An angiotensin-converting enzyme inhibitor improves left ventricular systolic and diastolic function in transfusion-dependent patients with beta-thalassemia major

Carvedilol improves left ventricular diastolic dysfunction in patients with transfusion-dependent thalassemia

Background:

Iron overload cardiomyopathy is the most common cause of death in patients with transfusion-dependent thalassemia.

Aim:

The aim of this study was to determine the efficacy of carvedilol treatment in patients with transfusion-dependent thalassemia who had left ventricular diastolic dysfunction.

Methods:

Eighteen patients with transfusion-dependent thalassemia who had left ventricular diastolic dysfunction were enrolled. All patients had normal left ventricular systolic function and were given carvedilol with the target dose of 0.8 mg/kg/day. Ventricular function and the level of cardiac iron were assessed by echocardiography and magnetic resonance imaging at 0, 3, and 6 months.

Results:

The median age of the patients was 19 years (range 13–25 years). Four patients had severe left ventricular Grade III diastolic dysfunction and fourteen patients had Grade II diastolic dysfunction. The grade of left ventricular diastolic dysfunction was improved at 3 months after the carvedilol treatment. The Doppler parameters, including pulmonary vein atrial reversal velocity, pulmonary vein atrial reversal duration, and the difference of pulmonary vein atrial reversal and the mitral valve atrial contraction wave duration at 3 months after the carvedilol treatment, were significantly lower than these parameters before the treatment.

Conclusions:

Among patients with transfusion-dependent thalassemia who had left ventricular diastolic dysfunction without systolic dysfunction, treatment with carvedilol for 3 months was associated with improvement in Doppler parameters of left ventricular diastolic function. However, this finding and its clinical significance need to be confirmed in further double-blind controlled studies.

Prevalence of left ventricular diastolic dysfunction by cardiac magnetic resonance imaging in thalassemia major patients with normal left ventricular systolic function

Background

The leading cause of mortality of thalassemia major patients is iron overload cardiomyopathy. Early diagnosis with searching for left ventricular diastolic dysfunction before the systolic dysfunction ensued might yield better prognosis. This study aimed to define the prevalence of the left ventricular diastolic dysfunction (LVDD) in thalassemia major patients with normal left ventricular systolic function and the associated factors.

Methods

Adult thalassemia major patients with normal left ventricular systolic function who were referred for cardiac T2* at Siriraj Hospital – Thailand’s largest national tertiary referral center – during the October 2014 to January 2017 study period. Left ventricular diastolic function was defined by mitral valve filling parameters and left atrial volume index using CMR. Patients with moderate to severe valvular heart disease, pericardial disease, or incomplete data were excluded. Baseline characteristics, comorbid diseases, current medication, and laboratory results were recorded and analyzed.

Results

One hundred and sixteen patients were included, with a mean age of 27.5 ± 13.5 years, 57.8% were female, and 87.9% were transfusion dependent. Proportions of homozygous beta-thalassemia and beta-thalassemia hemoglobin E were 12.1 and 87.9%, respectively. The baseline hematocrit was 26.3 ± 3.3%. The prevalence of LVDD was 20.7% (95% CI: 13.7–29.2%). Cardiac T2* was abnormal in 7.8% (95% CI: 3.6–14.2%). Multivariate analysis revealed age, body surface area, homozygous beta-thalassemia, splenectomy, heart rate, and diastolic blood pressure to be significantly associated with LVDD.

Conclusions

LVDD already exists from the early stages of the disease before the abnormal heart T2 * is detected. Homozygous beta-thalassemia and splenectomy were strong predictors of LVDD. These data may increase awareness of the disease, especially in the high risk groups.

Dynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study

BACKGROUND

Performance of the left ventricle during exercise stress in thalassaemia patients is uncertain. We aimed to explore the phenomenon of dynamic dyssynchrony and assess contractile reserve in patients with beta-thalassaemia major and determine their relationships with myocardial iron load.

METHODS AND RESULTS

Thirty-two thalassaemia patients (16 males), aged 26.8 ± 6.9 years, without heart failure and 17 healthy controls were studied. Their left ventricular (LV) volumes, ejection fraction, systolic dyssynchrony index (SDI), and myocardial acceleration during isovolumic LV contraction (IVA) were determined at rest and during submaximal bicycle exercise testing using 3-dimensional and tissue Doppler echocardiography. Myocardial iron load as assessed by T2* cardiac magnetic resonance in patients were further related to indices of LV dyssynchrony and contractile reserve. At rest, patients had significantly greater LV SDI (p<0.001) but similar IVA (p = 0.22) compared with controls. With exercise stress, the prevalence of mechanical dyssynchrony (SDI>4.6%, control+2SD) increased from baseline 25% to 84% in patients. Δ SDI(exercise-baseline) correlated with exercise-baseline differences in LV ejection fraction (p<0.001) and stroke volume (p = 0.006). Compared with controls, patients had significantly less exercise-induced increase in LV ejection fraction, cardiac index, and IVA (interaction, all p<0.05) and had impaired contractile reserve as reflected by the gentler IVA-heart rate slope (p = 0.018). Cardiac T2* in patients correlated with baseline LV SDI (r = -0.44, p = 0.011) and IVA-heart rate slope (r = 0.36, p = 0.044).

