Prevalence, Severity, and Prognostic Value of Sleep Apnea Syndromes in Cardiac Amyloidosis

Study Objectives: To assess prevalence, severity, and prognostic value of sleep-disordered breathing (SDB), in the three main cardiac amyloidosis (CA) types, i.e., light-chain (AL), transthyretin-related familial (m-TTR), or senile (WT-TTR). Methods: Patients consecutively referred for CA diagnosis work-up underwent cardiac assessment and nocturnal polygraphy. SDB was defined as apnea-hypopnea index (AHI) >= 5/h. Multivariate analysis was used to identify predictors of a major adverse cardiac event (MACE) defined as death, heart transplantation and acute heart failure. Results: Seventy CA patients were included (31 AL, 22 m-TTR, 17 WT-TTR). The mean +/- standard deviation age and left ventricular ejection fraction were 71 +/- 12 years and 49% +/- 13% and median (interquartile range) N terminal pro brain natriuretic peptide (NT-proBNP) was 3,932 (1,607; 7,028) pg/mL. The prevalence of SDB was 90% without difference between amyloidosis types. SDB was central in 27% and obstructive in 73%. AL had less frequent severe SDB compared to m-TTR and WT-TTR (P = 0.015) but longer time with peripheral capillary oxygen saturation (SpO(2)) < 90% (P = 0.037). After a median follow-up of 7.5 (2.8; 14.9) months, 49% patients experienced MACE. Time with nocturnal SpO(2) < 90% was the only independent predictor of MACE. The best-identified threshold was 30 min. Values > 30 min were associated with bad prognosis (Log-rank chi(2): 8.01, P value = 0.005). Using binomial logistic regression, determinants of time with nocturnal SpO(2) < 90% were New York Heart Association class (P = 0.011), and log-NT-proBNP (P = 0.04) but not AHI. Conclusions: In CA population, prevalence of SDB is high (90%) and dominated by the obstructive pattern. Bad prognosis in this population was driven by nocturnal desaturation, reflecting heart failure severity and respiratory involvement.