Preprocedural circulating galectin-3 and the risk of mortality after transcatheter aortic valve replacement: a systematic review and meta-analysis

Galectin-3 is an independent predictor of postoperative atrial fibrillation and survival after elective cardiac surgery

BACKGROUND

Postoperative atrial fibrillation (POAF) is a frequent complication after heart surgery and is associated with thromboembolic events, prolonged hospital stay, and adverse outcomes. Inflammation and fibrosis are involved in the pathogenesis of atrial fibrillation.

OBJECTIVE

The purpose of this study was to assess whether galectin-3, which reflects preexisting atrial fibrosis, has the potential to predict POAF and mortality after cardiac surgery.

METHODS

Four hundred seventy-five consecutive patients (mean age 67.4 ± 11.8 years; 336 (70.7%) male) undergoing elective heart surgery at the Medical University of Vienna were included in this prospective single-center cohort study. Galectin-3 plasma levels were assessed on the day before surgery.

RESULTS

The 200 patients (42.1%) who developed POAF had significantly higher galectin-3 levels (9.60 ± 6.83 ng/mL vs 7.10 ± 3.54 ng/mL; P < .001). Galectin-3 significantly predicted POAF in multivariable logistic regression analysis (adjusted odds ratio per 1-SD increase 1.44; 95% confidence interval 1.15-1.81; P = .002). During a median follow-up of 4.3 years (interquartile range 3.4-5.4 years), 72 patients (15.2%) died. Galectin-3 predicted all-cause mortality in multivariable Cox regression analysis (adjusted hazard ratio per 1-SD increase 1.56; 95% confidence interval 1.16-2.09; P = .003). Patients with the highest-risk galectin-3 levels according to classification and regression tree analysis (>11.70 ng/mL) had a 3.3-fold higher risk of developing POAF and a 4.4-fold higher risk of dying than did patients with the lowest-risk levels (≤5.82 ng/mL).

CONCLUSION

The profibrotic biomarker galectin-3 is an independent predictor of POAF and mortality after cardiac surgery. This finding highlights the role of the underlying arrhythmogenic substrate in the genesis of POAF. Galectin-3 may help to identify patients at risk of POAF and adverse outcome after cardiac surgery.

Severe Aortic Valve Stenosis and Pulmonary Hypertension: A Systematic Review of Non-Invasive Ways of Risk Stratification, Especially in Patients Undergoing Transcatheter Aortic Valve Replacement

Patients with severe aortic valve stenosis and concomitant pulmonary hypertension show a significantly reduced survival prognosis. Right heart catheterization as a preoperative diagnostic tool to determine pulmonary hypertension has been largely abandoned in recent years in favor of echocardiographic criteria. Clinically, determination of echocardiographically estimated systolic pulmonary artery pressure falls far short of invasive right heart catheterization data in terms of accuracy. The aim of the present systematic review was to highlight noninvasive possibilities for the detection of pulmonary hypertension in patients with severe aortic valve stenosis, with a special focus on cardiovascular biomarkers. A total of 525 publications regarding echocardiography, cardiovascular imaging and biomarkers related to severe aortic valve stenosis and pulmonary hypertension were analyzed in a systematic database analysis using PubMed Central®. Finally, 39 publications were included in the following review. It was shown that the current scientific data situation, especially regarding cardiovascular biomarkers as non-invasive diagnostic tools for the determination of pulmonary hypertension in severe aortic valve stenosis patients, is poor. Thus, there is a great scientific potential to combine different biomarkers (biomarker scores) in a non-invasive way to determine the presence or absence of PH.

Galectin-3 promotes calcification of human aortic valve interstitial cells via the NF-kappa B signaling pathway

BACKGROUND

Calcific aortic valve disease (CAVD) is an active pathobiological process that takes place at the cellular and molecular levels. It involves fibrosis and calcification of aortic valve leaflets, which eventually contributes to heart failure. Galectin-3 (Gal-3), a β-galactoside-binding lectin, is involved in myocardial fibrosis and remodeling. Our study aimed to explore how Gal-3 promoted the osteogenic differentiation of human aortic valve interstitial cells (hVICs) along with elucidating the underlying molecular mechanisms.

METHODS

To determine the Gal-3 expression in this study, we included the blood samples and aortic valves (AVs) from patients with CAVD (n=20) and normal controls (n=20). The hVICs were stimulated by Osteogenic medium (OM) and were treated with or without recombinant human Gal-3. Calcified transformation of hVICs was assessed by Alizarin Red S staining and osteogenic gene/protein expression. RNA-sequencing was performed for all different treatments to investigate differentially expressed genes (DEGs) along with exploring the enriched pathways for potential molecular targets of Gal-3. The targets were further detected using Western blotting and immunofluorescence staining.

RESULTS

Gal-3 levels were found to be significantly increased in CAVD patients. Treatment of valve interstitial cells (VICs) with Gal-3 led to a marked increase in Runx2 and ALP-mRNA/protein expression levels as well as calcification. Gene expression profiles of hVICs cultured with or without Gal-3 revealed 79 upregulated genes and 82 down-regulated genes, which were highly enriched in TNF and NF-κB signaling pathways. Furthermore, Gal-3 could activate the phosphorylation of IκBα and interfere with the translocation of p65 into the cell nucleus of hVICs. However, inhibition of this pathway can suppress the osteogenic differentiation by Gal-3.

CONCLUSIONS

Gal-3 acts as a positive regulator of osteogenic differentiation by activating the NF-κB signaling pathway in hVICs. Our findings provide novel mechanistic insights into the critical role of Gal-3 in the CAVD progression.