Association of cholesterol levels, hydroxymethylglutaryl coenzyme-A reductase inhibitor treatment, and progression of aortic stenosis in the community

Aortic valve disease: Current recommendations

Aortic stenosis is a common valvular abnormality. Surgical valve replacement is the standard of care for symptomatic patients with severe aortic stenosis and is appropriate for certain asymptomatic patients. Statin therapy may slow progression of the disease. Contrary to conventional wisdom, vasodilator therapy may in fact be safe and effective in certain instances of severe aortic stenosis. Chronic aortic regurgitation is commonly treated with vasodilator therapy, which is certainly indicated for the asymptomatic patient with hypertension. Surgery is recommended for left ventricular dilatation, diminished ventricular systolic function, or symptoms.

The cardioprotective effects of statins

In addition to their lipid-modulating properties, statins have a large number of beneficial cardiovascular effects that have emerged over time and that were not anticipated during drug development. The lipid and nonlipid effects act in a concerted way to reduce the ischemic burden of the myocardium and to protect it against injury. By acting on the vessel wall, statins may prevent lesion initiation and repair injuries, enhance myocardial perfusion, slow lesion progression, and prevent coronary occlusion. They may also directly reduce myocardial damage, favor myocardial repair, and protect against immune injury. This review focuses on properties of statins that contribute to their cardioprotective effect. The first section includes information on modulation of vascular tone, endothelial permeability and function, inhibition of complement injury, curbing of foam cell formation, antioxidant and anti-inflammatory properties, and profibrinolytic and anticoagulant activities. The second section relates to reduction of myocardial necrosis, myocardial hypertrophy, blood pressure, and heart failure, as well as mobilization of endothelial progenitor cells for repair, angiogenic effects, and immunomodulation. In many instances, results of in vitro and animal studies have raised expectations and prompted studies in humans. Several clinical trials have confirmed these expectations and have strengthened the value of statins as valuable antiatherosclerotic and cardioprotective agents.

Effect of statins on the progression of bioprosthetic aortic valve degeneration

To date, there is no proved medical therapy able to significantly reduce the degenerative process of biologic prosthetic aortic valves. It has recently been suggested that statins may reduce the progression of native aortic valve stenosis. We examined the effect of statin treatment on bioprosthetic aortic valve degeneration and found a beneficial effect of statins in slowing bioprosthetic degeneration.

Hypercholesterolemia is a risk factor for bioprosthetic valve calcification and explantation

OBJECTIVE

There are pathophysiologic similarities between calcification and atherosclerosis. We wished to determine whether risk factors for atherosclerosis were linked to bioprosthetic valve calcification and dysfunction.

METHODS

We performed a retrospective cohort study on 144 patients at a single institution who had bioprosthetic aortic or mitral valves removed, serum cholesterol levels recorded, and valve calcification assessed on the basis of hematoxylin and eosin staining and radiography of the valve. We also performed case-control analysis of a group of 66 patients whose tissue valves were explanted and compared them with an age- and position-matched group of 66 patients with similar duration of implantation. We also compared mean serum cholesterol levels.

RESULTS

In the retrospective cohort study cholesterol (P =.035), younger age at implantation (P =.014), and coronary artery disease (P =.017) were linked to calcification of the valve by means of univariate analysis. In stepwise multiple regression analysis only the mean serum cholesterol level was linked to calcification (P =.02). Sex, hypertension, smoking, diabetes, and implant position were not linked to calcification. In the case-control analysis the mean serum cholesterol level of the explanted valve group was significantly higher (189 vs 163 mg/dL, P <.0001) than that of the group whose valves did not require explantation. For those whose serum cholesterol levels were greater than 200 mg/dL, the odds ratio was 3.9 (95% confidence interval, 1.7-8.9) for valve explantation.

CONCLUSIONS

Increased serum cholesterol level may be a risk factor for bioprosthetic valve calcification requiring explantation.

Three dimensional volume quantification of aortic valve calcification using multislice computed tomography

OBJECTIVE

To assess a new multislice computed tomography (CT) technique for three dimensional quantification of aortic valve calcification volume (3D AVCV) and to study the relation between stenosis and calcification of the aortic valve.

METHODS

50 patients with echocardiographic calcification of the aortic valve underwent two separate ECG triggered multislice CT for quantification of 3D AVCV. The agreement between the two 3D AVCV scores was assessed and 3D AVCV was compared with echocardiographic markers of severity of aortic stenosis.

RESULTS

Overall the level of agreement between the two 3D AVCV scores was excellent (median interscan variability 7.9% (interquartile range 10.1); correlation coefficient, r = 0.99; repeatability coefficient 237.8 mm3 (limits of agreement -393 to 559 mm3)). However, the magnitude of the 3D AVCV did influence the interscan variability. The 3D AVCV correlated closely with the maximal predicted transvalvar gradient (r2 = 0.77) and aortic valve area (r2 = 0.73).

CONCLUSIONS

Multislice CT provides a technique for quantifying 3D AVCV that has good reproducibility. There is a close non-linear relation between echocardiographic parameters of severity of valve stenosis and 3D AVCV scores.

Is aortic stenosis a preventable disease?

Aortic stenosis (AS) is the most common valvular disease requiring valve replacement. Its prevalence increases with age. When the severity of AS is only mild to moderate, it is well tolerated. When it becomes severe, AS confers significant morbidity and mortality. Adverse events can be avoided if it is possible to prevent or retard the progression from mild or moderate AS to severe AS. Progression of AS parallels the progression of sclerotic changes involving the aortic valve, which share histological and immunochemical similarities with the process of atherosclerosis. Far from being just a degenerative process, the development of AS is a complex and highly regulated process with a number of modifiable factors. One of the key factors appears to be lipoproteins, which are intimately involved in several pathways crucial to the development of AS. The importance of lipoproteins is further supported by epidemiological and clinical studies showing a strong association between lipoproteins and AS. The time has come to initiate prospective studies to assess the effect of cholesterol lowering on the progression of AS.

Calcific aortic stenosis: new pathophysiologic insights and possible new medical therapy

Aortic stenosis is a progressive disease of aging with serious complications. A common disease of the elderly, it may inexorably progress to stenosis. Recent retrospective studies have correlated risk factors commonly associated with coronary and vascular atherosclerosis with an accelerated rate of aortic valve stenosis. Although hydroxymethyl glutaryl co-enzyme A reductase inhibitor (statin) treatment therapy has been shown to delay the rate of progression of valvular aortic stenosis, the salutary mechanism of the statin may be cholesterol-lowering and/or anti-inflammatory. Further prospective studies are warranted to investigate the mechanism and medical therapy of aortic sclerosis and stenosis.