Effect of hydroxymethylglutaryl coenzyme a reductase inhibitors on the progression of calcific aortic stenosis

Association of aortic valve calcification to the presence, extent, and composition of coronary artery plaque burden: from the Rule Out Myocardial Infarction using Computer Assisted Tomography (ROMICAT) trial

BACKGROUND

Aortic valve calcification (AVC) is associated with cardiovascular risk factors and coronary artery calcification. We sought to determine whether AVC is associated with the presence and extent of overall plaque burden, as well as to plaque composition (calcified, mixed, and noncalcified).

METHODS

We examined 357 subjects (mean age 53 +/- 12 years, 61% male) who underwent contrast-enhanced electrocardiogram-gated 64-slice multidetector computed tomography from the ROMICAT trial for the assessment of presence and extent of coronary plaque burden according to the 17-coronary segment model and presence of AVC.

RESULTS

Patients with AVC (n = 37, 10%) were more likely than those without AVC (n = 320, 90%) to have coexisting presence of any coronary plaque (89% vs 46%, P < .001) and had a greater extent of coronary plaque burden (6.4 vs 1.8 segments, P < .001). Those with AVC had >3-fold increase odds of having any plaque (adjusted odds ratio [OR] 3.6, P = .047) and an increase of 2.5 segments of plaque (P < .001) as compared to those without AVC. When stratified by plaque composition, AVC was associated most with calcified plaque (OR 5.2, P = .004), then mixed plaque (OR 3.2, P = .02), but not with noncalcified plaque (P = .96).

CONCLUSION

Aortic valve calcification is associated with the presence and greater extent of coronary artery plaque burden and may be part of the later stages of the atherosclerosis process, as its relation is strongest with calcified plaque, less with mixed plaque, and nonsignificant with noncalcified plaque. If AVC is present, consideration for aggressive medical therapy may be warranted.

New concepts in valvular hemodynamics: implications for diagnosis and treatment of aortic stenosis

Aortic valve stenosis (AS) is the third-most frequent heart disease after coronary artery disease and arterial hypertension, and it is associated with a high incidence of adverse outcomes. Recent data support the notion that AS is not an isolated disease uniquely limited to the valve. Indeed, AS is frequently associated with abnormalities of the systemic arterial system, and, in particular, with reduced arterial compliance, which may have important consequences for the pathophysiology and clinical outcome of this disease. Moreover, AS may also be associated with left ventricular systolic dysfunction and reduced transvalvular flow rate, which pose important challenges with regards to diagnostic evaluation and clinical decision making in AS patients. Hence, the assessment of AS severity, as well as its therapeutic management, should be conducted with the use of a comprehensive evaluation that includes not only the aortic valve, but also the systemic arterial system and the left ventricle because these three entities are tightly coupled from both a pathophysiological and a hemodynamic standpoint.

Clinical trials in heart valve disease

PURPOSE OF REVIEW

To summarize evidence from clinical trials of heart valve disease and identify areas where further trials are needed.

RECENT FINDINGS

Recent randomized studies suggest that statins do not influence progression of aortic stenosis. Other medical therapies with the potential to reduce progression of valve disease or decrease myocardial dysfunction include vasodilators in aortic regurgitation, angiotensin II receptor antagonists or beta-blockers in mitral regurgitation and angiotensin-converting enzyme inhibitors in aortic stenosis. However, these treatments have not been evaluated or have been evaluated only in small studies. Meta-analysis of randomized studies of antithrombotic strategies in patients with mechanical valves suggests overall risk is lower with the combination of warfarin with a lower target international normalized ratio and an antiplatelet drug. Novel anticoagulants have the potential to replace warfarin but have not yet been evaluated for this indication. Clinical trials are also needed to reliably evaluate different surgical strategies and novel percutaneous technology.

SUMMARY

Clinical trials in heart valve disease have important limitations, including the small number of trials undertaken and the small size of most studies. Many trials were undertaken more than 10-20 years ago in patients with earlier generation valve prostheses. To improve outcomes for patients with heart valve disease more clinical trials of contemporary approaches are needed.

Lowering plasma cholesterol levels halts progression of aortic valve disease in mice

BACKGROUND

Treatment of hyperlipidemia produces functional and structural improvements in atherosclerotic vessels. However, the effects of treating hyperlipidemia on the structure and function of the aortic valve have been controversial, and any effects could be confounded by pleiotropic effects of hypolipidemic treatment. The goal of this study was to determine whether reducing elevated plasma lipid levels with a "genetic switch" in Reversa mice (Ldlr-/-/Apob(100/100)/Mttp(fl/fl)/Mx1-Cre+/+) reduces oxidative stress, reduces pro-osteogenic signaling, and retards the progression of aortic valve disease.

METHODS AND RESULTS

After 6 months of hypercholesterolemia, Reversa mice exhibited increases in superoxide, lipid deposition, myofibroblast activation, calcium deposition, and pro-osteogenic protein expression in the aortic valve. Maximum aortic valve cusp separation, as judged by echocardiography, was not altered. During an additional 6 months of hypercholesterolemia, superoxide levels, valvular lipid deposition, and myofibroblast activation remained elevated. Furthermore, calcium deposition and pro-osteogenic gene expression became more pronounced, and the aortic cusp separation decreased from 0.85+/-0.04 to 0.70+/-0.04 mm (mean+/-SE; P<0.05). Rapid normalization of cholesterol levels at 6 months of age (by inducing expression of Cre recombinase) normalized aortic valve superoxide levels, decreased myofibroblast activation, reduced valvular calcium burden, suppressed pro-osteogenic signaling cascades, and prevented reductions in aortic valve cusp separation.

