Electrocardiographic markers for the early detection of cardiac disease in patients with beta-thalassemia major

Abstract

Objective: To comparatively evaluate P-wave dispersion (PWD) in patients with β-thalassemia major (TM) and healthy control subjects for the early prediction of arrhythmia risk.Methods: Eighty-one children with β-TM, aged 4-19 years, and 74 healthy children (control group) underwent routine electrocardiography and transthoracic echocardiography for cardiac evaluation. PWD was calculated as the difference between the maximum and the minimum P-wave duration.Results: There was a statistically significant difference between study and control groups in peak early (E) mitral inflow velocity and E/late (A) velocity ratio. Maximum P-wave duration and PWD were found to be significantly higher in β-TM patients than in control subjects. Conclusions:Increased PWD in our β-TM patients might be related to depression of intra-atrial conduction due to atrial dilatation and increased sympathetic activity. These patients should be closely followed up for risk of lifethreatening arrhythmias.J Pediatr (Rio J). 2010;86(2):159-162: Thalassemia major, P-wave dispersion, ferritin, cardiac involvement. Original article0021-7557/10/86-02/159 Jornal de PediatriaCopyright © 2010 by Sociedade Brasileira de Pediatria IntroductionCardiac failure and sudden death, the latter probably due to arrhythmias, remain the major causes of death in β-thalassemia major (TM). 1 Disease prognosis, however, has been modified with regular blood transfusions and iron chelation therapy with deferoxamine. 2 P-wave dispersion (PWD) is a simple electrocardiographic marker that has been reported to be associated with inhomogeneous and discontinuous propagation of sinus impulses. It has been defined as the difference between the maximum and the minimum P-wave duration. 3-4 Prolonged P-wave duration and increased PWD have been shown to carry an increased risk for atrial fibrillation. 4 Cardiomyopathy is associated with a four-to six-fold increase in the risk of developing atrial fibrillation. 5 The present study aimed to comparatively investigate these electrocardiographic markers in patients with β-TM and healthy control subjects for the early prediction of arrhythmia risk. MethodsThe study population consisted of two groups: Group I -81 children with β-TM; and group II -74 healthy children Peak mitral inflow velocities in early diastole (E) and after atrial contraction (A) were expressed as cm/s. Deceleration time of peak E filling velocity was measured in milliseconds.Overall LV diastolic dysfunction was defined as the presence of any abnormality of the mitral valve. Twelve-lead electrocardiogram (ECG) was recordedfor each patient and control subject at a rate of 50 mm/s.At the time of electrocardiographic recording, all subjects were in sinus rhythm and none were taking any type of antiarrhythmic agent. P-wave duration was measured manually by two of the investigators who were blinded to the participants' clinical status. All measurements were performed using calipers and magnifying lens to improve accuracy. The onset of P-wave was defined as the junctio...

Early electrocardiographic evaluation of atrial fibrillation risk in beta-thalassemia major patients

“…In literature, there are few studies about the electrocardiographic markers for the early detection of cardiac disease in patients with b-TM [31][32][33][34]. Nisli et al [13] showed an increased PD in b-TM children and supposed it could be related to depression of intra-atrial conduction due to atrial dilatation and increased sympathetic activity; however, their study presented some limitations: the restrictive diastolic filling pattern of b-TM patients and the lack evaluation of atrial dimension and iron deposition by cardiac magnetic resonance or tissue Doppler imaging. Myocardial iron content cannot be predicted from serum ferritin or liver iron, and conventional assessments of cardiac function can only detect those with advanced disease.…”

“…In previous studies, it was shown that PD prolongation is an independent risk factor for development of atrial fibrillation (AF) [11,12]. To our knowledge, little is still known about the influence of b-TM on PD [13]. The aim of our study was to evaluate the PD in b-TM patients with conserved systolic and diastolic functions.…”

Cardiac Iron Load and Novel P-Wave Measurements in Patients with Thalassemia Major: The role of P index and Interatrial Block

“…The generally accepted cut-off value for the Pd is above 40 ms, and for the P max it is above 120 ms of duration, and these values may predict AF development (16,19). Previously, prolongation of Pd in β-TM patients was described by Nisli et al (13), where an increased Pd was related to the depression of intra-atrial conduction due to atrial dilatation and increased sympathetic tone. However, their study did not evaluate diastolic functions and iron deposits using the cardiac T2*MRI, which may contribute to prolonged Pd.…”

“…Neither Pi nor IAB, reliable and novel markers of P wave abnormality, were examined in patients with β-TM. On the other hand, only two small studies have found increased Pd in patients with β-TM where Russo et al (12) have assessed the relationship between Pd and myocardial iron deposit as assessed by cardiac T2* magnetic resonance imaging (MRI) (12)(13).…”

Sustained Ventricular Tachycardia in a Patient with Thalassemia Major

“…7 In another study, β-thalassemia major patients, secondary to increased sympathetic activation and atrial dilatation, as a result of intra-atrial conduction delay, prolonged P-wave dispersion has been reported. 8 Ventricular arrhythmias, atrial arrhythmias in patients with thalassemia are rare and usually more resistant to antiarrhythmic therapy. Isma'eel et al, the incidence of ventricular late potentials on signal averaged ECG in patients with thalassemia is more than the normal individuals were determined.…”