Aortic valve replacement: is valve size important?

A parametric study regarding structural design of a bioprosthetic aortic valve by 3D fluid-structure interaction simulations

Since the introduction of transcatheter aortic valve (AV) implantation as a viable option, surgical bioprosthetic AVs have recently started incorporating shorter struts considering future valve-in-valve procedures. However, the effect of leaflet coaptation geometry on the longevity of these valves remains unexplored. To address this gap, we performed a finite element analysis on bioprosthetic AVs with varying strut heights using a two-way fluid-structure interaction method. To establish a baseline, we used a standard height based on a rendered platform image of the CE PERIMOUNT Magna Ease valve from Edward Lifesciences in Irvine, CA. Bovine pericardium properties were assigned to the leaflets, while normal saline properties were used as the recirculating fluid in hemodynamic simulations. The physiological pressure profile of the cardiac cycle was applied between the aorta and left ventricle. We calculated blood flow velocity, effective orifice area (EOA), and mechanical stress on the leaflets. The results reveal that as the strut height increases, the stroke volume increases, leakage volume decreases, and EOA improves. Additionally, the maximum mechanical stress experienced by the leaflet decreases by 62% as the strut height increases to 1.2 times the standard height. This research highlights that a low-strut design in bioprosthetic AVs may negatively affect their durability, which can be useful in design of next-generation bioprosthetic AVs.

Comparison of 1-year Follow-up Echocardiographic Outcomes of Sapien 3 Versus Evolut R Bioprosthetic Transcatheter Aortic Valves: A Single-center Retrospective Iranian Cohort Study

OBJECTIVE

The current study aimed to compare 1-year echocardiographic outcomes of the new generations of self-expanding (Evolut R) versus balloon-expandable (Sapien 3) bioprosthetic transcatheter aortic valves.

METHODS

In this study, gradients and flow velocities obtained from transthoracic Doppler-echocardiography were retrospectively collected from patients who underwent 2 new generations of transcatheter aortic valve implantation interventions with Sapien 3 and Evolut R valves. Patients underwent echocardiography before the procedure and at discharge, 6 months, and 1-year follow-up.

RESULTS

Of the 66 patients, 28 received Sapien 3 and 38 received Evolut R valves. Evolut R valve presented a lower mean gradient at all follow-up time points compared with Sapien 3 valves (14.4 mm Hg, 14.9 mm Hg, 15.5 mm Hg compared with 10.1 mm Hg, 11.6 mm Hg, 11.8 mm Hg, respectively; all P -values <0.001). Small valve sizes of Evolut R, including 23 and 26, had higher echocardiographic mean gradient or peak gradient at the time of discharge compared with larger valves, including sizes 29 and 34 (11.1 mm Hg and 11.2 mm Hg vs. 10.2 mm Hg, 9.1 mm Hg) and 1-year follow-up (11.0 mm Hg, 11.0 mm Hg vs. 9.9 mm Hg, 8.4 mm Hg; all P -values = 0.001). Although Sapien 3 valves demonstrated a higher peak gradient in smaller sizes at discharge (18.44 mm Hg in size 23 vs. 17.9 mm Hg, 16.5 mm Hg in size 26 and 29, respectively; P = 0.001), the peak gradients did not show a statistically significant difference in the 1-year follow-up.

CONCLUSIONS

The current study detected significantly lower mean and peak gradients in Evolut R compared with Sapien 3 at all follow-up time points. Furthermore, smaller valve sizes were associated with significantly higher gradients at all follow-ups, regardless of the valve type.

Figure of eight suture technique in aortic valve replacement decreases prosthesis-patient mismatch

BACKGROUND

While the pledget suture technique has been the standard for surgical aortic. valve replacement (AVR), discussion continues regarding the possibility of the nonpledget suture technique to produce superior structural and hemodynamic parameters. This study aims to assess the effectiveness of the figure-of-eight suture technique in AVR, as determined by the incidence of prosthesis-patient mismatch (PPM).

METHODS

We reviewed records of patients (N = 629) who underwent a surgical AVR procedure between January 2011 and July 2018 at a single institution. Indexed effective orifice area values and PPM incidence were calculated from implanted valve size and patient body surface area. Incidence of none, moderate, and severe PPM was compared across AVR suture techniques.

RESULTS

A total of 570 pledget and 59 figure-of-eight patients were compared for incidence of PPM. Patients who received AVR with the pledget suture technique had significantly lower echocardiographic measurements of baseline ejection fraction than patients who had received AVR with the figure-of-eight suture technique (p = 0.003). Patients who received the figure-of eight suture had a 14% decrease in moderate PPM compared to patients who received the pledget suture (p = 0.022). Patients who received the figure-of-eight suture also had a significantly higher rate of no PPM (p = 0.044).

CONCLUSIONS

The use of the figure-of-eight suture technique in AVR can reduce the incidence of moderate PPM. While the pledget suture is the standard technique in AVR, the figure-of-eight suture technique may offer better structural and hemodynamic outcomes, especially for patients with a smaller aortic annulus.

Implications of Coexisting Aortic Regurgitation in Patients With Aortic Stenosis

Background

Aortic regurgitation (AR) is a common comorbidity in patients with aortic stenosis (AS), but coexisting AR has often been excluded from major clinical studies on AS. The impact of coexisting AR on the natural history of AS has not been well-described.