CONCLUSIONS

Collectively, these data indicate that reducing plasma lipid levels by genetic inactivation of the mttp gene in hypercholesterolemic mice with early aortic valve disease normalizes oxidative stress, reduces pro-osteogenic signaling, and halts the progression of aortic valve stenosis.

Relationship of metabolic syndrome with incident aortic valve calcium and aortic valve calcium progression: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

Metabolic syndrome (MetS) has been associated with increased prevalence of aortic valve calcium (AVC) and with increased progression of aortic stenosis. The purpose of this study was to determine whether MetS is associated with increased risks for the development of new ("incident") AVC or for progression of established AVC as assessed by CT.

RESEARCH DESIGN AND METHODS

The relationships of MetS or its components as well as of diabetes to risks for incident AVC or AVC progression were studied among participants with CT scans performed at baseline and at either year 2 or year 3 examinations in the Multi-Ethnic Study of Atherosclerosis (MESA).

RESULTS

Of 5,723 MESA participants meeting criteria for inclusion, 1,674 had MetS by Adult Treatment Panel III criteria, whereas 761 had diabetes. Among the 5,123 participants without baseline AVC, risks for incident AVC, adjusted for time between scans, age, sex, race/ethnicity, LDL cholesterol, lipid-lowering medications, and smoking, were increased significantly for MetS (odds ratio [OR] 1.67 [95% CI 1.21-2.31]) or diabetes (2.06 [1.39-3.06]). In addition, there was an increase in incident AVC risk with increasing number of MetS components. Similar results were found using the International Diabetes Federation MetS criteria. Among the 600 participants (10.5%) with baseline AVC, neither MetS nor diabetes was associated with AVC progression.

CONCLUSIONS

In the MESA cohort, MetS was associated with a significant increase in incident ("new") AVC, raising the possibility that MetS may be a potential therapeutic target to prevent AVC development.

Aortic stenosis

In developed countries, aortic stenosis is the most prevalent of all valvular heart diseases. A manifestation of ageing, the disorder is becoming more frequent as the average age of the population increases. Symptomatic severe disease is universally fatal if left untreated yet is consistent with a typical lifespan when mechanical relief of the stenosis is provided in a timely fashion. Management of mild disease, severe asymptomatic disease, and far advanced disease, and the effect of new percutaneous treatments, provide both controversy and exciting promise to care of patients with aortic stenosis. We discuss these issues in this Review.

Efficacy of simvastatin treatment of valvular interstitial cells varies with the extracellular environment

OBJECTIVE

The lack of therapies that inhibit valvular calcification and the conflicting outcomes of clinical studies regarding the impact of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors on valve disease highlight the need for controlled investigations to characterize the interactions between HMG-CoA reductase inhibitors and valve tissue. Thus, we applied multiple in vitro disease stimuli to valvular interstitial cell (VIC) cultures and examined the impact of simvastatin treatment on VIC function.

METHODS AND RESULTS

VICs were cultured on 3 different substrates that supported various levels of nodule formation. Transforming growth factor (TGF)-beta1 was also applied as a disease stimulus to VICs on 2-D surfaces or encapsulated in 3-D collagen gels and combined with different temporal applications of simvastatin. Simvastatin inhibited calcific nodule formation in a dose-dependent manner on all materials, although the level of statin efficacy was highly substrate-dependent. Simvastatin treatment significantly altered nodule morphology, resulting in dramatic nodule dissipation over time, also in a substrate-dependent manner. These effects were mimicked in 3-D cultures, wherein simvastatin reversed TGF-beta1-induced contraction. Decreases in nodule formation were not achieved via the HMG-CoA reductase pathway, but were correlated with decreases in ROCK activity.

CONCLUSIONS

These studies represent a significant contribution to understanding how simvastatin may impact heart valve calcification.

Prevention of calcific aortic valve stenosis-fact or fiction?

Valve replacement is the only long-term effective treatment for calcific aortic valve stenosis. However, this treatment is aimed only at patients with advanced leaflet disease and symptoms of left ventricular obstruction. Over the past 15 years, our understanding of the pathogenesis of calcific aortic stenosis has changed significantly: away from a passive degenerative disease to an active process involving endothelial dysfunction, lipid accumulation, an inflammatory infiltrate, and a regulated process of calcification. Since many of the same processes are characteristic of atherosclerosis, trials have been undertaken to test whether medical therapy (statins, renin-angiotensin inhibition) can prevent or alter the disease course. Although retrospective and non-randomized studies suggested a positive effect with statins, benefit has not been seen in perspective randomized controlled trials, although two major studies are still in progress. Inhibition of renin-angiotensin has shown discordant results in retrospective studies with no randomized controlled data published. In the future, we need to consider other medical therapies that might target different pathways in this disease process. In addition, we need to define the optimal timing and duration of therapy for this chronic slowly progressive disease; treatments aimed at the early disease process may be ineffective with end-stage tissue changes.

