Assessment of left ventricular and atrial diastolic function using two-dimensional (2D) strain imaging in patients with β-thalassemia major

Cardiac complications in thalassemia throughout the lifespan: Victories and challenges

Thalassemias are among the most common hereditary diseases in the world because heterozygosity offers protection against malarial infection. Affected individuals have variable expression of alpha or beta chains that lead to their unbalanced utilization during hemoglobin formation, oxidative stress, and apoptosis of red cell precursors prior to maturation. Some individuals produce sufficient hemoglobin to survive but suffer the vascular stress imposed by chronic anemia and ineffective erythropoiesis. In other patients, mature red cell formation is insufficient, and chronic transfusions are required-suppressing anemia and ineffective erythropoiesis but at the expense of iron overload. The cardiovascular consequences of thalassemia have changed dramatically over the previous five decades because of evolving treatment practices. This review summarizes this evolution, focusing on complications and management pertinent to modern patient cohorts.

Speckle tracking echocardiography and β-thalassemia major. A systematic review

Heart disease is among the primary causes of morbidity and mortality in β-thalassemia major (β-TM). Conventional echocardiography has failed to identify myocardial dysfunction at an early stage among these patients, thus speckle tracking echocardiography (STE) has been lately used. The objectives of this review were to 1) identify all published studies having evaluated myocardial strain among β-TM patients, 2) gather their results, 3) compare their findings and 4) propose recommendations based on these data. Literature search was conducted in PubMed, SCOPUS and Cohrane Library. Data regarding left ventricular global longitudinal (LV-GLS), circumferential (LV-GCS) and radial strain (LV-GRS), right ventricular longitudinal strain (RV-GLS), left and right atrial strain were extracted. Thirty-five studies (34 original articles and 1 meta-analysis) have met the inclusion criteria. LV-GLS has been reported being worse in patients compared to controls in 13 of 21 studies, LV-GCS in 7 of 11 studies, LV-GRS in 6 of 7 studies, RV-GLS in 2 of 3 studies and left atrial strain in all case-control studies. Myocardial iron overload (MIO) patient subgroups had worse LV-GLS in 6 of 15 studies, LV-GCS in 2 of 7 studies and LV-GRS in none of 7 studies. A small number of studies suggest left atrial strain correlation with electrical atrial ectopy and atrial fibrillation. It is suggested that STE should be applied supplementary to conventional echocardiography for early identification of myocardial dysfunction among β-TM patients. Potential myocardial strain utilities could be screening for myocardial iron overload, left ventricular diastolic dysfunction and atrial fibrillation.

Left atrial deformation indices in β-thalassemia major patients

The presence of atrial cardiomyopathy in β-thalassemia major (β-TM) patients complicates their clinical condition. The diagnosis is challenging even with cardiac magnetic resonance (CMR) imaging. Novel echocardiographic techniques are applied to increase the diagnostic yield. Fifty-six β-TM patients and thirty age and sex-matched controls were included in the present cross-sectional study. Heart rate, PR duration, and P axis were measured by electrocardiography, left ventricular ejection fraction (LVEF) and end-diastolic diameter (LVEDD), ratio between early mitral inflow velocity and mitral annular early diastolic velocity (E/e'), left atrial volume index (LAVI), left atrial strain at reservoir (LASr), conduit (LAScd) and contraction (LASct) phases respectively, left ventricular global longitudinal strain (GLS) by echocardiography, and T2* calculation in patient group by CMR. PR duration, LVEF, LAVI, E/e', GLS, and left atrial deformation parameters differed between patients and controls (p <0.05). In patient group, left atrial strain was correlated with PR duration, LAVI, E/e', GLS, and T2* (p <0.05). T2* was correlated only with left atrial deformation indices (p <0.05). Patients with a history of atrial fibrillation were older, had lower heart rate, prolonged PR, increased E/e' and LAVI, and impaired left atrial strain (p <0.05). LASct differed relative to the presence of atrial fibrillation and myocardial iron overload. Atrial strain could be of clinical use in the early detection of atrial cardiomyopathy. An impaired LASct could identify β-TM patients with undetected episodes of atrial fibrillation. Finally, left atrial strain may be helpful in myocardial iron load estimation.

