Correlation between Mean Serum Ferritin Levels and Atrial Electrocardiographic Markers in Beta-Thalassemia Major

Background: Atrial fibrillation (AF) is the most common arrhythmia in patients with β-thalassemia major (β-TM) due to cardiac iron overload. AF may be predicted by changes in P wave parameters. The aim of this study was to evaluate the correlation between P-wave parameters and atrial markers with mean serum ferritin levels measured yearly. Methods: Fifty patients with β-TM and 50 healthy subjects as control group were enrolled in the study. Both groups underwent electrocardiography (ECG) and echocardiography. P-wave dispersion (PWd), maximum and minimum P-wave duration (P-max and P-min) were measured. Echocardiography was performed by pulse wave Doppler of the lateral mitral valve. Annual mean serum ferritin level was calculated through monthly sampling. Results: There were 22 men and 28 women with β-TM (mean age: 21.4±8.3 years). Mean serum ferritin levels were 1476.8±919.2 ng/ml. Systolic and diastolic blood pressure were significantly different between thalassemia and control groups (P<0.002 and P<0.004, respectively). There were significant differences between BMI, PWd, P-max and P-min (P<0.0001, respectively). A cut off value of 40 msec for PWd had a sensitivity of 100% and a specificity of 90.7% in identifying mean serum ferritin levels higher than 1078 ng/ml. Mean serum ferritin level of 1024 or more was associated with sensitivity of 100% and specificity of 90.1% for inter-atrial block > 110 msec. There were correlations between mean serum ferritin level and age of the patients along with PWd, P-min and P-max (P<0.0001, respectively). Conclusion: In β-TM, atrial parameters in ECG were correlated with both mean serum ferritin levels measured yearly and patients’ age. We recommend that in patients with thalassemia major with mean serum ferritin levels higher than 1000 ng/ml, P wave parameters should be carefully evaluated and closely followed.