Objectives

The authors compared clinical outcomes in medically managed patients with moderate-to-severe AS with or without coexisting AR.

Methods

Consecutive patients (N = 1,188) with index echocardiographic diagnosis of moderate-to-severe AS (aortic valve area <1.5 cm²) were studied. All patients were medically managed and were divided into those with coexisting AR (at least moderate severity) and those without. Adverse composite clinical outcomes were defined as mortality or admissions for congestive cardiac failure on subsequent follow-up. The authors compared differences in clinical profile and outcomes between the groups.

Results

There were 88 patients (7.4%) with coexisting AR and AS. These patients did not differ significantly in age, but had lower body mass index (22.9 ± 3.8 vs 25.3 ± 5.1 kg/m²), lower diastolic blood pressure (68.7 ± 10.7 vs 72.2 ± 12.3 mm Hg), larger end-diastolic volume index (68.8 ± 18.8 vs 60.4 ± 17.8 mL/m²) and larger left ventricular mass index (118.6 ± 36.4 vs 108.9 ± 33.1 g/m²). The prevalence of cardiovascular risk factors did not differ significantly. Coexisting AR was associated with increased incidence of adverse outcomes (log-rank 4.20; P = 0.040). On multivariable Cox regression, coexisting AR remained independently associated with adverse outcomes (HR: 1.36; 95% CI: 1.02-1.82) after adjusting for age, AS severity, left ventricular ejection fraction, and year of study.

Conclusions

In patients with AS, coexisting AR was associated with changes in echocardiographic profile and adverse outcomes.

Aortic root widening: “pro et contra”

In patients with a small aortic annulus, the clinical benefits of aortic valve replacement depend on avoidance of patient-prosthesis mismatch as it is associated with reduced overall survival. Aortic root widening or enlargement is a useful technique to implant larger valve prosthesis to prevent patient-prosthesis mismatch. Posterior annular enlargement is the commonest technique used for aortic root enlargement. Consistent enlargement of the aortic root requires more extensive procedures like Manouguian or Konno-Rastan techniques. The patients commonly selected are younger patients with good life expectancy. However, caution is advised in applying this procedure in elderly patients, patients with heavily calcified annulus and when performing concomitant procedures. There is no definitive conclusion on the best material to use for the reconstruction of aortic annulus and aorta in aortic root enlargement procedures.

Impact of valve size, predicted effective and indexed effective orifice area after aortic valve replacement

INTRODUCTION

The impact of manufacturer labeled prosthesis size and predicted effective orifice area (EOA) on long-term survival after aortic valve replacement is not clear although indexed effective orifice area (iEOA) has been associated with worse survival.

METHODS

Data was retrospectively collected from Jan 2000-Dec 2019 for prosthesis type, model, and size for isolated aortic valve replacements. Stratified survival was compared between groups and subgroups for labeled valve size, EOA and predicted patient prosthesis mismatch (PPM).

RESULTS

A total of 3444 patients were included. Moderate and severe PPM was 15.6% and 1.6%, respectively. Cumulative lifetime hazard was worse for biological valves (mortality: biological 77.7% vs. mechanical 64.8%, p = .001). Moderate prosthetic aortic stenosis (AS), (EOA = 1-1.5 cm² ) was 12.1% and severe prosthetic AS (EOA ≤ 1 cm² ) was 0.8%, respectively. Survival was 10.5 ± 0.4 years with moderate to severe prosthetic AS (EOA≤1.5 cm² ) versus 12.6 ± 0.2 years with mild to no prosthetic AS (EOA>1.5 cm² ), p = .001. Worse survival in the presence of moderate-severe prosthetic AS was seen with biological valves (9.7 ± 0.4 years vs. 11.2 ± 0.2 years, p = .001 for EOA≤1.5, >1.5 cm² , respectively). Moderate to severe PPM was associated with worse survival (11.1 ± 0.4 years for iEOA ≤ 0.85 cm² /m² vs. 12.5 ± 0.2 years with iEOA > 0.85 cm² /m² , p = .001). Moderate to severe PPM predicted worse long term survival (hazard ratio: 3.56; 95% confidence interval: 1.37-9.25; p = .009).

CONCLUSION

Predicted prosthetic moderate to severe AS and moderate to severe PPM adversely affect long term survival. Smaller valves are associated with reduced survival.

Accuracy of predicted effective orifice area in determining incidence of patient-prosthesis mismatch after transcatheter aortic valve replacement

OBJECTIVE

Patient-prosthesis mismatch (PPM) is associated with poor outcomes after aortic valve replacement. The aim of this study was to assess the accuracy of indexed effective orifice area (EOAi) charts in predicting PPM after transcatheter aortic valve replacement (TAVR).

METHODS

A retrospective review of 346 TAVR patients from January 2017 to November 2018 was performed. EOAi was predicted for patients based on published predictive tables using valve type, annulus diameter, and body surface area. Actual EOAi was calculated based on intraoperative transesophageal echocardiogram (TEE) measurements. PPM was defined by EOAi ≤ 0.85 cm² /m² . The accuracy of predicted PPM was assessed. Differences in clinical outcomes, including mean gradient, length of stay, mortality, complications, and change in Kansas City cardiomyopathy questionnaire score as an indicator of quality of life, were evaluated based on actual PPM.

