Natural history and left ventricular response in chronic aortic regurgitation

Machine learning-based risk stratification for mortality in patients with severe aortic regurgitation

Aims

The current guidelines recommend aortic valve intervention in patients with severe aortic regurgitation (AR) with the onset of symptoms, left ventricular enlargement, or systolic dysfunction. Recent studies have suggested that we might be missing the window of early intervention in a significant number of patients by following the guidelines.

Methods and results

The overarching goal was to determine if machine learning (ML)-based algorithms could be trained to identify patients at risk for death from AR independent of aortic valve replacement (AVR). Models were trained with five-fold cross-validation on a dataset of 1035 patients, and performance was reported on an independent dataset of 207 patients. Optimal predictive performance was observed with a conditional random survival forest model. A subset of 19/41 variables was selected for inclusion in the final model. Variable selection was performed with 10-fold cross-validation using random survival forest model. The top variables included were age, body surface area, body mass index, diastolic blood pressure, New York Heart Association class, AVR, comorbidities, ejection fraction, end-diastolic volume, and end-systolic dimension, and the relative variable importance averaged across five splits of cross-validation in each repeat were evaluated. The concordance index for predicting survival of the best-performing model was 0.84 at 1 year, 0.86 at 2 years, and 0.87 overall, respectively.

Conclusion

Using common echocardiographic parameters and patient characteristics, we successfully trained multiple ML models to predict survival in patients with severe AR. This technique could be applied to identify high-risk patients who would benefit from early intervention, thereby improving patient outcomes.

Diagnosis and Management of Aortic Valvular Disease in the Elderly

Aortic valvular disease, including aortic stenosis and aortic regurgitation, is increasingly common with age. Due to the aging population, more elderly patients are presenting with aortic valve pathology and expectations for prompt diagnosis and efficacious treatment. The current paradigm for aortic valve disease is based on surgical or interventional therapy. In this review, we discuss the approach to diagnosing aortic valvular disease and the different options for treatment based on the most recent evidence.

Predictors of heart failure and all-cause mortality in asymptomatic patients with moderate and severe aortic regurgitation

BACKGROUND

Class I indications for aortic valve replacement (AVR) for severe chronic aortic regurgitation (AR) include AR attributable symptoms or left ventricular (LV) ejection fraction <50%. As noninvasive estimates of elevated LV filling pressures (LVFP's) have been noted to predict heart failure (HF) readmission and all-cause mortality (ACM) in HF patients, we hypothesize that elevated LVFP's may also be independent predictors of HF and ACM in chronic AR.

METHODS

We developed a single center patient database of moderate or greater AR diagnoses between 2003 and 2008 and followed each patient through January 2013. We included patients with >30 days follow-up with interpretable Doppler-echocardiograms. We recorded demographic variables, EuroScore II, incident HF and ACM, and Doppler-echo variables of LV size, systolic and diastolic function.

RESULTS

Patients with severe AR (105 patients) and moderate AR (201 patients) had similar EuroScore II values and similar incident HF and ACM. For the 180 patients who developed HF, effective arterial elastance (aHR = 1.70 (1.01-2.83), p = .041), LV end-diastolic dimension (aHR = 1.83, (1.11-3.03), p = .0176), E/e' (aHR = 3.04, (1.83-5.05), p < .0001), eccentric hypertrophy (EH) (aHR = 2.39, (1.62-5.12), p = .0004), and tricuspid regurgitation (TR) velocity (aHR = 5.75, (3.70-10.36), p < .0001) were independent predictors. For the 118 patients with ACM, EH (aHR = 1.73, (1.02-3.28), p = .0414), systolic blood pressure (aHR = .58, (.33-.95), p = .0301), left atrial volume index (aHR = 1.82, (1.06-3.06), p = .0293), E/e' (aHR = 1.83, (1.07-3.08), p = .0280), and TR velocity (aHR = 4.14, (2.22-6.49), p < .0001) were independent predictors.

