High prevalence of raised lipoprotein(a) in patients with refractory angina

Association of KATP variants with CMD and RAP in CAD patients with increased serum lipoprotein(a) levels

CONTEXT

Refractory angina pectoris (RAP) is a specific subtype of coronary artery disease (CAD). Lipoprotein(a) [Lp(a)] and its induced coronary microvascular dysfunction (CMD) play an important role in pathogenesis of RAP, but its metabolism was mostly genetically determined. ATP-sensitive potassium channels (KATP) is involved in lipid metabolism and microvascular homeostasis, and becomes a promising target for the management of Lp(a) and its related RAP.

OBJECTIVE

To investigate associations of KATP variants with hyperlipoprotein(a)emia, CMD and RAP in CAD patients.

DESIGN, PATIENTS, SETTINGS

A total of 1,148 newly diagnosed CAD patients were prospectively selected, and divided into control [Lp(a) < 180 mg/dL] and case [Lp(a) ≥ 180 mg/dL, hyperlipoprotein(a)emia] group.

METHODS

9 KATP variants were genotyped by MassARRAY system. The expression profile of exosome-derived microRNAs (exo-miRs) was identified by next-generation sequencing, and the expression levels of differentially expressed exo-miRs were evaluated by qRT-PCR in verification cohort.

RESULTS

Three KATP variants were associated with increased risk of hyperlipoprotein(a)emia in CAD patients as follows: rs2285676 (AA + GA genotype, adjusted OR = 1.44, 95% CI: 1.10-1.88, P = 0.008), rs1799858 (CC genotype, adjusted OR = 1.33, 95% CI: 1.03-1.73, P = 0.030), and rs141294036 (CC genotype, adjusted OR = 1.43, 95% CI: 1.10-1.87, P = 0.008). Only rs141294036 was associated with increased risk of CMD (CC genotype, adjusted OR = 1.62, 95% CI: 1.23-2.13, P = 0.001), and further with increased RAP risk (CC genotype, adjusted HR = 2.05, 95% CI: 1.22-3.43, P = 0.007) after median follow-up of 50.6-months. Between the two genotypes of rs141294036, 152 exo-miRs were significantly differentially expressed, only 10 exo-miRs (miR-7110-3p, miR-548az-5p, miR-214-3p, let-7i-5p, miR-218-5p, miR-128-3p, miR-378i, miR-625-3p, miR-128-1-5p and miR-3187-3p) were further confirmed in RAP patients with hyperlipoprotein(a)emia and CMD.

CONCLUSION

KATP rs141294036 may serve a potential genetic marker for hyperlipoprotein(a)emia, CMD and RAP in CAD patients.

Lipoprotein(a): the underutilized risk factor for cardiovascular disease

Raised lipoprotein(a) [Lp(a)] is an important independent cardiovascular risk factor and predictor of adverse outcomes. Challenges remain with regards to the screening, diagnosis and management of this condition. Although further prospective randomised controlled data is required, there is growing evidence suggesting that lowering Lp(a) may reduce the risk of cardiovascular events and ameliorate symptoms.

Apheresis as novel treatment for refractory angina with raised lipoprotein(a): a randomized controlled cross-over trial

Aims

To determine the clinical impact of lipoprotein apheresis in patients with refractory angina and raised lipoprotein(a) > 500 mg/L on the primary end point of quantitative myocardial perfusion, as well as secondary end points including atheroma burden, exercise capacity, symptoms, and quality of life.

Methods

We conducted a single-blinded randomized controlled trial in 20 patients with refractory angina and raised lipoprotein(a) > 500 mg/L, with 3 months of blinded weekly lipoprotein apheresis or sham, followed by crossover. The primary endpoint was change in quantitative myocardial perfusion reserve (MPR) assessed by cardiovascular magnetic resonance. Secondary endpoints included measures of atheroma burden, exercise capacity, symptoms and quality of life.

Results

The primary endpoint, namely MPR, increased following apheresis (0.47; 95% CI 0.31-0.63) compared with sham (-0.16; 95% CI - 0.33-0.02) yielding a net treatment increase of 0.63 (95% CI 0.37-0.89; P < 0.001 between groups). Improvements with apheresis compared with sham also occurred in atherosclerotic burden as assessed by total carotid wall volume (P < 0.001), exercise capacity by the 6 min walk test (P = 0.001), 4 of 5 domains of the Seattle angina questionnaire (all P < 0.02) and quality of life physical component summary by the short form 36 survey (P = 0.001).

Conclusion

Lipoprotein apheresis may represent an effective novel treatment for patients with refractory angina and raised lipoprotein(a) improving myocardial perfusion, atheroma burden, exercise capacity and symptoms.