RESULTS

Of the 346 patients analyzed, 44 (12.7%) of patients had PPM on intraoperative TEE. Of the 182 patients who received Sapien 3 valves, 42 (23.1%) were predicted to have PPM while 25 (13.7%) had actual PPM. Of the 164 patients who received Evolut valves, 3 (1.8%) were predicted to have PPM while 19 (11.6%) had actual PPM. EOAi charts had poor sensitivity (40.0% for Sapien 3; 5.25% for Evolut) and positive predictive value (23.8% for Sapien 3; 33.3% for Evolut) for both valve types.

CONCLUSION

Preoperative prediction of PPM in TAVR patients using tables of expected EOA demonstrates significant variation from actual PPM. The utility of EOAi charts to predict PPM in patients undergoing TAVR may be limited.

Early evaluation of the aortic root after Nicks' procedure

Objective(s)

To determine the influence of surgical techniques adopted to avoid suture line disruption, periprosthetic leakage, patch dislodgement, pericardial patch aneurysm formation, and the long-term stability of aortic root enlargement (ARE) during aortic valve replacement (AVR).

Methods

One hundred fifteen patients undergoing AVR or combined aortic and mitral valve replacements with Nicks' posterior ARE between 1997 and 2019 underwent long-term echocardiographic and angio-computed tomographic evaluation. Age was 11-72 years (AVR: median, 30; interquartile range, 21-47 years; AVR and mitral valve replacement: median, 27.5; interquartile range, 20-37.5 years). The aortotomy was closed using autologous pericardial patch and Teflon-buttressed sutures.

Results

Hospital mortality was 1.7% (n = 2), with 4 (3.5%) late deaths. At a mean follow-up of 123.11 ± 77.67 months, the survival probability from Kaplan–Meier was 93.25 ± 0.03%. No cases of severe prosthesis–patient mismatch (PPM) were observed, and only 2 patients had moderate PPM. Median aortic root diameters at the level of sinus of Valsalva and sinotubular junction were 32 (29-35) mm and 33 (30-36) mm, respectively, at discharge, and were 33 (30-36) mm, and 33 (31-37) mm, respectively, at latest follow-up, with no cases of late pericardial patch aneurysm.

Conclusions

ARE is a safe adjunct to AVR in patients with a small aortic annulus to prevent PPM. Retention of a pericardial collar and Teflon-buttressed sutures is an expedient, safe, and effective technique in reducing bleeding at the enlarged ventriculo-aortic junction. Autologous pericardial patch aortoplasty is not associated with late aneurysm/pseudoaneurysm formation.

Patient prosthesis mismatch and its impact on left ventricular regression following aortic valve replacement in aortic stenosis patients

Introduction

Patient prosthesis mismatch is known to alter post-operative remodeling of left ventricle adversely in aortic stenosis patients. An indexed orifice area of 0.85 is considered as conventional cutoff for patient prosthesis mismatch based on hemodynamic principles. Many patients have smaller annulus and annulus enlargement techniques may be required to avoid this benchmark which complicates the surgery.

Aims and objectives

To determine incidence of patient prosthesis mismatch (PPM) in our population, to assess left ventricle (LV) regression and impact of indexed effective orifice area on LV regression, and to determine a minimum acceptable cut off indexed orifice area that will result in LV regression.

Materials and methods

A single-center retrospective observational study of all patients who underwent aortic valve replacement surgery for severe aortic stenosis between July 2015 and December 2015 was conducted. Patients who underwent concomitant revascularization or other valve surgery were excluded. Data regarding conventional risk factors for PPM, valve type, and indexed orifice area as well as pre-operative and late post-operative LV mass were collected.

Observations

Thirty-seven of the 91 patients satisfied inclusion criteria. All patients had significant regression in LV mass. The incidence of PPM was 68%. Regression of indexed left ventricular mass showed a positive correlation of with indexed effective orifice area of the prosthetic valve. The correlation coefficient is + 0.48 (95% CI 0.18-0.698). Left ventricular mass regression was significantly higher in patients with indexed effective orifice area more than 0.75 (68.89 ± 29 vs 122.55 ± 58.84, p = 0.028). Relative left ventricular regression also was significantly higher in patients with an indexed effective orifice area more than 0.75 (39.53 ± 13.13 vs 49.73 ± 15.56, p = 0.022). There is a positive correlation between left ventricular regression and the reduction in mean gradient achieved by valve replacement. The correlation coefficient was + 0.35 (95% CI 0.03-0.61).

Conclusions

The incidence of PPM was found to be comparable to literature. There is a positive correlation between left ventricular regression and indexed effective orifice area of the prosthetic valve. Left ventricular regression was significantly higher in patients with an indexed effective area more than 0.75. This can be considered as criteria for significant PPM in study population.

Late clinical outcomes after mechanical aortic valve replacement for aortic stenosis: old versus new prostheses

Background

The study aimed to evaluate the late clinical outcomes of new-generation mechanical valves for severe aortic stenosis (AS) compared with old mechanical valves.

