Sébastien Bergeron

Comparison of the hemodynamic performance of percutaneous and surgical bioprostheses for the treatment of severe aortic stenosis.

OBJECTIVES This study was undertaken to compare the hemodynamic performance of a percutaneous bioprosthesis to that of surgically implanted (stented and stentless) bioprostheses for the treatment of severe aortic stenosis. METHODS Fifty patients who underwent percutaneous aortic valve implantation (PAVI) with the Cribier-Edwards or Edwards SAPIEN bioprosthetic valve (Edwards Lifesciences, Inc., Irvine, California) were matched 1:1 for sex, aortic annulus diameter, left ventricular ejection fraction, body surface area, and body mass index, with 2 groups of 50 patients who underwent surgical aortic valve replacement (SAVR) with a stented valve (Edwards Perimount Magna [SAVR-ST group]), or a stentless valve (Medtronic Freestyle, Medtronic, Minneapolis, Minnesota [SAVR-SL group]). Doppler echocardiographic data were prospectively obtained before the intervention, at discharge, and at 6- to 12-month follow-up. RESULTS Mean transprosthetic gradient at discharge was lower (p < 0.001) in the PAVI group (10 +/- 4 mm Hg) compared with the SAVR-ST (13 +/- 5 mm Hg) and SAVR-SL (14 +/- 6 mm Hg) groups. Aortic regurgitation (AR) occurred more frequently in the PAVI group (mild: 42%, moderate: 8%) compared with the SAVR-ST (mild: 10%, moderate: 0%) and SAVR-SL (mild: 12%, moderate: 0%) groups (p < 0.0001). At follow-up, the mean gradient in the PAVI group remained lower (p < 0.001) than that of the SAVR-ST group, but was similar to that of the SAVR-SL group. The incidence of severe prosthesis-patient mismatch was significantly lower (p = 0.007) in the PAVI group (6%) compared with the SAVR-ST (28%) and SAVR-SL (20%) groups. However, the incidence of AR remained higher (p < 0.0001) in the PAVI group compared with the 2 other groups. CONCLUSIONS PAVI provided superior hemodynamic performance compared with the surgical bioprostheses in terms of transprosthetic gradient and prevention of severe prosthesis-patient mismatch, but was associated with a higher incidence of AR.

Comparison Between Transcatheter and Surgical Prosthetic Valve Implantation in Patients With Severe Aortic Stenosis and Reduced Left Ventricular Ejection Fraction

Background— Patients with severe aortic stenosis and reduced left ventricular ejection fraction (LVEF) have a poor prognosis with conservative therapy but a high operative mortality when treated surgically. Recently, transcatheter aortic valve implantation (TAVI) has emerged as an alternative to surgical aortic valve replacement (SAVR) for patients considered at high or prohibitive operative risk. The objective of this study was to compare TAVI and SAVR with respect to postoperative recovery of LVEF in patients with severe aortic stenosis and reduced LV systolic function. Methods and Results— Echocardiographic data were prospectively collected before and after the procedure in 200 patients undergoing SAVR and 83 patients undergoing TAVI for severe aortic stenosis (aortic valve area ≤1 cm2) with reduced LV systolic function (LVEF ≤50%). TAVI patients were significantly older (81±8 versus 70±10 years; P<0.0001) and had more comorbidities compared with SAVR patients. Despite similar baseline LVEF (34±11% versus 34±10%), TAVI patients had better recovery of LVEF compared with SAVR patients (&Dgr;LVEF, 14±15% versus 7±11%; P=0.005). At the 1-year follow-up, 58% of TAVI patients had a normalization of LVEF (>50%) as opposed to 20% in the SAVR group. On multivariable analysis, female gender (P=0.004), lower LVEF at baseline (P=0.005), absence of atrial fibrillation (P=0.01), TAVI (P=0.007), and larger increase in aortic valve area after the procedure (P=0.01) were independently associated with better recovery of LVEF. Conclusion— In patients with severe aortic stenosis and depressed LV systolic function, TAVI is associated with better LVEF recovery compared with SAVR. TAVI may provide an interesting alternative to SAVR in patients with depressed LV systolic function considered at high surgical risk.

