Optimisation of individual cardiovascular risk assessment in a German coronary artery disease cohort using a commercial test for genetic polymorphisms - a pilot study

BACKGROUND AND AIMS

Assessment of cardiovascular risk using established risk scores such as ESC SCORE2 or PROCAM insufficiently emphasise the role of genetic factors. We hypothesise that commercially available genetic assays may provide additional information on hereditary cardiovascular risk in a timely and cost-efficient manner.

METHODS

In a cohort of 51 patients treated for coronary artery disease (CAD) at University Hospital Heidelberg, Germany, a subgroup of patients with "unstable" CAD (i.e. recurrent acute coronary syndrome) was identified and compared to patients with "stable" disease (i.e. chronic coronary syndrome). Gene array analysis using a commercial assay for 15 potentially pathogenic polymorphisms revealed our cohort's genetic risk profile regarding atherosclerotic/thromboembolic events. Improvement of cardiovascular risk assessment based on established risk scores was analysed using net reclassification, logistic regression and receiver operating characteristic (ROC) analysis.

RESULTS

Discriminatory capacity of traditional risk scores such as SCORE2 or PROCAM with regard to stable and unstable CAD groups was poor (ROC AUC <0.5). Patients with "unstable" CAD exhibited a significantly increased frequency of pathogenic eNOS 894 T and MTHFR 1298 C polymorphisms compared to "stable" CAD patients, and information on these polymorphisms individually as well as combinations with additional polymorphisms included in the assay such as ACE D/D or PAI-1 5 G variants markedly improved risk prediction compared to SCORE2/PROCAM alone (ROC AUC ≥0.75).

CONCLUSION

Commercially available assays for genetic polymorphisms may provide valuable information on individual genetic cardiovascular risk, potentially guiding future primary and/or secondary preventative therapies for coronary artery disease.

Identification of Specific Coronary Artery Disease Phenotypes Implicating Differential Pathophysiologies

Background and Aims

The roles of multiple risk factors of coronary artery disease (CAD) are well established. Commonly, CAD is considered as a single disease entity. We wish to examine whether coronary angiography allows to identify distinct CAD phenotypes associated with major risk factors and differences in prognosis.

Methods

In a cohort of 4,344 patients undergoing coronary angiography at Heidelberg University Hospital between 2014 and 2016, cluster analysis of angiographic reports identified subgroups with similar patterns of spatial distribution of high-grade stenoses. Clusters were independently confirmed in 3,129 patients from the LURIC study.

Results

Four clusters were identified: cluster one lacking critical stenoses comprised the highest percentage of women with the lowest cardiovascular risk. Patients in cluster two exhibiting high-grade stenosis of the proximal RCA had a high prevalence of the metabolic syndrome, and showed the highest levels of inflammatory biomarkers. Cluster three with predominant proximal LAD stenosis frequently presented with acute coronary syndrome and elevated troponin levels. Cluster four with high-grade stenoses throughout had the oldest patients with the highest overall cardiovascular risk. All-cause and cardiovascular mortality differed significantly between the clusters.

Conclusions

We identified four phenotypic subgroups of CAD bearing distinct demographic and biochemical characteristics with differences in prognosis, which may indicate multiple disease entities currently summarized as CAD.

Extracellular vesicles in cardiovascular calcification: expanding current paradigms

Vascular calcification is a major contributor to the progression of cardiovascular disease, one of the leading causes of death in industrialized countries. New evidence on the mechanisms of mineralization identified calcification-competent extracellular vesicles (EVs) derived from smooth muscle cells, valvular interstitial cells and macrophages as the mediators of calcification in diseased heart valves and atherosclerotic plaques. However, the regulation of EV release and the mechanisms of interaction between EVs and the extracellular matrix leading to the formation of destabilizing microcalcifications remain unclear. This review focuses on current limits in our understanding of EVs in cardiovascular disease and opens up new perspectives on calcific EV biogenesis, release and functions within and beyond vascular calcification. We propose that, unlike bone-derived matrix vesicles, a large population of EVs implicated in cardiovascular calcification are of exosomal origin. Moreover, the milieu-dependent loading of EVs with microRNA and calcification inhibitors fetuin-A and matrix Gla protein suggests a novel role for EVs in intercellular communication, adding a new mechanism to the pathogenesis of vascular mineralization. Similarly, the cell type-dependent enrichment of annexins 2, 5 or 6 in calcifying EVs posits one of several emerging factors implicated in the regulation of EV release and calcifying potential. This review aims to emphasize the role of EVs as essential mediators of calcification, a major determinant of cardiovascular mortality. Based on recent findings, we pinpoint potential targets for novel therapies to slow down the progression and promote the stability of atherosclerotic plaques.

Discoidin Domain Receptor-1 Regulates Calcific Extracellular Vesicle Release in Vascular Smooth Muscle Cell Fibrocalcific Response via Transforming Growth Factor-β Signaling

OBJECTIVE

Collagen accumulation and calcification are major determinants of atherosclerotic plaque stability. Extracellular vesicle (EV)-derived microcalcifications in the collagen-poor fibrous cap may promote plaque rupture. In this study, we hypothesize that the collagen receptor discoidin domain receptor-1 (DDR-1) regulates collagen deposition and release of calcifying EVs by vascular smooth muscle cells (SMCs) through the transforming growth factor-β (TGF-β) pathway.

APPROACH AND RESULTS

SMCs from the carotid arteries of DDR-1(-/-) mice and wild-type littermates (n=5-10 per group) were cultured in normal or calcifying media. At days 14 and 21, SMCs were harvested and EVs isolated for analysis. Compared with wild-type, DDR-1(-/-) SMCs exhibited a 4-fold increase in EV release (P<0.001) with concomitantly elevated alkaline phosphatase activity (P<0.0001) as a hallmark of EV calcifying potential. The DDR-1(-/-) phenotype was characterized by increased mineralization (Alizarin Red S and Osteosense, P<0.001 and P=0.002, respectively) and amorphous collagen deposition (P<0.001). We further identified a novel link between DDR-1 and the TGF-β pathway previously implicated in both fibrotic and calcific responses. An increase in TGF-β1 release by DDR-1(-/-) SMCs in calcifying media (P<0.001) stimulated p38 phosphorylation (P=0.02) and suppressed activation of Smad3. Inhibition of either TGF-β receptor-I or phospho-p38 reversed the fibrocalcific DDR-1(-/-) phenotype, corroborating a causal relationship between DDR-1 and TGF-β in EV-mediated vascular calcification.

CONCLUSIONS

DDR-1 interacts with the TGF-β pathway to restrict calcifying EV-mediated mineralization and fibrosis by SMCs. We therefore establish a novel mechanism of cell-matrix homeostasis in atherosclerotic plaque formation.