV GLS, LV GCS, and right ventricular GLS (p < 0.05 for each one). Moreover, a significant difference detected between the group of TM - MIO and TM + MIO and control group in terms of GLS (p < 0.001). The optimal cutoff value of GLS for prediction of cardiac T2* < 20 ms was at - 16.5% with sensitivity and specificity of 73% and 63%, respectively. Our study demonstrates that strain values measured by FT and myocardial T2* values are correlated. FT-CMR can be considered as an efficient tool for early detection of iron deposition and its effects on cardiac tissue so that proper and timely modification could have applied to chelation therapy.

How to diagnose heart failure with preserved ejection fraction: the HFA-PEFF diagnostic algorithm: a consensus recommendation from the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

Making a firm diagnosis of chronic heart failure with preserved ejection fraction (HFpEF) remains a challenge. We recommend a new stepwise diagnostic process, the 'HFA-PEFF diagnostic algorithm'. Step 1 (P=Pre-test assessment) is typically performed in the ambulatory setting and includes assessment for heart failure symptoms and signs, typical clinical demographics (obesity, hypertension, diabetes mellitus, elderly, atrial fibrillation), and diagnostic laboratory tests, electrocardiogram, and echocardiography. In the absence of overt non-cardiac causes of breathlessness, HFpEF can be suspected if there is a normal left ventricular (LV) ejection fraction, no significant heart valve disease or cardiac ischaemia, and at least one typical risk factor. Elevated natriuretic peptides support, but normal levels do not exclude a diagnosis of HFpEF. The second step (E: Echocardiography and Natriuretic Peptide Score) requires comprehensive echocardiography and is typically performed by a cardiologist. Measures include mitral annular early diastolic velocity (e'), LV filling pressure estimated using E/e', left atrial volume index, LV mass index, LV relative wall thickness, tricuspid regurgitation velocity, LV global longitudinal systolic strain, and serum natriuretic peptide levels. Major (2 points) and Minor (1 point) criteria were defined from these measures. A score ≥5 points implies definite HFpEF; ≤1 point makes HFpEF unlikely. An intermediate score (2-4 points) implies diagnostic uncertainty, in which case Step 3 (F₁ : Functional testing) is recommended with echocardiographic or invasive haemodynamic exercise stress tests. Step 4 (F₂ : Final aetiology) is recommended to establish a possible specific cause of HFpEF or alternative explanations. Further research is needed for a better classification of HFpEF.

The correlation between cardiac magnetic resonance T2* and left ventricular global longitudinal strain in people with β-thalassemia

BACKGROUND

Heart failure is the biggest cause of mortality and morbidity in people with thalassemia, and iron deposition in cardiac tissue impairs cardiovascular function. Therefore, early detection of cardiac involvement is important to improve the prognosis in these individuals.

METHOD

Two- and three-dimensional echocardiography was performed to evaluate left ventricular ejection fraction (LVEF), left ventricular volumes and diameters, and global longitudinal strain (GLS) in 130 individuals with β-thalassemia using the speckle tracking method. Magnetic resonance imaging (MRI) was carried out on both the heart and liver. The participants were divided into 2 groups based on cardiac T2* values (normal and abnormal cardiac iron load), and the correlation between cardiac T2* MRI and GLS was evaluated.

RESULTS

The statistical analysis showed a significant correlation between cardiac T2* MRI and left ventricular global longitudinal strain. There was a significant difference in global longitudinal strain (P < .0001), liver MRI T2*( P < .0001), and left ventricular ejection fraction (P < .001) between the 2 groups. The optimal cutoff value for GLS was -18.5% with sensitivity and specificity 73.0% and 63.0%, respectively (postitive predictive value = 50%, negative predictive value = 82.3%, AUC = 0.742, std. error = 0.046) which predicts T2* value of <20 ms, according to cardiac MRI.

CONCLUSIONS

The participants with cardiac iron overload had a lower GLS than those without one. This suggests that GLS may be a useful method to predict myocardial iron overload particularly in β-thalassemia patients with subclinical cardiac involvement.

Myocardial deformation in iron overload cardiomyopathy: speckle tracking imaging in a beta-thalassemia major population

Traditional echocardiography is unable to detect neither the early stages of iron overload cardiomyopathy nor myocardial iron deposition. The aim of the study is to determine myocardial systolic strain indices in thalassemia major (TM), and assess their relationship with T2*, a cardiac magnetic resonance index of the severity of cardiac iron overload. 55 TM cases with recent cardiac magnetic resonance (CMR-T2*) underwent speckle tracking analysis to assess regional myocardial strains and rotation. The results were compared with a normal control group (n = 20), and were subsequently analyzed on the basis of the CMR-T2* values. Two TM groups were studied: TM with significant cardiac iron overload ("low" T2*, ≤20 ms; n = 21), and TM with normal T2* values ("normal" T2*, >20 ms; n = 34). TM patients show significant, uniform decrease in circumferential and radial strain (P < 0.05), and a remarkable reduction in end-systolic rotation, both global, and for all segments (P < 0.001). No significant differences were found between the low- and the normal T2* group either in regional strains and rotation or in standard echocardiographic and CMR parameters. Spearman's correlation coefficient shows no significant correlation between myocardial strains, rotation and cardiac T2* values. In conclusion, our results are in accordance with recent evidence that myocardial iron overload is not the only mechanism underlying iron cardiomyopathy in TM. Strain imaging can predict subclinical myocardial dysfunction irrespective of CMR-T2* values, although it cannot replace CMR-T2* in assessing cardiac iron overload. Finally, it might be useful to appropriately time cardioactive treatment.

