Thierry Le Tourneau

Aortic valve replacement for Low-Flow/Low-Gradient aortic stenosis - Operative risk stratification and long-term outcome: A European Multicenter study

OBJECTIVES We evaluated a large multicenter series of patients operated on for low-flow/low-gradient aortic stenosis (LF/LGAS) to stratify the operative risk, assess whether perioperative mortality has decreased over recent years, and analyze the post-operative outcome. BACKGROUND Although LF/LGAS is classically associated with a high operative risk, few data are available concerning the results of surgery in this setting. METHODS A total of 217 consecutive patients (168 men, 77%) with severe aortic stenosis (area <1 cm(2)), low ejection fraction (EF) (<or=35%), and low mean gradient (MG) (<or=30 mm Hg) who underwent aortic valve replacement (AVR) between 1990 and 2005 were included. RESULTS Perioperative mortality was 16% and decreased dramatically from 20% in the 1990 to 1999 period to 10% in the 2000 to 2005 period. Higher European System for Cardiac Operative Risk Evaluation score (EuroSCORE), very low MG and EF, New York Heart Association functional class III or IV, history of congestive heart failure, and multivessel coronary artery disease (MVD) were associated with perioperative mortality. On multivariate analysis, very low pre-operative MG and MVD were predictors of excess perioperative mortality. In the subgroup of patients with dobutamine stress echocardiography, the absence of contractile reserve was a strong predictor of perioperative mortality. Overall 5-year survival rate was 49 +/- 4%. Lower MG, higher EuroSCORE, prior atrial fibrillation, and MVD were identified as independent predictors of overall long-term mortality. CONCLUSIONS In view of the very poor prognosis of unoperated patients, the current operative risk, and the long-term outcome after surgery, AVR is the treatment of choice in the majority of cases of LF/LGAS.

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.

Impact of Left Atrial Volume on Clinical Outcome in Organic Mitral Regurgitation

OBJECTIVES The purpose of this paper was to assess the link between left atrial (LA) volume at diagnosis and outcome of patients with mitral regurgitation (MR). BACKGROUND Left atrial enlargement is a consequence of organic MR, but its association with clinical outcome independently of MR severity is uncertain. METHODS We prospectively enrolled 492 patients (age 63 +/- 15 years, 60% men) in sinus rhythm with organic MR (regurgitant volume 68 +/- 42 ml/beat) and performed at baseline triple echocardiographic quantitation (MR severity, LA volume, and left ventricular characteristics). Outcome with medical and surgical management was analyzed. RESULTS Left atrial volume indexed to body surface area (LA index) was 55 +/- 26 ml/m(2) (<40 ml/m(2) in 158 patients, 40 to 59 ml/m(2) in 160 patients, and > or =60 ml/m(2) in 174 patients). Under medical management, 5-year survival was 80 +/- 2.9% and cardiac events 28 +/- 3%. Adjusting for established predictors of outcome, LA index was independently associated with survival after diagnosis (hazard ratio [HR]: 1.3 [95% confidence interval (CI): 1.1 to 1.5] per 10 ml/m(2) increment, p = 0.001). Patients with LA index > or =60 ml/m(2) had lower 5-year survival than those with no or mild LA enlargement (p < 0.0001) and than the rates of survival expected in the U.S. population (53 +/- 8.6% vs. 76%, p = 0.017). Compared with patients with LA index <40 ml/m(2), those with LA index > or =60 ml/m(2) had increased mortality (HR: 2.8 [95% CI: 1.2 to 6.5], p = 0.016) and cardiac events (HR: 5.2 [95% CI: 2.6 to 10.9], p < 0.0001) with medical management. Mitral surgery was associated with decreased mortality (HR: 0.46 [95% CI: 0.26 to 0.84], p = 0.01) and cardiac events (HR: 0.38 [95% CI: 0.23 to 0.62], p = 0.0001) and after surgery patients with LA index > or =60 ml/m(2) versus <60 ml/m(2) did not incur excess mortality or cardiac events (both p > 0.30). CONCLUSIONS In organic MR, LA index at diagnosis predicts long-term outcome, incrementally to known predictors of outcome. This marker of risk is particularly important because mitral surgery in these patients markedly improves outcome and restores life expectancy. LA index should be measured in routine clinical practice for risk-stratification and for clinical decision making in patients with organic MR.

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.

