Cardiac Stimulation Threshold in Familial Amyloidosis with Polyneuropathy

It has been suggested that a higher cardiac stimulation threshold reduces the applicabilty of pacemaker therapy in cardiac amyloidosis. We therefore reviewed threshold data in patients with familial amyloidosis with polyneuropathy (FAP), which is an inherited type of systemic amyloidosis, invariably involving the heart. Fourteen FAP patients treated with a pacemaker were studied. The mean (±SD) voltage stimulation threshold during implantation was 1.0 ± 0.5 V, and noninvasive follow-up 6 months later revealed a mean Vario threshold of 1.9 ± 0.5 V. Beyond this time, the threshold tended to be stable, and high threshold exit block did not occur in any patient. Several FAP patients did show a moderately elevated threshold, and a multiprogrammable pulse generator with a high output capability is recommended when pacemaker therapy is considered in these patients.