Left ventricular torsional mechanics and myocardial iron load in beta-thalassaemia major: a potential role of titin degradation

BACKGROUND

Iron may damage sarcomeric proteins through oxidative stress. We explored the left ventricular (LV) torsional mechanics in patients with beta-thalassaemia major and its relationship to myocardial iron load. Using HL-1 cell and B6D2F1 mouse models, we further determined the impact of iron load on proteolysis of the giant sarcomeric protein titin.

METHODS AND RESULTS

In 44 thalassaemia patients aged 25 ± 7 years and 38 healthy subjects, LV torsion and twisting velocities were determined at rest using speckle tracking echocardiography. Changes in LV torsional parameters during submaximal exercise testing were further assessed in 32 patients and 17 controls. Compared with controls, patients had significantly reduced LV apical rotation, torsion, systolic twisting velocity, and diastolic untwisting velocity. T2* cardiac magnetic resonance findings correlated with resting diastolic untwisting velocity. The increments from baseline and resultant LV torsion and systolic and diastolic untwisting velocities during exercise were significantly lower in patients than controls. Significant correlations existed between LV systolic torsion and diastolic untwisting velocities in patients and controls, both at rest and during exercise. In HL-1 cells and ventricular myocardium of B6D2F1 mice overloaded with iron, the titin-stained pattern of sarcomeric structure became disrupted. Gel electrophoresis of iron-overloaded mouse myocardial tissue further showed significant decrease in the amount of titin isoforms and increase in titin degradation products.

CONCLUSIONS

Resting and dynamic LV torsional mechanics is impaired in patients with beta-thalassaemia major. Cell and animal models suggest a potential role of titin degradation in iron overload-induced alteration of LV torsional mechanics.

Review of Journal of Cardiovascular Magnetic Resonance 2012

There were 90 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2012, which is an 8% increase in the number of articles since 2011. The quality of the submissions continues to increase. The editors are delighted to report that the 2011 JCMR Impact Factor (which is published in June 2012) has risen to 4.44, up from 3.72 for 2010 (as published in June 2011), a 20% increase. The 2011 impact factor means that the JCMR papers that were published in 2009 and 2010 were cited on average 4.44 times in 2011. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is approximately 25%, and has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

Cardiovascular function and treatment in β-thalassemia major: a consensus statement from the American Heart Association

This aim of this statement is to report an expert consensus on the diagnosis and treatment of cardiac dysfunction in β-thalassemia major (TM). This consensus statement does not cover other hemoglobinopathies, including thalassemia intermedia and sickle cell anemia, in which a different spectrum of cardiovascular complications is typical. There are considerable uncertainties in this field, with a few randomized controlled trials relating to treatment of chronic myocardial siderosis but none relating to treatment of acute heart failure. The principles of diagnosis and treatment of cardiac iron loading in TM are directly relevant to other iron-overload conditions, including in particular Diamond-Blackfan anemia, sideroblastic anemia, and hereditary hemochromatosis. Heart failure is the most common cause of death in TM and primarily results from cardiac iron accumulation. The diagnosis of ventricular dysfunction in TM patients differs from that in nonanemic patients because of the cardiovascular adaptation to chronic anemia in non-cardiac-loaded TM patients, which includes resting tachycardia, low blood pressure, enlarged end-diastolic volume, high ejection fraction, and high cardiac output. Chronic anemia also leads to background symptomatology such as dyspnea, which can mask the clinical diagnosis of cardiac dysfunction. Central to early identification of cardiac iron overload in TM is the estimation of cardiac iron by cardiac T2* magnetic resonance. Cardiac T2* <10 ms is the most important predictor of development of heart failure. Serum ferritin and liver iron concentration are not adequate surrogates for cardiac iron measurement. Assessment of cardiac function by noninvasive techniques can also be valuable clinically, but serial measurements to establish trends are usually required because interpretation of single absolute values is complicated by the abnormal cardiovascular hemodynamics in TM and measurement imprecision. Acute decompensated heart failure is a medical emergency and requires urgent consultation with a center with expertise in its management. The first principle of management of acute heart failure is control of cardiac toxicity related to free iron by urgent commencement of a continuous, uninterrupted infusion of high-dose intravenous deferoxamine, augmented by oral deferiprone. Considerable care is required to not exacerbate cardiovascular problems from overuse of diuretics or inotropes because of the unusual loading conditions in TM. The current knowledge on the efficacy of removal of cardiac iron by the 3 commercially available iron chelators is summarized for cardiac iron overload without overt cardiac dysfunction. Evidence from well-conducted randomized controlled trials shows superior efficacy of deferiprone versus deferoxamine, the superiority of combined deferiprone with deferoxamine versus deferoxamine alone, and the equivalence of deferasirox versus deferoxamine.