Intensive lipid-lowering therapy for patients with aortic stenosis

It has been suggested by several retrospective studies that lipid-lowering therapy (compared with treatment with medications other than statins) retards the progression of aortic stenosis. Additional evidence for this has emerged from the prospective (nonrandomized) Rosuvastatin Affecting Aortic Valve Endothelium (RAAVE) study, although not from findings of the randomized, double-blind Scottish Aortic Stenosis and Lipid Lowering Trial, Impact on Regression (SALTIRE). Currently, 2 larger randomized studies of aortic stenosis are in progress. These studies have longer durations than SALTIRE. The Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study, with 1,873 patients, is the largest study with the longest planned length of treatment (4 to 7 years) that will assess whether lipid-lowering therapy slows the progression of aortic stenosis and the degradation of the aortic valve, thereby potentially reducing the urgency for surgery or at least delaying the need for surgery, relieving adverse hemodynamic consequences of aortic stenosis, and possibly decreasing mortality and morbidity in these patients. The Aortic Stenosis Progression Observation: Measuring Effects of Rosuvastatin (ASTRONOMER) trial, a study of disease progression, involves 272 patients with aortic stenosis, with treatment arms of rosuvastatin 40 mg/d and placebo for 3 to 5 years. In conclusion, the SEAS and ASTRONOMER studies will help resolve the contradictory findings of SALTIRE and RAAVE on the benefit of intensive lipid-lowering treatment in aortic stenosis.

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.

C-Reactive protein predicts severity, progression, and prognosis of asymptomatic aortic valve stenosis

BACKGROUND

C-Reactive protein (CRP) has been shown to play a pivotal role in the pathogenesis of atherosclerosis progression. The aim of this study was to assess whether CRP predicts severity, progression, and prognosis of aortic valve stenosis (AS).

METHODS

One hundred and thirty-five patients with asymptomatic AS were studied. Patients were diagnosed as mild (n = 18, aortic valve area [AVA] > or =1.5 cm(2)), moderate (n = 57, AVA 1.0-1.49 cm(2)), or severe AS (n = 60, AVA <1.0 cm(2)) by Doppler echocardiography. Patients with serial (baseline and at 1 year) echocardiographic examination (n = 47) were grouped as either slow (n = 22, DeltaAVA <-0.15 cm(2)/y) or rapid progression group (n = 25, DeltaAVA > or =-0.15 cm(2)/y). In addition, long-term prognosis was compared between patients with low CRP (n = 68, CRP <0.15 mg/dL) and those with high CRP (n = 67, CRP > or =0.15 mg/dL).

RESULTS

Baseline CRP was significantly higher in patients with severe AS than in those with mild or moderate AS (mild AS 0.17 +/- 0.43, moderate AS 0.22 +/- 0.28, severe AS 0.53 +/- 0.66 mg/dL, P = .001). By multivariate logistic regression analysis, CRP was an independent predictor of severe AS (odds ratio 3.51, P = .015). Similarly, CRP was significantly higher in the rapid progression group than in the slow progression group (0.56 +/- 0.76 vs 0.19 +/- 0.25 mg/dL, P = .004). Furthermore, long-term survival was significantly lower in the high CRP group than in the low CRP group (log rank: P < .001).

CONCLUSION

C-Reactive protein predicts severity, progression, and prognosis in patients with asymptomatic AS.

Intensive lipid lowering with simvastatin and ezetimibe in aortic stenosis

BACKGROUND

Hyperlipidemia has been suggested as a risk factor for stenosis of the aortic valve, but lipid-lowering studies have had conflicting results.

METHODS

We conducted a randomized, double-blind trial involving 1873 patients with mild-to-moderate, asymptomatic aortic stenosis. The patients received either 40 mg of simvastatin plus 10 mg of ezetimibe or placebo daily. The primary outcome was a composite of major cardiovascular events, including death from cardiovascular causes, aortic-valve replacement, nonfatal myocardial infarction, hospitalization for unstable angina pectoris, heart failure, coronary-artery bypass grafting, percutaneous coronary intervention, and nonhemorrhagic stroke. Secondary outcomes were events related to aortic-valve stenosis and ischemic cardiovascular events.

RESULTS

During a median follow-up of 52.2 months, the primary outcome occurred in 333 patients (35.3%) in the simvastatin-ezetimibe group and in 355 patients (38.2%) in the placebo group (hazard ratio in the simvastatin-ezetimibe group, 0.96; 95% confidence interval [CI], 0.83 to 1.12; P=0.59). Aortic-valve replacement was performed in 267 patients (28.3%) in the simvastatin-ezetimibe group and in 278 patients (29.9%) in the placebo group (hazard ratio, 1.00; 95% CI, 0.84 to 1.18; P=0.97). Fewer patients had ischemic cardiovascular events in the simvastatin-ezetimibe group (148 patients) than in the placebo group (187 patients) (hazard ratio, 0.78; 95% CI, 0.63 to 0.97; P=0.02), mainly because of the smaller number of patients who underwent coronary-artery bypass grafting. Cancer occurred more frequently in the simvastatin-ezetimibe group (105 vs. 70, P=0.01).

CONCLUSIONS

Simvastatin and ezetimibe did not reduce the composite outcome of combined aortic-valve events and ischemic events in patients with aortic stenosis. Such therapy reduced the incidence of ischemic cardiovascular events but not events related to aortic-valve stenosis. (ClinicalTrials.gov number, NCT00092677.)