CONCLUSIONS

Elevated TR velocity and EH were strong markers of HF and ACM in patients with asymptomatic severe AR and in moderate AR.

Mitral Plasticity: The Way to Prevent the Burden of Ischemic Mitral Regurgitation?

The ischemic impairment of the left ventricular contractility, followed by an adverse remodeling leading to the displacement of the papillary muscles (PMs), increased tethering forces and loss of valve competence has been the long-term accepted definition of ischemic mitral regurgitation (IMR). Over the years, different approaches of management have attempted to address valve regurgitation, nevertheless failing to achieve satisfactory outcomes. Recent studies have observed some structural and molecular changes of the mitral valve (MV), challenging the concept of a bystander passive to the subvalvular involvement. Indeed, the solely mechanical stretch of the PMs, as in the dilated left ventricle because of the aortic valve regurgitation, is not enough in causing relevant MV regurgitation. This setting triggers a series of structural changes called “mitral plasticity,” leaflets increase in their size among others, ensuring an adequate systolic area closure. In contrast, the ischemic injury not only triggers the mechanical stretch on the subvalvular apparatus but is also a powerful promotor of profibrotic processes, with an upregulation of the transforming growth factor (TGF)-β signaling pathway, leading to a MV with exuberant leaflet thickness and impaired mobility. In this article, we revise the concept of IMR, particularly focusing on the new evidence that supports dynamic changes in the MV apparatus, discussing the consequent clinical insights of “mitral plasticity” and the potential therapeutic implications.

2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the valvular heart disease guideline provides recommendations for clinicians to diagnose and manage valvular heart disease as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to March 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, Cochrane, Agency for Healthcare Research and Quality Reports, and other selected database relevant to this guideline. Structure: Many recommendations from the earlier valvular heart disease guidelines have been updated with new evidence and provides newer options for diagnosis and treatment of valvular heart disease. This summary includes only the recommendations from the full guideline which focus on diagnostic work-up, the timing and choice of surgical and catheter interventions, and recommendations for medical therapy. The reader is referred to the full guideline for graphical flow charts, text, and tables with additional details about the rationale for and implementation of each recommendation, and the evidence tables detailing the data considered in developing these guidelines.

Association of Left Ventricular Volume in Predicting Clinical Outcomes in Patients with Aortic Regurgitation

BACKGROUND

Aortic regurgitation (AR) is a common valvular lesion associated with increased mortality once the left ventricle enlarges significantly or develops systolic dysfunction (ejection fraction < 50%). Valve guidelines recommend aortic valve repair or replacement (AVR) for left ventricular (LV) linear end-systolic dimension ≥ 50 mm or end-diastolic dimension ≥ 65 mm. However, chamber quantification guidelines recommend using LV volume for LV size determination because linear measurements may not accurately reflect LV remodeling. The aim of this study was to evaluate the correlation of LV volumes with linear dimensions, interobserver variability in the estimation of volumes, and the association of volumes with outcomes in patients with AR.

METHODS

A total of 1,100 consecutive patients with chronic moderate to severe and severe AR on echocardiography between 2004 and 2019 were retrospectively analyzed. The modified Simpson disk summation method was used for LV volume estimation. The primary outcome was all-cause mortality; the secondary outcome was mortality censored at AVR.

RESULTS

Patients' age was 60 ± 17 years, and 198 were women (18%). Volumes were measured using the biplane method in 939 patients (85%) and the monoplane method in 161 (15%); end-systolic volume was normal in 169 (11%). Correlations between volumes and linear dimensions were 0.5 for end-diastolic volume and 0.6 for end-systolic volume. At median follow-up of 5.4 years (interquartile range, 2.4-10.0 years), 216 patients had died and 539 had undergone AVR. Indexed LV end-systolic volume (iLVESV) and indexed left ventricular end-systolic dimension were both associated with mortality and symptoms, but the association of iLVESV was stronger. iLVESV, age, male gender, Charlson comorbidity index, New York Heart Association functional class III or IV, and time-dependent AVR were independently associated with all-cause mortality. Interobserver variability in the estimation of LV volumes in 200 patients included intraclass coefficients of 0.94 (95% CI, 0.92-0.95) for end-diastolic volume and 0.88 (95% CI, 0.78-0.93) for end-systolic volume. Patients with iLVESV ≥ 45 mL/m² had lower survival and a higher prevalence of symptoms than those with volumes < 45 mL/m².

