Angiotensin-converting enzyme gene polymorphism influences degree of left ventricular hypertrophy and its regression in patients undergoing operation for aortic stenosis

Heart failure and excess mortality after aortic valve replacement in aortic stenosis

INTRODUCTION

In aortic stenosis (AS), the heart transitions from adaptive compensation to an AS cardiomyopathy and eventually leads to decompensation with heart failure. Better understanding of the underpinning pathophysiological mechanisms is required in order to inform strategies to prevent decompensation.

AREAS COVERED

In this review, we therefore aim to appraise the current pathophysiological understanding of adaptive and maladaptive processes in AS, appraise potential avenues of adjunctive therapy before or after AVR and highlight areas of further research in the management of heart failure post AVR.

EXPERT OPINION

Tailored strategies for the timing of intervention accounting for individual patient's response to the afterload insult are underway, and promise to guide better management in the future. Further clinical trials of adjunctive pharmacological and device therapy to either cardioprotect prior to intervention or promote reverse remodeling and recovery after intervention are needed to mitigate the risk of heart failure and excess mortality.

Comparison of Aortic Gradient and Ventricular Mass after Valve Replacement for Aortic Stenosis with Rapid Deployment, Sutureless, and Conventional Bioprostheses

BACKGROUND

The use of rapid deployment and sutureless aortic prostheses is increasing. Previous reports have shown promising results on haemodynamic performance and mortality rates. However, the impact of these bioprostheses on left ventricular mass (LVM) regression remains unknown. We decided to study the changes in remodelling and LVM regression in isolated severe aortic stenosis treated with conventional or Perceval® or Intuity® valves.

METHOD AND RESULTS

From January 2011 to January 2016, 324 bioprostheses were implanted in our centre. The collected characteristics were divided into 3 groups: conventional valves, Perceval®, and Intuity®, and they were analysed after 12 months. There were 183 conventional valves (56%), 72 Perceval® (22%), and 69 Intuity® (21.2%). The statistical analysis showed significant differences in transprosthetic postoperative peak gradient (23 [18-29] mm Hg vs. 21 [16-29] mm Hg and 18 [14-24] mm Hg, p < 0.001), ventricular mass electrical criteria regression (Sokolow and Cornell products), and 1-year survival (90 vs. 93% and 97%, log rank p value = 0.04) in conventional, Perceval®, and Intuity® groups.

CONCLUSIONS

We observed differences in haemodynamic, electrocardiographic, and echocardiographic parameters related to the different types of prosthesis. Patients with the Intuity® prosthesis had the highest reduction in peak aortic gradient and the higher ventricular mass regression. Besides, patients with the Intuity® prosthesis had less risk of mortality during follow-up than the other two groups. Further studies are needed to confirm these findings.

Pathophysiological coronary and microcirculatory flow alterations in aortic stenosis

Regulation of coronary blood flow is maintained through a delicate balance of ventriculoarterial and neurohumoral mechanisms. The aortic valve is integral to the functions of these systems, and disease states that compromise aortic valve integrity have the potential to seriously disrupt coronary blood flow. Aortic stenosis (AS) is the most common cause of valvular heart disease requiring medical intervention, and the prevalence and associated socio-economic burden of AS are set to increase with population ageing. Valvular stenosis precipitates a cascade of structural, microcirculatory, and neurohumoral changes, which all lead to impairment of coronary flow reserve and myocardial ischaemia even in the absence of notable coronary stenosis. Coronary physiology can potentially be normalized through interventions that relieve severe AS, but normality is often not immediately achievable and probably requires continued adaptation. Finally, the physiological assessment of coronary artery disease in patients with AS represents an ongoing challenge, as the invasive physiological measures used in current cardiology practice are yet to be validated in this population. This Review discusses the key concepts of coronary pathophysiology in patients with AS through presentation of contemporary basic science and data from animal and human studies.

Medical Treatment of Aortic Stenosis

Untreated, severe, symptomatic aortic stenosis is associated with a dismal prognosis. The only treatment shown to improve survival is aortic valve replacement; however, before symptoms occur, aortic stenosis is preceded by a silent, latent phase characterized by a slow progression at the molecular, cellular, and tissue levels. In theory, specific medical therapy should halt aortic stenosis progression, reduce its hemodynamic repercussions on left ventricular function and remodeling, and improve clinical outcomes. In the present report, we performed a systematic review of studies focusing on the medical treatment of patients with aortic stenosis. Lipid-lowering therapy, antihypertensive drugs, and anticalcific therapy have been the main drug classes studied in this setting and are reviewed in depth. A critical appraisal of the preclinical and clinical evidence is provided, and future research avenues are presented.

Impact of Valvuloarterial Impedance on Concentric Remodeling in Aortic Stenosis and Its Regression after Valve Replacement

Background

Left ventricle (LV) in patients with aortic stenosis (AS) faces a double hemodynamic load incorporating both valvular stenosis and reduced systemic arterial compliance (SAC). This study aimed to evaluate the impact of global LV afterload on LV hypertrophy (LVH) before and after aortic valve replacement (AVR).

Methods

The study cohort included 453 patients (247 males; mean age, 64 ± 11 years) who underwent AVR. Pre- and post-AVR echocardiographic examinations were retrospectively analyzed including an index of valvuloarterial impedance (Z_VA) and LV mass index/LV end-diastolic volume index (LVMI/LVEDVI) as a parameter of LVH.

Results

Pre-AVR LVMI/LVEDVI was 2.7 ± 0.9 g/mL with an aortic valve area (AVA) of 0.6 ± 0.2 cm². Z_VA was 5.9 ± 1.9 mm Hg/mL/m² and showed a stronger correlation (β = 0.601, p < 0.001) with pre-AVR LVMI/LVEDVI than indexed AVA (β = 0.061, p = 0.19), transvalvular peak velocity (β = 0.211, p < 0.001). During a median follow-up of 3.5 years, patients had a 18.8 ± 10.4% decrease in the LV geometry index with a decrease in SAC from 1.20 ± 0.48 to 1.00 ± 0.38 mL/m²/mm Hg (p < 0.001). Pre-AVR LV ejection fraction (r = 0.284, p < 0.001) and Z_VA (r = 0.523, p < 0.001) were independent factors associated with LVH regression in 322 patients with follow-up duration >1 year after AVR.

Conclusion

Z_VA is a major determinant of concentric remodeling in AS before AVR and LVH regression after AVR, which should be incorporated in routine evaluation of AS.

Practical Pharmacogenomic Approaches to Heart Failure Therapeutics

OPINION STATEMENT

The major challenge in applying pharmacogenomics to everyday clinical practice in heart failure (HF) is based on (1) a lack of robust clinical evidence for the differential utilization of neurohormonal antagonists in the management of HF in different subgroups, (2) inconsistent results regarding appropriate subgroups that may potentially benefit from an alternative strategy based on pharmacogenomic analyses, and (3) a lack of clinical trials that focused on testing gene-guided treatment in HF. To date, all pharmacogenomic analyses in HF have been conducted as post hoc retrospective analyses of clinical trial data or of observational patient series studies. This is in direct contrast with the guideline-directed HF therapies that have demonstrated their safety and efficacy in the absence of pharmacogenomic guidance. Therefore, the future of clinical applications of pharmacogenomic testing will largely depend on our ability to incorporate gene-drug interactions into the prescribing process, requiring that preemptive and cost-effective testing be paired with decision-support tools in a value-based care approach.

