ABSTRACT
The association between elevated lipoprotein(a) [Lp(a)] and poor outcomes in coronary
artery disease (CAD) has been addressed for decades. However, little is known about
the prognostic value of Lp(a) in patients with myocardial infarction with nonobstructive
coronary arteries (MINOCA). A total of 1179 patients with MINOCA were enrolled and
divided into low, medium, and high Lp(a) groups based on the cut-off value of 10 and
30mg/dL. The primary endpoint was major adverse cardiovascular events (MACE), a composite
of all-cause death, nonfatal MI, nonfatal stroke, revascularization, and hospitalization
for unstable angina or heart failure. Kaplan-Meier and Cox regression analyses were
performed. Accuracy was defined as area under the curve (AUC) using a receiver-operating
characteristic analysis. Patients with higher Lp(a) levels had a significantly higher
incidence of MACE (9.5%, 14.6%, 18.5%; p = 0.002) during the median follow-up of 41.7
months. The risk of MACE also increased with the rising Lp(a) levels even after multivariate
adjustment [low Lp(a) group as reference, medium group: hazard ratio (HR) 1.55, 95%
confidence interval (CI): 1.02-2.40, p = 0.047; high group: HR 2.07, 95% CI: 1.32-3.25,
p = 0.001]. Further, clinically elevated Lp(a) defined as Lp(a) ≥30 mg/dL was closely
associated with an increased risk of MACE in overall and in subgroups (all p <0.05).
When adding Lp(a) (AUC 0.61) into the Thrombolysis in Myocardial Infarction (TIMI)
score (AUC 0.68), the combined model (AUC 0.73) yielded a significant improvement
in discrimination for MACE (ΔAUC 0.05, p = 0.032). In conclusion, elevated Lp(a) was
strongly associated with a poor prognosis in patients with MINOCA. Adding Lp(a) to
traditional risk score further improved risk prediction. Our data, for the first time,
confirmed the Lp(a) as a residual risk factor for MINOCA.