CONCLUSIONS

Echocardiographic LV volume assessment had good reproducibility in patients with moderate to severe and severe AR. The correlation between linear dimensions and volumes was limited. Both iLVESV and indexed left ventricular end-systolic dimension were associated with worse outcomes, but the association of iLVESV was stronger. iLVESV ≥ 45 mL/m² was associated with worse outcomes.

Prevalence and relevance of impaired left ventricular function in chronic moderate regurgitation of native aortic valves

Background: Reduced ejection fraction (EF) in chronic moderate aortic regurgitation (AR) could be either due to a late remodelling response after longstanding moderate AR, or could represent a specific phenotype of cardiomyopathy (CMP) with concomitant AR. The aim of this study was to analyse progression of left ventricular (LV) impairment in moderate AR. Methods: All patients in our echocardiography database between 2005 and 2016 were screened to identify pure chronic moderate AR, excluding significant coronary artery disease (CAD) or concomitant valve disease. Remaining 152 patients were divided into three groups: (a) preserved systolic LV function; (b) reduced LV EF and prediagnosed concomitant cardiomyopathy (CMP); (c) reduced LV EF without prediagnosed CMP. Results: The majority patients (group A = 66%) had preserved systolic LV function, remaining oligosymptomatic with stable LVEDD at follow-up. Non-CMP patients with reduced EF at baseline (group C = 18%) were significantly older (group C: 74 vs. group A: 61 years, p < .001) whereas left ventricular end-diastolic diameter (LVEDD) significantly increased over time (p = .046). Development of renal insufficiency, atrial fibrillation and NYHA > II were significant risk factors linked to the worsening of LV function in patients with moderate AR. Conclusion: Preserved LV EF and LVEDD remain stable over a long lasting period in the majority of patients. However, these data suggest that some patients develop reduced LV EF, even without progression of AR to severe, especially if renal insufficiency or atrial fibrillation are present.

Clinical events and echocardiographic lesion progression rate in subjects with mild or moderate aortic regurgitation

Background: The rate of progression of aortic regurgitation (AR) is not well described. Current guidelines state that asymptomatic patients with mild AR should be followed up every 3–5 years and 1–2 yearly for moderate AR. This study describes the lesion and clinical based progression of mild and moderate AR in a population of patients undergoing systematic follow-up. Methods and results: 341 patients with either mild or moderate AR were included. The rates of clinical events (death, aortic valve replacement and cardiac hospitalization) and progression of AR are reported. 341 patients were included; mean age was 71.1 years (IQR 66–80 years) and the median follow-up period was 4.6 (IQR 2–6.7) years. 292 patients did not have any events during follow-up. 3 patients required aortic valve replacement (2 of these due to severe aortic stenosis and 1 due to severe mitral regurgitation and co-existent moderate AR). 44 patients required cardiac hospitalization. 9 patients died during follow-up and 35 patients (10%) showed a progression of AR during follow-up with an average time of 4.0 ± 2.6 years. 8 patients (2.3% of the total) progressed to severe AR. Patients with mixed valvular pathology showed a greater increase in AR progression (27 (15%) vs 8 (5%); P = 0.004). Conclusions: Over medium term systematic follow-up progression and clinical events in patients with AR is rare, regardless of etiology. Patients who suffered from AR as an isolated valve pathology were less likely to show AR progression over time.

Reduced Longitudinal Function in Chronic Aortic Regurgitation

Background

Chronic aortic regurgitation (AR) patients demonstrate left ventricular (LV) remodeling with increased LV mass and volume but may have a preserved LV ejection fraction (EF). We hypothesize that in chronic AR, global longitudinal systolic and diastolic function will be reduced despite a preserved LV EF.

