Association between a reduction in triglyceride levels and risk of cardiovascular events.

Background: Previous analyses have reported that low triglyceride (TG) levels were associated with a reduced risk of cardiovascular events in a primary prevention cohort. However, it remains unclear whether a reduction in TG levels directly contributes to cardiovascular risk reduction. Objective: To investigate whether a reduction in TG levels is associated with a decreased risk of cardiovascular events in primary and secondary prevention cohorts. Methods: This retrospective study was conducted with a nationwide health insurance claims database, with medical checkups between January 2005 and August 2020 in Japan. We included patients with baseline TG levels ≥150 mg/dL and classified them into primary or secondary prevention of cardiovascular events. TG levels at one year were used to stratify patients into four groups: low (≤100 mg/dL), normal (100-149 mg/dL), high (150-499 mg/dL), and very high (≥500 mg/dL). The primary outcome was major adverse cardiovascular events (MACE). Results: In the primary prevention cohort, a reduction TG levels to ≤150 mg/dL was significantly associated with a reduced risk of MACE. No significant association was observed in the secondary prevention cohort. In subgroup analyses stratified by LDL-C target achievement, patients with elevated LDL-C showed a trend toward lower event risk with decreasing TG levels. Conclusion: A weak association was found between a reduction in TG levels and a reduced risk of cardiovascular events in the primary prevention population. However, prospective, randomized, placebo-controlled, and large cardiovascular outcomes trials are needed to prove that substantial reductions in TG levels correlate with cardiovascular event risk reduction.