Methods

We retrospectively reviewed data from 254 patients with severe AS, who underwent primary mechanical aortic valve replacement from 1995 to 2013. Patients were classified into two groups: old-valve group (n=65: 33 ATS standard, 32 Medtronic-Hall) and new-valve group (n=189: 113 St. Jude Regent, 46 On-X, 30 Sorin Overline). Median patient age was 58 years (Q1-Q3: 52-61). With propensity score matching based on demographic information, 56 patients in the old-valve group were matched with 177 patients in the new-valve group. The median follow-up duration was 91 months (Q1-Q3: 48-138).

Results

Cardiac-related mortality and hemorrhagic events were significantly lower in the new-valve group (P=0.047 and P=0.032, respectively). The median international normalized ratio (INR) at follow-up was significantly higher in the old-valve group [2.23, Q1-Q3: 2.14-2.35 (old-valve group); 2.08, Q1-Q3: 1.92-2.23 (new-valve group), P<0.001]. The incidence of prosthesis-patient mismatch (PPM) was significantly higher in the old-valve group (P<0.001). Multivariate analysis of the total population revealed that PPM was a significant risk factor for cardiac-related events [hazard ratio (HR) =5.279, 95% CI, 1.886-14.561, P=0.002] and showed higher trend of increasing mortality (HR =3.082, P=0.076).

Conclusions

New mechanical prostheses showed a better hemodynamic performance and lower incidence of PPM. Anticoagulation strategy to lower the target INR in patients with new mechanical valves may improve late outcomes by reducing hemorrhagic events.

Does the disparity in baseline characteristics of patients undergoing transcatheter aortic valve replacement with 23 mm vs. 26 mm valves impact clinical outcome?

OBJECTIVES

We sought to identify if baseline characteristic differences in patients who receive a 23 mm vs. 26 mm valve impact clinical outcomes.

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is currently an approved therapy for patients with severe aortic stenosis who are considered inoperable or are at high risk.

METHODS

We retrospectively examined baseline characteristics and outcomes of patients receiving a 23 mm (n = 132) vs. 26 mm valve (n = 81) via the transfemoral approach.

RESULTS

Gender (P < 0.01), previous coronary artery bypass surgery (P < 0.01), history of atrial fibrillation (P = 0.04), and mean Society of Thoracic Surgeons (STS) score (P < 0.01) were significantly different between groups. There were no significant differences in the rates of minor/major vascular complications (2.2 vs. 3.7%, P = 0.68 and 13.0 vs. 12.3%, P = 0.89, respectively). Bleeding complications were also comparable (major bleed 2.3 vs. 1%, P >0.99, minor bleed 19.0 vs. 22.0%, P = 0.67 and life threatening bleed 7.0 vs. 5.0%, P = 0.77). In-hospital death (6.0 vs. 5.0%, P >0.99), 30-day all-cause death (7.6 vs. 6.2%, P = 0.69), and all-cause death at 1 year (17.4 vs. 25.9%, P = 0.13) were also similar between groups. Gender, valve size, previous coronary bypass surgery and atrial fibrillation were not independently associated with mortality; however, on multivariate analysis STS score was (HR 1.11; 95% CI 1.02-1.19; P = 0.01).

CONCLUSION

Patients undergoing TAVR with 23 and 26 mm valves have similar clinical outcomes despite significant differences in baseline characteristics. © 2015 Wiley Periodicals, Inc.

[Reverse myocardial remodeling in patients with aortic valve disease and mitral insufficiency in early postoperative period]

Surgical treatment of patients with aortic valve disease and concomitant mitral insufficiency remains debatable. We analyzed early postoperative results of surgical treatment of 80 patients depending on type of surgery. All patients were divided into three groups: the 1st - aortic valve replacement in patients without mitral valve dysfunction (control group) (n=44); the 2nd - isolated aortic valve replacement in patients with concomitant mitral regurgitation degree 2-3 (n=18), the 3rd - simultaneous aortic and mitral valve replacement (n=18). Combined valve replacement was associated with more intraoperative blood loss (852.78±442.08 ml) compared with aortic valve replacement (658.7±374.09 ml), p<0.05. In patients with mitral regurgitation greater hematocrit decrease was observed (22.13±3.6% in group 2 and 21.4±4.48 in group 3) in comparison with control group (24.17±3.72% in group 1), p<0.05. Incidence of postoperative complications did not differ in all groups. Mortality rate was 6.8% in group 1 and 11.1% in group 3, there were no deaths in group 2. Both valves correction provided faster myocardial remodeling. Left ventricular end-diastolic volume decreased on 50 ml in group 3, on 33.67 ml in group 2 and on 50.73 ml in group 1 (p<0.05). Pulmonary pressure decreased on 20 mm Hg in group 3, on 13 mm Hg - in group 2 and on 12.57 mm Hg - in group 1, p<0.05. In groups 1 and 3 pulmonary pressure became normal after operation, in group 2 signs of pulmonary hypertension were observed (pressure - 35.3 mm Hg). Analysis of the results showed that simultaneous mitral and aortic valves replacement initiates normalization of intracardiac hemodynamics in early postoperative period.