Native cardiac magnetic resonance T1 mapping and cardiac mechanics as assessed by speckle tracking echocardiography in patients with beta-thalassaemia major

BACKGROUND

We hypothesize that cardiac magnetic resonance (CMR) native T1 is associated with myocardial deformation in thalassaemia patients. The present study aimed to compare CMR native T1 values to conventional T2* values in patients with beta-thalassaemia and to explore relationships between these CMR parameters of myocardial iron overload and left ventricular (LV) and left atrial (LA) myocardial deformation.

METHODS

Thirty-four (16 males) patients aged 35.5 ± 9.2 years were studied. Myocardial T2* and T1 mapping were performed to assess the cardiac iron overload, while two-dimensional speckle-tracking echocardiography was performed in determine LV and LA myocardial deformation.

RESULTS

T2* was 36.4 ± 8.7 ms with 3 patients having myocardial iron load (T2*<20 ms). The native T1 was 947.1 ± 84.8 ms, which was significantly lower than the reported normal values in the literature. There was a significant correlation between T1 and T2* values (r = 0.68, p < 0.001). There were no significant correlations between T1 and T2* values and conventional and tissue Doppler parameters of left ventricular systolic and diastolic function. On the other hand, T1, but not T2*, values were found to correlate negatively with maximum LA area indexed by body surface area (r = -0.34, p = 0.047) and positively with LA strain rate at atrial contraction (r = 0.36, p = 0.04). There were no associations between either of these CMR parameters with indices of ventricular deformation.

CONCLUSIONS

In patients with beta-thalassaemia major, native T1 values are decreased, associated with T2* values, and correlated with maximum LA area and LA strain rate at atrial contraction.

Association between left ventricular strain and cardiac iron load in beta-thalassaemia major: a cardiac magnetic resonance study

OBJECTIVE

To evaluate the utility of cardiac magnetic resonance feature tracking-derived left ventricular strain in assessing cardiac dysfunction and investigate the correlation between left ventricular strain and myocardial T2* in patients with beta-thalassaemia major.

METHODS

Forty-two patients with beta-thalassaemia major, having a mean age of 22.49 ± 8.48 years, and age-matched healthy controls were enrolled in the study. The observer drew regions of interest on the interventricular septum, and T2* decay curves were calculated accordingly. The short-axis cine images were used to derive left ventricular circumferential and radial strains, and the long-axis four-chamber and two-chamber images were used to assess left ventricular longitudinal strain.

RESULTS

The mean global left ventricular strains were lower in beta-thalassaemia major patients than the controls (p < 0.05). Left ventricular strains of beta-thalassaemia major patients with cardiac T2* values of > 20 ms were also significantly reduced compared with the controls (p < 0.05); there was no difference between the mean left ventricular ejection fractions of the two groups (p = 0.84). Cardiac T2* showed a weak correlation with left ventricular ejection fraction (r = 0.33, p = 0.03), while the left ventricular circumferential strain showed a good positive correlation with cardiac T2* (r = 0.6, p < 0.0001).

CONCLUSION

Compared with healthy controls, patients with beta-thalassaemia major, including those with myocardial T2* values of >20 ms, showed reduced global left ventricular strains. Left ventricular circumferential strain was positively correlated with myocardial T2*. Left ventricular strain analysis using cardiac magnetic resonance feature tracking may have utility in beta-thalassaemia major assessment.Key FindingsPatients with beta-thalassaemia major, including those with myocardial T2* values of >20 ms, had reduced global left ventricular strains.Cardiac T2* showed a weak correlation with left ventricular ejection fraction, while the left ventricular circumferential strain showed a good positive correlation with cardiac T2*.ImportanceLeft ventricular strain using cardiac magnetic resonance feature tracking might be used as an adjunct in assessing cardiac functions in beta-thalassaemia major.

