Discordance between LDL cholesterol and apolypoprotein B. Which to prefer to guide treatment?

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Current cardiovascular risk guidelines recommend target values of low-density lipoprotein cholesterol (LDLc) < 55 mg/dL and apolipoprotein B (apoB) < 65 mg/dL. However, they don’t clarify what the attitude should be when one of the two targets is not achieved. Our objective was to establish the prevalence of LDLc and ApoB discordance in a secondary prevention population in our cardiac rehabilitation unit and describe the size of LDLc particles in this cohort of patients. We conducted a retrospective observational study including patients with previous ischemic heart disease with lipid-lowering treatment in secondary prevention followed up in our cardiac rehabilitation unit between February 2022 and September 2022. We present a series of 100 patients with a mean age of 60.5 years (S.D. 9.7), 79% male, with high prevalence of cardiovascular risk factors (59% hypertension, 26% diabetes mellitus, 52% smokers). All patients received lipid-lowering therapies, with statins alone or in combination with Ezetimibe. 30 patients (30%) had LDLc > 55 mg/dL and ApoB < 65 mg/dL, 37 (37%) reached target LDL and ApoB levels (LDLc < 55 mg/dL and ApoB < 65 mg/dL), and 33 (33%) did not reach any of the target levels (LDLc > 55mg/dL and ApoB > 65 mg/dL). No patient had LDLc < 55mg/dL and ApoB > 65mg/dL. Among patients with ApoB target level achieved and LDLc > 55mg/dL, the mean LDLc/ApoB ratio was 1.1 (S.D. 0.1). The mean ratios stratified by LDLc level are represented in Figure 1 and specified in Table 1. The conclusion of our study is that in clinical practice we find a group of patients with discrepancy between LDLc and ApoB levels that is not represented in the main studies of cardiovascular outcomes. Therefore, we do not know what therapeutic approach we should take. It is known that these relatively high LDLc values when apoB is in range correspond to larger and less dense particles, and therefore less atherogenic, and it has been suggested that ApoB levels better reflect residual risk than LDLc in statin-treated patients. At this point, the question that arises is: should we take these patients to an LDL < 55mg/dL or is their lipid risk controlled?