Stage-related effect of statin treatment on the progression of aortic valve sclerosis and stenosis

It has been suggested that statins could slow the progression of aortic stenosis (AS), but this hypothesis is still debated and has not been validated in large series of patients by long-term follow-up studies. Moreover, information about the role of statins in patients with different degrees of severity of AS is scarce. From our 1988 to 2007 echocardiographic database, we retrospectively identified all asymptomatic patients with aortic valve sclerosis (abnormal irregular thickening of the aortic valve with a peak aortic velocity [Vmax] > or =1.5 and <2 m/s), mild AS (Vmax > or =2 and <3 m/s), and moderate AS (Vmax > or =3 and <4 m/s), age > or =50 years, and with > or =2 echocardiographic studies > or =2 years apart. Exclusion criteria were moderate/severe aortic regurgitation, bicuspid aortic valve, rheumatic valve disease, and ejection fraction <40%. The final study population consisted of 1,046 patients (mean age 70 +/- 8 years, 587 men); 309 were treated with statins. Mean follow-up duration was 5.6 +/- 3.2 years (range 2 to 19). Progression of AS was slower in patients receiving statins compared with untreated patients in aortic sclerosis (0.04 +/- 0.09 vs 0.07 +/- 0.10 m/s/year, p = 0.01) and mild AS (0.09 +/- 0.15 vs 0.15 +/- 0.15 m/s/year, p = 0.001), but not in moderate AS (0.21 +/- 0.18 vs 0.22 +/- 0.15 m/s/year, p = 0.70). In multivariate analysis only statin therapy, initial Vmax, and dialysis were independently related to progression of aortic valve disease. In conclusion, in a large series of patients with long-term follow-up, statins were effective in slowing the progression of aortic valve disease in aortic sclerosis and mild AS, but not in moderate AS. These results suggest that statin therapy should be taken into consideration in the early stages of this common disease.

Prognosis and risk factors in patients with asymptomatic aortic stenosis and their modulation by atorvastatin (20 mg)

The aim of the prospective, randomized, placebo-controlled Tyrolean Aortic Stenosis Study (TASS) was to characterize the natural history and risk factors and their possible modulation by new-onset atorvastatin treatment (20 mg/day vs placebo) in patients with asymptomatic calcified aortic stenosis. Forty-seven patients without previous lipid-lowering therapy or indications for it according to guidelines at study entry were randomized to atorvastatin treatment or placebo and prospectively followed for a mean study period of 2.3 +/- 1.2 years. Patients' prognoses were worse than expected, with 24 (51%) experiencing major adverse clinical events, in most cases the new onset of symptoms followed by aortic valve replacement. In multivariate regression analysis, independent risk factors for worse clinical outcomes were aortic valve calcification, as assessed by multidetector computed tomography, and plasma levels of C-reactive protein. In univariate analysis, mean systolic pressure gradient or an increased N-terminal-pro-B-type natriuretic peptide plasma level allowed the prediction of major adverse clinical events as well, whereas concomitant coronary calcification, age, and the initiation of atorvastatin treatment had no significant prognostic implication. As shown in a subgroup of 35 patients (19 randomly assigned to atorvastatin and 16 to placebo), annular progression in aortic valve calcification and hemodynamic deterioration were similar in both treatment groups. In conclusion, TASS could demonstrate a poor clinical outcome in patients with asymptomatic calcified aortic stenosis which can be predicted by new risk factors such as strong AVC or increased plasma levels of CRP or NT-proBNP. The study does not support the concept that treatment with a HMG-CoA reductase inhibitor (20 mg atorvastatin once daily) halts the progression of calcified aortic stenosis.

High levels of high sensitivity C-reactive protein predict the progression of chronic rheumatic mitral stenosis

BACKGROUND

High sensitive C-Reactive Protein (hs-CRP) predicts morbidity and mortality in various clinical conditions. The effect of hsCRP on progression of chronic rheumatic mitral stenosis (CRMS) has not been demonstrated.

METHODS AND RESULTS

A total of 132 patients with CRMS (95 female, 37 male) and 145 control (100 female, 45 male) were included in the study. Baseline clinical, echocardiographic, hematologic and hs-CRP measurements were collected prospectively. Mean mitral valve area (MVA) was 1.4 +/- 0.3 cm(2), mean wilkins valve score value was 8.9 +/- 1.7, left atrial diameter was 5.0 +/- 0.7 cm, left atrial area was 37.2 +/- 12.6 cm(2), and systolic pulmonary arterial pressure (SPAP) was 44 +/- 11 mmHg in patients with CRMS. The mean levels of hs-CRP value, fibrinogen, and mean platelet volume (MPV) were significantly higher in CRMS group compared to control group. The levels of hsCRP were found to be positively correlated with mean Wilkins valve score value, SPAP, presence of atrial fibrillation (AF), left atrial diameter, left atrial area, presence of LASEC(+), fibrinogen, and MPV and inversely correlated with MVA in patients with CRMS. Linear regression analysis revealed that the hsCRP level independently affects mean Wilkins valve score value, left atrial area (LAA), LASEC(+) and AF in the patients with CRMS.

CONCLUSIONS

These results suggest that increased hsCRP levels are associated with CRMS severity. These association may be important when treating patients with CRMS.

Established and emerging vascular risk factors and the development of aortic stenosis: an opportunity for prevention?

BACKGROUND

Aortic stenosis (AS) is the commonest valvular heart disease in the developed world. It is becoming increasingly accepted that the pathogenesis of AS and of its preceding abnormalities, aortic valve sclerosis (AVS) and aortic valve calcification (AVC), shares many characteristics with the atherosclerotic process.

OBJECTIVE

To assess the contribution of established and emerging vascular risk factors in the development of AS and to evaluate the potential of pharmacological intervention to modify the natural history of AS.

METHODS

We reviewed the epidemiological data that link AS and atherosclerosis and studies of vasculoprotective agents in patients with AS.

RESULTS/CONCLUSIONS

AS, AVS and AVC share many common risk factors with atherosclerosis and are possible markers of preclinical vascular disease. Statins appear to delay the progression of AS. However, more studies are needed before introducing such pharmacologic treatment for AS. The future may point towards targeted prevention of AS.

