Combined Cardiac Damage Staging by Echocardiography and Cardiac Catheterization in Patients With Clinically Significant Aortic Stenosis

Absolute coronary flow and microvascular resistance before and after transcatheter aortic valve implantation

BACKGROUND

Severe aortic stenosis (AS) is associated with left ventricular (LV) remodelling, likely causing alterations in coronary blood flow and microvascular resistance.

AIMS

We aimed to evaluate changes in absolute coronary flow and microvascular resistance in patients with AS undergoing transcatheter aortic valve implantation (TAVI).

METHODS

Consecutive patients with AS undergoing TAVI with non-obstructive coronary artery disease in the left anterior descending artery (LAD) were included. Absolute coronary flow (Q) and microvascular resistance (Rμ) were measured in the LAD using continuous intracoronary thermodilution at rest and during hyperaemia before and after TAVI, and at 6-month follow-up. Total myocardial mass and LAD-specific mass were quantified by echocardiography and cardiac computed tomography. Regional myocardial perfusion (QN) was calculated by dividing absolute flow by the subtended myocardial mass.

RESULTS

In 51 patients, Q and R were measured at rest and during hyperaemia before and after TAVI; in 20 (39%) patients, measurements were also obtained 6 months after TAVI. No changes occurred in resting and hyperaemic flow and resistance before and after TAVI nor after 6 months. However, at 6-month follow-up, a notable reverse LV remodelling resulted in a significant increase in hyperaemic perfusion (QN,hyper: 0.86 [interquartile range {IQR} 0.691.06] vs 1.20 [IQR 0.99-1.32] mL/min/g; p=0.008; pre-TAVI and follow-up, respectively) but not in resting perfusion (QN,rest: 0.34 [IQR 0.30-0.48] vs 0.47 [IQR 0.36-0.67] mL/min/g; p=0.06).

CONCLUSIONS

Immediately after TAVI, no changes occurred in absolute coronary flow or coronary flow reserve. Over time, the remodelling of the left ventricle is associated with increased hyperaemic perfusion.

Myocardial sodium-glucose cotransporter 2 expression and cardiac remodelling in patients with severe aortic stenosis: The BIO-AS study

AIM

Cardiac remodelling plays a major role in the prognosis of patients with aortic stenosis (AS) and could impact the benefits of aortic valve replacement. Our study aimed to evaluate the expression of sodium-glucose cotransporter 2 (SGLT2) gene and protein in patients with severe AS stratified in high gradient (HG) and low flow-low gradient (LF-LG) AS and its association with cardiac functional impairments.

METHODS AND RESULTS

Gene expression and protein levels of main biomarkers of cardiac fibrosis (galectin-3, sST2, serpin-4, procollagen type I amino-terminal peptide, procollagen type I carboxy-terminal propeptide, collagen, transforming growth factor [TGF]-β), inflammation (growth differentiation factor-15, interleukin-6, nuclear factor-κB [NF-κB]), oxidative stress (superoxide dismutase 1 [SOD1] and 2 [SOD2]), and cardiac metabolism (sodium-hydrogen exchanger, peroxisome proliferator-activated receptor [PPAR]-α, PPAR-γ, glucose transporter 1 [GLUT1] and 4 [GLUT4]) were evaluated in blood samples and heart biopsies of 45 patients with AS. Our study showed SGLT2 gene and protein hyper-expression in patients with LF-LG AS, compared to controls and HG AS (p < 0.05). These differences remained significant even after adjusting for age, gender, body mass index, history of diabetes mellitus, arterial hypertension, and coronary artery disease. SGLT2 gene expression was positively correlated with: (i) TGF-β (r = 0.72, p < 0.001) and collagen (r = 0.73, p < 0.001) as markers of fibrosis; (ii) NF-κB (r = 0.36, p < 0.01) and myocardial interleukin-6 (r = 0.68, p < 0.001) as markers of inflammation: (iii) SOD2 (r = -0.38, p < 0.006) as a marker of oxidative stress; (iv) GLUT4 (r = 0.33, p < 0.02) and PPAR-α (r = 0.36, p < 0.01) as markers of cardiac metabolism.

CONCLUSION

In patients with LF-LG AS, SGLT2 gene and protein were hyper-expressed in cardiomyocytes and associated with myocardial fibrosis, inflammation, and oxidative stress.