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Relation Between Iron-Overload Indices, Cardiac Echo-Doppler,and Biochemical Markers in Thalassemia Intermedia

Hussain Isma’eel, MDa, Abdul Hamid El Chafic, MDa, Fuad El Rassi, MDa, Adlette Inati, MDb,c,Susan Koussa, MDb, Rose Daher, MDa, Walid Gharzuddin, MDa, Samir Alam, MDa, and

Ali Taher, MDa,b,*

Cardiovascular impairment is a major cause of morbidity and mortality in patients withthalassemia intermedia. In this study, echocardiographic assessment of left heartcondition was performed in patients with thalassemia intermedia, and its relation tohematologic variables—amino terminal pro-brain natriuretic peptide (NT-proBNP),ferritin, hemoglobin—and liver iron concentration (LIC) was investigated. Echocardio-graphic assessment was performed using pulse-wave Doppler and tissue Doppler imaging.Data from 74 patients with thalassemia intermedia—35 men, 39 women, mean age 26.5years (8 to 63) —were randomly selected and evaluated. Blood samples were collected forNT-proBNP levels in a random subgroup of 19 patients. Mean baseline values werehemoglobin 8.4 g/dl (4.9 to 13.1), serum ferritin 902.6 ng/ml (15 to 4,140), LIC 9.0 mg Fe/g(0.5 to 32.1), and NT-proBNP 113.5 pg/ml (16.4 to 371). Correlation between LIC andpulmonary artery systolic pressure was significant, suggesting that iron loading in the liveris indicative of cardiovascular sequelae. NT-proBNP was significantly correlated with theratio of the left ventricular early rapid filling wave to early diastolic velocity at the mitralannulus (r � 0.50, p � 0.04) and hemoglobin (r � �0.49, p � 0.03), but not with othercharacteristics assessed. In conclusion, this study has highlighted the importance of usingtissue Doppler imaging rather than pulse-wave Doppler to characterize left ventricular dia-stolic dysfunction in patients with thalassemia intermedia. Demonstration of the correlation ofLIC and pulmonary artery systolic pressure independent of left ventricular filling pressuressupports our hypothesis that left ventricular diastolic dysfunction does not contribute to theincreased pulmonary artery systolic pressure in patients with thalassemia intermedia. © 2008

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n contrast to patients with thalassemia major, most patientsith thalassemia intermedia present with mild anemia re-uiring only occasional blood transfusion therapy. Overany years, even a mild anemic state can result in signifi-

ant clinical sequelae due to chronic hypoxia, leading toultiple system damage, iron overload, and compensatory

tates.1,2 One affected system is the cardiovascular system,amage to which is a common cause of death in patientsith thalassemia intermedia.3–6 Conventional pulse-waveoppler echocardiography is the most commonly used tool

or assessing cardiac function (systolic and diastolic) and,hereby, predicting prognosis.7 However, tissue Dopplermaging is increasingly used for greater accuracy, particu-arly in subjects with milder forms of cardiac disease. Car-iac function (filling pressures) can also be determined by

aDepartment of Internal Medicine Hematology-Oncology Division,merican University of Beirut, Medical Center, Beirut; bChronic Careenter, Hazmieh; and cDepartment of Pediatrics, Rafik Hariri Universityospital, Beirut, Lebanon. Manuscript received February 1, 2008; revisedanuscript received and accepted March 17, 2008.

This study was supported by a research grant from Novartis Pharma-euticals Corporation, East Hanover, New Jersey.

*Corresponding author: Tel: 00-961-1-350-000, ext. 5392; fax: 00-961--370-814.

mE-mail address: ataher@aub.edu.lb (A. Taher).

002-9149/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved.oi:10.1016/j.amjcard.2008.03.066

ssessment of the amino terminal pro-brain natriuretic pep-ide (NT-proBNP).

ethods

his was a cross-sectional study of randomly selected pa-ients with thalassemia intermedia treated at a chronic careenter in Hazmieh, Lebanon. The sampling frame consistedf 170 patients with thalassemia intermedia �2 years ofge, and a simple random sample was obtained. Patientsere excluded if they had clinical signs suggesting heart

ailure or existing pulmonary hypertension, required cardio-ctive medications, or received transfusion therapy morerequently than at 3-month intervals. A medical history wasompiled, including drug history, co-morbid illnesses andistory of transfusion. Liver iron concentration (LIC) waseasured by R2* magnetic resonance imaging.Patients were referred to an outpatient clinic for at rest

ransthoracic pulse-wave Doppler echocardiography tovaluate left heart chamber diameter, geometry, and func-ion and to detect pulmonary hypertension (defined as pul-onary artery pressure �30 mm Hg). Tissue Doppler im-

ging was also performed to evaluate left ventriculariastology. The left ventricle was considered to be dilated ifnd diastolic diameter/body surface area was �3.1 cm/m2

or men and �3.2 cm/m2 for women.8 Left ventricular

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364 The American Journal of Cardiology (www.AJConline.org)