Involvement of the -420C>G RETN polymorphism in myocardial fibrosis in patients with hypertrophic cardiomyopathy

AIMS

Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy and fibrosis. HCM is an autosomal-dominant disease caused by more than 400 mutations in sarcomeric genes. Changes in nonsarcomeric genes contribute to its phenotypic heterogeneity. Cardiac fibrosis can be studied using late gadolinium enhancement (LGE) cardiac magnetic resonance imaging. We evaluated the potential role of two polymorphisms in nonsarcomeric genes on interstitial fibrosis in HCM.

MATERIALS AND METHODS

Two polymorphisms in nonsarcomeric genes [ACE (deletion of 287 bp in the 16th intron) and RETN (-420C>G)] were analysed in 146 HCM patients. Cardiac fibrosis was assessed using LGE to determine the number of affected segments.

RESULTS

Allelic frequencies in ACE and RETN polymorphisms were consistent with the Hardy-Weinberg equilibrium (both P > 0.05). We found that the presence of the polymorphic allele in the -420C>G RETN polymorphism was independently associated with the number of affected segments of LGE (P = 0.038). Increased circulating resistin concentration, measured by enzyme-linked immunosorbent assay, was associated with a higher degree of cardiac fibrosis. Myocardial fibrosis, assessed by Masson's trichrome staining, was associated with the -420C>G RETN polymorphism in 46 tissue samples obtained by septal myectomy (P = 0.044).

CONCLUSIONS

The -420C>G RETN polymorphism was independently associated with the degree of cardiac fibrosis, assessed by LGE, in patients with HCM. In addition, there was an association between the polymorphism and the circulating resistin levels as well as with myocardial fibrosis in tissues obtained by myectomy. Investigating the physiological implication of the RETN polymorphism in HCM in combination with the use of imaging technologies might help to establish the severity of disease in patients with HCM.

Regression of left ventricular mass after implantation of the sutureless 3f Enable aortic bioprosthesis

Left ventricular hypertrophy in aortic stenosis is considered a compensatory response for the maintenance of systolic function but a risk factor for cardiac morbidity and death. We investigated the degree of left ventricular mass regression after implantation of the sutureless Medtronic 3f Enable Aortic Bioprosthesis. We studied 19 patients who, from May 2010 through July 2011, underwent isolated aortic valve replacement with the 3f Enable bioprosthetic valve, with clinical and echocardiographic follow-up at 6 months. The mean age was 77.1 ± 5.1 years (range, 68-86 yr); 14 patients were women (73.7%); and the mean logistic EuroSCORE was 15.4% ± 11.8%. Echocardiography was performed preoperatively, at discharge, and at 6 months' follow-up. The left ventricular mass was calculated by means of the Devereux formula and indexed to body surface area. The left ventricular mass index decreased from 146.1 ± 47.6 g/m(2) at baseline to 118.1 ± 39.8 g/m(2) at follow-up (P=0.003). The left ventricular ejection fraction did not change significantly. The mean transaortic gradient decreased from 57.3 ± 14.2 mmHg at baseline to 12.3 ± 4.6 mmHg at discharge and 12.2 ± 5.3 mmHg at follow-up (P <0.001), and these decreases were accompanied by substantial clinical improvement. No moderate or severe paravalvular leakage was present at discharge or at follow-up. In isolated aortic stenosis, aortic valve replacement with the 3f Enable bioprosthesis results in significant regression of left ventricular mass at 6 months' follow-up. However, this regression needs to be verified by long-term echocardiographic follow-up.

Left ventricular mass regression after two alternative sutureless aortic bioprostheses

OBJECTIVE

Left ventricular (LV) hypertrophy in aortic stenosis (AS) constitutes a risk factor for cardiac morbidity and mortality. The aim of this study was to investigate the degree of LV mass regression after aortic valve replacement (AVR) with two alternative sutureless self-expanding strategies: Perceval S (Sorin Group, Saluggia, Italy) (P) and 3f Enable (Medtronic, ATS Medical, Minneapolis, MN USA) (E) aortic bioprostheses.

METHODS

Between March 2010 and December 2011, 129 patients with symptomatic AS underwent AVR with the Perceval S or 3f Enable bioprostheses in two cardiac surgery departments (Massa, Italy; Nuremberg, Germany). We analyzed 45 patients in group P and 19 in group E undergoing isolated AVR with a 6-month follow-up. The LV mass was calculated using the Devereux formula and was indexed to body surface area.

RESULTS

Baseline patient characteristics showed no significant differences between the two groups. There were no in-hospital deaths. Two patients in group P died at follow-up versus zero in group E (P = 0.49). Mean LV mass index decreased from 146.6 (78) g/m at baseline to 123.3 (63) g/m at follow-up (P < 0.001) in group P and from 146.1 (47.6) g/m to 118.1 (39.8) g/m (P = 0.003) in group E, with no significant difference between the two groups (P = 0.315). This effect was accompanied by significant clinical improvement.

CONCLUSIONS

In isolated AS, AVR with sutureless bioprostheses is associated with a significant regression in LV mass at 6-month follow-up. No significant differences were present between the two alternative sutureless strategies. However, regression needs an evaluation with long-term echocardiographic examinations.

Association of the common genetic polymorphisms and haplotypes of the chymase gene with left ventricular mass in male patients with symptomatic aortic stenosis

We investigated the association between polymorphisms and haplotypes of the chymase 1 gene (CMA1) and the left ventricular mass index (LVM/BSA) in a large cohort of patients with aortic stenosis (AS). Additionally, the gender differences in cardiac remodeling and hypertrophy were analyzed. The genetic background may affect the myocardial response to pressure overload. In human cardiac tissue, CMA1 is involved in angiotensin II production and TGF-β activation, which are two major players in the pathogenesis of hypertrophy and fibrosis. Preoperative echocardiographic data from 648 patients with significant symptomatic AS were used. The LVM/BSA was significantly lower (p<0.0001), but relative wall thickness (RWT) was significantly higher (p = 0.0009) in the women compared with the men. The haplotypes were reconstructed using six genotyped polymorphisms: rs5248, rs4519248, rs1956932, rs17184822, rs1956923, and rs1800875. The haplotype h1.ACAGGA was associated with higher LVM/BSA (p = 9.84×10⁻⁵), and the haplotype h2.ATAGAG was associated with lower LVM/BSA (p = 0.0061) in men, and no significant differences were found in women. Two polymorphisms within the promoter region of the CMA1 gene, namely rs1800875 (p = 0.0067) and rs1956923 (p = 0.0015), influenced the value of the LVM/BSA in males. The polymorphisms and haplotypes of the CMA1 locus are associated with cardiac hypertrophy in male patients with symptomatic AS. Appropriate methods for the indexation of heart dimensions revealed substantial sex-related differences in the myocardial response to pressure overload.

The global burden of aortic stenosis

Degenerative, calcific valvular aortic stenosis (AS), caused by an active process of atherosclerosis, calcification and ossification, is the most common cause of AS in industrialized nations. The prevalence of calcific AS is age-dependent, and thus is expected to increase due to demographic aging of the global population. It is well recognized that severe AS carries a poor prognosis if left untreated. Despite this recognition, many patients are inappropriately denied surgery because of perceived risk. This article will examine the etiology, prevalence, and current trends in the treatment of degenerative AS focusing on indications for surgical aortic valve replacement.

Myocardial stress and hypertrophy: a complex interface between biophysics and cardiac remodeling

Pressure and volume overload results in concentric and eccentric hypertrophy of cardiac ventricular chambers with, respectively, parallel and series replication of sarcomeres. These divergent patterns of hypertrophy were related 40 years ago to disparate wall stresses in both conditions, with systolic wall stress eliciting parallel replication of sarcomeres and diastolic wall stress, series replication. These observations are relevant to clinical practice, as they relate to the excessive hypertrophy and contractile dysfunction regularly observed in patients with aortic stenosis. Stress-sensing mechanisms in cardiomyocytes and activation of cardiomyocyte death by elevated wall stress continue to intrigue cardiovascular scientists.