Usefulness of exercise-stress echocardiography for risk stratification of true asymptomatic patients with aortic valve stenosis

Aims Abnormal exercise test defined as the occurrence of exercise limiting symptoms, fall in blood pressure below baseline, or complex ventricular arrhythmias is useful to predict clinical events in asymptomatic patients with aortic stenosis (AS). The purpose of this study was to determine whether exercise-stress echocardiography (ESE) adds any incremental prognostic value to resting echocardiography in patients with AS having a normal exercise response. Methods and results One hundred and eighty-six asymptomatic patients with at least moderate AS and preserved LV ejection fraction (≥50%) were assessed by Doppler-echocardiography at rest and during a maximum ramp semi-supine bicycle exercise test. Fifty-one (27%) patients had an abnormal exercise test and were excluded from the present analysis. Among the 135 patients with normal exercise test, 67 had an event (aortic valve replacement motivated by symptoms or cardiovascular death) at a mean follow-up of 20 ± 14 months. The variables independently associated with events were: age ≥65 years [hazard ratio (HR) = 1.96; 95% confidence interval (CI): 1.15–3.47; P = 0.01], diabetes, (HR = 3.20; 95% CI: 1.33–6.87; P = 0.01), LV hypertrophy (HR = 1.96; 95% CI: 1.17–3.27; P = 0.01), resting mean gradient >35 mmHg (HR = 3.60; 95% CI: 2.11–6.37; P < 0.0001), and exercise-induced increase in mean gradient >20 mmHg (HR = 3.83; 95% CI: 2.16–6.67; P < 0.0001). Conclusion The exercise-induced increase in transvalvular gradient may be helpful to improve risk stratification in asymptomatic AS patients with normal exercise response. These results thus suggest that ESE may provide additional prognostic information over that obtained from standard exercise testing and resting echocardiography.

Feasibility and Initial Results of Percutaneous Aortic Valve Implantation Including Selection of the Transfemoral or Transapical Approach in Patients With Severe Aortic Stenosis

The purpose of this study was to evaluate the feasibility and initial results of a multidisciplinary percutaneous aortic valve implantation (PAVI) program including the transfemoral approach (TFA) and the transapical approach (TAA). This was a prospective registry including all patients with symptomatic severe aortic stenosis who were evaluated for PAVI and those who finally underwent the procedure. All patients were considered very high risk or nonsurgical candidates, and an algorithm based on prespecified criteria was used to determine the most appropriate approach (TFA vs TAA) for each patient. The Edwards-Sapien valve was used in all cases, and all procedures were performed without cardiopulmonary bypass. A total of 29 consecutive patients were evaluated for PAVI, and 22 of them underwent the procedure (mean age 84 +/- 7 years, predicted surgical mortality 26 +/- 16%), with 11 patients selected for each approach. Reasons for selecting TAA rather than TFA were the following: small diameter and/or severe calcification of the iliofemoral arteries (4 patients), peripheral vascular disease (4 patients), porcelain aorta (2 patients), and horizontal ascending aorta (1 patient). Successful aortic valve implantation was obtained in 91% of the procedures, and procedural and 30-day mortality were 4.3% and 8.7%, respectively. There were no cases of myocardial infarction, vascular complications, or cerebrovascular accident. PAVI was associated with a significant reduction in mean aortic gradient (baseline 34 +/- 10 mm Hg, postprocedure 9 +/- 3 mm Hg, p <0.001), with no cases of severe aortic regurgitation. After a median follow-up period of 6 months, there were no additional major adverse cardiac events, and no significant changes in hemodynamic aortic valve parameters were observed. In conclusion, this study demonstrates the feasibility and low complication rate of a PAVI program using a prospective strategy for the selection of the TFA or TAA, with half of the patients selected for each approach.

Predictive factors, efficacy, and safety of balloon post-dilation after transcatheter aortic valve implantation with a balloon-expandable valve

OBJECTIVES This study sought to evaluate the predictive factors, effects, and safety of balloon post-dilation (BPD) for the treatment of significant paravalvular aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI). BACKGROUND Very few data exist on BPD after TAVI with a balloon-expandable valve. METHODS A total of 211 patients who underwent TAVI with a balloon-expandable valve were included. BPD was performed after TAVI if paravalvular AR ≥ 2 was identified by transesophageal echocardiography. Clinical events and echocardiographic data were prospectively recorded, and median follow-up was 12 (6 to 24) months. RESULTS BPD was performed in 59 patients (28%), leading to a reduction in at least 1 degree of AR in 71% of patients, with residual AR <2 in 54% of the patients. The predictors of the need for BPD were the degree of valve calcification and transfemoral approach, with valve calcification volume >2,200 and >3,800 mm(3) best determining the need for and a poor response to BPD, respectively. Patients who underwent BPD had a higher incidence of cerebrovascular events at 30 days (11.9% vs. 2.0%, p = 0.006), with most (83%) events within the 24 h after the procedure occurring in patients who had BPD. No significant changes in valve area or AR degree were observed at follow-up in BPD and no-BPD groups. CONCLUSIONS BPD was needed in about one-fourth of the patients undergoing TAVI with a balloon-expandable valve and was successful in about one-half of them. A higher degree of valve calcification and transfemoral approach predicted the need for BPD. BPD was not associated with any deleterious effect on valve function at mid-term follow-up, but a higher rate of cerebrovascular events was observed in patients who had BPD.