0.8 � (1.04[(LVIDd � PWTd � SWTd)3 � (LVIDd)3]) �.6}/body surface area, where LVIDd is the left ventricularnternal dimension at end diastole, PWTd is the posteriorall thickness at end diastole, and SWTd is the septal wall

hickness at end diastole.Left ventricular mass index was considered abnormal if

95 g/m2 for women or �115 g/m2 for men.8 Furtheralculation of relative wall thickness by the formula (2 �WTd)/LVIDd, permits the categorization of an increase in

eft ventricular mass index as either concentric (relative wallhickness �0.4) or eccentric (relative wall thickness �0.4)ypertrophy and allows identification of concentric remod-ling (normal left ventricular mass with increased relativeall thickness).8 Left ventricular systolic dysfunction wasefined by an ejection fraction of �55%9 and pulmonaryypertension by an at rest pulmonary artery systolic pres-ure of �30 mm Hg.10

Pulse-wave Doppler was used to determine the left ven-ricular early rapid filling wave (E), filling wave velocityue to atrial contraction (A), deceleration time, pulmonaryein systolic velocity, and pulmonary vein diastolic veloc-ty. Diastolic function was classified as normal (E/A �1,ulmonary vein systolic velocity � pulmonary vein dia-tolic velocity, 160 �deceleration time �240), as impairedelaxation (E/A �1, pulmonary vein systolic velocity �ulmonary vein diastolic velocity, deceleration time �240),s pseudonormal pattern (E/A �1, pulmonary vein systolicelocity � pulmonary vein diastolic velocity, 160 �decel-ration time �200), or restrictive pattern (E/A �1.5, decel-ration time �160, pulmonary vein systolic velocity �ulmonary vein diastolic velocity). Tissue Doppler imagingas used to calculate the early diastolic velocity at theitral annulus (Ea), which is the average of the measured

arly diastolic velocity at lateral and septal levels of theitral annulus.11

Assessment of heart failure was performed by assessingT-proBNP levels in blood samples collected from a ran-om subgroup of 19 patients. NT-proBNP is consideredormal for patients �50 years old if �153 pg/ml in womennd �88 pg/ml in men. It is considered normal for patients50 years old if �334 pg/ml for women and �227 pg/ml

or men.Microsoft Office Excel 2003 (Microsoft Corporation,

edmond, Washington) and SPSS for Windows 15.0 (SPSSnc., Chicago, Illinois) software programs were used fortatistical analysis and graphical demonstrations. Linear re-

able 1atient demographic and hematologic profile (n � 74)

ariable

omen 39ean age, yrs � SD (range) 27 � 12 (8�63)

revious splenectomy 56eceiving iron chelation 11ean weight (kg � SD) 54.0 � 12.8ean body surface area, m2 � SD (range) 1.5 � 0.3 (0.82–2.1)ean hemoglobin, g/dl � SD (range) 8.4 � 1.9 (4.9–13.1)ean serum ferritin, ng/ml � SD (range) 903 � 662 (15�4,140)

IC, mg Fe/g (range) 9.0 � 7.4 (0.5–32.1)

ression and partial correlation was used to investigate for a

elationships between variables. One-way analysis of vari-nce was used to compare means of continuous variablesnd was followed by Bonferroni posthoc analysis. Contin-ous variables were expressed as mean � SD.

esults

ata from 74 patients with thalassemia intermedia werencluded in these analyses, the characteristics of which areummarized in Table 1. In the subgroup of patients in whichT-proBNP levels were determined (n � 19), mean valuesere seen to be 113.5 � 88.0 pg/ml (range 16.4 to 371).evels were greater than the upper limit of normal in 7atients (36.8%); 20 patients had never received transfusionherapy, 30 had been transfused once in their lifetime, 15ad been transfused several times, and 2 patients wereeceiving transfusions every 6 months and 7 patients everymonths.Echocardiographic measurements are listed in Tables 2

nd 3. Pulmonary hypertension was present in 15 (38.5%) inhe patient group, excluding 35 patients with undetectedricuspid regurgitation. Left ventricular and left arterial di-atation were significantly greater than the normal range in8 (68.6%) and 51 patients (76.1%), respectively. Left ven-ricular mass index was increased in 34 patients (49.3%), allf whom displayed signs of eccentric hypertrophy. The leftentricular ejection fraction was within normal range forost of the patients; only 3 had a left ventricular ejection

raction �55%. The patient group showed a significantncrease in all diastolic characteristics as listed in Table 3.ssessment showed normal functioning in 38.9% of pa-

ients, impaired relaxation in 8.3%, pseudonormal in 40.3%,nd restrictive in 12.5%.