Prosthesis-patient mismatch causes a significantly increased risk of operative mortality in aortic valve replacement

BACKGROUND

Small aortic prosthesis can lead to prosthesis-patient mismatch (PPM). Implanting such small prosthesis remains a controversial issue. This study was done to investigate whether or not PPM causes an increased operative mortality in aortic valve replacement (AVR).

METHODS

Two-hundred-two consecutive patients undergoing primary AVR in a tertiary hospital were included. The sample was grouped according to the aortic valve prosthesis size: ≤21 mm (small) and >21 mm (standard). The effect of variables on outcomes was determined by univariate and multivariable regression analyses.

RESULTS

PPM was found significantly more among patients with AVR ≤ 21 mm (P < 0.0001). Moreover, the likelihood of mortality also was significantly higher in these patients (P < 0.0001). Univariate analysis demonstrated small prosthesis size, urgent operation, PPM, female gender, and NYHA Class IV as significant predictors of mortality. Multivariate regression identified female gender, PPM, and urgent operation as the key independent predictors of mortality.

CONCLUSION

PPM and female gender are significant predictors of mortality. Care should be taken to prevent PPM by implanting larger prosthesis especially in females.

Can postoperative mean transprosthetic pressure gradient predict survival after aortic valve replacement?

Background

In this study, we sought to determine the effect of the mean transprosthetic pressure gradient (TPG), measured at 6 weeks after aortic valve replacement (AVR) or AVR with coronary artery bypass grafting (CABG) on late all-cause mortality.

Methods

Between January 1998 and March 2012, 2,276 patients (mean age 68 ± 11 years) underwent TPG analysis at 6 weeks after AVR (n = 1,318) or AVR with CABG (n = 958) at a single institution. Mean TPG was 11.6 ± 7.8 mmHg and median TPG 11 mmHg. Based on the TPG, the patients were split into three groups: patients with a low TPG (<10 mmHg), patients with a medium TPG (10–19 mmHg) and patients with a high TPG (≥20 mmHg). Cox proportional-hazard regression analysis was used to determine univariate predictors and multivariate independent predictors of late mortality.

Results

Overall survival for the entire group at 1, 3, 5, and 10 years was 97, 93, 87 and 67 %, respectively. There was no significant difference in long-term survival between patients with a low, medium or high TPG (p = 0.258). Independent predictors of late mortality included age, diabetes, peripheral vascular disease, renal dysfunction, chronic obstructive pulmonary disease, a history of a cerebrovascular accident and cardiopulmonary bypass time. Prosthesis–patient mismatch (PPM), severe PPM and TPG measured at 6 weeks postoperatively were not significantly associated with late mortality.

Conclusions

TPG measured at 6 weeks after AVR or AVR with CABG is not an independent predictor of all-cause late mortality and there is no significant difference in long-term survival between patients with a low, medium or high TPG.

Impact of prosthesis-patient mismatch on early and late mortality after aortic valve replacement

BACKGROUND

The influence of prosthesis-patient mismatch (PPM) on survival after aortic valve replacement (AVR) remains controversial. In this study, we sought to determine the effect of PPM on early (≤30 days) and late mortality (>30 days) after AVR or AVR combined with coronary artery bypass grafting (AVR with CABG).

METHODS

Between January 1998 and March 2012, 2976 patients underwent AVR (n= 1718) or AVR with CABG (n=1258) at a single institution. PPM was defined as an indexed effective orifice area (EOAI) ≤0.85 cm2/m2 and patients were divided into two groups based on the existence of PPM. Cumulative probability values of survival were estimated with Kaplan-Meier method and compared between groups using Breslow test. Univariate and multivariate independent predictors of early mortality were identified using logistic regression. Cox proportional-hazard regression analysis was used to determine univariate and multivariate independent predictors of late mortality.

RESULTS

Early mortality was 6.7% in the PPM group vs 4.7% in the group with no PPM (p=0.013). Late mortality for the PPM group at 1, 5 and 10 years was 4%, 16% and 43%, respectively. Late mortality for the group with no PPM at 1, 5 and 10 years was 4%, 15% and 33% respectively. Independent predictors of early mortality included age, severely impaired left ventricular (LV) function, endocarditis, renal dysfunction, chronic obstructive pulmonary disease (COPD) and cardiopulmonary bypass (CPB) time. Multivariate independent predictors of late mortality included age, severely impaired LV function, diabetes, peripheral vascular disease (PVD), renal dysfunction, history of a cerebrovascular accident (CVA), CPB time and a history of previous cardiac surgery. PPM was not an independent predictor of early or late mortality.

CONCLUSION

PPM is not an independent predictor of both early and late mortality after AVR or AVR combined with CABG.

Is the threshold for postoperative prosthesis-patient mismatch the same for all prostheses?

PURPOSE

The effective orifice area index (EOAI) is used to define the prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR). However, few studies have so far evaluated whether the cutoff value for PPM varies across prostheses. This study assessed the hemodynamics in patients given a mechanical valve and then re-evaluated the validity of the commonly accepted threshold.

METHODS

The subjects included 329 patients that underwent AVR with a St. Jude Medical Regent valve. The transvalvular pressure gradient and EOAI were determined echocardiographically, and the commonly accepted threshold was analyzed in relation to survival.

