Hemochromatosis

ECG 1: Sinus rhythm; bifid P wave, prolonged PR interval (first degree AV block); low QRS voltage in limb leads; repolarization disorders in the anterior leads with negative T waves from V2 to V6;

Comments: This patient with beta-thalassemia who underwent multiple transfusions presented with hemochromatosis with cardiac involvement. Hemochromatosis may be primary (autosomal recessive transmission) or secondary (repeated blood transfusions, cirrhosis, hepatitis C, etc.) and is characterized by iron tissue overload (hemosiderosis). Cardiac involvement usually occurs late after prolonged latency, and its incidence varies according to the cause (very common in patients with beta-thalassemia). The diagnosis of cardiac involvement is essentially based on Doppler echocardiography. Myocyte iron overload leads to a decrease in left ventricular distensibility with initially diastolic dysfunction and abnormal left ventricular filling. Later on, progression of the disease leads to ventricular dilatation with left ventricular systolic dysfunction without wall thickening.

In the presence of cardiac involvement, the electrocardiogram is usually abnormal with evidence of non-specific myocardial involvement. Alterations in repolarization, low QRS voltages, rhythmic and conduction disorders are observed in decreasing order of frequency.

• The changes in the T wave (inversion or flattening) are almost constant and of early onset; their topography is either diffuse or more often located anteriorly than laterally or posteriorly; the QT interval can be prolonged;
• A reduced voltage of the QRS complexes predominant in the limb branches is observed in approximately half of the cases and is an indicator of the evolution of the disease; the electrical pattern (association between low voltage and diffuse repolarization disorders) is quite similar to that observed in chronic pericarditis;
• Mostly supraventricular rhythm disorders are observed in about one third of patients (incidence increases with disease progression);
• Conduction disorders (atrioventricular block or bundle branch block) are relatively rare but may reveal the disease;

Take-home message: In a patient with hemochromatosis and cardiac involvement, the electrocardiogram may show a reduction in the voltage of the QRS complexes associated with non-specific repolarization disorders.