Subclinical Left Ventricular Dysfunction in Children and Adolescence With Thalassemia Intermedia

BACKGROUND

Cardiac complications are important causes of morbidity in patients with thalassemia intermedia (TI). We aimed to assess left ventricular (LV) function, using new tissue Doppler imaging (TDI) indices, in order to diagnose early ventricular impairment in asymptomatic children and adolescence with the TI.

MATERIALS AND METHODS

We investigated possible differences in echocardiographic systolic and diastolic parameters between a population of 28 asymptomatic patients (mean age, 13.6 ± 5.7 years) and 35 age-matched healthy control members. All of them underwent 2-D, pulsed Doppler, and tissue Doppler echocardiographic studies for the assessment of the LV mass, Trans-mitral velocities, mitral annular systolic and diastolic velocities, myocardial performance index (MPI), and myocardial acceleration during isovolumic contraction (IVA). The cardiac iron load was estimated by magnetic resonance imaging T2*.

RESULTS

Left ventricular hypertrophy (LVH) was found in 13 (46.4%) patients. We found significantly reduced TDI-derived peak systolic myocardial velocity (s') in patients, whereas no significant difference was identified between the patients and control group members when the IVA was compared. The ratio of peak mitral inflow velocity to annular early diastolic velocity (E/e') of the mitral valve as an index of the diastolic function was significantly higher in patients (9 ± 1 vs. 6 ± 1, p < 0.05). Choosing a TDI-derived MPI > 0.33 as a cutoff point, the global LV dysfunction was detected with a sensitivity of 78% and a specificity of 80%. The patients with LVH significantly exhibited higher values of TDI-MPI and lower values of s' velocity and IVA when compared against the subjects with normal LV mass.

CONCLUSION

Subtle LV systolic and diastolic dysfunction develops early in young patients with the TI who have normal cardiac iron concentration. Moreover, LV remodeling as a main cardiac adaptive response plays a principal role in developing myocardial impairment.

Analysis of The Left Atrial Function Using Two-Dimensional Strain in Patients with Recent Diagnosis of Hereditary Hemochromatosis

Hereditary Hemochromatosis (HH) is a genetic condition associated with a systemic iron overload. Heart failure is an important cause of mortality. It has been demonstrated early stages of systolic and diastolic left ventricular dysfunction in previous studies. The aim of the study is to compare the left atrial (LA) function between asymptomatic HH patients and a control group using 2D speckle tracking. Prospective study. LA strain, LA strain rate and LA volumetric parameters during the reservoir, conduit and contraction phases were studied. The LA Stiffness Index was calculated by the ratio between E/e and LA reservoir strain. 30 patients with HH (90% males, 47 ± 18 years old) and 30 healthy controls (85% males, 45 ± 13 years old) were included. LA volume was similar in both groups. No differences were observed in LA ejection fraction (EF), LA passive EF and LA active ejection fraction between both groups. On the contrary, the HH group had lower LA strain during the reservoir (31.5 ± 6.5% vs 38.3 ± 7.9%; P=0.002), and conduit phases (-18 ± 7% vs -23.3 ± 6.4%; P=0.01) and lower LA conduit strain rate (-1.7 ± 0.7 seg^-1 vs -2.1 ± 0.5 seg^-1; P=0.02) than controls. The LA stiffness index was significantly higher in the HH group (0.25 ± 0.9 vs 0.19 ± 0.6; P=0.01) Early abnormalities in the LA function could be detected by using 2D speckle tracking study despite no evidence of changes in atrial size or volumetric parameters.