Methods

We studied with Doppler echocardiography 27 normal subjects, 87 patients with chronic AR with a LV EF > 50% (AR + PEF), 66 patients with an EF < 50% [AR + reduced LV ejection fraction (REF)] and 82 patients with hypertensive heart disease. LV volume, transmitral spectral and tissue Doppler were obtained. Myocardial velocities and their timing and longitudinal strain of the proximal and mid wall of each of the 3 apical views were obtained.

Results

As compared to normals, global longitudinal strain was reduced in AR + PEF (13.8 ± 4.0%) and AR + REF (11.4 ± 4.7%) vs. normals (18.4 ± 3.6%, both p < 0.001). As an additional comparison group for AR + PEF, global longitudinal strain was reduced as compared to patients with hypertensive heart disease (p = 0.032). The average peak diastolic annular velocity (e') was decreased in AR + PEF (6.9 ± 3.3 cm/s vs. 13.4 ± 2.6 cm/s, p < 0.001) and AR + REF (4.8 ± 2.1 cm/s, p < 0.001). Peak rapid filling velocity/e' (E/e') was increased in both AR + PEF (14.4 ± 6.2 vs. 6.2 ± 1.3, p < 0.001) and AR + REF (18.8 ± 6.4, p < 0.001 vs. normals). Independent correlates of global longitudinal strain (r = 0.6416, p < 0.001) included EF (p < 0.0001), E/e' (p < 0.0001), and tricuspid regurgitation velocity (p = 0.0176).

Conclusion

With chronic AR, there is impaired longitudinal function despite preserved EF. Moreover, global longitudinal strain was well correlated with noninvasive estimated LV filling pressures and pulmonary systolic arterial pressures.

Mixed aortic valve disease in the young: initial observations

The short-term surgical results for mixed aortic valve disease (MAVD) and the long-term effects on the left ventricle (LV) are unknown. Retrospective review identified patients with at least both moderate aortic stenosis (AS) and aortic regurgitation (AR) before surgical intervention. A one-to-one comparison cohort of patients with MAVD not referred for surgical intervention was identified. The 45 patients in this study underwent surgical management for MAVD. A control group of 45 medically managed patients with MAVD also was identified. Both groups had elevated LV end-diastolic volume (EDV), elevated LV mass, a normal LV mass:volume ratio (MVR), and a normal ejection fraction. Both groups had diastolic dysfunction shown by early diastolic pulsed-Doppler mitral inflow/early diastolic tissue Doppler velocity z-score. The LV end-diastolic pressure (EDP) was correlated with age (R = 0.4; p = 0.03) and LV MVR (R = 0.4; p = 0.03) but not with AS, AR, or the score combining gradient and LV size. As shown by 6- to 12-month postoperative echocardiograms, aortic valve gradients and AR significantly improved (gradient 65 ± 17 to 28 ± 18 mmHg, p = 0.01; median regurgitation grade moderate to mild; p < 0.01), LV EDV normalized, and LV mass significantly improved (p < 0.01). Diastolic dysfunction was unchanged. Symptoms did not correlate with any measured parameter, but the preoperative symptoms resolved. In conclusion, despite diastolic dysfunction, systolic function is invariably preserved, and symptoms are not correlated with aortic valve function or LV EDP. Current surgical practice preserves LV mechanics and results in short-term improvement in valve function and symptoms.

Mitral valve enlargement in chronic aortic regurgitation as a compensatory mechanism to prevent functional mitral regurgitation in the dilated left ventricle

OBJECTIVES

The aim of this study was to test the hypothesis that mitral valve (MV) enlargement occurring in chronic aortic regurgitation (AR) prevents functional mitral regurgitation (FMR).

BACKGROUND

Chronic AR causes left ventricular (LV) dilation, creating the potential for FMR. However, FMR is typically absent during compensated AR despite substantial LV enlargement. Increased mitral leaflet area has been identified in AR, but it is unknown whether increased MV size can represent a compensatory mechanism capable of preventing FMR.