According to conventional echocardiographic measure-ents (i.e., pulse wave Doppler), the majority of patients

62.2%) showed diastolic dysfunction, and age was found toe significantly different in patients with impaired relax-tion and the other groups. Conversely, tissue Doppler im-ging showed that none of the patients had significant dia-tolic dysfunction (i.e., E/Ea ratio �15). Statistical analysiso determine associated characteristics with left ventricularass index, left ventricular end diastolic diameter index,

nd left atrial diameter index showed the only significantalues to be with left ventricular end diastolic diameterndex as listed in Table 4. In brief, women with moderatelynlarged left ventricles were associated with the highestulmonary artery systolic pressure and E/Ea ratio.

A significant correlation existed between peak systolicricuspid gradient and LIC level (r � 0.50, p � 0.01)ndependent of age and hemoglobin level, and no correla-ion was observed with serum ferritin (Figure 1). NT-roBNP was significantly correlated with E/Ea ratio (r �.50, p � 0.04) and hemoglobin (r � �0.49, p � 0.03;igures 2 and 3) but not with age, LIC, mean serum ferritin,

eft ventricular end-diastolic diameter, left ventricular massndex, or left ventricular ejection fraction.

iscussion

n this study we demonstrated a correlation between LIC

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365Miscellaneous/Iron Overload and Cardiac Function

ence to suggest that iron loading in the liver is indicative ofardiovascular sequelae.5,12 Although pulmonary artery sys-olic pressure can be partly increased by increased fillingressures, a correlation between pulmonary artery systolicressure and either E/Ea ratio or NT-proBNP (the besteasures of filling pressure or diastolic impairment cur-

ently available) was not observed. In contrast to previousbservations,6 our data demonstrated that there is no corre-ation between age or hemoglobin level with the tricuspidradient, suggesting that pulmonary hypertension is stronglyffected by iron overload and not merely a consequence of thehronic hypoxic damage that progresses with age. The same

able 2chocardiographic assessment

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Normal

Mild

eft ventricular end diastolic diameter index 28.2 30.8eft ventricular mass index 43.2 18.9eft atrial diameter index 20.6 38.2

Patients are categorized based on reference values for left ventricular m

able 3iastolic function

ulse Wave Doppler

2–20

TI(n � 24)

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114.8 � 14.1 8853.3 � 11.5 49

atio of E to A 2.2 � 0.5 1.9eceleration time 166.0 � 30.4 142ulmonary vein systolic velocity 57.1 � 13.6 48ulmonary vein diastolic velocity 61.0 � 9.0 60atio of pulmonary vein systolic velocityto pulmonary vein diastolic velocity

1.0 � 0.3 0.8

E/Ea �878.5

E/Ea � ratio of E to Ea; TI � thalassemia intermedia.

able 4eft ventricular end diastolic diameter index

Women

Normal Abnormal

Mild Moderate Se

ricuspid gradient, mm Hg 29.4 24.8 35.3 2/Ea 6.0 7.6 8.6/A 1.8 1.6 1.8IC, mg Fe/g 7.9 8.0 9.5erum ferritin, ng/ml 1,036.6 1,024.3 1,083.2 39emoglobin, g/dl 8.4 7.9 7.7

A � filling wave due to A; E/Ea � ratio of E to Ea.

orrelation did not reach statistical significance when body t

ron burden was evaluated by serum ferritin levels ratherhan by LIC, which is well known to be inferior to LIC as

prognostic and iron load measuring tool in thalassemiantermedia.13 The mechanism by which iron overload con-ributes to pulmonary artery systolic pressure remains theubject of some speculation. After excluding iron overloadn the heart using R2* magnetic resonance imaging (unpub-ished data), which is the most accurate means of assessingardiac iron and diastolic impairment, we are inclined tottribute these findings to increased cardiac output conditionecause of chronic anemia and/or iron overloaded states inhe lung parenchyma.14 Preferential iron deposition in cer-

Men (%)

ormal Normal Abnormal

erate Severe Mild Moderate Severe

.2 12.8 42.9 28.6 5.7 22.9

.6 16.2 59.4 25.0 12.5 3.1

.6 23.5 27.3 36.4 12.1 24.2

ents.