Left Ventricular Response to Exercise in Aortic Stenosis: An Exercise Echocardiographic Study

Background: While normal at rest, left ventricular (LV) systolic function may become abnormal during exercise in patients with aortic stenosis. Once contraindicated in patients with aortic stenosis, exercise testing is now recommended in asymptomatic patients with aortic stenosis to elicit symptoms and thereby ascertain the need for aortic valve replacement. However, the clinical significance of an abnormal LV response to exercise in asymptomatic patients with aortic stenosis remains unknown. Objective: The aim of this study was to evaluate the clinical implications of an abnormal LV response during exercise in the setting of aortic stenosis. Methods: We monitored the LV response to exercise by 2D‐Doppler echocardiography during a symptom limited semirecumbent bicycle exercise in 50 patients with tight aortic stenosis (aortic valve area ≤ 1.0 cm2) and a normal LV systolic function (LV ejection fraction, EF ≥ 50%) and followed them for an average of 11 months. Results: Twenty patients had an abnormal LV response to exercise with a mean decrease in LV EF from 64 ± 10 to 53 ± 12% while 30 patients had a normal LV response to exercise with a mean increase in LV EF from 62 ± 7 to 70 ± 8%. Patients with an abnormal LV response during exercise were more likely to develop symptoms during exercise than patients with a normal LV response: 80% versus 27% (P < 0.0001). The survival free of cardiac events was significantly lower in patients with abnormal LV response to exercise than in patients with a normal response (P = 0.03). Conclusion: Exercise echocardiography provides objective data that facilitate interpretation of exercise elicited symptoms in asymptomatic patients with severe aortic stenosis. In addition, an abnormal LV response to exercise may predict a poor outcome.

Echocardiography predictors and prognostic value of pulmonary artery systolic pressure in chronic organic mitral regurgitation

Objective To evaluate the predictors of pulmonary artery systolic pressure (PASP) in organic mitral regurgitation (MR) and its prognostic value after surgery. Design Prospective observational study, conducted from 1998 to 2006. Setting Echocardiography and cardiac surgery departments, University Hospital. Patients Echocardiography was carried out in 256 patients (63±12 years, 170 male) with organic MR (degenerative aetiology: 91%) referred for surgery. Main outcome measures Echocardiography predictors of PASP. Postoperative end points were overall mortality and cardiovascular mortality. Results Baseline PASP was 45±14 mmHg, ranging from 25 to 105 mmHg. PASP was ≥50 mmHg in 82 patients (32%). Left atrial volume (p=0.003), mitral deceleration time (p<0.0001) and mitral medial E/E′ (p<0.0001) were independent predictors of PASP, whereas left ventricular size and systolic function were not predictors. Mitral valve repair was performed in 194 patients (76%) and mitral valve replacement in 62 (24%). In a Cox model mitral valve repair (HR=0.41 (95% CI 0.20 to 0.85), p=0.016) and PASP (HR=1.43 (95% CI 1.09 to 1.88) per 10 mmHg increment, p=0.011) were independent predictors of overall mortality, even after adjustment for known predictors. PASP (HR=1.49 (95% CI 1.03 to 2.16) per 10 mmHg increment, p=0.033) was also an independent predictor of cardiac mortality. Eight-year survival after surgery was 58.6% and 86.6% in patients with baseline PASP ≥50 mmHg or <50 mmHg, respectively (p<0.0001). Conclusions In organic MR, mitral deceleration time, mitral E/E′ and left atrial volume correlate with PASP. Pulmonary artery systolic pressure ≥50 mmHg is an independent predictor of overall and cardiovascular mortality after surgery in organic MR.

Role of Nitric Oxide in Restenosis After Experimental Balloon Angioplasty in the Hypercholesterolemic Rabbit: Effects on Neointimal Hyperplasia and Vascular Remodeling

OBJECTIVES The purpose of this study was to assess the effects of L-arginine and N(G)-nitro-L-arginine methyl ester (L-NAME) on neointimal hyperplasia and vascular remodeling after balloon angioplasty in the hypercholesterolemic rabbit. BACKGROUND Restenosis after balloon angioplasty is a consequence of both neointimal hyperplasia and vessel remodeling. Nitric oxide inhibits neointimal hyperplasia, but its effect on vessel remodeling is unknown. METHODS Six weeks after induction of bilateral iliac atherosclerosis, 48 rabbits underwent successful angioplasty in 75 vessels. Eight rabbits (acute group) were sacrificed immediately after angioplasty. The remaining animals received either placebo (chronic control group), or a diet supplemented with either L-arginine (1.5 g/kg/day), or L-NAME (15 mg/kg/day) for 4 weeks after angioplasty. RESULTS The intimal area was significantly greater in the chronic control group compared to the acute group (2.60+/-1.03 mm2 vs. 1.35+/-0.62 mm2). This increase in intimal area was lower in the L-arginine group (1.79+/-0.61 mm2), and greater in the L-NAME group (3.23+/-0.92 mm2). The area circumscribed by the internal elastic lamina (IEL) increased significantly in the control group compared to the acute group (from 2.52+/-0.66 to 3.33+/-0.85 mm2); a more marked increase occurred in the L-NAME group (3.90+/-0.85 mm2). By contrast, IEL area was unchanged in the L-arginine group (2.41+/-0.62 mm2). As a result, there was no significant difference in lumen area after 4 weeks in the chronic groups (control: 0.74+/-0.38 mm2; L-arginine: 0.50+/-0.43 mm2; L-NAME: 0.48+/-0.42 mm2). CONCLUSIONS Our results demonstrate that L-arginine inhibits whereas L-NAME stimulates neointimal hyperplasia after experimental balloon angioplasty in the hypercholesterolemic rabbit. However, the lack of vessel enlargement in the L-arginine group resulted in a similar final lumen size in the L-NAME and L-arginine groups.