Interaction of age with lipoproteins as predictors of aortic valve calcification in the multi-ethnic study of atherosclerosis

BACKGROUND

Previous epidemiologic studies have shown that low-density lipoprotein is an independent risk factor for prevalent aortic valve calcification (AVC); however, to our knowledge, the interactions between plasma lipoprotein concentrations and age on the relative risks (RRs) for AVC prevalence and severity have not been examined in a large, racially and ethnically diverse cohort.

METHODS

Using stepwise RR regression, the relationships of baseline fasting lipid levels and lipoprotein levels to baseline prevalence and severity of AVC were determined in 5801 non-statin-using participants in the Multi-Ethnic Study of Atherosclerosis (MESA).

RESULTS

In age-stratified, adjusted analyses, the low-density lipoprotein-associated RRs (95% confidence intervals) for prevalent AVC were higher for younger compared with older participants (age 45-54 years, 1.69 [1.19-2.39]; age 55-64 years, 1.48 [1.24-1.76]; age 65-74 years, 1.09 [0.95-1.25]; and age 75-84 years, 1.16 [0.99-1.36]; P interaction = .04]. There was a similar, significant interaction of age with total cholesterol-associated RR for prevalent AVC (P interaction = .04). In contrast, total- to high-density lipoprotein cholesterol ratio RRs were similar across all age strata (P interaction = .68). At multivariate analyses, no lipoprotein parameter was associated with AVC severity.

CONCLUSIONS

In this racially and ethnically diverse, preclinical cohort, low-density lipoprotein was a risk factor for AVC only in participants younger than 65 years, whereas the total cholesterol/high-density lipoprotein cholesterol ratio was associated with a modest increased risk of AVC across all ages. These findings may have important implications for the efficacy of and targets for dyslipidemia therapies in calcific aortic valve disease.

Mechanism of pi-induced vascular calcification

Vascular calcification is clinically important in the development of cardiovascular disease. It has been suggested that apoptosis is one of the processes regulating calcification in vascular smooth muscle cells (VSMC). In this review, we discuss the role of apoptosis in inorganic phosphate (Pi)- induced calcification, focusing on regulation of the survival pathway mediated by growth arrest- specific gene 6 (Gas6). Further, we mention the beneficial effect of statins mediated by inhibition of apoptosis which is accompanied by restoration of the Gas6-mediated survival pathway. These findings indicate that Gas6 is a novel target of statins' effects to prevent vascular calcification.

Aortic sclerosis, aortic stenosis and lipid-lowering therapy

Calcific aortic stenosis (AS) is a progressive disease that has, until recently, been considered to be a degenerative and unmodifiable process induced by long-lasting mechanical stress. However, histopathologic studies have now demonstrated that the development and progression of calcific AS is based on an active process, sharing a number of similarities with atherosclerosis. Inflammation, lipid infiltration, dystrophic calcification, ossification, platelet deposition and endothelial dysfunction have been observed in both diseases. In addition, several studies have suggested that AS and atherosclerosis share a number of risk factors, such as hypercholesterolemia, elevated lipoprotein (a), smoking, hypertension and diabetes. These findings suggest that statin therapy could be beneficial in AS by its lipid-lowering and/or anti-inflammatory effects, as is the case in atherosclerosis. Although this concept has been supported by experimental work and by four retrospective clinical studies observing significantly slower rates of hemodynamic progression in statin-treated patients, a prospective randomized trial (Scottish Aortic Stenosis and Lipid Lowering Trial, Impact on Regression [SALTIRE]; 80mg of atorvastatin vs placebo) yielded a negative result. In contrast to the retrospective analyses, according to the study protocol, patients with hyperlipidemia had to be excluded in this trial. A recent prospective study (Rosuvastatin Affecting Aortic Valve Endothelium [RAAVE]) treating hypercholesteremic patients with rosuvastatin, found a significantly slower rate of progression in these patients compared with patients with normal cholesterol levels who were left untreated, suggesting that statin therapy may only be beneficial in patients with hyperlipidemia. Lipid-lowering therapy with statins can, therefore, currently only be recommended in this subgroup of patients with AS.

Risk factors for progression of calcific aortic stenosis and potential therapeutic targets

Current thought regarding the progression of calcific aortic stenosis (AS) is presented. After summarizing contemporary ideas about AS pathogenesis, the present article examines the factors that may affect disease progression. Data indicate that this process may be accelerated by aortic valve structure, degree of valvular calcification, chronic renal insufficiency and cardiovascular risk factors such as diabetes and dyslipidemia. Finally, the present review discusses potential therapeutic targets to slow AS progression.

Complement system is activated in stenotic aortic valves

OBJECTIVE

To examine the role of the complement system, a source of powerful proinflammatory mediators, in aortic valve stenosis (AS).

METHODS AND RESULTS

Stenotic aortic valves (n=24) were obtained at valve replacement surgery, and non-stenotic (n=12) and early sclerotic (n=4) valves at cardiac transplantations. The terminal complement complex C5b-9 was stained by immunohistochemistry. Expression of the anaphylatoxin receptors C3aR and C5aR was studied in the valves by immunohistochemistry and RT-PCR, and in isolated valve myofibroblasts after stimulation with potential AS-accelerating factors (TNF-alpha and cigarette smoke) by RT-PCR. Cultured myofibroblasts were exposed to C3a, and their secretion of proinflammatory cytokines was assessed by ELISA. C5b-9 was found already in early aortic valve lesions, and its deposition was augmented in advanced stenotic valves. In stenotic valves, expression of C3aR mRNA was upregulated (p<0.05) and strong staining of C3aR and C5aR was detected. Myofibroblasts in stenotic, but not in control valves, expressed C3aR, and, in isolated myofibroblasts, TNF-alpha and cigarette smoke induced C3aR mRNA expression (p<0.05 for both). Stimulation of myofibroblasts with C3a resulted in enhanced secretion of MCP-1 (p<0.001), IL-6 (p=0.003), and IL-8 (p=0.03).