Altered regional cardiac wall mechanics are associated with differential cardiomyocyte calcium handling due to nebulette mutations in preclinical inherited dilated cardiomyopathy

Nebulette (NEBL) is a sarcomeric Z-disk protein involved in mechanosensing and force generation via its interaction with actin and tropomyosin-troponin complex. Genetic abnormalities in NEBL lead to dilated cardiomyopathy (DCM) in humans and animal models. The objectives of this study are to determine the earliest preclinical mechanical changes in the myocardium and define underlying molecular mechanisms by which NEBL mutations lead to cardiac dysfunction. We examined cardiac function in 3-month-old non-transgenic (non-Tg) and transgenic (Tg) mice (WT-Tg, G202R-Tg, A592E-Tg) by cardiac magnetic resonance (CMR) imaging. Contractility and calcium transients were measured in isolated cardiomyocytes. A592E-Tg mice exhibited enhanced in vivo twist and untwisting rate compared to control groups. Ex vivo analysis of A592E-Tg cardiomyocytes showed blunted calcium decay response to isoproterenol. CMR imaging of G202R-Tg mice demonstrated reduced torsion compared to non-Tg and WT-Tg, but conserved twist and untwisting rate after correcting for geometric changes. Ex vivo analysis of G202R-Tg cardiomyocytes showed elevated calcium decay at baseline and a conserved contractile response to isoproterenol stress. Protein analysis showed decreased α-actinin and connexin43, and increased cardiac troponin I phosphorylation at baseline in G202R-Tg, providing a molecular mechanism for enhanced ex vivo calcium decay. Ultrastructurally, G202R-Tg cardiomyocytes exhibited increased I-band and sarcomere length, desmosomal separation, and enlarged t-tubules. A592E-Tg cardiomyocytes also showed abnormal ultrastructural changes and desmin downregulation. This study showed distinct effects of NEBL mutations on sarcomere ultrastructure, cellular contractile function, and calcium homeostasis in preclinical DCM in vivo. We suggest that these abnormalities correlate with detectable myocardial wall motion patterns.

Review of Journal of Cardiovascular Magnetic Resonance 2011

There were 83 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2011, which is an 11% increase in the number of articles since 2010. The quality of the submissions continues to increase. The editors had been delighted with the 2010 JCMR Impact Factor of 4.33, although this fell modestly to 3.72 for 2011. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, we remain very pleased with the progress of the journal's impact over the last 5 years. Our acceptance rate is approximately 25%, and has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors feel it is useful to summarize the papers for the readership into broad areas of interest or theme, which we feel would be useful, so that areas of interest from the previous year can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

Evaluation of left ventricular torsion by cardiovascular magnetic resonance

Recently there has been considerable interest in LV torsion and its relationship with symptomatic and pre-symptomatic disease processes. Torsion gives useful additional information about myocardial tissue performance in both systolic and diastolic function. CMR assessment of LV torsion is simply and efficiently performed. However, there is currently a wide variation in the reporting of torsional motion and the procedures used for its calculation. For example, torsion has been presented as twist (degrees), twist per length (degrees/mm), shear angle (degrees), and shear strain (dimensionless). This paper reviews current clinical applications and shows how torsion can give insights into LV mechanics and the influence of LV geometry and myocyte fiber architecture on cardiac function. Finally, it provides recommendations for CMR measurement protocols, attempts to stimulate standardization of torsion calculation, and suggests areas of useful future research.

Assessment of cardiac iron deposition in sickle cell disease using 3.0 Tesla cardiovascular magnetic resonance

Many patients with sickle cell disease receive blood transfusions as a life-saving treatment. However, excess transfusions may lead to increased body iron burden. Specifically, heart failure due to cardiac iron overload is the leading cause of death in these patients. The purpose of this study was to investigate the potential role of high-field 3.0-Tesla (T) cardiovascular magnetic resonance (CMR) for assessment of cardiac iron content by measuring the transverse relaxivity rate R2*. The R2* was measured in calibrated phantoms with different iron concentrations at 3.0T and 1.5T using optimized pulse sequences. Myocardial R2* was measured at 3.0T in a group of sickle cell disease patients with different disease stages, and the results were compared to the serum ferritin levels and hepatic R2*. The phantom R2* measurements at 3.0T were double those at 1.5T, and the measurements of both systems showed linear relationships with iron concentration. The 3.0T R2* was more sensitive than 1.5T in detecting low iron concentration. In patients, myocardial R2* had weak and good correlations with hepatic R2* and serum ferritin levels, respectively. Bland-Altman analysis showed low inter- and intra-observer variabilities. In conclusion, measuring myocardial R2* at 3.0T is a promising technique with high sensitivity and reproducibility for evaluating cardiac iron overload in sickle cell disease patients.