Coexisting cardiac diseases and pressure recovery phenomenon contribute to discrepancy between the echocardiographic severity of aortic stenosis and left ventricular hypertrophy

BACKGROUND

Assessing left ventricular (LV) hypertrophy (LVH) is an important step in the echocardiographic diagnosis of aortic stenosis (AS). We aimed to investigate the causes of discrepancies between the degrees of AS and LVH.

METHODS

The study subjects consisted of 149 consecutive patients with AS having aortic valve area <2.0 cm(2) (mean age 72.5 ± 11.9 years, 67 men and 82 women). Coexisting cardiac diseases were determined based on echocardiographic findings and comprehensive clinical judgment. Echocardiographic measurements included LV mass index (LVMI), aortic valve area index (AVAI), transaortic mean pressure gradient (MPG), valvulo-arterial impedance (Zva), energy loss coefficient (ELCo), and energy loss index (ELI).

RESULTS

LVMI was not significantly correlated with AVAI and Zva, and had a weak correlation with MPG (r = 0.305, p = 0.0001). There were 55 patients in group A (non-severe AS without significant LVH), 58 in group B (non-severe AS with significant LVH), 7 in group C (severe AS without significant LVH), and 29 in group D (severe AS with significant LVH). Coexisting cardiac diseases were more frequently observed (p = 0.0003) in group B (50 %) than in group A (18 %). In group C, ELCo and (ELI - AVAI)/ELI were significantly greater than in group D (p = 0.043 and 0.007, respectively).

CONCLUSION

Significant LVH seen in less than moderate AS is often due to coexisting cardiac diseases, and there may be an overestimation of AS severity due to pressure recovery among patients with apparently severe AS who do not have significant LVH.

Left ventricular global systolic longitudinal deformation and prognosis 1 year after femoral and apical transcatheter aortic valve implantation

BACKGROUND

Aortic valve replacement is the recommended therapy for patients with severe aortic stenosis who have symptoms or decreased left ventricular (LV) function. Transcatheter aortic valve implantation (TAVI) is a treatment alternative in surgically high-risk or inoperable patients with severe aortic stenosis. The objective of this study was to analyze LV function assessed by global LV longitudinal systolic strain (GLS) and relation to prognosis in patients with severe aortic stenosis treated with femoral or apical TAVI.

METHODS

Two-dimensional echocardiography was performed before and 1 year after TAVI. Ejection fraction (EF) was retrospectively measured using the biplane Simpson's method, and GLS was obtained as an average of 16 segments in the three standard apical views by speckle-tracking. GE Vivid 7 and Vivid 9 machines were used for echocardiography, and speckle-tracking analysis was performed using EchoPAC PC '08 version 7.0.1.

RESULTS

The total population consisted of 100 TAVI patients. Eighty-one patients survived to 1-year follow-up, with a mean age of 81 ± 7 years (range, 64-93 years) and a mean European System for Cardiac Operative Risk Evaluation score of 9.6 ± 2.7. Nineteen patients died before 1-year follow-up (12 women), with a mean age of 82 ± 7 years (range, 66-92 years) and a mean European System for Cardiac Operative Risk Evaluation score of 10.5 ± 2.8. No differences were found between the 19 patients who died before follow-up and the 81 patients who survived to 1-year follow-up. GLS was increased significantly 1 year after TAVI. In 34 patients with EFs > 50%, GLS increased from -15.3 ± 3.4 to -17.1 ± 3.6 (P = .04). In these patients, the mean EF increased numerically from 57.9 ± 5.3% to 60 ± 7.7% (P = .19). In 74 patients with EFs ≤ 50%, mean GLS and EF improved significantly from -10 ± 2.8 to -13.8 ± 3.8 (P < .0001) and 39 ± 9.4% to 52 ± 12.5% (P < .0001), respectively. The 1-year gain in EF was the same after femoral TAVI (9.7 ± 10.1%) and after apical TAVI (8 ± 10.8%) (P = .52). Furthermore, GLS did not differ significantly after femoral and apical TAVI (-3.8 ± 3.3 and -2.6 ± 3.7, respectively, P = .21). There was no difference in causes of death according to approach. In the total population (n = 100), 35 deaths occurred, 19 before 1-year follow-up and 16 afterward. The median follow-up time was 30 months. Twenty-five patients (71%) died from cardiac causes. Overall 1-year mortality was 19%, and overall 2-year mortality was 28%. In the patients who died, the median survival time in the apical group was 28.5 ± 15.4 months, compared with 31.6 ± 19 months in the femoral group (P = .47). There was no impact on prognosis according to high (≥47.5%) versus low (<47.5%) baseline EF or high (≥11.95%) versus low (<11.95%) baseline GLS. However, the magnitude of changes in GLS seemed to have a prognostic impact.

CONCLUSIONS

LV EF and longitudinal systolic deformation were improved in TAVI independent of technical approach using the Edwards SAPIEN valve prosthesis during 1-year follow-up. The mortality rate was comparable between technical approaches and independent of baseline LV function. However, patients with the greatest improvement in LV systolic longitudinal deformation after TAVI had a lower mortality rate.

Congenital valvular aortic stenosis in young adults: predictors for rate of progression of stenosis and aortic dilatation

BACKGROUND

Congenital aortic stenosis (AS) is the most common obstructive left-sided cardiac lesion in young adults, however little is known about the progression in adults. Therefore, we aimed to evaluate the progression rate of AS and aortic dilatation in a large multicenter retrospective cohort of asymptomatic young adults with congenital valvular AS.

METHODS

Data were obtained from chart abstraction. Linear mixed-effects models were used to evaluate the progression of AS and aortic dilatation over time. A joint model combining longitudinal echocardiographic and survival data was used for survival analysis.

RESULTS

A total of 414 patients (age 29 ± 10 years, 68% male) were included. Median follow-up duration was 4.1 (2.5-5.1) years (1587 patient-years). Peak aortic velocity was 3.4 ± 0.7 m/s at baseline and did not change over time in the total patient population (-0.01 ± 0.03 m/s/year). Increased left ventricular mass was significantly associated with faster AS progression (p<0.001). Aortic dilatation was present in 34% at baseline and 48% at follow-up (p<0.001). The aortic diameter linearly increased over time with a rate of 0.7 ± 0.2mm/year. Rate of aortic dissection was 0.06% per patient-year. Seventy patients required an aortic valve intervention (4.4% per patient-year), with AS progression rate as most powerful predictor (HR 5.11 (95% CI 3.47-7.53)).

CONCLUSIONS

In the majority of patients with mild-to-moderate congenital AS, AS severity does not progress over time. However patients with left ventricular hypertrophy are at risk for faster progression and should be monitored carefully. Although aortic dissections rarely occur, aortic dilatation is common and steadily progresses over time, warranting serial aortic imaging.

Left ventricular remodeling and hypertrophy in patients with aortic stenosis: insights from cardiovascular magnetic resonance

BACKGROUND

Cardiovascular magnetic resonance (CMR) is the gold standard non-invasive method for determining left ventricular (LV) mass and volume but has not been used previously to characterise the LV remodeling response in aortic stenosis. We sought to investigate the degree and patterns of hypertrophy in aortic stenosis using CMR.

METHODS

Patients with moderate or severe aortic stenosis, normal coronary arteries and no other significant valve lesions or cardiomyopathy were scanned by CMR with valve severity assessed by planimetry and velocity mapping. The extent and patterns of hypertrophy were investigated using measurements of the LV mass index, indexed LV volumes and the LV mass/volume ratio. Asymmetric forms of remodeling and hypertrophy were defined by a regional wall thickening ≥ 13 mm and >1.5-fold the thickness of the opposing myocardial segment.

