Lipoprotein(a)-hyperlipoproteinemia as cause of chronic spinal cord ischemia resulting in progressive myelopathy - successful treatment with lipoprotein apheresis

Burden of elevated lipoprotein(a) among patients with atherosclerotic cardiovascular disease: Evidence from a systematic literature review and feasibility assessment of meta-analysis

BACKGROUND

Elevated lipoprotein(a) [Lp(a)] level is an independent genetic risk factor that increases the risk of atherosclerotic cardiovascular disease (ASCVD) by 2-4 fold. We aimed to report the burden of clinically relevant elevated Lp(a) in secondary prevention ASCVD population as the evaluation of such evidence is lacking.

METHODS

A systematic literature review (SLR) was conducted using Embase®, MEDLINE®, and MEDLINE® In-Process databases to identify studies reporting burden of elevated Lp(a) levels from January 1, 2010, to March 28, 2022. Full-text, English-language studies including ≥500 participants with ≥1 Lp(a) assessment were included.

RESULTS

Sixty-one studies reported clinical burden of elevated Lp(a). Of these, 25 observational studies and one clinical trial reported clinical burden of clinically relevant elevated Lp(a) levels. Major clinical outcomes included major adverse cardiovascular event (MACE; n = 20), myocardial infarction (MI; n = 11), revascularization (n = 10), stroke (n = 10), cardiovascular (CV) mortality (n = 9), and all-cause mortality (n = 10). Elevated Lp(a) levels significantly increased the risk of MACE (n = 15) and revascularization (n = 8), while they demonstrated a trend for positive association with remaining CV outcomes. Meta-analysis was not feasible for included studies due to heterogeneity in Lp(a) thresholds, outcome definitions, and patient characteristics. Three studies reported humanistic burden. Patients with elevated Lp(a) levels had higher odds of manifesting cognitive impairment (odds ratio [OR] [95% confidence interval; CI]: 1.62 [1.11-2.37]) and disability related to stroke (OR [95% CI]:1.46 [1.23-1.72)]) (n = 2). Elevated Lp(a) levels negatively correlated with health-related quality of life (R = -0.166, p = 0.014) (n = 1). A single study reported no association between elevated Lp(a) levels and economic burden.

CONCLUSIONS

This SLR demonstrated a significant association of elevated Lp(a) levels with major CV outcomes and increased humanistic burden in secondary prevention ASCVD population. These results reinforce the need to quantify and manage Lp(a) for CV risk reduction and to perform further studies to characterize the economic burden.

A role for spinal cord hypoxia in neurodegeneration

The vascular system of the spinal cord is particularly complex and vulnerable. Damage to the main vessels or alterations to the regulation of blood flow will result in a reduction or temporary cessation of blood supply. The resulting tissue hypoxia may be brief: acute, or long lasting: chronic. Damage to the vascular system of the spinal cord will develop after a traumatic event or as a result of pathology. Traumatic events such as road traffic accidents, serious falls and surgical procedures, including aortic cross-clamping, will lead to an immediate cessation of perfusion, the result of which may not be evident for several days, but may have long-term consequences including neurodegeneration. Pathological events such as arterial sclerosis, venous occlusion and spinal cord compression will result in a progressive reduction of blood flow, leading to chronic hypoxia. While in some situations the initial pathology is exclusively vascular, recent research in neurodegenerative disease has drawn attention to concomitant vascular anomalies in disorders, including amyotrophic lateral sclerosis, spinal muscular atrophy and muscular sclerosis. Understanding the role of, and tissue response to, chronic hypoxia is particularly important in these cases, where inherent neural damage exacerbates the vulnerability of the nervous system to stressors including hypoxia.