CONCLUSIONS

Resting LV dyssynchrony is associated with myocardial iron load. Exercise stress further unveils LV dynamic dyssynchrony and impaired contractile reserve in patients with beta-thalassaemia major.

Modern treatment of thalassaemia intermedia

The term thalassaemia intermedia includes a large spectrum of conditions of varying severity. Blood transfusion and chelation are necessary in some patients, especially during childhood, in order to promote growth and prevent bone deformities. Alloimunisation, however, is frequent and can be difficult to control. Splenectomy is usually needed at some time because of hypersplenism and mechanical encumbrance. Reactivation of HbF is possible only in a small proportion of patients: hydroxycarbamide (also known as hydroxyurea) appears to be the most effective drug for this purpose. Antioxidant agents, although theoretically useful, do not improve haemoglobin levels. Stem cell transplantation is an option limited to the severe forms. Gene therapy and other molecular approaches are subjects of intense study. Numerous complications, including pulmonary hypertension, thrombotic events, pseudoxanthoma elasticum and osteoporosis, have been described and all contribute to complicate the treatment of a disease that represents a significant burden for the patients and their families.

Heart failure in beta-thalassemia syndromes: a decade of progress

The thalassemias are common monogenic disorders of hemoglobin synthesis. beta-thalassemias are the most important among the thalassemia syndromes and have become a worldwide clinical problem due to an increasing immigrant population. In beta-thalassemia major, regular blood transfusions are necessary early in life. Beta-thalassemia intermedia refers to a less severe phenotype, whereas beta-thalassemia/hemoglobin E disease encompasses a broad phenotypic spectrum. Blood transfusions and increased gastrointestinal iron absorption result in iron overload and tissue damage. Among patients with beta-thalassemia major, biventricular, dilated cardiomyopathy remains the leading cause of mortality. In some patients, a restrictive type of left ventricular cardiomyopathy or pulmonary hypertension is noted. The clinical course, although variable and occasionally fulminant, is more benign in recent than in older series. Myocarditis has been described as a cause of left-sided heart failure in younger patients. Pulmonary arterial hypertension is the principal cause of heart failure in beta-thalassemia intermedia. Chelation therapy has improved prognosis in beta-thalassemia major both by reducing the incidence of heart failure and by reversing cardiomyopathy. Estimation of the patient's cardiac risk is mainly based on clinical criteria and serial echocardiography. A new cardiovascular magnetic resonance technique will probably fulfill the need for more precise risk stratification in beta-thalassemia syndromes. By increasing the proportion of patients on optimal chelation, survival in beta-thalassemia major may further improve. Recent advances in gene therapy are expected to result in the long-awaited cure of this disease.

Ventriculo-vascular interactions in patients with beta thalassaemia major

OBJECTIVES

To determine potential interactions between the heart and arterial system in patients with beta thalassaemia major.

DESIGN AND PATIENTS

Vascular compliance, systemic vascular resistance, and left ventricular (LV) contractility was determined in 34 asymptomatic thalassaemia patients at 2-4 hours after blood transfusion and also in 34 age and sex matched controls using a non-invasive device. The results were compared between groups and inter-relationships between LV contractility and indices of vascular load were explored.

SETTING

Tertiary paediatric cardiac centre.

RESULTS

When compared with controls, patients had greater systemic vascular resistance (1633 (259) v 1377 (276) dynes/s/cm5, p < 0.001) and effective arterial elastance (E(a)) (1.86 (0.25) v 1.65 (0.29) mm Hg/ml, p = 0.001), an index of combined pulsatile and static vascular load. On the other hand, their systolic blood pressure (104 (9) v 112 (13) mm Hg, p = 0.006), pulse pressure (45 (9) v 57 (10) mm Hg, p < 0.001), adjusted systemic vascular compliance (1.21 (0.09) v 1.37 (0.14), p < 0.001), adjusted brachial artery distensibility (21 (0.29) v 7.95 (0.29)%/mm Hg, p < 0.001) and LV+dP/dt (1059 (183) v 1239 (237) mm Hg/s, p = 0.001) were significantly lower. Significant determinants of LV contractility, as reflected by LV+dP/dt, were age (standardised beta = -0.24, p = 0.003), body mass index (standardised beta = -0.34, p = 0.004), systolic blood pressure (standardised beta = 0.90, p < 0.001), and effective E(a) (standardised beta = -0.50, p < 0.001) (model R2 = 0.69). No significant correlation existed between serum ferritin concentration and any of the cardiac or vascular indices.

CONCLUSION

An unfavourable ventriculo-vascular interaction, as characterised by impaired cardiac contractility and increased static and pulsatile vascular load, occurs in patients with beta thalassaemia major.