RESULTS

Ninety-one patients (61 ± 21 years; 57 male) with aortic stenosis (aortic valve area 0.93 ± 0.32 cm2) were recruited. The severity of aortic stenosis was unrelated to the degree (r2=0.012, P=0.43) and pattern (P=0.22) of hypertrophy. By univariate analysis, only male sex demonstrated an association with LV mass index (P=0.02). Six patterns of LV adaption were observed: normal ventricular geometry (n=11), concentric remodeling (n=11), asymmetric remodeling (n=11), concentric hypertrophy (n=34), asymmetric hypertrophy (n=14) and LV decompensation (n=10). Asymmetric patterns displayed considerable overlap in appearances (wall thickness 17 ± 2mm) with hypertrophic cardiomyopathy.

CONCLUSIONS

We have demonstrated that in patients with moderate and severe aortic stenosis, the pattern of LV adaption and degree of hypertrophy do not closely correlate with the severity of valve narrowing and that asymmetric patterns of wall thickening are common.

Midwall fibrosis is an independent predictor of mortality in patients with aortic stenosis

OBJECTIVES

The goal of this study was to assess the prognostic significance of midwall and infarct patterns of late gadolinium enhancement (LGE) in aortic stenosis.

BACKGROUND

Myocardial fibrosis occurs in aortic stenosis as part of the hypertrophic response. It can be detected by LGE, which is associated with an adverse prognosis in a range of other cardiac conditions.

METHODS

Between January 2003 and October 2008, consecutive patients with moderate or severe aortic stenosis undergoing cardiovascular magnetic resonance with administration of gadolinium contrast were enrolled into a registry. Patients were categorized into absent, midwall, or infarct patterns of LGE by blinded independent observers. Patient follow-up was completed using patient questionnaires, source record data, and the National Strategic Tracing Service.

RESULTS

A total of 143 patients (age 68 ± 14 years; 97 male) were followed up for 2.0 ± 1.4 years. Seventy-two underwent aortic valve replacement, and 27 died (24 cardiac, 3 sudden cardiac deaths). Compared with those with no LGE (n = 49), univariate analysis revealed that patients with midwall fibrosis (n = 54) had an 8-fold increase in all-cause mortality despite similar aortic stenosis severity and coronary artery disease burden. Patients with an infarct pattern (n = 40) had a 6-fold increase. Midwall fibrosis (hazard ratio: 5.35; 95% confidence interval: 1.16 to 24.56; p = 0.03) and ejection fraction (hazard ratio: 0.96; 95% confidence interval: 0.94 to 0.99; p = 0.01) were independent predictors of all-cause mortality by multivariate analysis.

CONCLUSIONS

Midwall fibrosis was an independent predictor of mortality in patients with moderate and severe aortic stenosis. It has incremental prognostic value to ejection fraction and may provide a useful method of risk stratification.

The ACE gene and human performance: 12 years on

Some 12 years ago, a polymorphism of the angiotensin I-converting enzyme (ACE) gene became the first genetic element shown to impact substantially on human physical performance. The renin-angiotensin system (RAS) exists not just as an endocrine regulator, but also within local tissue and cells, where it serves a variety of functions. Functional genetic polymorphic variants have been identified for most components of RAS, of which the best known and studied is a polymorphism of the ACE gene. The ACE insertion/deletion (I/D) polymorphism has been associated with improvements in performance and exercise duration in a variety of populations. The I allele has been consistently demonstrated to be associated with endurance-orientated events, notably, in triathlons. Meanwhile, the D allele is associated with strength- and power-orientated performance, and has been found in significant excess among elite swimmers. Exceptions to these associations do exist, and are discussed. In theory, associations with ACE genotype may be due to functional variants in nearby loci, and/or related genetic polymorphism such as the angiotensin receptor, growth hormone and bradykinin genes. Studies of growth hormone gene variants have not shown significant associations with performance in studies involving both triathletes and military recruits. The angiotensin type-1 receptor has two functional polymorphisms that have not been shown to be associated with performance, although studies of hypoxic ascent have yielded conflicting results. ACE genotype influences bradykinin levels, and a common gene variant in the bradykinin 2 receptor exists. The high kinin activity haplotye has been associated with increased endurance performance at an Olympic level, and similar results of metabolic efficiency have been demonstrated in triathletes. Whilst the ACE genotype is associated with overall performance ability, at a single organ level, the ACE genotype and related polymorphism have significant associations. In cardiac muscle, ACE genotype has associations with left ventricular mass changes in response to stimulus, in both the health and diseased states. The D allele is associated with an exaggerated response to training, and the I allele with the lowest cardiac growth response. In light of the I-allele association with endurance performance, it seems likely that other regulatory mechanisms exist. Similarly in skeletal muscle, the D allele is associated with greater strength gains in response to training, in both healthy individuals and chronic disease states. As in overall performance, those genetic polymorphisms related to the ACE genotype, such as the bradykinin 2 gene, also influence skeletal muscle strength. Finally, the ACE genotype may influence metabolic efficiency, and elite mountaineers have demonstrated an excess of I alleles and I/I genotype frequency in comparison to controls. Interestingly, this was not seen in amateur climbers. Corroboratory evidence exists among high-altitude settlements in both South America and India, where the I allele exists in greater frequency in those who migrated from the lowlands. Unfortunately, if the ACE genotype does influence metabolic efficiency, associations with peak maximal oxygen consumption have yet to be rigorously demonstrated. The ACE genotype is an important but single factor in the determinant of sporting phenotype. Much of the mechanisms underlying this remain unexplored despite 12 years of research.

Left ventricular mass regression one year after transcatheter aortic valve implantation

BACKGROUND

Left ventricular (LV) hypertrophy is associated with LV diastolic dysfunction and constitutes a risk factor for cardiac morbidity and mortality. The objective of this study was to investigate the degree of LV mass regression and the changes of LV diastolic function one year after transcatheter aortic valve implantation (TAVI).

METHODS

Echocardiography was performed at baseline, before discharge, and at one-year follow-up in 63 consecutive patients with severe aortic stenosis who underwent TAVI with the Medtronic CoreValve System (Medtronic Inc, Minneapolis, MN). The LV mass was calculated using the Devereux formula and indexed to body surface area.

RESULTS

One-year all-cause mortality was 29%. The LV mass index decreased from 126 ± 42 g/m(2) at baseline to 110 ± 30 g/m(2) at one-year follow-up (p < 0.001). Left ventricular ejection fraction and LV diastolic function did not change significantly. Mean transaortic gradient decreased from 47 ± 19 mm Hg at baseline to 9 ± 5 mm Hg at discharge and 9 ± 4 mm Hg at one year (p < 0.001), and was accompanied by significant clinical improvement. More than mild paravalvular aortic regurgitation was found in 24% and 15% of patients at discharge and one-year follow-up, respectively.

CONCLUSIONS

A significant regression in LV mass was found one year after TAVI. However, regression was incomplete and was not accompanied by an improvement in LV diastolic function.

Impact of polymorphisms in the renin–angiotensin–aldosterone system on hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a clinically heterogeneous autosomal dominant heart disease characterised by left ventricular hypertrophy in the absence of another cardiac or systemic disease that is capable of producing significant wall thickening. Microscopically it is characterised by cardiomyocyte hypertrophy, myofibrillar disarray and fibrosis. The phenotypic expression of HCM is multifactorial, with the majority of cases occurring secondary to mutations in genes encoding the sarcomere proteins. In conjunction with the genetic heterogeneity of HCM, phenotypic expression also exhibits a high level of variability even within families with the same aetiological mutation, and may be influenced by additional genetic factors. Polymorphisms of the renin–angiotensin–aldosterone system (RAAS) represent an attractive hypothesis as potential disease modifiers, as these genetic variants alter the ‘activation status’ of the RAAS, which leads to more left ventricular hypertrophy through different pathways. The main objective of this review is to provide an overview of the role of different polymorphisms identified in the RAAS, in patients with HCM.