Early Structural Valve Deterioration of Mitroflow Aortic Bioprosthesis Mode, Incidence, and Impact on Outcome in a Large Cohort of Patients

Background— Structural valve deterioration (SVD) is a major flaw of bioprostheses. Early SVD has been suspected in the last models of Mitroflow bioprosthesis. We sought to assess the incidence, mode, and impact of SVD on outcome in a large series of Mitroflow aortic valve replacement. Methods and Results— Six hundred seventeen consecutive patients (aged 76.1±6.3 years) underwent aortic valve replacement with a Mitroflow prosthesis (models 12A/LX) between 2002 and 2007. By echocardiography, 39 patients developed early SVD (1.66% per patient-year), with stenosis as the main mode (n=36). Mean delay to SVD was only 3.8±1.4 years, and 5-year SVD-free survival was 91.6% (95% confidence interval [CI], 88.7–94.7) for the whole cohort and 79.8% (95% CI, 71.2–89.4) and 94.0% (95% CI, 90.3–97.8) for 19- and 21-mm sizes, respectively. Among the 39 patients with SVD, 13 patients (33%) had an accelerated SVD once the mean gradient exceeded 30 mm Hg. Valve-related death was 46.2% in this SVD subgroup. Five-year overall survival was 69.6% (95% CI, 65.7–73.9). In multivariable analysis, SVD was the strongest correlate of overall mortality (hazard ratio=7.7; 95% CI, 4.4–13.6). Conclusions— Early SVD is frequent in Mitroflow bioprosthesis (models 12A/LX), especially for small sizes (19 and 21 mm), and reduces overall survival. An unpredictable accelerated pattern of SVD constitutes a life-threatening condition. In view of the large number of Mitroflow valves implanted worldwide, one can expect an epidemic of SVD and valve-related deaths, which represents a major public health issue, especially in the elderly. Hence, a close follow-up with yearly echocardiography after Mitroflow implantation is advisable. An urgent reoperation should be discussed in patients with severe SVD even though they are still asymptomatic.Background— Structural valve deterioration (SVD) is a major flaw of bioprostheses. Early SVD has been suspected in the last models of Mitroflow bioprosthesis. We sought to assess the incidence, mode, and impact of SVD on outcome in a large series of Mitroflow aortic valve replacement. Methods and Results— Six hundred seventeen consecutive patients (aged 76.1±6.3 years) underwent aortic valve replacement with a Mitroflow prosthesis (models 12A/LX) between 2002 and 2007. By echocardiography, 39 patients developed early SVD (1.66% per patient-year), with stenosis as the main mode (n=36). Mean delay to SVD was only 3.8±1.4 years, and 5-year SVD-free survival was 91.6% (95% confidence interval [CI], 88.7–94.7) for the whole cohort and 79.8% (95% CI, 71.2–89.4) and 94.0% (95% CI, 90.3–97.8) for 19- and 21-mm sizes, respectively. Among the 39 patients with SVD, 13 patients (33%) had an accelerated SVD once the mean gradient exceeded 30 mm Hg. Valve-related death was 46.2% in this SVD subgroup. Five-year overall survival was 69.6% (95% CI, 65.7–73.9). In multivariable analysis, SVD was the strongest correlate of overall mortality (hazard ratio=7.7; 95% CI, 4.4–13.6). Conclusions— Early SVD is frequent in Mitroflow bioprosthesis (models 12A/LX), especially for small sizes (19 and 21 mm), and reduces overall survival. An unpredictable accelerated pattern of SVD constitutes a life-threatening condition. In view of the large number of Mitroflow valves implanted worldwide, one can expect an epidemic of SVD and valve-related deaths, which represents a major public health issue, especially in the elderly. Hence, a close follow-up with yearly echocardiography after Mitroflow implantation is advisable. An urgent reoperation should be discussed in patients with severe SVD even though they are still asymptomatic. # CLINICAL PERSPECTIVE {#article-title-37}