METHODS

Database review of 816 patients with at least moderate AR evaluated the prevalence of FMR. A total of 90 patients were enrolled prospectively for 3-dimensional echocardiography (30 AR, 30 FMR, and 30 controls) to assess MV geometry including total leaflet area.

RESULTS

FMR was present in 5.6% of AR patients by database review. Prospectively, only 1 AR patient had more than mild FMR despite increased LV end-diastolic volume (82 ± 22, 86 ± 23, and 51 ± 12 cm(3)/m(2), respectively, for AR, FMR vs. control patients; p < 0.01) and similar sphericity index, annular area, and tethering distances compared with FMR. Total MV area was largest in AR (31.3% greater than normal), increasing significantly more than in FMR. The ratio of valve size to closure area was maintained in AR, whereas decreases in this ratio and LV ejection fraction independently predicted FMR.

CONCLUSIONS

FMR prevalence is low in chronic AR. MV leaflet area is significantly increased compared with control and FMR patients, preserving a normal relationship to the area needed for closure in the dilated LV. Understanding the mechanisms underlying this adaptation could lead to new therapeutic interventions to prevent FMR.

Aortic valve and ascending aorta guidelines for management and quality measures: executive summary

The Society of Thoracic Surgeons Clinical Practice Guidelines are intended to assist physicians and other health care providers in clinical decision making by describing a range of generally acceptable approaches for the diagnosis, management, or prevention of specific diseases or conditions. These guidelines should not be considered inclusive of all proper methods of care or exclusive of other methods of care reasonably directed at obtaining the same results. Moreover, these guidelines are subject to change over time, without notice. The ultimate judgment regarding the care of a particular patient must be made by the physician in light of the individual circumstances presented by the patient.

Pulmonary hypertension and long-term mortality in aortic and mitral regurgitation

BACKGROUND

Outcomes data in patients with aortic regurgitation or mitral regurgitation have been limited to small series with generally <10 years of follow-up. The quantitative impact of pulmonary artery hypertension has not been well described. The purpose of this study was to describe the 15-year mortality of aortic regurgitation and mitral regurgitation.

METHODS

Our institution's electronic echocardiography database was queried to identify those patients examined in 1992 and reported to have at least mild aortic regurgitation or mitral regurgitation. Patients were classified by semi-quantitative degree of regurgitation. Pulmonary artery systolic pressure was categorized as normal, borderline, mild, or moderate or greater hypertension (pulmonary artery systolic pressure >40 mm Hg). Age-stratified Cox proportional hazards models compared survival among groups and adjusted for sex, depressed left ventricular ejection fraction, and pulmonary artery systolic pressure. Mortality data were obtained from the 2008 Social Security Death Index.

RESULTS

Of 4984 echocardiograms performed in 4050 patients, 1156 patients (28%; aged 72±14 years) had at least mild aortic regurgitation and 1971 patients (49%; aged 69±16 years) had at least mild mitral regurgitation. Overall 15-year mortality in patients with aortic regurgitation was 74% and similar for all grades of aortic regurgitation. Overall 15-year mortality in patients with mitral regurgitation was 71% and got progressively worse with increasing severity grade of mitral regurgitation (63% for mild to 81% for at least moderate-to-severe). For both aortic and mitral regurgitation, moderate or greater pulmonary artery systolic hypertension was associated with increased mortality (in patients with aortic regurgitation, hazard ratio [HR], 1.94; 95% confidence interval [CI], 1.58-2.41, and in mitral regurgitation patients, HR, 1.48; 95% CI, 1.26-1.75).

CONCLUSION

Long-term (15-year) survival of patients with aortic regurgitation is poor and is independent of regurgitation severity. In contrast, long-term survival of patients with mitral regurgitation correlates with regurgitation severity. For both groups, moderate or greater pulmonary artery systolic hypertension identified those at highest risk.

