Lipoprotein (a) Levels and Abdominal Aortic Aneurysm. A Systematic Review and Meta-analysis.

BACKGROUND: Several studies have linked high Lipoprotein (a) (Lp(a)) concentrations to cardiovascular events, including the formation of Abdominal Aortic Aneurysms (AAA). We review and meta-analyze existing evidence on the association of Lp(a) levels with AAA. METHODS: Studies evaluating the link of Lp(a) with AAA, up to December 27th 2021, were identified by a systematic search of PubMed, SCOPUS, and Web of Science databases. The results were qualitatively and quantitatively synthesized according to PRISMA guidelines. Results are presented as standardized mean differences (SMD) with 95% confidence intervals (CI). RESULTS: A total of 5,078 subjects (1,637 patients with AAA vs. 3,441 controls) from 11 studies were included in the meta-analysis, with a mean age of 69.9 years and a male sex prevalence of 85.8%. Based on the qualitative synthesis, high Lp(a) concentrations are linked to abdominal aortic wall degradation and extracellular matrix disarrangement. Moreover, despite the considerable variability among races, high Lp(a) levels are related to increased AAA risk, independently of race differences. Accordingly, patients with AAA displayed significantly higher Lp(a) levels compared to controls (SMD: 0.86, 95% CI: 0.55-1.17, p < 0.001). The outcome was not affected in a sensitivity analysis excluding three outlying studies (SMD: 0.40, 95% CI: 0.22-0.58, p < 0.001). CONCLUSION: This meta-analysis indicates the association between high Lp(a) levels and the presence of AAA, although existing literature presents high heterogeneity. Further studies are needed to standardize Lp(a) measurements and to conclude whether Lp(a) can be used as a sensitive biomarker of early presymptomatic AAA diagnosis.

Polycythemia Vera in a Patient With Heterozygous Beta-Thalassemia: Coincidence or Causal Relationship?

Polycythemia vera (PV) and heterozygous beta-thalassemia (HBT) have opposing effects on the hematocrit (Hct) and may mask the presence of each other. Missing the diagnosis of PV may have serious consequences, mainly by exposing the patient to the risk of thromboses. We present a case where the diagnosis of PV was delayed due to the coexistence of HBT, and review the relevant literature. It can be postulated that "stress erythropoiesis", known to occur in patients with thalassemic syndromes, increases the probability of somatic JAK2 mutations leading to development of PV.