CONCLUSIONS

In stenotic aortic valves, complement is activated leading to generation of the anaphylatoxins C3a and C5a. Upregulation of C3aR in the valves as a result of inflammation and external risk factors, such as cigarette smoke, leads to an inflammatory response in aortic valve myofibroblasts. Complement activation in stenotic valves emerges as a novel pathogenic component of AS and may serve as a therapeutic target in this disease.

Modulation of calcification of vascular smooth muscle cells in culture by calcium antagonists, statins, and their combination

Background Vascular calcification is an organized process in which vascular smooth muscle cells (VSMCs) are implicated primarily. The purpose of the present study was to assess the effects of calcium antagonists and statins on VSMC calcification in vitro. Methods VSMC calcification was stimulated by incubation in growth medium supplemented with 10 mmol/l β-glycerophosphate, 8 mmol/l CaCl₂, 10 mmol/l sodium pyruvate, 1 μmol/l insulin, 50 μg/ml ascorbic acid, and 100 nmol/l dexamethasone (calcification medium). Calcification, proliferation, and apoptosis of VSMCs were quantified. Results Calcium deposition was stimulated dose-dependently by β-glycerophosphate, CaCl₂, and ascorbic acid (all P < 0.01). Addition of amlodipine (0.01–1 μmol/l) to the calcification medium did not affect VSMC calcification. However, atorvastatin (2–50 μmol/l) stimulated calcium deposition dose-dependently. Combining treatments stimulated calcification to a degree similar to that observed with atorvastatin alone. Both atorvastatin and amlodipine inhibited VSMC proliferation at the highest concentration used. Only atorvastatin (50 μmol/l) induced considerable apoptosis of VSMCs. Conclusion In vitro calcification of VSMCs is not affected by amlodipine, but is stimulated by atorvastatin at concentrations ≥10 μmol/l, which could contribute to the plaque-stabilizing effect reported for statins.

Interventional therapies for heart failure in the elderly

The aging of a population replete with risk factors for heart failure (HF) (coronary heart disease, diabetes, and hypertension) coupled with a declining age-adjusted mortality rate for coronary artery and hypertensive heart diseases has created, and will continue to create, a literal explosion in the prevalence of HF in the United States. Despite advances in maximal medical therapy, however, most patients who have symptomatic HF can expect functional impairment, interludes of worsening symptomatology, and a shortened lifespan. This article updates the use of interventional therapies for the treatment of elderly patients who have HF caused by coronary artery disease, valvular heart disease, congenital heart disease, myocardial disease, and renal vascular disease.

Aortic valve stenosis: an active atheroinflammatory process

PURPOSE OF REVIEW

To summarize the current understanding of the pathobiology of aortic valve stenosis and portray the major advances in this field.

RECENT FINDINGS

Stenotic aortic valves are characterized by atherosclerosis-like lesions, consisting of activated inflammatory cells, including T lymphocytes, macrophages, and mast cells, and of lipid deposits, calcific nodules, and bone tissue. Active mediators of calcification and cells with osteoblast-like activity are present in diseased valves. Extracellular matrix remodeling, including collagen synthesis and elastin degradation by matrix metalloproteinases and cathepsins, contributes to leaflet stiffening. In experimental animals, hypercholesterolemia induces calcification and bone formation in aortic valves, which can be inhibited by statin treatment. The potential of statins to retard progression of aortic valve stenosis has also been recognized in clinical studies; however, further prospective trials are needed. Angiotensin II-forming enzymes are upregulated in stenotic valves. Angiotensin II may participate in profibrotic progression of aortic valve stenosis and may serve as a possible therapeutic target.

SUMMARY

Recent findings regarding the interaction of inflammatory cells, lipids, mediators of calcification, and renin-angiotensin system in stenotic valves support the current opinion of aortic valve stenosis being an actively regulated disease, potentially amenable to targeted molecular therapy. Evidence from prospective clinical studies is eagerly awaited.

Valvular aortic stenosis in the elderly

Elderly patients with valvular aortic stenosis have an increased prevalence of coronary risk factors, of coronary artery disease, and evidence of other atherosclerotic vascular diseases. Statins may reduce the progression of aortic stenosis (AS). Angina pectoris, syncope or near syncope, and congestive heart failure are the 3 classic manifestations of severe AS. Prolonged duration and late peaking of an aortic systolic ejection murmur best differentiate severe AS from mild AS on physical examination. Doppler echocardiography is used to diagnose the prevalence and severity of AS. The indications for cardiac catheterization and the medical management of AS are discussed. Once symptoms develop, aortic valve replacement (AVR) should be performed in patients with severe or moderate AS. Other indications for AVR are discussed. Warfarin should be administered indefinitely after AVR in patients with a mechanical aortic valve and in patients with a bioprosthetic aortic valve who have either atrial fibrillation, prior thromboembolism, left ventricular systolic dysfunction, or a hypercoagulable condition. Patients with a bioprosthetic aortic valve without any of these 4 risk factors should be treated with aspirin 75-100 mg daily.