Early Hemodynamic Results of the Shelhigh SuperStentless Aortic Bioprostheses

BACKGROUND

Stentless valves have been demonstrated excellent hemodynamic performances favoring the recovery of left ventricular function and the ventricular hypertrophy regression. The aim of the study was to evaluate the early hemodynamic performance of the Shelhigh SuperStentless aortic valve (AV).

METHODS

Between July 2003 and June 2005, 35 patients (18 females; age 70.8 +/- 11.7 years, range: 22-85) underwent AV replacement with the Shelhigh SuperStentless bioprostheses. Most recurrent etiology was senile degeneration in 25 (71%) patients and 24 (69%) were in New York Heart Association (NYHA) functional class III or IV. Concomitant coronary artery bypass grafting was performed in nine patients (25.7%) and mitral valve surgery in two patients (5.7%). Doppler echocardiography was performed before surgery, at six-month and one-year follow-up.

RESULTS

There were no hospital deaths and no valve-related perioperative complications. During one-year follow-up, no endocarditis or thromboembolic events were registered, no cases of structural dysfunction or valve thrombosis were noted. Mean and peak transvalvular gradients significantly decrease after AV replacement, with an evident reduction to approximately 50% of the preoperative values at six months. A 20% reduction was also observed for left ventricular mass (LVM) index at six months, with a further regression at one year. Correspondingly, significant increases in effective orifice area (EOA) and indexed EOA were determined after surgery (0.87 +/- 0.14 versus 1.84 +/- 0.29 cm2 and 0.54 +/- 0.19 versus 1.05 +/- 0.20 cm2/m2, respectively). Valve prosthesis-patient mismatch was moderate in five patients and severe in one case.

CONCLUSIONS

Shelhigh SuperStentless AV provided good and encouraging hemodynamic results. Long-term follow-up is necessary to evaluate late hemodynamic performance and durability of this stentless bioprosthesis.

Angiotensin II reactivation and aldosterone escape phenomena in renin-angiotensin-aldosterone system blockade: is oral renin inhibition the solution?

This editorial considers the use of the first selective oral renin inhibitor, aliskiren, in reducing angiotensin (Ang) II reactivation or aldosterone (ALDO) escape during renin-angiotensin-aldosterone system (RAAS) inhibition. RAAS blockade with angiotensin converting enzyme inhibitors (ACEIs) and/or angiotensin receptor AT(1) blockers (ARBs) is very useful for the treatment of arterial hypertension, chronic heart failure (CHF), atherosclerosis and diabetes. 'Ang II reactivation' and 'ALDO escape' or 'breakthrough' have been observed during either ACEI or ARB treatment, and may attenuate the clinical benefit of RAAS blockade. Renin and Ang I accumulate during ACE inhibition, and might overcome the ability of an ACEI to effectively suppress ACE activity. There is also data suggesting that 30 - 40% of Ang II formation in the healthy human during RAAS activation is formed via renin-dependent, but ACE-independent, pathways. Moreover, ACE gene polymorphisms contribute to the modulation and adequacy of the neurohormonal response to long-term ACE inhibition, at least in patients with CHF (up to 45% of CHF patients have elevated Ang II levels despite the long-term use of an ACEI) or diabetes. The reactivated Ang II promotes ALDO secretion and sodium reabsorption. ALDO breakthrough also occurs during long-term ARB therapy, mainly by an AT(2)-dependent mechanism. This was related to target-organ damage in animal models. Oral renin inhibition with aliskiren has showed excellent efficacy and safety in the treatment of hypertension. Aliskiren can be co-administered with ACEIs, ARBs or hydrochlorothiazide. Furthermore, there is evidence suggesting that aliskiren reduces Ang II reactivation in ACE inhibition and ALDO escape during treatment with an ACEI or an ARB, at least to the degree that this is associated with the RAAS. For RAAS-independent ALDO production, the combination of aliskiren with eplerenone might prove useful.

The role and regulation of cardiac angiotensin-converting enzyme for noninvasive molecular imaging in heart failure

Congestive heart failure is a pathologic condition characterized by progressive decrease in left ventricular contractility and consequent decline of cardiac output. There is convincing clinical and experimental evidence that the renin-angiotensin system (RAS) and its primary effector peptide, angiotensin II, are linked to the pathophysiology of interstitial fibrosis, cardiac remodeling, and heart failure. In addition to the traditional endocrine or circulating RAS, an active tissue RAS has been characterized. Tissue angiotensin-converting enzyme and locally synthesized angiotensin II, for example, by chymase, exert local trophic effects that modulate gene expression, which regulates growth and proliferation in both myocytes and nonmyocytes. The existence of the tissue RAS offers an opportunity for targeted imaging, which may be of considerable value for guiding medical therapy.

Stentless valves for aortic valve replacement: where do we stand?

PURPOSE OF REVIEW

Following more than a decade's experience with stentless valves and the development of better profiled stented valves, the article discusses the advantages of stentless valves regarding hemodynamic performance, left ventricular mass regression, durability and survival.

RECENT FINDINGS

Recent studies show that stentless valves remain hemodynamically superior compared with modern porcine stented valves. This superiority is, however, rarely reported in comparison with modern pericardial stented valves. In general, patient-prosthesis mismatch is less frequent in stentless vs. stented valves. Recent randomized trials comparing stentless valves and modern stented valves show equivalent left ventricular mass regression at 1 year. At 10 years, stentless valve durability is excellent and comparable with that of stented valves. Recent comparative studies do not confirm the previously reported midterm survival advantages of stentless valves.

SUMMARY

Improvement of stented valves has significantly reduced the hemodynamic differences between them and their stentless counterpart. Patients with small aortic annulus, however, should benefit from a stentless valve due to the better expected gradients and lower risk of patient-prosthesis mismatch. Midterm results suggest equivalent durability and survival for both prosthesis types but additional and longer-term trials are necessary to confirm these results.

Effect of the increase in valve area after aortic valve replacement with a 19-mm aortic valve prosthesis on left ventricular mass regression in patients with pure aortic stenosis

OBJECTIVES

Although patients with aortic stenosis, who receive 19-mm valves, are at high risk for prosthesis-patient mismatch, most of them show a significant left ventricular mass (LVM) regression postoperatively. The aim of this study was to identify factors predicting postoperative relative LVM regression in this subgroup of patients.

METHODS

A population of 44 patients operated on for pure aortic stenosis and receiving a 19-mm valve was studied by echocardiography at 1.4 +/- 0.5 years postoperatively.

RESULTS

The mean relative LVM regression was -19.3 +/- 18.9%, the mean gradient drop was -31.6 +/- 13.3 mmHg, and the mean Delta increase in aortic area index (postoperative aortic area index minus preoperative aortic area index) was 0.30 +/- 0.14 cm/m. Thirty-two patients had an indexed effective orifice area of less than 0.8 cm/m. At multivariate analysis (r = 0.63; r = 40%; P < 0.0001) preoperative LVM (P = 0.006), hypertension (P = 0.018) and Delta aortic area index (P = 0.049) were independent predictors of relative LVM regression.

CONCLUSIONS

Our study shows that, at least 1 year postoperatively, in patients receiving a 19-mm valve, LVM regression is influenced by several parameters, in particular preoperative LVM, hypertension and the magnitude of the increase in aortic area.