Left ventricular myocardial remodeling and contractile state in chronic aortic regurgitation

BACKGROUND

In chronic aortic regurgitation, eccentric hypertrophy, with combined concentric hypertrophy of the left ventricle, is an important adaptive response to volume overload, which in itself is a compensatory mechanism for permitting the ventricle to normalize its afterload and to maintain normal ejection performance (physiologic hypertrophy). However, progressive dilatation of the left ventricle leads to depressed left ventricular (LV) contractility and myocardial structural changes, including cellular hypertrophy and interstitial fibrosis (pathological hypertrophy).

HYPOTHESIS

The study was undertaken to determine the relationship between left ventricular myocardial structure and contractile function in 14 patients with chronic aortic regurgitation by cardiac catheterization and endomyocardial biopsies.

METHODS

Myocardial cell diameter and percent interstitial fibrosis were obtained from biopsy samples. Contractile function was evaluated from the ratio of end-systolic wall stress to end-systolic volume index (ESS/ESVI) and the ejection fraction-end-systolic stress (EF-ESS) relationship, which was obtained from 30 normal control subjects.

RESULTS

Myocardial cell diameter correlated significantly with the ESVI (r = 0.72, p < 0.005), ejection fraction (r = -0.58, p < 0.05), and ESS/ESVI (r = -0.58, p < 0.05). The percent interstitial fibrosis also correlated inversely with ESS/ESVI (r = -0.71, p < 0.005). Compared with very few patients with an ESVI < 70 ml/m2, the majority of patients with ESVI > or = 70 ml/m2 had a cell diameter of > or = 30 microns and a percent interstitial fibrosis of > or = 10%. The nine patients who had depressed contractile function, as assessed from the EF-ESS relationship, had a higher percent interstitial fibrosis (p < 0.05) than five patients showing a normal EF-ESS relationship, despite the fact that there was no significant difference in myocardial cell diameter between them. Thus, advanced cellular hypertrophy and excessive interstitial fibrosis were significantly and independently associated with myocardial contractile dysfunction and appeared to be responsible for ventricular remodeling.

CONCLUSION

Our findings suggest that in many patients with aortic regurgitation, eccentric hypertrophy changes its nature from physiologic to nonphysiologic during the earlier stages in the course of the disease rather than during the stage described previously.

Prognostic value of preoperative indexed end-systolic left ventricle diameter in the outcome after surgery in patients with chronic aortic regurgitation

BACKGROUND

End-systolic diameter (ESD) is an important parameter in the prognosis and indication for surgery in chronic aortic regurgitation (AR). It has been suggested that ESD values noncorrected for body surface area (BSA) could be inappropriate in the management of patients with extreme BSA. The aim of the study was to assess the usefulness of indexed ESD (IESD) of the left ventricle in the management of patients with severe isolated chronic AR.

METHODS

One hundred forty-seven patients underwent surgery for chronic AR and were followed up for a mean of 8 +/- 6 years (1-22 years). A post hoc assessment was made of the prognostic value of preoperative ESD and IESD in different BSA percentiles: group 1, <or= 25th percentile (BSA 1.43-1.68 m(2), n = 40); group 2, >25th percentile and <or=75th percentile (BSA 1.69-1.91 m(2), n = 68); and group 3, >75th percentile (BSA 1.92-2.24 m(2), n = 39).

RESULTS

Age-adjusted preoperative ESD and IESD were independent predictors of mortality or heart failure in the entire population. Magnitude of the relative risk was slightly greater using preoperative IESD than ESD (HR 1.07, 95% CI 1.01-1.29, P = .017; HR 1.04, 95% CI 1.01-1.08, P = .016). In group 1, the age-adjusted expected mortality rate would drop if IESD of 25 mm/m(2) was used as a surgical criterion instead of ESD 50 mm, from 37.94% to 24.27% at 10 years (P = .002).

CONCLUSIONS

The use of IESD improves the prediction of unfavorable outcomes after surgery in patients with low BSA but not in those with high BSA. In patients with low BSA, IESD >or=25 mm/m(2) should be used as a cutoff point for surgery rather than ESD >50 mm.

