Trends, burden, and impact of arrhythmia on cardiac amyloid patients: A 16-year nationwide study from 1999 to 2014

Background: Patients with cardiac amyloidosis (CA) have increased mortality, which can be explained in part by an increased risk of arrhythmias. The burden of arrhythmias in CA, their predictors, and impact on in-hospital outcomes remains unclear. The role of implantable cardioverter-defibrillators (ICD) in this population is also uncertain. Methods: We queried the National Inpatient Sample (NIS) using ICD-9-CM codes 277.39 and 425.7 to identify CA. Twelve common arrhythmias were extracted using appropriate, validated ICD-9-CM codes. ICD implantation was identified using procedure ICD-9 codes 37.94 to 37.98, 00.51 and 00.54. Results: There were a total of 145,920 CA hospitalizations between 1999 and 2014 in the United States and 56,199 (38.5%) of them were associated with arrhythmias. The prevalence of arrhythmias remained relatively constant from 41.5% in 1999 to 40.2% in 2014. The most common arrhythmia was atrial fibrillation (25.4%). In-patient mortality was significantly higher in CA patients with arrhythmias (10.4% vs 6.5%, P <.001). ICD implantation was performed in 1,381 (0.94%) patients with CA and analysis revealed an incremental trend in implantation over the study period (0.48% in 1999 to 0.65% in 2014). In-hospital mortality was significantly lower in patients who underwent ICD implantation (3.7% vs 8%; P =.0078). CA patients with arrhythmias also had an increased cost of hospitalization and length of stay ($65,046 ± 1,079 vs $53,322 ± 687 and 8.3 ± 0.1 vs 7.4 ± 0.1 days, respectively; P <.0001). Conclusion: Cardiac arrhythmias are common in patients with CA and are associated with worse in-hospital outcomes, increased length of stay, and cost of hospitalization.