Calcific aortic valve disease: imaging studies and therapeutic interventions

Echocardiography is the predominant imaging method used for patients with aortic valve disease because of its excellent diagnostic accuracy, high reproducibility and noninvasive nature. Cardiac catheterization is typically reserved for patients in whom the diagnosis remains unclear, those requiring coronary angiography prior to valve replacement, and in the setting of complex valve disease. Cardiac computed tomography (CT) has recently been applied as a research tool to quantify the amount of aortic valve calcium (AVC), which has served as a clinical end point in several medical therapy trials. Medical therapy for aortic valve disease remains an active area of clinical research. Multiple retrospective studies have shown a benefit for 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HMG-CoA reductase inhibitors or statins) in reducing disease progression. However, two recently completed prospective, randomized trials yielded conflicting results. The data for using angiotensin converting enzyme (ACE) inhibitors are in the preliminary stages. This review will focus on imaging methods that are available for patients with aortic valve disease and summarize the recent trials that have evaluated medical therapy aimed to reduce progression of aortic valve disease.

Insights Into Degenerative Aortic Valve Disease

Despite the dramatic decline of rheumatic heart disease over the past 5 decades, there has not been a concordant decline in the prevalence of valvular heart disease. Degenerative aortic valve disease (DAVD) has become the most common cause of valvular heart disease in the Western world, causing significant morbidity and mortality. No longer considered a benign consequence of aging, valve calcification is the result of an active process that, much like atherosclerotic vascular disease, is preceded by basement membrane disruption, inflammatory cell infiltration, and lipid deposition and is associated with diabetes, hypercholesterolemia, hypertension, and tobacco use. These realizations, in addition to pathological insights gained from emerging imaging modalities, have lead to the exploration of a variety of therapeutic interventions to delay or prevent the progression of DAVD. Inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, angiotensin-converting enzyme, and matrix metalloproteinase have all been studied as potential disease modifiers. Moreover, tissue engineering, aided by emerging stem cell technology, holds immense potential for the treatment of valvular heart disease as adjuncts to surgical interventions. Here we review the epidemiology and pathophysiology of DAVD, in addition to highlighting emerging therapeutic interventions for this growing problem.

Reassessment of statins to retard the progression of aortic stenosis

Aortic valve stenosis is the most common indication for surgical valve replacement in the United States and Europe. For years, this valve lesion was thought to be a passive degenerative disease. In the past decade there have been a number of studies indicating that the risk factors for valvular heart disease are the same as those for vascular atherosclerosis. This correlation with atherosclerosis and valvular heart disease indicates that medical therapy may have a role in slowing the progression of this disease process. Currently, the retrospective studies indicate that medical therapy slows the progression of this disease. The prospective data are currently conflicting in terms of the final outcomes for treating the disease process with medical therapy. This review outlines the growing number of clinical studies implicating the potential for medical therapy in this patient population.

Cholesterol-years score is associated with development of senile degenerative aortic stenosis in heterozygous familial hypercholesterolemia

We retrospectively evaluated the frequency and identified the factors associated with the development of aortic stenosis (AS) in 96 patients with heterozygous familial hypercholesterolemia (FH). The frequency of AS was 31% (4/13) and that of critical stenosis was 15% (2/13) in older patients over the age of 70 years. All 4 patients with AS were female aged more than 70 years who were diagnosed with FH when aged more than 60 years. There were no significant differences in conventional coronary risk factors; however, the age at cardiac catheterization, age at diagnosis of FH and the cholesterol-years score (CYS) with AS were significantly higher than those without AS (p=0.006, p=0.017, p=0.021, respectively). In multiple regression analysis, CYS was a significant independent predictor for the development of AS (p=0.037) in 13 older patients over the age of 70 years. These results suggest that physicians should be aware that AS needs attention in older patients with heterozygous FH, especially women who have been diagnosed late in life and those who have been inadequately treated.

Rationale, design, and baseline characteristics of a randomized trial to assess the effect of cholesterol lowering on the progression of aortic stenosis: the Aortic Stenosis Progression Observation: Measuring Effects of Rosuvastatin (ASTRONOMER) trial

BACKGROUND

Aortic stenosis (AS) is a common health problem in the western world. Recent studies have suggested that cholesterol lowering may have a salutary effect on the progression of AS. The primary objective of the ASTRONOMER study is to determine whether patients with AS randomized to rosuvastatin will experience less progression in AS severity as measured by aortic transvalvular gradients and valve areas. The secondary objectives are to determine the effect of rosuvastatin on the rate of cardiac death and aortic valve replacement and to assess the time to outcome during a follow-up of 3 to 5 years.

METHOD

This is a double-blind placebo-controlled study. Patients with mild to moderate AS are randomized to receive 40 mg/d of rosuvastatin or placebo. Patients with any clinical indication for the use of cholesterol-lowering agents according to the 2000 Canadian guidelines are excluded.

RESULTS

Recruitment of 272 patients from 23 Canadian sites was completed in December 2005. Compared with patients with AS in published trials, the patients in the ASTRONOMER study are younger (58.1 +/- 13.6 years), have less severe AS (AS jet velocity 3.2 +/- 0.4 m/s), and are composed of a great proportion (48.9%) of patients with bicuspid aortic valve.

CONCLUSIONS

Prevention of the development of severe AS needs to be tested in large randomized studies. Recruitment for the ASTRONOMER trial has been completed and results will be available at the end of 2008.