Advancement of echocardiography for surveillance of iron overload cardiomyopathy: comparison to cardiac magnetic resonance imaging

The prevalence of iron overload cardiomyopathy (IOC) is increasing. Patients with transfusion-dependent anemias or conditions associated with increased iron absorption over time are at a significant risk for the development of iron-overloaded states such as IOC. Current guidelines regarding the diagnostic evaluation and follow-up of patients at risk for IOC exist, and are composed of multiple components, including such as echocardiography, genetic testing, magnetic resonance imaging of liver, and cardiac magnetic resonance imaging (CMR). While these are considered reliable for the evaluation of patients at risk for an iron-overloaded state, there is an access challenge associated with initial and serial CMR scanning in this patient population. Furthermore, there are other limiting factors, such as patient characteristics that may preclude the use of CMR as a viable diagnostic imaging modality for these patients. On the other hand, recent evidence in the literature suggests that transthoracic echocardiography, which has had significant technological advances, can equal or even outperform CMR to identify cardiac functional abnormalities such as subclinical left ventricular strain and left atrial functional abnormalities in iron overload conditions. Therefore, there is a potential role of more frequent use of echocardiography for surveillance of the development of IOC. Our purpose with this narrative review is to describe recent advances in echocardiography and propose a potential increased use of echocardiography in the surveillance of the development of IOC.

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.

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.

Left and Right Atrial Function and Remodeling in Beta-Thalassaemia Major

This study aimed to assess left (LA) and right atrial (RA) function in patients with beta-thalassaemia major. Thirty-eight patients (19 males) aged 34.5 ± 10.7 years and 43 (18 males) controls aged 30.3 ± 12.6 years (p = 0.12) were studied. The maximum RA and LA areas were measured using two-dimensional planimetry, while atrial and ventricular strain and strain rates were quantified using speckle-tracking echocardiography. Compared with controls, patients had significantly reduced LA and RA peak positive strain and total strain, and LA strain rate during ventricular systole and at atrial contraction (all p < 0.05). The LA and RA strain parameters were significantly associated (all p < 0.05). The maximum LA (10.2 ± 1.6 cm²/m² vs. 8.6 ± 1.3 cm²/m², p < 0.001) and RA (9.2 ± 1.2 cm²/m² vs. 7.5 ± 1.3 cm²/m², p < 0.001) areas were significantly greater in patients than controls. The LV and RV strain and early strain rates were similar between patients and controls (all p > 0.05). Four patients with significant myocardial iron overload had larger LA area (p < 0.001) than those without. Functional and structural remodeling of both the right and left atria occurs in patients with beta-thalassaemia major, even in the absence of ventricular diastolic dysfunction.

Echocardiografic abnormalities in patients with sickle cell/β-thalassemia do not depend on the β-thalassemia phenotype

OBJECTIVES AND METHODS

We evaluated possible relationships between echocardiographic findings and clinical and laboratory parameters, in a cohort of Brazilian patients diagnosed with sickle cell/β-thalassemia, to better understand the cardiac involvement in this disease.

RESULTS

Left atrial (LA) and left ventricular (LV) dilation were found in 19.5 and 11% of patients, respectively; systolic left ventricular dysfunction was present in a single patient. There were no differences in masses and volumes of cardiac chambers comparing Sβ⁰ with Sβ⁺ patients, and no relationship between these parameters and specific complications of the disease. However, parameters of altered ventricular geometry were significantly correlated with serum creatinine, hepatic transaminases and bilirubin levels. Moreover, 3 patients presented stroke; they were significantly older [53 (41-56)×37.5 (18-70), p=0.048], had higher values of LV posterior wall diastolic thickness [10 (10-11)×8 (6-14), p=0.03], LV mass [226 (194-260)×147 (69-537), p=0.039] and LA/aortic ratio [1.545 (1.48-1.61)×1.26 (0.9-1.48), p=0.032].