Long-Term Outcome of Surgically Treated Aortic Regurgitation

OBJECTIVES

The purpose of this study was to compare postoperative outcome in two groups of patients with chronic severe aortic regurgitation (AR): those operated on early and those operated on late according to the guidelines.

BACKGROUND

The impact of earlier surgery for chronic severe AR as defined in guidelines has not been evaluated.

METHODS

A total of 170 patients with chronic severe AR submitted to aortic valve replacement were prospectively followed up. Patients were divided in two groups depending on the clinical situation at the time of surgery. Group A were 60 patients who were operated on following guidelines advice of earlier surgery, and group B were 110 patients who were operated on late with regard to guideline recommendations.

RESULTS

Follow-up was 10 +/- 6 years (1 to 22 years). During follow-up 44 patients died, 7 patients (12%) from group A and 37 (37%) from group B (p = 0.001). The cause of death was non-cardiac in 11 patients, 2 (3%) in group A and 9 (8%) in group B. Cardiac deaths occurred in 33 patients, 5 (9%) from group A and 28 (28%) from group B (p = 0.002). Causes of death differed between groups A and B: heart failure or sudden death were significantly more frequent in group B (20 patients vs. 1 patient, p = 0.001). Overall survival in groups A and B was 90 +/- 4% vs. 75 +/- 8% at 5 years, 86 +/- 5% vs. 64 +/- 5% at 10 years, and 78 +/- 7% vs. 53 +/- 6% at 15 years, respectively (p = 0.009).

CONCLUSIONS

Early operation as defined in the guidelines improves long-term survival in patients with chronic AR.

Valvular Heart Disease

Aortic regurgitation (AR) is characterized by diastolic reflux of blood from the aorta into the left ventricle (LV). Acute AR typically causes severe pulmonary edema and hypotension and is a surgical emergency. Chronic severe AR causes combined LV volume and pressure overload. It is accompanied by systolic hypertension and wide pulse pressure, which account for peripheral physical findings, such as bounding pulses. The afterload excess caused by systolic hypertension leads to progressive LV dilation and systolic dysfunction. The most important diagnostic test for AR is echocardiography. It provides the ability to determine the cause of AR and to assess the severity of AR and its effect on LV size, function, and hemodynamics. Many patients with chronic severe AR may remain clinically compensated for years with normal LV function and no symptoms. These patients do not require surgery but can be followed carefully for the onset of symptoms or LV dilation/dysfunction. Surgery should be considered before the LV ejection fraction falls below 55% or the LV end-diastolic dimension reaches 55 mm. Symptomatic patients should undergo surgery unless there are excessive comorbidities or other contraindications. The primary role of medical therapy with vasodilators is to delay the need for surgery in asymptomatic patients with normal LV function or to treat patients in whom surgery is not an option. The goal of vasodilator therapy is to achieve a significant decrease in systolic arterial pressure. Future therapies may focus on molecular mechanisms to prevent adverse LV remodeling and fibrosis.

Angiotensin-converting enzyme inhibitor captopril prevents volume overload cardiomyopathy in experimental chronic aortic valve regurgitation

The efficacy of angiotensin-converting enzyme inhibitors (ACEIs) in the treatment of chronic aortic regurgitation (AR) is not well established and remains controversial. The mechanisms by which ACEIs may protect against left-ventricular (LV) volume overload are not well understood, and clinical trials performed until now have yielded conflicting results. This study was therefore performed to assess the effectiveness of two different doses of the ACEI captopril in a rat model of chronic AR. We compared the effects of a 6-month low-dose (LD) (25 mg/kg) or higher dose (HD) (75 mg/kg) treatment with captopril on LV function and hypertrophy in Wistar rats with severe AR. Untreated animals developed LV eccentric hypertrophy and systolic dysfunction. LD treatment did not prevent hypertrophy and provided modest protection against systolic dysfunction. HD treatment preserved LV systolic function and dimensions and tended to slow hypertrophy. The cardiac index remained high and similar among all AR groups, treated or not. Tissue renin-angiotensin system (RAS) analysis revealed that ACE activity was increased in the LVs of AR animals and that only HD treatment significantly decreased angiotensin II receptor mRNA levels. Fibronectin expression was increased in the LV or AR animals, but HD treatment almost completely reversed this increase. The ACE inhibitor captopril was effective at high doses in this model of severe AR. These effects might be related to the modulation of tissue RAS and the control of fibrosis.

