Mediation effect analysis of lipoprotein levels on BMI and cardiovascular outcomes in patients with heart failure.

BACKGROUND

Among heart failure patients with obesity, the prognosis is better than those with normal weight, a phenomenon known as the obesity paradox. However, it is unclear whether lipoprotein levels play a mediating role in the machine of the obesity paradox.

METHODS

The study included 1663 heart failure patients hospitalized from January, 2019 through August, 2022. Kaplan-Meier survival analysis and Log-rank tests were performed for three endpoints in order to determine cumulative event-free survival. We investigated the correlation between Body Max Index (BMI) and outcomes by multifactorial Cox models. Mediation analysis was applied to study the presence and magnitude of mediation effects of triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoprotein A1 and apolipoprotein B, with the association between BMI and endpoints.

RESULTS

In MACCEs, the median follow-up period was 679 days. In Cox model, compared with the underweight group, a high BMI level was significantly associated with lower all-cause mortality (HR=0.47, 95%CI 0.31~0.69, p<0.001, obese vs underweight), cardiovascular mortality (HR=0.46, 95%CI 0.30~0.73, p<0.001, obese vs underweight) and the incidence of MACCEs (HR=0.68, 95%CI 0.53~0.88, p=0.003, obese vs underweight). Mediation analysis revealed that TG was the strongest mediator between BMI and endpoints, with proportions of mediated effects of 6.6% (95%CI 2.2%~18.0%, p=0.0258, in all-cause death),7.0% (95%CI 2.3%~18.9%, p=0.0301, in cardiovascular death) and 10.2% (95%CI 3.3%~27.4%, p=0.0185, in MACCEs).

CONCLUSIONS

There is an "obesity paradox" in patients with heart failure, and lipoprotein levels especially triglyceride mediate the association between BMI and cardiovascular outcomes.