Prognostic value of electrocardiographic low voltages in patients affected by AL amyloidosis AL amyloidosis is a systemic diseases characterized by extracellular deposition, in various tissues, of immunoglobulin (Ig) light chain or a Ig light chain fragment synthesized by clonal bone marrow plasma cells. Cardiac involvement is not only frequent but it is also the most common cause of death. The 12-leads electrocardiogram (ECG) reflects the infiltrative nature of this disease with low voltages in the limb leads, pseudoinfarction patterns and abnormalities of conduction such as fascicular block or varying degree atrioventricular block. In particular the presence of low voltages was defined as QRS voltage amplitude ≤0.5 mV in all limb leads. Besides confirming the importance of a simple, affordable and non-invasive tool such as ECG for the diagnose of cardiac AL amyloidosis, aim of the present study was to assess the potential prognostic role of low ECG voltages. We enrolled 126 consecutive never-treated subjects, in whom a first diagnosis of primary AL amyloidosis was concluded in 2009 at the Pavia Amyloidosis Center. The cohort was divided into two groups depending on the presence (n=86) or the absence (n=40) of cardiac involvement and, along with the staging system proposed by the Mayo Clinic, into 3 stages with different prognosis: STAGE 1 (n=24), STAGE 2 (n=46), STAGE 3 (n=56). Standard 12-leads ECG and cardiac echo-colorDoppler data were evaluated at diagnosis, and prognosis was assessed after a median follow up of 500 days. When compared with patients without myocardial involvement, cardiac AL patients showed a higher prevalence of low voltages (61.6% vs 17.5%, p<0.0001). Kaplan-Meier survival analysis revealed a significantly higher mortality in patients with low voltages when compared with patient without low voltages (p=0.0356). The same trend wasn’t confirmed in the group with cardiac involvement (p=0.613). This is most likely due to the fact that in this disease cardiac involvement is itself the most important and robust prognostic factor. The identification of low voltages allowed us to identify 2 subgroups with different prognosis inside STAGE 2. In detail 18-month survival was 55% for patients in STAGE 2 with low voltages as opposed to 88% for patients in the same stage but without low voltages. Beyond confirming the diagnostic value of the presence of low ECG voltages in patients affected by AL amyloidosis, these data demonstrate the prognostic value of such a simple parameter as a factor that, together with the Mayo staging system, can help patient stratification at diagnosis.
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