RESULTS

The mechanical valves very often yielded a postoperative transvalvular pressure gradient >10 mmHg, and thus, clinically significant residual pressure, regardless of the EOAI. The slope of the curve describing the relationship between the transvalvular pressure gradient and EOAI was gentler than that reported for bioprosthetic valves, for which the pressure gradient rises sharply at EOAI <0.85 cm(2)/m(2). The commonly defined PPM did not affect the long-term survival or regression of the left ventricular mass index.

CONCLUSIONS

The relationship between the transvalvular pressure gradient and the EOAI in patients given a mechanical prosthesis differed from the reference standard. These data suggest the need to reconsider the appropriate cutoff value for PPM in relation to different prostheses.

Mid-term outcomes after aortic valve replacement with the 17-mm St. Jude Medical Regent valve

BACKGROUND

When aortic valve replacement (AVR) is performed in patients with a small aortic annulus, prosthesis-patient mismatch (PPM) is of concern. We investigated the mid-term outcomes of AVR with a 17-mm mechanical prosthesis.

METHODS AND RESULTS

Seventy-eight patients with aortic stenosis underwent AVR with a 17-mm St. Jude Medical Regent prosthesis. Echocardiography was performed preoperatively, at discharge, and at follow-up (mean follow-up, 33 months). Patients were divided into 2 groups: with and without PPM at discharge. Between-group differences in postoperative variables, particularly survival, were analyzed. Overall hospital mortality was 2.6%. Actuarial 1- and 5-year survival rates were 95% and 79%, respectively. Diabetes and renal insufficiency were associated with long-term mortality. Freedom from major adverse valve-related cardiac events at 1 year and 5 years was 97.3% and 93.9%, respectively. Diabetes was shown to be an independent risk factor for major adverse valve-related cardiac events. Echocardiography 13 months after AVR showed a significant increase in mean effective orifice area index, decrease in mean left ventricular-aortic pressure gradient, and decrease in mean left ventricular mass index. PPM at discharge did not influence long-term survival or left ventricular mass regression.

CONCLUSIONS

The 17-mm Regent prosthesis provided satisfactory clinical and hemodynamic results. It is a reliable choice for patients with a small aortic annulus.

Small prosthesis size in aortic valve replacement does not affect mortality

BACKGROUND

Small prosthesis size has been associated with poorer postoperative outcomes in aortic valve replacement (AVR). We hypothesized that the use of small aortic valve (AV) prostheses does not independently increase operative mortality following AVR, but that mortality may instead be related to comorbidities.

METHODS

We examined the mortality among 4,621 patients who underwent primary AVR operations at 13 different statewide centers from 2003 to 2008. Patients were stratified by prosthesis size into groups with small (≤21 mm, n=1,810) and standard AV prostheses (≥23 mm, n=2,811). The effect of prosthesis size on outcomes was evaluated with univariate and multivariable regression analyses.

RESULTS

Operative mortality among patients undergoing primary AVR operations was 3.7%. Among isolated operations, small AV prostheses were implanted in more females (79.9% vs 21.0%, p<0.001) and older patients (68.9±12.3 years vs 63.8±13.9 years, p<0.001) than were standard-size AV prostheses, and carried a higher predicted risk of mortality according to the Society of Thoracic Surgeons Predicted Risk of Mortality Score (3.1 [interquartile range, 3.0] versus 2.2 [2.0], p<0.001) than did standard-size AV prostheses. Small AV prostheses incurred more major complications (19.5% vs 15.7%, p=0.01), a greater mortality (3.9% vs 2.3%, p=0.03), a longer postoperative length of stay (6.0 [3.0] vs 5.0 [3.0] days, p<0.001), and higher total costs ($29,738 [18,196] vs $26,679 [14,890], p<0.001) than did standard AV prostheses. However, when analyzed with multivariate regression, small AV prosthesis size and female gender were not independent predictors of operative mortality, whereas advanced age, cardiopulmonary bypass time, and aortic annular enlargement were important predictors of operative mortality.

CONCLUSIONS

Small aortic valve prosthesis size does not independently increase operative mortality following primary AVR. Increased morbidity and mortality among patients undergoing the implantation of small AV prostheses is related to the confounding effects of preoperative and operative risk factors. Annular enlargement may not always reduce mortality.

Defining patient-prosthesis mismatch and its effect on survival in patients with impaired ejection fraction

BACKGROUND

How best to define patient-prosthesis mismatch (PPM) continues to be debated. Over time, the indexed effective orifice area has become the most widely used method. However, the clinical relevance of PPM remains controversial.

METHODS

The indexed geometric orifice area and indexed effective orifice area were calculated for 143 patients having undergone aortic valve replacement with a normal left ventricular function 0.45 or less. Using the indexed geometric orifice area method, PPM was defined as nonsignificant if 1.2 cm(2)/m(2) or greater and as significant if less than 1.2 cm(2)/m(2). Using the indexed effective orifice area method, PPM was considered as nonsignificant if greater than 0.85 cm(2)/m(2), as moderate if greater than 0.65 cm(2)/m(2) and less than or equal to 0.85 cm(2)/m(2), and as severe PPM if 0.65 cm(2)/m(2) or less.

