The role of the atrial electromechanical delay in predicting atrial fibrillation in beta-thalassemia major patients.

BACKGROUND: Paroxysmal atrial tachyarrhythmias frequently occur in beta-thalassemia major (ß-TM) patients. The aim of the current study was to evaluate the atrial electromechanical delay (AEMD) in a large ß-TM population with normal cardiac function and its relationship to atrial fibrillation (AF) onset. METHODS: Eighty ß-TM patients (44 men, 36 women), with a mean age of 36.2 ± 11.1 years, and 80 healthy subjects used as controls, matched for age and gender, were studied for the occurrence of AF during a 5-year follow-up, through 30-day external loop recorder (ELR) monitoring performed every 6 months. Intra-AEMD and inter-AEMD of both atria were measured through tissue Doppler echocardiography. P-wave dispersion (PD) was carefully measured using 12-lead electrocardiogram (ECG). RESULTS: Compared to the healthy control group, the ß-TM patients showed a statistically significant increase in inter-AEMD, intra-left AEMD, maximum P-wave duration, and PD. Dividing the ß-TM group into two subgroups (patients with or without AF), the inter-AEMD, intra-left AEMD, maximum P-wave duration, and PD were significantly higher in the subgroup with AF compared to the subgroup without AF. There were significant good correlations of intra-left AEMD and inter-AEMD with PD. A cut-off value of 40.1 ms for intra-left AEMD had a sensitivity of 76.2% and a specificity of 97.5% in identifying ß-TM patients with AF risk. A cut-off value of 44.8 ms for inter-AEMD had a sensitivity of 81.2% and a specificity of 98.7% in identifying this category of patients. CONCLUSIONS: Our results showed that the echocardiographic atrial electromechanical delay indices (intra-left and inter-AEMD) and the PD were significantly increased in ß-TM subjects with normal cardiac function. PD and AEMD represent non-invasive, inexpensive, useful, and simple parameters to assess the AF risk in ß-TM patients.

Atrial Fibrillation and Beta Thalassemia Major: The Predictive Role of the 12-lead Electrocardiogram Analysis.

BACKGROUND: Paroxysmal atrial tachyarrhythmias frequently occur in beta-thalassemia major (ß-TM) patients.The aim of our study was to investigate the role of maximum P-wave duration (P max) and dispersion (PD), calculated trough a new manually performed measurement with the use of computer software from all 12-ECG-leads,as predictors of atrial-fibrillation (AF) in ß-TM patients with conserved systolic or diastolic cardiac function during a twelve-months follow-up. MATERIALS AND METHODS: 50 ß-TM-patients (age38.4±10.1; 38M) and 50-healthy subjects used as controls, matched for age and gender, were studied for the occurrence of atrial arrhythmias during a 1-year follow-up, through ECG-Holter-monitoring performed every three months. The ß-TM-patients were divided into two groups according to number and complexity of premature-supraventricular-complexes at the Holter-Monitoring (Group1: <30/h and no repetitive forms, n:35; Group2: >30/h or couplets, or run of supraventricular tachycardia and AF, n:15). RESULTS: Compared to the healthy control-group, ß-TM patients presented increased P-max (107.5± 21.2 vs 92.1±11ms, P=0.03) and PD-values (41.2±13 vs 25.1±5 ms,P=0.03). In the ß-TM population, the Group2 showed a statistically significant increase in PD (42.8±8.6 vs 33.2±6.5ms, P<0.001) and P-max (118.1±8.7 vs 103.1±7.5ms, P<0.001) compared to the Group1. Seven ß-TM patients who showed paroxysmal AF during this study had significantly increased P-max and PD than the other patients of the Group2. Moreover, P-max (OR:2.01; CI:1.12-3.59; P=0.01) and PD (OR=2.06;CI:1.17-3.64;P=0.01) demonstrated a statistically significant association with the occurrence of paroxysmal AF,P min was not associated with AF-risk (OR=0.99; CI:0.25-3.40; P=0.9) in ß-TM-patients. A cut-off value of 111ms for P-max had a sensitivity of 80% and a specificity of 87%, a cut-off value of 35.5ms for PD had a sensitivity of 90% and a specificity of 85% in identifying ß-TM patients at risk for AF. CONCLUSION: Our results indicate that P-max and PD are useful electrocardiographic markers for identifying the ß-TM-high-risk patients for AF onset, even when the cardiac function is conserved.

