Body surface potential maps in patients with familial amyloid polyneuropathy

The purpose of this study was to evaluate the characteristics of body surface potential maps in patients with cardiac amyloidosis. The study population consisted of 30 patients with familial amyloid polyneuropathy and 50 age-matched normal volunteers. The patients were classified into one of the following three stages: stage I, peripheral neuropathy limited to the lower limbs; stage II, neuropathy involving both the lower and upper limbs; and stage III, bedridden because of extensive progressive neuropathy. Electrodes for the body surface potential maps were placed at 87 points (59 anterior and 28 posterior) on the chest. To analyze these body surface electrocardiograms, isopotential maps, isochrone maps, and isointegral maps were used. The mean values of the positive potential were significantly lower in the advanced stage (1.9 +/- 0.2 mV in stage I, 1.0 +/- 0.2 mV in stage II, and 0.7 +/- 0.2 mV in stage III). Prolongation of ventricular activation time was observed on the anterior and lateral chest. The mean QRST isointegral maps of the patients in the advanced stage of cardiac amyloidosis showed a large negative area over the anterior and left lateral chest, the positive areas were small and their potentials were very low. In addition, 18 (60%) of the 30 patients had a multipolar pattern in the QRST isointegral maps. The changes of the body surface potential maps correlated with clinical staging and echocardiographic findings.