RESULTS

The number of patients classified as having PPM differed according to the method used to predict its presence (PPM: Effective orifice area method = 72.7%; geometric method = 19.6%). Regardless of the method used to classify PPM there was no significant effect on mortality (adjusted hazard ratio: 2.65 at 1 year, 0.99 at 5 years, 0.92 at 9 years; p = not significant). The postoperative mean transvalvular gradient (17.1 ± 6.5 mm Hg) and left ventricular function (0.50 ± 0.145) improved significantly compared with the preoperative findings.

CONCLUSIONS

The method used to calculate PPM resulted in significant classification discordance. However, regardless of classification, the presence of PPM did not adversely affect long-term outcome.

Impact of concomitant aortic regurgitation on long-term outcome after surgical aortic valve replacement in patients with severe aortic stenosis

Background

Prognostic value of concomitant aprtic regurgitation (AR) in patients operated for severe aortic stenosis (AS) is not clarified. The aim of this study was to prospectively examine the impact of presence and severity of concomitant AR in patients operated for severe AS on long-term functional capacity, left ventricular (LV) function and mortality.

Methods

Study group consisted of 110 consecutive patients operated due to severe AS. The patients were divided into AS group (56 patients with AS without AR or with mild AR) and AS+AR group (54 patients with AS and moderate, severe or very severe AR). Follow-up included clinical examination, six minutes walk test (6MWT) and echocardiography 12 and 104 months after AVR.

Results

Patients in AS group had lower LV volume indices throughout the study than patients in AS+AR group. Patients in AS group did not have postoperative decrease in LV volume indices, whereas patients in AS+AR group experienced decrease in LV volume indices at 12 and 104 months. Unlike LV volume indices, LV mass index was significantly lower in both groups after 12 and 104 months as compared to preoperative values. Mean LVEF remained unchanged in both groups throughout the study. NYHA class was improved in both groups at 12 months, but at 104 months remained improved only in patients with AS. On the other hand, distance covered during 6MWT was longer at 104 months as compared to 12 months only in AS+AR group (p = 0,013), but patients in AS group walked longer at 12 months than patients in AS+AR group (p = 0,002). There were 30 deaths during study period, of which 13 (10 due to cardiovascular causes) in AS group and 17 (12 due to cardiovascular causes) in AS+AR group. Kaplan-Meier analysis showed that the survival probability was similar between the groups. Multivariate analysis identified diabetes mellitus (beta 1.78, p = 0.038) and LVEF < 45% (beta 1.92, p = 0.049) as the only independent predictor of long-term mortality.

Conclusion

Our data indicate that the preoperative presence and severity of concomitant AR has no influence on long-term postoperative outcome, LV function and functional capacity in patients undergoing AVR for severe AS.

Left ventricular reverse remodeling in percutaneous and surgical aortic bioprostheses: an echocardiographic study

BACKGROUND

Surgical aortic valve replacement (SAVR) is the definitive proven therapy for patients with severe aortic stenosis who have symptoms or decreased left ventricular (LV) function. The development of transcatheter aortic valve implantation (TAVI) offers a viable and "less invasive" option for the treatment of patients with critical aortic stenosis at high risk with conventional approaches. The main objective of this study was the comparison of LV hemodynamic and structural modifications (reverse remodeling) between percutaneous and surgical approaches in the treatment of severe aortic stenosis.

METHODS

Fifty-eight patients who underwent TAVI with the CoreValve bioprosthetic valve were compared with 58 patients with similar characteristics who underwent SAVR. Doppler echocardiographic data were obtained before the intervention, at discharge, and after 6-month to 12-month follow-up.

RESULTS

Mean transprosthetic gradient at discharge was lower (P<.003) in the TAVI group (10±5 mm Hg) compared with the SAVR group (14±5 mm Hg) and was confirmed at follow-up (10±4 vs 13±4 mm Hg, respectively, P<.001). Paravalvular leaks were more frequent in the TAVI group (trivial to mild, 69%; moderate, 14%) than in the SAVR group (trivial to mild, 30%; moderate, 0%) (P<.0001). The incidence of severe prosthesis-patient mismatch (PPM) was significantly lower (P<.004) in the TAVI group (12%) compared with the SAVR group (36%). At follow-up, LV mass and LV mass indexed to height and to body surface area improved in both groups, with no significant difference. In patients with severe PPM, only the TAVI subgroup showed significant reductions in LV mass. LV ejection fraction improved at follow-up significantly only in TAVI patients compared with baseline values (from 50.2±9.6% to 54.8±7.3%, P<.0001).

CONCLUSIONS

Hemodynamic performance after TAVI was shown to be superior to that after SAVR in terms of transprosthetic gradient, LV ejection fraction, and the prevention of severe PPM, but with a higher incidence of aortic regurgitation. Furthermore, LV reverse remodeling was observed in all patients in the absence of PPM, while the same remodeling occurred only in the TAVI subgroup when severe PPM was present.

Clinical outcome of aortic valve replacement with 16-mm ATS-advanced performance valve for small aortic annulus

BACKGROUND

Various surgical techniques have been proposed to treat small aortic annulus. We have used small-diameter mechanical valves for small aortic annulus. The present study examined aortic valve replacement with small diameter mechanical valves to determine their effectiveness.