CONCLUSIONS

Cardiac involvement in this disease does not appear to depend on the thalassemia phenotype. The presence of signs of myocardial remodeling in this group of patients was related to multi-organ impairment and rendered a higher propensity for stroke in older patients, suggesting the need for greater vigilance and control of associated factors.

Association of GSTT1/GSTM1 and ApoE variants with left ventricular diastolic dysfunction in thalassaemia major patients

BACKGROUND

Cardiomyocytes are particularly susceptible to complications from iron loading. The blood transfusions in thalassaemia major create loading of iron that cannot be naturally excreted. Apolipoprotein E and Glutathione S-transferase act as the scavenger of free radicals, which are generated due to excess iron. The variants of Apolipoprotein E (ApoE) and Glutathione S-transferase (GST) may play a role in oxidative damage-induced cardiomyopathy, so we aimed to study the association of genetic variants of these genes on diastolic dysfunction in our patients.

MATERIALS AND METHODS

One hundred and five β-thalassaemia patients older than 10 years were enrolled for the study. Two-dimensional and M-mode echocardiography analysis was done in all patients. Genotyping of the genetic variants of aforementioned genes was done using the PCR-RFLP method. Serum Glutathione S-transferase levels were estimated by ELISA.

RESULTS

Diastolic dysfunction was observed in 24 (22.8%) patients, whereas left ventricular hypertrophy was present in 37(35.2%) patients. There was a significant association of GSTM1 null allele with diastolic dysfunction only. Serum GST levels were also positively correlated with e/a and e/e' ratio. Positive association of ApoE E2 allele with the diastolic dysfunction was also seen.

CONCLUSIONS

Patients having Glutathione S-transferase M1 allele and Apolipoprotein E E2 allele are predisposed to oxidative stress-induced cardiac injury.

Left atrial active contractile function parameters assessed by cardiac MR are sensitive to myocardial iron

PURPOSE

To determine the impact of myocardial iron overload on left atrial (LA) volume and function using MR in patients with systemic iron overload.

MATERIALS AND METHODS

Thirty-eight patients with systemic iron overload disease and 10 controls underwent 1.5 Tesla MR performing steady state free precession short-axis cine-series of the LA. Three-dimensional-volumetry was assessed to calculate LA volumes and function. Parameters were indexed (i) to body surface area. The myocardial transverse relaxation rate R2* was determined in the ventricular septum using a multi-echo GRE sequence (breathhold; electrocardiography triggered; 12 echoes; echo time = 1.3-25.7 ms).

RESULTS

Significantly decreased active atrial emptying fraction (AAEF) (23% [95%-range, 7-34] versus 36% [95%-range, 14-49], P = 0.009), active atrial emptying volume (AAEVi) (5.5 mL/m² [95%-range, 2-11] versus 11.9 mL/m² [95%-range, 3-23], P = 0.008), and active peak emptying rate (APERi) (46 mL/s/m² [95%-range, 29-69] versus 75 mL/s/m² [95%-range, 45-178], P < 0.001) were found for patients with myocardial iron overload (R2* > 40 s^-1 ) compared with patients with normal myocardial iron levels (R2* < 40 s^-1 ). Receiver operating characteristics (ROC) analysis revealed higher potential to indicate myocardial iron overload for the AAEF (area under the ROC curve [AUC] = 0.84; P < 0.0001), APERi (AUC = 0.87; P < 0.0001), and AAEVi (AUC = 0.80; P < 0.0001) compared with LA ejection fraction (LAEF) (AUC = 0.68; P = 0.02) with equal sensitivities and specificities of 82% (AAEF), 79% (APERi), 73% (AAEVi), and 57% (LAEF).

CONCLUSION

MR parameters of active LA contractile function were associated with myocardial iron overload. This cross-sectional study suggests impaired active LA contractile function to be sensitive to myocardial iron toxicity.

LEVEL OF EVIDENCE

3 J. Magn. Reson. Imaging 2017;45:535-541.