Electrocardiographic changes and clinical outcomes after transapical aortic valve implantation

BACKGROUND Transapical aortic valve implantation (TAVI) for the treatment of severe aortic stenosis requires the insertion of a large catheter through the left ventricular apex. However, the electrocardiographic (ECG) changes associated with the incision and repair of the left ventricular apex and the potential damage to the conduction system caused by implanting a balloon-expandable valve in aortic position are not known. The objective of our study was to determine the incidence, type, and timing of ECG changes associated with TAVI. METHODS The standard 12-lead ECGs of 33 consecutive patients (mean age 81 +/- 9 years, 13 men) diagnosed with symptomatic severe aortic stenosis (valve area 0.62 +/- 0.16 cm(2)) who underwent TAVI with an Edwards-SAPIEN valve were analyzed at baseline (within 24 hours before the procedure), immediately (within 6 hours) after the procedure, at hospital discharge, and at 1-month follow-up. RESULTS There were no procedural deaths, and 30-day mortality was 6%. The incidence of complete left ventricular branch block (LBBB) and left anterior hemiblock (LAHB) increased from 9% and 3% at baseline to 27% and 36% after the procedure, respectively (P < .03 for both). A lower (ventricular) position of the valve relative to the hinge point of the anterior mitral leaflet was associated with a higher incidence of new LBBB (35% vs 0%, P = .029); and a greater valve size-aortic annulus ratio, with the occurrence of new LAHB (1.20 +/- 0.07 vs 1.14 +/- 0.06, P = .021). At 1-month follow-up, the rate of LBBB and LAHB decreased to 13% and 10%, respectively (P = not significant compared with baseline). There were no cases of new atrioventricular block, and no patient needed pacemaker implantation. Transient (<48 hours) ST-elevation changes, mostly in the anterior and/or lateral leads, occurred in 6 patients (18%) immediately after the procedure; but only 1 of these patients presented new Q waves at 1-month follow-up. CONCLUSIONS Transapical aortic valve implantation was associated with a significant but transient (<1 month) increase in LBBB and LAHB, with no patient requiring pacemaker implantation. These changes were partially related to both lower (more ventricular) valve positioning and greater valve oversizing. Transient (<48 hours) ST-segment elevation changes occurred in about one fifth of the patients after the procedure, but only a minority developed new Q waves in the ECG.

The SHP-1 protein tyrosine phosphatase negatively modulates glucose homeostasis

The protein tyrosine phosphatase SHP-1 is a well-known inhibitor of activation-promoting signaling cascades in hematopoietic cells but its potential role in insulin target tissues is unknown. Here we show that Ptpn6me-v/me-v (also known as viable motheaten) mice bearing a functionally deficient SHP-1 protein are markedly glucose tolerant and insulin sensitive as compared to wild-type littermates, as a result of enhanced insulin receptor signaling to IRS-PI3K-Akt in liver and muscle. Downregulation of SHP-1 activity in liver of normal mice by adenoviral expression of a catalytically inert mutant of SHP-1, or after small hairpin RNA–mediated SHP-1 silencing, further confirmed this phenotype. Tyrosine phosphorylation of CEACAM1, a modulator of hepatic insulin clearance, and clearance of serum [125I]-insulin were markedly increased in SHP-1–deficient mice or SHP-1–deficient hepatic cells in vitro. These findings show a novel role for SHP-1 in the regulation of glucose homeostasis through modulation of insulin signaling in liver and muscle as well as hepatic insulin clearance.

Stress echocardiography to assess stenosis severity and predict outcome in patients with paradoxical low-flow, low-gradient aortic stenosis and preserved LVEF.

The objective of this study was to examine the value of stress-echocardiography in patients with paradoxical low-flow, low-gradient (PLFLG) aortic stenosis (AS). The projected aortic valve area (AVAProj) at a normal flow rate was calculated in 55 patients with PLFLG AS. In the subset of patients (n = 13) who underwent an aortic valve replacement within 3 months after stress echocardiography, AVA(Proj) correlated better with the valve weight compared to traditional resting and stress echocardiographic parameters of AS severity (AVA(Proj): r = -0.78 vs. other parameters: r = 0.46 to 0.56). In the whole group (N = 55), 18 (33%) patients had an AVA(Proj) >1.0 cm(2), being consistent with the presence of pseudo severe AS. The AVA(Proj) was also superior to traditional parameters of stenosis severity for predicting outcomes (hazard ratio: 1.32/0.1 cm(2) decrease in AVA(Proj)). In patients with PLFLG AS, the measurement of AVA(proj) derived from stress echocardiography is helpful to determine the actual severity of the stenosis and predict risk of adverse events.