Age Group (yrs)

21–40 41–65

TI(n � 39)

Normal(n � 51)

TI(n � 11)

Normal(n � 33)

106.4 � 23.1 75 � 13 92.6 � 19.7 71 � 1361.7 � 16.5 51 � 11 78.7 � 16.5 57 � 13

1.8 � 0.6 1.5 � 0.4 1.2 � 0.3 1.3 � 0.3197.9 � 34.2 166 � 14 224.2 � 36.3 181 � 1958.3 � 13.2 44 � 10 64.5 � 15.4 49 � 860.5 � 13.6 47 � 11 52.7 � 9.5 41 � 8

1.0 � 0.3 1.0 � 0.3 1.3 � 0.4 1.2 � 0.2

Tissue Doppler Imaging

8 � E/Ea �15 E/Ea �1521.5 0

Men

p Value Normal Abnormal p Value

Mild Moderate Severe

0.01 30.8 35.1 — 26.3 0.60.0 6.5 6.5 6.8 6.5 1.00.3 1.8 2.0 1.8 2.3 0.40.9 12.5 8.7 3.1 8.3 0.40.4 1,377.8 841.0 511.0 1,008.4 0.20.8 9.6 8.8 9.6 7.6 0.2

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366 The American Journal of Cardiology (www.AJConline.org)

transfusion versus increased absorption) has been demon-trated and could be occurring here. Initiating iron chelationherapy, depending on LIC levels, may therefore help torevent serious complications such as pulmonary hyperten-ion in patients with thalassemia intermedia.1,6,15,16

Evaluation of left ventricular function demonstrated sim-lar findings to those reported by Aessops et al.2,4,6 Thereas a significant increase in left ventricular mass and di-

meter with eccentric hypertrophy in approximately 50% ofur patients.9 This reflects cardiac compensation and adap-ation to the chronic high-output anemic state. Systolicunction was generally normal, but diastolic dysfunctionas impaired in the majority as determined by pulse-waveoppler.17 However, the more advanced tissue Doppler

maging7 shows that the majority had normal filling pres-ure and none had a significant diastolic dysfunction. Thisiscrepancy is primarily due to the higher values obtainedsing pulse-wave Doppler, which reflects the hyperdynamic

igure 1. Correlation between peak systolic tricuspid gradient and LIC.olid symbols � LIC; open symbols � serum ferritin; solid line represents

he correlation between tricuspid gradient and LIC; broken line shows theorrelation between tricuspid gradient and serum ferritin levels.

Figure 2. Correlation of NT-proBNP and E/Ea ratio.

tate18 and the increased preload (as shown in the increase p

n E, A, pulmonary vein systolic velocity and pulmonaryein diastolic velocity) that is commonly observed in pa-ients with chronic anemia.19 Pulse-wave Doppler may,herefore, be a less accurate approach to assessing diastolicunction in patients for whom cardiac function is preloadependent, and tissue Doppler imaging should be consid-red.20 In addition, this stresses the need to adopt age-pecific pulse-wave Doppler ranges when interpreting dia-tolic function. This is a significant limitation of severaltudies that have grouped patients of different age groups.

In agreement with data published by Kremastinos et al21

n patients with thalassemia major, our study has demon-trated that NT-proBNP levels correlate with E/Ea ratio,hich is an accurate indicator of diastolic dysfunction,articularly in mild diseases. This demonstrates that NT-roBNP testing is a sensitive tool that reflects diastolicunction.22 A significant, negative correlation was also ob-erved with hemoglobin level, indicating a risk of develop-ng cardiac dysfunction in the patients with higher degreesf anemia. However, no correlation was observed betweenT-proBNP and LIC or between NT-proBNP and pulmo-ary artery systolic pressure. This suggests that, in patientsith thalassemia intermedia, the left ventricular stretchechanisms (secondary to the increased plasma volume that

s commonly encountered in patients with anemia) are theajor source of NT-proBNP rather than the right ventricular

train of increased pulmonary artery systolic pressure.23,24

owever, the relatively low pulmonary artery systolic pres-ure values may have contributed to this conclusion and thiseeds to be investigated in patients with relatively moder-te-to-severe pulmonary hypertension. Nevertheless, ourata, in agreement with other studies, demonstrate that, inomen, moderately enlarged left ventricles are associatedith higher pulmonary artery systolic pressure values. This

tudy is limited by the small patient number, particularlyegarding NT-proBNP and its relation to an increase inulmonary artery systolic pressure. The absence of a de-ected tricuspid regurgitation jet has contributed to thisimitation, although previous studies have shown that a lackf tricuspid regurgitation jet detection is seen only in pa-ients with low pulmonary artery systolic pressure. Further-ore an age- and gender-matched control group would have

Figure 3. Correlation of NT-proBNP and hemoglobin.

rovided valuable comparison, particularly with respect to

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367Miscellaneous/Iron Overload and Cardiac Function

ulse-wave Doppler values. The inclusion of right ventric-lar function assessments in future studies would serve toocalize the source of pathology in thalassemia intermediaardiopathy.

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3. Ferrara M, Matarese SM, Borrelli B, Perrotta A, Simeone G, Greco N,Iarussi D, Esposito L. Cardiac involvement in beta-thalassemia majorand beta-thalassemia intermedia. Hemoglobin 2004;28:123–129.

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