Introduction: Ceramides and sphingomyelins (sphingolipids) are circulating lipids involved in multiple physiological pathways relevant to heart failure (HF) and atrial fibrillation (AF), including apoptosis, oxidative stress, and inflammation. Experimental studies suggest that sphingolipids with different saturated fatty acids exhibit different biological activities, but their relationships with HF and AF are unknown.
Hypothesis: Higher levels of plasma ceramide and sphingomyelin that contain the fatty acid 16:0 are associated with higher risks of HF and AF; and higher levels of ceramides and sphingomyelins that contain the fatty acid 20:0, 22:0 or 24:0 are associated with lower risks.
Methods: We measured sphingolipids in the Cardiovascular Health Study (CHS) in plasma samples from 1994-95 (N=4026) or from 1992-93 (N=586). We assessed the separate associations of the levels of 8 sphingolipids with risks of incident HF and incident AF using Cox regression. A p-value threshold of 0.006 was used to account for multiple testing.
Results: Among 4,612 participants, 1179 incident HF and 1198 incident AF occurred during >40,000 person-years of follow-up. In adjusted analyses, higher levels of Cer-16 (ceramide with 16:0) and SM-16 (sphingomyelin with 16:0) were associated with higher risk of incident HF, but not with risk of incident AF (Table). In contrast, higher levels of Cer-20, Cer-22 and Cer-24 were each associated with lower risk of AF, but not with risk of HF. Higher levels of SM-20, SM-22, and SM-24 tended to be associated with lower risks of AF and HF, with only the association of SM-20 with AF significant.
Conclusions: Plasma levels of ceramide and sphingomyelin with 16:0 show different associations with HF and AF than species with 20:0, 22:0 or 24:0. Associations of Cer-16 and SM-16 specifically with higher risk of HF may be due to a role of apoptosis in HF. The novel findings that Cer-20, Cer-22, and Cer-24 are associated with lower risk of AF warrant further examination of the role of these sphingolipids in protecting from AF.