Prophylactic pacemaker implantation in familial amyloid polyneuropathy

BACKGROUND Familial amyloid polyneuropathy (FAP) is an autosomic dominant disease with a high rate of conduction disorders and increased risk of sudden death. Prophylactic cardiac pacing may be considered in asymptomatic patients with FAP. However, the potential benefits are unknown. OBJECTIVE To document conduction disorders in a large series of FAP and the incidence of high-degree atrioventricular (AV) block in patients with prophylactic pacemaker (PM). METHODS From January 1999 to January 2010, 262 patients with FAP were retrospectively evaluated. Prophylactic PM was implanted in patients with His-ventricular interval >= 70 ms, His-ventricular interval >55 ms associated with a fascicular block, a first-degree AV block, or a Wenckebach anterograde point <= 100 beats/min. The spontaneous AV conduction was then analyzed by temporarily inhibiting the PM. RESULTS As compared with patients with prophylactic PM (n = 100) and patients implanted given a class I/IIa indication (n = 18), the patients who did not require PM (n = 144) were younger and displayed less severe cardiac involvement. Follow-up after prophylactic PM implantation was analyzed in 95 of the 100 patients over 45 +/- 35 months, and a high-degree AV block was documented in 24 of the 95 patients (25%). The risk of high-degree AV block was higher in patients with first-degree AV block or Wenckebach anterograde point <= 100 beats/min (hazard ratio 3.5; 95% confidence interval 1.2-10) while microvoltage on surface electrocardiogram reduced the risk (hazard ratio 0.2; 95% confidence interval 0.1-0.7). CONCLUSION In FAP with conduction disorders, prophylactic PM implantation prevented major cardiac events in 25% of the patients over a 45-month mean follow-up. It is suggested that prophylactic PM implantation prevented symptomatic bradycardia in these patients.