New understanding about calcific aortic stenosis and opportunities for pharmacologic intervention:

Lipid-mediated inflammation and degeneration of bioprosthetic heart valves

BACKGROUND

The durability of bioprosthetic valves is limited by structural valve degeneration (SVD) leading to bioprostheses (BPs) stenosis or regurgitation. We hypothesized that a lipid-mediated inflammatory mechanism is involved in the SVD of BPs.

MATERIAL AND METHODS

Eighteen Freestyle stentless BP valves were explanted for SVD at a mean time of 5.9 +/- 3 years after implantation and were analysed by immunohistochemistry and transmission electron microscopy (TEM).

RESULTS

The mean age of the patients was 65 +/- 8 years and there were 11 male and seven female patients. Two of the 18 BPs had macroscopic calcification, whereas the other valves had minimal or no macroscopic calcification. Tears at the commissures leading to regurgitation was present in 16 BPs. Immunohistochemistry showed the presence of oxidized low-density lipoprotein (ox-LDL) and glycosaminoglycans in the fibrosa layer of 13 BPs. Areas with ox-LDL were infiltrated by macrophages (CD68(+)) co-expressing the scavenger receptor CD36 and metalloproteinase-9 (MMP-9). Zymogram showed the active form of MMP-9 within explanted BPs. EM studies revealed the presence of lipid-laden cells featuring foam cells and fragmented collagen. Nonimplanted control BPs obtained from the manufacturer (n = 4) had no evidence of lipid accumulation, inflammatory cell infiltration or expression of MMP9 within the leaflets.

CONCLUSIONS

These results support the concept that lipid-mediated inflammatory mechanisms may contribute to the SVD of BPs. These findings suggest that modification of atherosclerotic risk factors with the use of behavioural or pharmacological interventions could help to reduce the incidence of SVD.

Association between carotid and coronary artery disease in patients with aortic valve stenosis: an angiographic study

BACKGROUND

Patients with aortic stenosis have a high prevalence of coronary artery disease, but there is little information about the association of coronary artery disease and carotid artery disease.

METHODS

The study includes 317 consecutive patients with aortic stenosis, who underwent carotid and coronary angiography during the same catheterization before aortic valve replacement.

RESULTS

At univariate analysis, the prevalence of coronary artery disease was associated with (1) presence of carotid artery disease (P < .001); (2) angina pectoris as presentation symptom (P < .001); (3) age more than 65 years (P < .05); and (4) hypertension (P < .05). At multivariate analysis, only carotid artery disease, angina, and age emerged as independent predictors of coronary artery disease. The combination of 2 variables (carotid artery disease, angina) allowed the identification of 4 groups, with decreasing prevalence of coronary artery disease: (1) angina+/carotid artery disease+: 85%; (2) angina-/ carotid artery disease+: 50%; (3) angina+/carotid artery disease-: 41%; (4) angina-/carotid artery disease-: 21% (P < .001).

CONCLUSION

In patients with symptomatic aortic stenosis, the presence of significant carotid artery disease is a strong marker of significant coronary artery disease.