ACE gene dosage modulates pressure-induced cardiac hypertrophy in mice and men

The influence of genetic factors on complex phenotypes is context dependent, posing a challenge to quantify the role of single gene variants on this process. Moreover, redundancy and reserve capacity among control systems prevent most physiological stimuli to destabilize these processes. To test whether small gene perturbation can disrupt this equilibrium under pathological conditions, mice harboring one, two, or three copies of the angiotensin converting enzyme ( Ace) gene were submitted to 3 and 6 wk of pressure overload (PO). Direct systolic blood pressure (SBP), as an index of cardiac afterload, and left ventricle mass index (LVMI) were measured. LVMI under normotension was the same regardless of the Ace genotype, but the slopes of the LVMI/SBP curves increased in the three- vs. one-copy group by ∼50% upon 3- or 6-wk PO. Angiotensin II AT1 receptor blocker treatment produced a significant pressure independent decrease in the LVMI/SBP ratio. Unlike the one-copy group, PO resulted in a significant reduction in angiotensinogen and an increase in Ace mRNA expression accompanied by an increase in cardiac angiotensin II levels in the three-copy group. Similarly, the human ACE D gene variant influenced cardiac mass, estimated by Sokolov-Lyon index, in a sample of 1,507 individuals from an urban population only in individuals in the 4th quartile of the blood pressure distribution. Collectively, these data provide direct evidence that ACE gene dosage per se does not influence cardiac mass but upon a pathological stimulus, such as elevation in blood pressure, it modulates cardiac mass in both mice and humans.

Impact of the improvement of valve area achieved with aortic valve replacement on the regression of left ventricular hypertrophy in patients with pure aortic stenosis

BACKGROUND

Previous studies have reported that patient-prosthesis mismatch may be associated with lesser regression of left ventricular hypertrophy. However, among the patients with mismatch, the extent of left ventricular mass regression varied markedly from one patient to another, and we hypothesized that it could be related to the magnitude of the increase in valve area achieved with aortic valve replacement. Our aim was to examine the relationship between the improvement in valve effective orifice area obtained with aortic valve replacement and the extent of postoperative left ventricular mass regression in patients with patient-prosthesis mismatch.

METHODS

Preoperative and postoperative measurements of valve effective orifice area, transvalvular pressure gradient, and left ventricular mass were obtained by Doppler echocardiography in 111 patients with pure aortic stenosis who were found to have patient-prosthesis mismatch based on an indexed effective orifice area of 0.8 cm2/m2 or less after operation.

RESULTS

On average, the valve effective orifice area increased by 0.45 +/- 0.24 cm2/m2 with operation, and mean transvalvular pressure gradients decreased by -31.6 +/- 13.5 mm Hg. The absolute and relative differences between preoperative and postoperative left ventricular mass were -28 +/- 30 g and -17% +/- 18%, respectively. In multivariate analysis, higher preoperative left ventricular mass (p < 0.0001) and larger increase in indexed valve effective orifice area with operation (p = 0.019) were independently associated with greater left ventricular mass regression.

CONCLUSIONS

This study shows that in patients with patient-prosthesis mismatch, the degree of left ventricular mass regression is influenced by the increase in valve effective orifice area achieved by aortic valve replacement.

Factors influencing the mean postoperative gradients across stentless porcine valves

BACKGROUND

To study the preoperative and intraoperative variables influencing the mean post-operative transvalvular gradient across stentless porcine valves.

METHODS

From 1995 to 2002, 84 patients underwent stentless valve insertion. The mean age was 73 years, and 63% were male. The valve pathology was aortic stenosis (AS) in 79%, aortic regurgitation (AR) in 12%, and mixed in 9%. Valve sizes ranged from 21 to 29 with size 27 being most frequent. 54% of patients had concomitant procedures. Patients had at least yearly clinical and echocardiographic follow-up.

RESULTS

There was no operative mortality. 9.5% of the patients had significant postoperative complications. The average echo interval was 18.6 months (range 1-88). The overall mean transvalvular gradient was 9.88+/-5.67 (SD) mmHg. Variables associated with significantly reduced gradients were: larger valve sizes (p=0.002), younger age (p=0.05), pre-op AR (p=0.008), and increasing post-operative interval (p=0.05). The mean gradients decreased by 0.28 mmHg for each post-operative year. The method of implantation did not significantly affect gradients (p=0.26).

CONCLUSIONS

Excellent mean transvalvular gradients were achieved with stentless valves studied, with a low operative risk. The gradients did not appear to be related to intra-operative factors, suggesting that insertion techniques can be tailored to suit patient conditions and surgeon preferences.

Rest and Exercise Performance of the Medtronic Advantage Bileaflet Valve in the Aortic Position

BACKGROUND

The aim of the study was to evaluate rest and exercise performance and left ventricular mass regression of the Medtronic Advantage (Medtronic, Inc, Minneapolis, MN) prosthesis in the aortic position at 1 year at a single center as part of a multicenter, prospective clinical trial.

METHODS

Between May 2002 and June 2003, 63 consecutive patients underwent aortic valve replacement with a Medtronic Advantage prosthesis (84.1% male; mean age, 56.0 +/- 9.7 years; ejection fraction, 56.5 +/- 15.8%). Valve lesions were stenosis (n = 20), mixed (n = 34), and insufficiency (n = 9). Concomitant procedures were performed in 34.9%. Follow-up was 100% complete. Echocardiographic data were obtained early postoperatively and at 1 year, combined with stress echocardiography by treadmill. Mean pressure gradients, stroke volume, and left ventricular mass were determined by echocardiography. Data are presented as mean +/- standard deviation.

RESULTS

Operative mortality was 0%. Valve-related complications were observed in 2 patients (endocarditis, n = 1; thromboembolic event, n = 1). There was no case of antithromboembolic hemorrhage, prosthesis-related explant, or reoperation. One patient showed moderate paravalvular regurgitation. Mean pressure gradients 1 year postoperatively ranged from 6.3 to 11.0 mm Hg across all valve sizes. Left ventricular mass regression at 1 year was 18.4% across all valve sizes (p < 0.001). No severe patient-prosthesis mismatch (effective orifice area index < or = 0.65 cm2/m2) could be observed.

CONCLUSIONS

After 1 year, the Medtronic Advantage valve shows comparable transvalvular mean pressure gradients across the valve sizes used during rest and exercise. This is accompanied by a significant left ventricular mass regression, an important indicator for long-term survival.

Exercise hemodynamics of bovine versus porcine bioprostheses: a prospective randomized comparison of the mosaic and perimount aortic valves

OBJECTIVE

This prospective randomized study compares a porcine with a bovine bioprosthesis in the aortic position with regard to hemodynamic performance during exercise.

METHODS

Between August of 2000 and December of 2002, 136 patients underwent aortic valve replacement with the porcine Medtronic Mosaic (n = 66) or the bovine Carpentier-Edwards Perimount (n = 70) bioprosthesis. Transthoracic echocardiography was performed to assess hemodynamic and dimensional data preoperatively and 10 months postoperatively; the latter follow-up included stress echocardiography with treadmill exercise.

RESULTS

At rest and during exercise (25 and 50 W), there was a significant difference in mean pressure gradient between the bovine and the porcine valves with labeled sizes 21 and 23, with superiority of the Perimount prosthesis. There was no difference in effective orifice area and incidence of patient-prosthesis mismatch among all sizes. The left ventricular mass index decreased significantly within 10 months postoperatively in the size 23 bovine group and the size 25 porcine group.

CONCLUSIONS

Our data show a significant superiority of pressure gradients for the bovine bioprosthesis, especially with small valve sizes, when compared with the porcine device, which is more distinctive during exercise.

Left ventricular hypertrophy in aortic valve stenosis: preventive or promotive of systolic dysfunction and heart failure?

