Lp(a) tracks coronary complexity mainly in patients under 45 with premature MI, Northeast Indian cohort of 100 (Maedica Bucur 2026)

Background: Conventional lipid parameters may not adequately reflect coronary lesion complexity in myocardial infarction (MI), particularly in premature cases. Advanced lipid markers such as lipoprotein(a) [Lp(a)], apolipoprotein B (ApoB) and the ApoB/ApoA1 ratio may better represent atherogenic burden.

Aim: To evaluate the association between lipid parameters and SYNTAX score in patients with premature MI. An exploratory age-stratified analysis comparing patients aged <45 years and 45-55 years was additionally performed.

Methods: In this hospital-based cross-sectional study, consecutive MI patients aged ≤55 years with angiographically confirmed coronary artery disease (CAD) were enrolled. Blood samples were collected at admission prior to initiation of therapy for assessment of lipid profile, including Lp(a), ApoA1, ApoB and ApoB/ApoA1 ratio. SYNTAX score was categorized as low (≤22) or high (>22). Associations were analysed using Student's t-test, Spearman correlation, multivariate logistic regression and receiver operating characteristic (ROC) curve analysis.

Results: Among 100 patients (mean age 46.5 ± 6.2 years; 85% males), 37% had high SYNTAX scores as well as significantly higher Lp(a), ApoB and ApoB/ApoA1 ratio (p<0.01), while conventional lipid parameters were not significantly different. These associations appeared more pronounced among patients aged <45 years and formal interaction analysis provided additional evidence of an age-dependent relationship between Lp(a) and high SYNTAX score [interaction odds ratio (OR) 0.952, 95% confidence interval (CI) 0.917-0.989, p=0.011]. SYNTAX score correlated positively with Lp(a) (ρ=0.275, p=0.006), ApoB (ρ=0.347, p<0.001) and ApoB/ApoA1 ratio (ρ=0.352, p<0.001). In multivariable analysis, hypertension independently predicted high SYNTAX score (adjusted OR 3.46, p=0.012), whereas associations of advanced lipid markers were attenuated after multivariable adjustment. ROC analysis showed modest discriminative ability for Lp(a) (AUC 0.64, 95% CI: 0.52-0.77), with limited performance for ApoB and ApoB/ApoA1 ratio.

Conclusion: Advanced lipid markers, particularly Lp(a) and ApoB/ApoA1 ratio, were associated with greater angiographic complexity in premature MI. Exploratory analyses suggested stronger associations among patients aged <45 years, particularly for Lp(a), and formal interaction analysis further supported an age-dependent relationship between Lp(a) and high SYNTAX score. However, their modest discriminative ability and lack of independent association after multivariable adjustment suggest that these markers should be considered adjunctive indicators of atherogenic burden rather than standalone predictors.