Calcific aortic stenosis: an update

Calcific aortic stenosis in the elderly is the number one cause of surgical valve replacement in the US and Europe. The incidence of calcific aortic stenosis is increasing as the general age of the population increases. For many years, rheumatic heart disease was the main cause of aortic valve disease. Over the last half century, however, there has been a change from a rheumatic etiology to a 'degenerative' mechanism because of the increase in access to health care in developed countries and the increasing age of the population in the US and Europe. For many years 'degenerative' aortic stenosis was thought to be caused by the passive accumulation of calcium on the surface of the aortic valve leaflet. Recent studies have demonstrated, however, that the etiology of aortic valve disease has a similar pathophysiology to that of vascular atherosclerosis, and that the treatment of this disease could be similar to that of chronic vascular atherosclerosis. This Review will discuss our current understanding of the pathophysiology, risk factors, cellular mechanisms, diagnosis and finally, future medical therapies for calcific aortic stenosis.

Angiotensin Receptor-1 Blocker Inhibits Atherosclerotic Changes and Endothelial Disruption of the Aortic Valve in Hypercholesterolemic Rabbits

OBJECTIVES

We sought to examine the effect of angiotensin receptor blocker (ARB) on the formation of lesions in the aortic valves of hypercholesterolemic rabbits.

BACKGROUND

Recently, atherosclerosis has been recognized as a mechanism that is responsible for calcific aortic stenosis. The effect of ARBs might help to prevent aortic stenosis because they have multiple antiatherosclerotic effects.

METHODS

Male Japanese white rabbits (n = 36) were separated as follows: control with chow diet (C) and vehicle (V) groups, both of which were fed a 1% cholesterol diet for 8 weeks, and an ARB group (A), which was fed a 1% cholesterol diet for 8 weeks with ARB (olmesartan, 1 mg/kg/day) for the last 4 weeks.

RESULTS

This dose of olmesartan did not affect either blood pressure or cholesterol levels. Dietary cholesterol induced fatty deposition with macrophage accumulation and osteopontin coexpression in valve leaflets, whereas ARB decreased macrophage accumulation (% area: V, 9.3 +/- 0.34; A, 1.4 +/- 0.30; p = 0.003) and osteopontin expression (p = 0.017). Angiotensin-converting enzyme was also up-regulated in V and decreased by olmesartan (p = 0.015). Immunohistochemistry with anti-CD31 antibody revealed that dietary cholesterol disrupted and olmesartan preserved endothelial integrity on the lesion-prone aortic side of the valve (% CD31-positive circumference: V, 30 +/- 3.7; A, 62 +/- 4.8; p = 0.003). Numbers of alpha-smooth muscle actin-positive myofibroblasts were increased in V and decreased by olmesartan (p = 0.003). Real-time polymerase chain reaction revealed that increased amounts of messenger ribonucleic acid for osteoblast-specific transcription factor core binding factor alpha-1 in V were diminished by olmesartan.

CONCLUSIONS

Atherosclerotic changes in the aortic valves of rabbits fed with cholesterol were inhibited by ARB, whereas endo-thelial integrity was preserved and transdifferentiation into myofibroblasts and/or osteoblasts in valve leaflets was inhibited.

Critical appraisal of C-reactive protein throughout the spectrum of cardiovascular disease

Clinicians involved in the care of patients with cardiovascular conditions have recently been confronted with an important body of literature linking inflammation and cardiovascular disease. Indeed, the level of systemic inflammation as measured by circulating levels of C-reactive protein (CRP) has been linked to prognosis in patients with atherosclerotic disease, congestive heart failure, atrial fibrillation, myocarditis, aortic valve disease and heart transplantation. In addition, a number of basic science reports suggest an active role for CRP in the pathophysiology of cardiovascular diseases. This article explores the potential role of CRP in disease initiation, progression, and clinical manifestations and reviews its role in the prediction of future events in clinical practice. Therapeutic interventions to decrease circulating levels of CRP are also reviewed.

Ongoing clinical trials of the pleiotropic effects of statins

BACKGROUND

The multiple effects (ie, pleiotropic effects of statins) have received increasing recognition and may have clinical applicability across a broad range of cardiovascular and noncardiovascular conditions.

OBJECTIVE

To determine the relevance and significance of ongoing clinical trials of the pleiotropic effects of statins, focusing on nonlipid effects.

METHOD

Ongoing trials were identified through personal communication, reports presented at scientific meetings (2000-2004), and queries made to AstraZeneca, Bristol-Myers Squibb Co, Merck & Co, Novartis, and Pfizer, manufacturers of the currently marketed statins. Published trials and other source material were identified through electronic searches on MEDLINE (1990-2003), abstract books, and references identified from bibliographies of pertinent articles. Eligible studies were the clinical trials of statins currently under way in which primary or secondary outcomes included the statins' nonlipid (ie, pleiotropic) effect(s). Data were extracted and trial quality was assessed by the authors.

RESULTS

Of the 22 ongoing trials of the nonlipid effects of statins identified, 10 assessed inflammatory markers and plaque stabilization, 4 assessed oxidized low density lipoprotein/vascular oxidant stress, 3 assessed end-stage renal disease, 3 assessed fibrinogen/viscosity, 2 assessed endothelial function, 2 assessed acute coronary syndrome, 2 assessed aortic stenosis progression, and 1 each assessed hypertension, osteoporosis, ischemic burden, Alzheimer's disease, multiple sclerosis, and stroke (outcomes often overlapped).

CONCLUSION

Given the excellent safety and tolerability of statins as a class, full exploration of their pleiotropic effects has the potential to provide additional benefits to many patients.