Asymptomatic valvular disease: who benefits from surgery?

Routine physical examination and noninvasive imaging frequently lead to the diagnosis of valvular heart disease in asymptomatic patients. The decision to proceed to surgical repair or replacement is based on an informed evaluation of the risks of surgery versus those encountered with a nonoperative course. In determining whether symptoms are present, stress testing may be helpful, as many patients with significant valvular lesions have a tendency to limit their daily physical exertion to levels that do not provoke symptoms. The two most feared consequences of conservative management, sudden death and permanent myocardial damage, are rare in asymptomatic patients with severe aortic stenosis or regurgitation. Surgery for asymptomatic aortic stenosis is performed only for certain high-risk subsets of patients, including those with left ventricular dysfunction, ventricular arrhythmia, and critically small valves. Asymptomatic patients with aortic regurgitation and mitral regurgitation should undergo surgery if they have systolic dysfunction or marked ventricular enlargement.

Aortic valve disease: Current recommendations

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

Left ventricular response to sustained volume overload from chronic aortic valve regurgitation in rats

OBJECTIVES

Aortic regurgitation (AR) induces left ventricular (LV) eccentric hypertrophy in response to chronic volume overload. Patients suffering from this disease often remain asymptomatic for decades before progressive LV dysfunction develops silently. Because of this slow evolution, large clinical trials with long-term follow-up on subjects with chronic AR are hard to perform. To overcome this problem, animal models have been developed in the past but results were very heterogeneous.

METHODS

Helped by echocardiography, we refined a known technique to induce homogeneous degrees of severe AR in Wistar-Kyoto rats. The effects on LV function without treatment and with nifedipine (25 mg/kg daily) (a drug currently recommended in humans with chronic AR) were evaluated by echocardiography.

RESULTS

Over 6 months, nontreated animals developed progressive LV dilatation and eccentric hypertrophy, characteristic of chronic LV volume overload. The animals also developed progressive LV systolic dysfunction, mimicking closely the evolution of the disease in humans. Abnormal filling parameters were also detected in the majority of animals. Systolic and diastolic abnormalities were prevented but only partially in the group treated with nifedipine.

CONCLUSION

This model can be used to study chronic AR and LV dysfunction associated with the disease. Nifedipine seems to protect the LV against chronic volume overload but only partially. Treatment strategies currently used in humans deserve further investigation.

[Current standard in diagnosis and therapy of heart valve lesions]

We present a survey of the current standard in diagnosis and therapy of the most frequent heart valve lesions. During the last 50 years there has been a dramatic shift concerning the etiology of valve lesions with a rise of the agedependent degenerative towards rheumatic valve diseases. The aim of the diagnostic evaluation of valve lesions is primarily the clinical and hemodynamic grading of the severity of the valve disease, the recognition of relevant coexisting cardiac and extracardiac diseases and furthermore, an optimal timing of surgery in close correlation with the cardiac surgeons.

Aortic Insufficiency

Echocardiography is a reliable and reproducible method for evaluation of aortic insufficiency (AI). AI has a variety of etiologies, including congenital or acquired, and may present as an acute situation or as a chronic condition. Regardless of the clinical presentation, patient symptoms and physical signs may not be present unless the AI has progressed to a moderate or severe degree. As the severity of AI increases, there are changes in the pathophysiology of the heart, including an increase in left ventricle dimensions and chamber compliance. Echocardiographic methods to evaluate AI include two-dimensional, m-mode, color flow imaging, and pulsed wave and continuous wave Doppler. The combined use of multiple techniques provides more thorough and accurate quantification, both during follow-up of the disease process and after surgical correction.