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

Although previous studies have documented a variety of electrocardiogram abnormalities in beta-thalassemia major (ß-TM), little is known about P-wave dispersion (PD), an independent risk factor for development of atrial fibrillation. The aim of our study was to evaluate PD in ß-TM patients with conserved systolic and diastolic functions. The study involved 40 ß-TM patients (age 37.5 ± 10.2; 33 M) and 40 healthy subjects used as controls, matched for age and gender. PD was carefully measured using a 12-lead electrocardiogram. Cardiac iron levels were measured by cardiac magnetic resonance T2 star (CMR T2*) imaging. Comparing to the healthy control group, ß-TM group presented increased values of the PD (40.1 ± 12.9 vs. 24 ± 7 ms; P < 0.004) and decreased CMR T2* imaging (29 ± 15 vs. 55 ± 13 ms; P = 0.03). We found a significant correlation between PD and CMR T2* values. Our study showed a significant increase of PD in ß-TM patients with conserved systolic and diastolic cardiac functions. Our results indicate that PD is correlated to myocardial iron deposit, as assessed by CMR T2* imaging.

Dispersion of repolarization and beta-thalassemia major: the prognostic role of QT and JT dispersion for identifying the high-risk patients for sudden death.

BACKGROUND: Patients with beta-thalassemia major (ß-TM) are at increased risk for sudden cardiac death (SCD). Heterogeneity of ventricular repolarization is considered to provide an electrophysiological substrate for malignant arrhythmias. QT dispersion (QTc-D) and JT dispersion (JTc-D) are electrocardiographic parameters indicative of heterogeneity of ventricular repolarization. The aim of our study was to evaluate the heterogeneity of ventricular repolarization in patients with beta-thalassemia and to test the hypothesis that an abnormal QTc and JTc dispersion may predict SCD in this population. MATERIALS AND METHODS: The study involved 51 patients with ß-TM (age 33.9±8.4; 33M) and 51 healthy subjects used as controls, matched for age, gender, and body mass index (BMI). Among the ß-TM group, 14 patients with ß-TM (age 27±6.64; 11M) died from SCD during follow-up. For each patient, QTD and JTD intervals were calculated. RESULTS: Compared to the healthy control group, ß-TM group presented increased values of the QTc-D (65.36±33.95 vs. 37, 62±17.65; P<0.003) and JTc-D (74.64±33.27 vs. 40.32±12.45; P<0.001). In the ß-TM sudden death group, QTc-D and JTc-D were significantly greater than in survived ß-TM group (92.70±44.24 vs. 56.14±23.80, P=0.0001; 101.54±47.93 vs. 64.47±17.90, P=0.0001). A cutoff value of 70ms for QTc-D had a sensitivity and specificity of 77% in identifying patients at risk for SCD. A cutoff value of 100ms for JTc-D had a sensitivity of 65% and a specificity of 94% in identifying this category of patients. CONCLUSION: ß-TM is associated with significant changes in heterogeneity of ventricular repolarization. QTc and JTc dispersion are useful markers of risk of SCD in patients with ß-TM.

Guideline recommendations for heart complications in thalassemia major.

Thalassemia major is an inherited hemoglobin disorder resulting in a chronic hemolytic anemia. Transfusion therapy together with elevated gastrointestinal absorption of iron determines iron overload, which causes most of the mortality and morbidity associated with the disease. Heart complications represent the leading cause of mortality in this disease, although, because of an improvement in chelation treatment, an important and progressive increase of life expectancy mainly as a result of a reduction in mortality due to cardiac dysfunction has been demonstrated in recent years. Clinical pictures of heart damage range from the involvement of the ventricles to pulmonary hypertension or symptomatic ventricular or supra-ventricular arrhythmias. For this reason, the possibility of having specific recommendations is noteworthy. These recommendations outline the definition, the follow-up and the treatment of the main heart complications in this group of patients. The identification of topics and the nomination of the committee were made on behalf of the Society for the Study of Thalassemia and Hemoglobinopathies (SoSTE). The document obtained the auspices of ANMCO, SIC, SIRM and the Cardiovascular Magnetic Resonance Working Groups of the ANMCO, SIC and SIRM. All recommendations provided in this document have been performed according to the American Cardiology College (ACC) and American Heart Association (AHA) guidelines. Moreover, the recommendations were reviewed by two external referees before the definitive approval.