METHODS

The study included 67 patients who underwent elective, isolated aortic valve replacement with ATS-Advanced Performance (AP) valves (ATS Medical, Inc, Minneapolis, MN) within our department. The patients were divided into two groups; patients receiving the 16-mm AP valve (16-mm group) and those receiving valves 18-mm AP or larger (>16-mm group).

RESULTS

The mean age of the 16-mm group was significantly higher than that of the >16-mm group. Body surface area was significantly smaller in the 16-mm group than the >16-mm group. We found no significant differences in preoperative conditions between the groups. The effective orifice area index of the mechanical valve was lower in the 16-mm group (0.87+/-0.06 vs 1.12+/-0.13 cm2/m2, p<0.0001). Six patients (40%) in the 16-mm group fell into the category of prosthesis-patient mismatch cases. Although the postoperative pressure gradient was higher in the 16-mm group (33.7+/-12.5 vs 23.16+/-8.78, p<0.01), left ventricular mass index and left ventricular ejection fraction at early and at late follow-up improved from the preoperative period in both groups. We found no significant differences in incidence of postoperative complications, including death.

CONCLUSIONS

We believe aortic valve replacement with small-diameter mechanical valves (the ATS-AP valves) in patients with a small annulus provides satisfactory remote prognosis. The use of mechanical valves in elderly patients is considered acceptable with strict clinical monitoring to prevent thromboembolism and anticoagulation therapy-induced complications.

The 17-mm St. Jude Medical Regent valve is a valid option for patients with a small aortic annulus

BACKGROUND

When aortic valve replacement is performed in patients with a small aortic annulus, prosthesis-patient mismatch is of concern. Such prosthesis-patient mismatch may affect postoperative clinical status and survival. We investigated the outcomes of isolated aortic valve replacement performed with a 17-mm mechanical prosthesis in patients with aortic stenosis.

METHODS

Twenty-three patients with aortic stenosis (mean age, 74.6 +/- 6.3 years) underwent isolated aortic valve replacement with a 17-mm St. Jude Medical Regent prosthesis. Mean body surface area was 1.41 +/- 0.13 m(2). Preoperative echocardiography yielded a mean aortic valve area of 0.36 +/- 0.10 cm(2)/m(2), a mean left ventricular-aortic pressure gradient of 68.4 +/- 25.3 mm Hg, and a mean left ventricular mass index of 200 +/- 69 g/m(2).

RESULTS

There was no operative mortality, and there were no valve-related events. Echocardiography at 14.0 +/- 10.0 months after aortic valve replacement showed a significant increase in the mean effective orifice area index (0.95 +/- 0.24 cm(2)/m(2)), decrease in the mean left ventricular-aortic pressure gradient (17.4 +/- 8.2 mm Hg), and decrease in the mean left ventricular mass index (124 +/- 37 cm(2)/m(2)). Prosthesis-patient mismatch (effective orifice area index < 0.85 cm(2)/m(2)) was present in 8 patients at discharge. In these patients as well as in those without prosthesis-patient mismatch, the left ventricular mass index decreased remarkably during follow-up.

CONCLUSIONS

Aortic valve replacement with a 17-mm Regent prosthesis appears to provide satisfactory clinical and hemodynamic results in patients with a small aortic annulus. Remarkable left ventricular mass regression during follow-up was achieved irrespective of the effective orifice area index at discharge.

Hemodynamic evaluation and midterm outcome of aortic valve replacement with size 19 Perimount prosthetic valve

BACKGROUND

We sought to investigate the effect of patient prosthesis mismatch on hemodynamic profile using dobutamine stress echocardiography, and to evaluate midterm survival of patients undergoing aortic valve replacement with 19-mm Perimount (Baxter Healthcare, Santa Ana, California) aortic prosthetic valves.

METHODS

Between December 1, 1999, and August 17, 2005, 147 patients (mean age, 76.8 +/- 5.51 years) had aortic valves replaced with 19-mm Perimount prostheses. Dobutamine stress echocardiography was performed in a subgroup of 24 patients (mean age, 76.6 +/- 5.60 years). Univariable predictors of peak transprosthetic gradient (PTG) under maximum stress, adjusted for resting PTG, were investigated by regression. Survival in the whole cohort was described, and univariable predictors of survival were investigated by Cox regression.

RESULTS

In the stress echocardiography subgroup, cardiac output (p < 0.0001), PTG (p < 0.0001), and effective orifice area index increased significantly (p = 0.002) under stress. Peak transprosthetic gradient under stress was strongly associated with PTG at rest (p < 0.0001). After controlling for PTG at rest, no other variables were associated with PTG under stress. In the whole cohort, mean duration of follow-up was 2.21 years; 23 patients died. Neither body surface area nor effective orifice area index was significantly associated with survival.

CONCLUSIONS

The 19-mm Perimount aortic prosthesis has acceptable hemodynamic performance. Transvalvular gradients were within a clinically acceptable range, both at rest and under stress. These findings suggest that patient-prosthesis mismatch is unlikely to cause a clinically important problem when the prosthesis is used, which is consistent with survival experience in the whole cohort.