Effect of mitral valve surgery on exercise capacity, ventricular ejection fraction and neurohormonal activation in patients with severe mitral regurgitation

OBJECTIVES The purpose of this study was to prospectively investigate the effects of surgical correction of mitral regurgitation (MR) on exercise performance, cardiac function and neurohormonal activation. BACKGROUND Little is known about the effect of surgical correction of MR on functional status or on neurohormonal activation. METHODS Cardiopulmonary exercise test, radionuclide angiography and blood samples for assessment of neurohormonal status were obtained in 40 patients with nonischemic MR before and within one year (216+/-80 days) after surgery. Twenty-four patients underwent mitral valve repair (MVr), and 16 underwent valve replacement (VR) with anterior chordal transection. RESULTS Despite an improvement in New York Heart Association functional class, exercise performance did not change (peak oxygen consumption: 19.3+/-6.1 to 18.5+/-5.6 ml/kg/min, percentage of maximal predicted oxygen consumption: 79.5+/-18.2% to 76.8+/-16.9%). After surgery, left ventricular (LV) ejection fraction (EF) decreased (64.2+/-10.3% to 59.9+/-11.4%, p = 0.003) while right ventricular (RV) EF increased (41.4+/-9.6% to 44.7+/-9.5%, p = 0.03). Left ventricular EF did not change after MVr (64.3+/-11.5% to 61.5+/-12.2%), but RVEF improved (40.4+/-9.2% to 46.0+/-10.0%, p = 0.02). In contrast, VR was associated with an impairment of LV function in the apicolateral area and a decrease in LVEF (64.1+/-8.5% to 57.4+/-10.0%, p = 0.01), whereas RVEF did not change (42.9+/-10.3% to 42.8+/-8.6%). Moreover, there was only a slight decrease in neurohormonal activation after surgery. CONCLUSIONS Despite an improvement in symptomatic status, exercise performance was not improved seven months after either MVr or VR for MR, and neurohormonal activation persisted. Compared with MVr, VR resulted in a significant impairment of cardiac function in this study.

Clinical Context and Mechanism of Functional Tricuspid Regurgitation in Patients With and Without Pulmonary Hypertension

Background— Functional tricuspid regurgitation (FTR) with structurally normal valve is of poorly defined mechanisms. Prevalence and clinical context of idiopathic FTR (Id-FTR) (without overt TR cause) are unknown. Methods and Results— To investigate prevalence, clinical context, and mechanisms specific to FTR types, Id-FTR versus pulmonary hypertension-related (PHTN-FTR, systolic pulmonary pressure ≥50 mm Hg), we analyzed 1161 patients with prospectively quantified TR. Id-FTR (prevalence 12%) was associated with aging and atrial fibrillation. For mechanistic purposes, we measured valvular and right ventricular (RV) remodeling in 141 Id-FTR matched to 140 PHTN-FTR and to 99 controls with trivial TR for age, sex, atrial fibrillation, and ejection fraction. PHTN-FTR and Id-FTR were also matched for TR effective-regurgitant-orifice (ERO). Id-FTR valvular alterations (versus controls) were largest annular area (3.53±0.6 versus 2.74±0.4 cm2, P<0.0001) and lowest valvular/annular coverage ratio (1.06±0.1 versus 1.45±0.2, P<0.0001) but normal valve tenting height. PHTN-FTR had mild annular enlargement but excessive valve tenting height (0.8±0.3 versus 0.35±0.1 cm, P<0.0001). Valvular changes were linked to specific RV changes, largest basal dilatation, and normal length (RV conical deformation) in Id-FTR versus longest RV with elliptical/spherical deformation in PHTN-FTR. With increasing FTR severity (ERO ≥40 mm2), changes specific to each FTR type were accentuated, and RV function (index of myocardial performance) was consistently reduced. Conclusions— Id-FTR is frequent, linked to aging and atrial fibrillation, can be severe, and is of unique mechanism. In Id-FTR, excess annular and RV-basal enlargement exhausts valvular/annular coverage reserve, and RV conical deformation does not cause notable valvular tenting. Conversely, PHTN-FTR is determined by valvular tethering with tenting linked to RV elongation and elliptical/spherical deformation. These specific FTR-mechanisms may be important in considering surgical correction in FTR.