AIMS

In aortic stenosis (AS), left ventricular (LV) hypertrophy is considered a compensatory response helping maintain systolic function. Recent research in experimental AS suggests, however, that LV hypertrophy is not necessary to sustain LV contractions but may in fact be maladaptive. The present work aimed to clarify the role of LV hypertrophy in AS-related heart failure (HF) in man.

METHODS AND RESULTS

We studied 137 adult patients with isolated AS undergoing pre-operative echocardiography and cardiac catheterization. HF was diagnosed by the European criteria and LV hypertrophy by sex-specific limits of echocardiographic LV mass. The higher the LV mass was, the poorer was the LV ejection fraction (beta=-0.26, P< 0.001, linear regression) and the greater the likelihood of HF independent of the severity of AS (P< 0.001, logistic regression). In the subgroup of critical AS (valve area <0.4 cm(2)/m(2), n=85), patients with absent LV hypertrophy (n=19) had better preserved ejection fraction (mean+/-SE, 64+/-3 vs. 57+/-2%, P=0.045) and less HF (16 vs. 48%, P=0.025) than patients with LV hypertrophy (n=66).

CONCLUSION

In isolated AS, increased LV mass predicts the presence of systolic dysfunction and HF independent of the severity of valvular obstruction. LV hypertrophy may be maladaptive rather than beneficial in AS in man.

Impact of Valve Prosthesis-Patient Mismatch on Left Ventricular Mass Regression Following Aortic Valve Replacement

BACKGROUND

Valve prosthesis-patient mismatch is a frequent problem in patients undergoing aortic valve replacement and its main hemodynamic consequence is to generate high transvalvular gradients through normally functioning prosthetic valves. The persistence of high gradients may hinder or delay the regression of left ventricular hypertrophy after aortic valve replacement.

METHODS

The aim of the study was to determine the impact of prosthesis-patient mismatch on the postoperative regression of left ventricular mass. Left ventricular mass was measured by Doppler echocardiography in 109 patients undergoing aortic valve replacement with a single type of bioprosthesis (Carpentier-Edwards Perimount) for pure aortic stenosis. Prosthesis-patient mismatch was defined as a projected indexed effective orifice area less than 0.90 cm2/m2. On this basis, 58/109 (53.2%) patients had prosthesis-patient mismatch.

RESULTS

There was a good correlation (r = 0.61, p < 0.001) between the postoperative mean transprosthetic gradient and the projected indexed effective orifice area. The absolute and relative left ventricular mass regression was significantly (p = 0.002 and p = 0.01, respectively) lower in patients with prosthesis-patient mismatch (-48 +/- 47 g, -17% +/- 16%) compared to those with no prosthesis-patient mismatch (-77 +/- 49 g, -24% +/- 14%). In multivariate analysis, a larger projected indexed effective orifice area, female gender and a higher preoperative left ventricular mass are independent predictors of greater left ventricular mass regression.

CONCLUSIONS

This study shows that in patients with pure aortic stenosis prosthesis-patient mismatch is associated with lesser regression of left ventricular hypertrophy after aortic valve replacement. These findings may have important clinical implications given that prosthesis-patient mismatch is frequent in these patients.

Impact of angiotensin-converting enzyme gene polymorphism on neurohormonal responses to high- versus low-dose enalapril in advanced heart failure

BACKGROUND

The impact of angiotensin-converting enzyme (ACE) gene polymorphism on neurohormonal dose response to ACE inhibitor therapy is unclear.

METHODS

ACE Insertion (I) or Deletion (D) genotype was determined in 74 patients with chronic heart failure who were randomly assigned to receive either high-dose or low-dose enalapril over a period of 6 months. Monthly pre-enalapril and post-enalapril neurohormone levels (serum ACE activity (sACE), plasma angiotensin II (A-II), plasma renin activity (PRA), and serum aldosterone (ALDO) were compared between genotype subgroups and between patients who received high- or low-dose enalapril within each genotype subgroup.

RESULTS

At baseline, predose/postdose sACE and postdose PRA were significantly higher in the DD genotype. At 6-month follow-up, postdose sACE was reduced in a dose-dependent fashion in all three genotypes (P < .05). However, predose and postdose ALDO and A-II levels did not differ between each genotype subgroup at baseline or by enalapril dose within each genotype subgroup. ALDO escape and A-II reactivation were not affected by ACE genotype or enalapril dosage.

CONCLUSIONS

Predose sACE were consistently higher in the DD genotype when compared with ID or II subgroups. Despite a dose-dependent suppression of sACE, there were no observed statistically significant differences in ALDO and A-II suppression or escape with escalating doses of enalapril within each subgroup.

Mass regression in aortic stenosis after valve replacement with small size pericardial bioprosthesis

BACKGROUND

The aim of the study was to determine whether left ventricular mass regression is influenced by valve size after the implantation of a Carpentier-Edwards Perimount (CEP) pericardial bioprosthesis for pure aortic stenosis.

METHODS

Patients receiving 19-mm, 21-mm, and 23-mm CEP aortic valves underwent echocardiography preoperatively and at least 1 year after surgery (mean, 2.3 +/- 1 years) and the echocardiograms were compared within and between groups.

RESULTS

The study involved a total of 88 patients: 34 receiving 19-mm CEPs, 29 receiving 21-mm CEPs, and 25 receiving 23-mm CEPs. The mean postoperative prosthetic gradients were respectively 20.6 +/- 6.6 mm Hg, 17.9 +/- 5.8 mm Hg, and 13.2 +/- 4.1 mm Hg (p = 0.0001); the mean postoperative valve areas were respectively 1.24 +/- 0.16 cm(2), 1.45 +/- 0.2 cm(2), and 1.63 +/- 0.21 cm(2) (p = 0.0001). In comparison with the preoperative echocardiographic measurements absolute left ventricular mass significantly decreased by -54.1 +/- 48.8 g, -54.1 +/- 55.1 g, and -74.4 +/- 57.4 g respectively with no statistically significant between-group difference (analysis of variance) but ventricular septum and posterior wall thickness significantly decreased in each group (p < 0.05).

CONCLUSIONS

The implantation of 19-mm, 21-mm, and 23-mm CEP aortic prostheses significantly reduces left ventricular mass without any size-related differences.

Genetic variants of angiotensin II receptors and cardiovascular risk in hypertension

Renin-angiotensin systems may mediate cardiovascular disease pathogenesis through a balance of actions of angiotensin II on (potentially proatherogenic) constitutive type 1 (AT1R) and (potentially antiatherogenic) inducible type 2 (AT2R) receptors. We explored such potential roles in a prospective candidate gene association study. Cardiovascular end points (fatal, nonfatal, and silent myocardial infarction and coronary artery bypass surgery/angioplasty) were documented among 2579 healthy UK men (mean age, 56.1+/-3.5 years; median follow-up, 10.1 years) genotyped for the AT1R1166A>C and the X chromosome located AT2R1675A>G and 3123C>A polymorphisms. Baseline characteristics, including blood pressure, were independent of genotype. The AT1R1166CC genotype was associated with relative cardiovascular risk (hazard ratio, 1.65 [1.05 to 2.59]; P=0.03) independent of blood pressure. Systolic blood pressure was associated with risk (P=0.0005), but this association was restricted to AT2R1675A allele carriers (P<0.00001), with G allele carriers protected from the risk associated with blood pressure (P=0.18). Hypertensive carriers with the AT2R1675A/3123A haplotype were at most risk, with 37.5% having an event. This is the first study to demonstrate an association of AT2R genotype with coronary risk, an effect that was confined to hypertensive subjects and supports the concept that the inducible AT2R is protective. Conversely, the AT1R1166CC genotype was associated with cardiovascular risk irrespective of blood pressure. These data are important to our understanding of the divergent role of angiotensin II acting at its receptor subtypes and coronary disease pathogenesis and for the development of future cardiovascular therapies.