Usefulness of TEE as the Primary Imaging Technique to Guide Transcatheter Transapical Aortic Valve Implantation

OBJECTIVES The aim of this study was to: 1) determine the usefulness of transesophageal echocardiography (TEE) as the primary technique to guide transapical (TA) transcatheter aortic valve implantation (TAVI); and 2) to compare TEE with angiography as the primary imaging modality for TA-TAVI guidance. BACKGROUND TEE has been routinely used as an adjunct to angiography during TA-TAVI procedures, but very few data exist on the use of TEE as the primary imaging technique guiding TA-TAVI. METHODS One hundred consecutive high-risk patients (mean age 79 ± 9 years, mean logistic EuroSCORE: 25.8 ± 17.6%) who underwent TA-TAVI in our center were included. The Edwards valve was used in all cases, and all procedures were performed in an operating room without hybrid facilities. The TA-TAVI was primarily guided by angiography in the first 25 patients (A-TAVI group) and by TEE in the last 75 patients (TEE-TAVI group). Procedural, 30-day, and follow-up results were evaluated. RESULTS No differences were observed between groups at baseline except for a higher (p = 0.001) prevalence of moderate or severe mitral regurgitation in the TEE-TAVI group. The procedure was successful in 97.3% and 100% of the patients in the TEE-TAVI and A-TAVI groups, respectively (p = 1.0), and a lower contrast volume was used in the TEE-TAVI group (12 [5 to 20] ml vs. 40 [20 to 50] ml, p < 0.0001). There were no differences between groups in the occurrence of valve malposition needing a second valve (TEE-TAVI: 5.3%; A-TAVI: 4%; p = 1.0) or valve embolization (TEE-TAVI: 1.3%; A-TAVI: 4%; p = 0.44). The results regarding post-procedural valve hemodynamic status and aortic regurgitation were similar between groups. The survival rates at 30-day and 1-year follow-up were 87% and 75% in the TEE-group and 88% and 84% in the A-TAVI group, respectively (log-rank = 0.49). CONCLUSIONS TEE-TAVI was associated with similar acute and midterm results as A-TAVI and significantly reduced contrast media use during the procedures. These results suggest the feasibility and safety of performing TA-TAVI procedures in an operating room without hybrid facilities, but larger studies are needed to confirm these findings.

Validation and Characterization of Transcatheter Aortic Valve Effective Orifice Area Measured by Doppler Echocardiography

OBJECTIVES The objectives were to compare different Doppler echocardiographic methods for the measurement of prosthetic valve effective orifice area (EOA) following transcatheter aortic valve implantation (TAVI) and to determine the factors influencing the EOA of transcatheter balloon expandable valves. BACKGROUND Previous studies have used different methods for the measurement of the valve EOA following TAVI. Factors influencing the EOA of transcatheter valves are unknown. METHODS A total of 122 patients underwent TAVI with the use of the Edwards-SAPIEN valve (Edwards Lifesciences, Irvine, California). The EOA was measured by transthoracic echocardiography at hospital discharge, 6 months and 1 year after TAVI with the use of 2 methods as described in previous studies. In Method #1 (EOA(1)), LVOT diameter (LVOTd) entered in the continuity equation was measured at the base of prosthesis cusps whereas, in Method #2 (EOA(2)), LVOTd was measured immediately proximal to the prosthesis stent. RESULTS The average EOA(2) (1.57 ± 0.41 cm(2)) was larger (p < 0.01) than the EOA(1) (1.21 ± 0.38 cm(2)). Accordingly, incidence of severe PPM (indexed EOA ≤0.65 cm(2)/m(2)) was 3-fold lower with the use of EOA(2) than with EOA(1) (9% vs. 33%; p < 0.001). Mean transprosthetic gradient correlated better (p = 0.03) with indexed EOA(2) (r = -0.70, p < 0.0001) than with indexed EOA(1) (r = -0.58, p < 0.0001). Intraobserver and interobserver variability were lower for EOA(2) compared to EOA(1) (intra: 5% vs. 7%, p = 0.06; inter: 6% vs. 14%; p < 0.001). Aortic annulus size was the sole independent determinant (p = 0.01) of prosthetic valve EOA(2). The average EOA varied from 1.37 ± 0.23 cm(2) for aortic annulus size <19 mm up to 1.90 ± 0.17 cm(2) for size >23 mm. CONCLUSIONS When estimating the EOA of Edwards-SAPIEN valves by Doppler-echocardiography, it is recommended to use the LVOT diameter and velocity measured immediately proximal to the stent. The main determinant of the EOA of transcatheter valves is the patients annulus size and these valves provide excellent hemodynamics even in patients with a small aortic annulus.