Polymorphisms in the RAS and cardiac function

Since the discovery of the polymorphism in the angiotensin converting enzyme (ACE) and the consequences of this polymorphism on the activity levels of the enzyme, numerous association studies have been performed. However, these investigations do not often adhere to the most stringent criteria for such studies. The initial study reporting a positive association of the ACE polymorphism and myocardial infarction showed an increased risk of the DD genotype. This initial association was eventually refuted by a large, well conducted association study, which found a risk ratio of 1.02 after combining their own data with all published data. Although such large, well conducted association studies have not been performed in left ventricular (LV) hypertrophy, the association between DD genotype and hypertrophy is more convincing with a 192% excess risk of LV hypertrophy in untreated hypertensives. The role of ACE genotype in LV growth is well established, especially in athletes. In heart failure, large studies or meta-analyses have not been performed, because most studies have selected different end-points. This hampers a proper meta-analysis of the results obtained in associations with heart failure. As most association studies do not fulfill the criteria for good association studies and use too small sample sizes, it remains important to perform a meta-analysis to add meaning to the results of such studies. Above all, it is important to obey the rules set for association studies, large sample size, small P values, report associations that make biological sense and alleles that affect the gene product in a physiologically meaningful way.

Late hemodynamic and clinical outcomes of aortic valve replacement with the Carpentier-Edwards Perimount pericardial bioprosthesis

OBJECTIVES

The aim of this study was to investigate the long-term clinical and hemodynamic outcomes after aortic valve replacement with the Carpentier-Edwards Perimount bioprosthesis (Edwards Lifesciences, Irvine, Calif), which has been used in our institution since 1984.

METHODS

From January 1984 to December 1995, the Carpentier-Edwards pericardial bioprosthesis was used for aortic valve replacement in 254 patients (male/female ratio 117:137) with a mean age of 71 years (range 25-87 years). Before the operation, 216 patients (85%) were in New York Heart Association functional class III or IV. The predominant diagnosis was aortic stenosis (n = 219, 86%). Associated surgical procedures included coronary artery bypass grafting in 130 cases (51%), mitral valve replacement in 11 cases (4%), and tricuspid or mitral valve repair in 12 cases (5%). Previous cardiac operations had been performed in 36 cases (14%). Follow-up was 100% complete at a mean of 60 +/- 31 months. Univariate estimates of time-related cumulative probabilities were calculated by the Kaplan-Meier method. Multivariable adjustment was performed by Cox proportional hazards regression. Echocardiography was performed in 61% of long-term survivors.

RESULTS

There were 11 early deaths (4%) and 58 late deaths. Actuarial survivals at 5, 10, and 12 years were 80% +/- 3%, 50% +/- 8%, and 36% +/- 9%, respectively. At 12 years the freedom from cardiac death was 73% +/- 7%, the freedom from valve-related death was 84% +/- 11%, the freedom from valve reoperation was 83% +/- 9%, the freedom from primary tissue failure was 86% +/- 9%, the freedom from thromboembolism was 67% +/- 13%, and the freedom from endocarditis was 98% +/- 1%. Echocardiography was performed on long-term survivors (mean follow-up 67 +/- 25 months) and showed that transvalvular peak and mean pressure differences measured with Doppler echocardiography were 23.2 +/- 9.6 and 12.3 +/- 4.8 mm Hg, respectively. Aortic regurgitation was found by Doppler echocardiography to be none or trivial, mild, moderate, and severe in 64%, 30%, 3%, and 1% of patients, respectively. Mean left ventricular mass index was 107.2 +/- 35.3 g/m(2) (118.9 +/- 40.2 g/m(2) in men and 98.8 +/- 28.8 g/m(2) in women) at late follow-up. One third of all patients, regardless of sex (n = 26/64 women and n = 14/45 men), had evidence of left ventricular hypertrophy. However, our analyses indicate that the residual left ventricular hypertrophy was not caused by valve mismatch but was probably multifactorial.

CONCLUSION

The Carpentier-Edwards Perimount bioprosthesis has provided satisfactory clinical and hemodynamic outcome. However, at long-term follow-up about one third of the patients being investigated still had left ventricular hypertrophy examined by echocardiography.

Genetic polymorphisms in the renin-angiotensin-aldosterone system associated with expression of left ventricular hypertrophy in hypertrophic cardiomyopathy: a study of five polymorphic genes in a family with a disease causing mutation in the myosin binding protein C gene

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is an inherited disease of the sarcomere characterised clinically by myocardial hypertrophy and its consequences. Phenotypic expression is heterogeneous even within families with the same aetiological mutation and may be influenced by additional genetic factors.

OBJECTIVE

To determine the influence of genetic polymorphisms of the renin-angiotensin-aldosterone system (RAAS) on ECG and two dimensional echocardiographic left ventricular hypertrophy (LVH) in genetically identical patients with HCM.

PATIENTS AND METHODS

Polymorphisms of five RAAS components were determined in 26 gene carriers from a single family with HCM caused by a previously identified myosin binding protein C mutation. Genotypes associated with a higher activation status of the RAAS were labelled "pro-LVH genotypes".

RESULTS

There was a non-biased distribution of pro-LVH genotypes in the gene carriers. Those without pro-LVH genotypes did not manifest cardiac hypertrophy whereas gene carriers with pro-LVH genotypes did (mean (SD) left ventricular muscle mass 190 (48) v 320 (113), p = 0.002; interventricular septal thickness 11.5 (2.0) v 16.4 (6.7), p = 0.01; pathological ECG 0% (0 of 10) v 63% (10 of 16), respectively). Multivariate analysis controlling for age, sex, and hypertension confirmed an independent association between the presence of pro-LVH polymorphisms and left ventricular mass. When each polymorphism was assessed individually, carriers of each pro-LVH genotype had a significantly greater left ventricular mass than those with no pro-LVH mutation; these associations, with the exception of cardiac chymase A AA polymorphism (p = 0.06), remained significant in multivariate analysis.

CONCLUSION

Genetic polymorphisms of the RAAS influence penetrance and degree of LVH in 26 gene carriers from one family with HCM caused by a myosin binding protein C mutation.

Lack of association among five genetic polymorphisms of the renin-angiotensin system and cardiac hypertrophy in patients with aortic stenosis

BACKGROUND

Patients with aortic stenosis (AS) have left ventricular hypertrophy (LVH). It is thought that LVH in these patients is a consequence of chronic left ventricular pressure overload. However, there is only a poor correlation between the degree of AS and the degree of LVH. Genetic polymorphisms of the renin-angiotensin-aldosterone system (RAAS) have been considered to trigger the response of the left ventricle to chronic pressure overload and determine the degree of LVH in patients with AS.

METHODS

One hundred five consecutive patients with symptomatic AS were examined by echocardiography and left heart catheterization to determine the severity of AS and LVH. Five genetic polymorphisms of the RAAS (ACE, AGTR1, AGT, CMA, CYP11B2) were analyzed in all patients and the results of genetic analysis were correlated to severity of AS and LVH to determine the importance of the polymorphisms for LVH.

RESULTS

All tested genotypes were in Hardy-Weinberg equilibrium and allele frequencies were similar to other study populations. There was no correlation between the severity of AS and the severity of LVH. There was no association between the five tested genotypes of the RAAS and the severity of AS (mean gradient and area of the aortic valve) or LVH (LV muscle mass).

CONCLUSION

We conclude that LVH in patients with AS is not determined by the tested genetic polymorphisms of the RAAS.