The physiological burden of the 6-minute walk test compared with cardiopulmonary exercise stress test in patients with severe aortic atenosis

Background Management of aortic stenosis (AS) relies on symptoms. Exercise testing is recommended for asymptomatic patients with significant AS but is often experienced as forbidding and/or technically unrealistic for patients who are often frail, deconditioned, and intimidated by the exercise test. We compared the physiological burden assessed with gas exchange assessments to gauge and respiratory exchange ratio (RER) of a 6-minute walk test (6MWT) to a cardiopulmonary exercise stress test (CPET) in patients with severe AS. peak oxygen utilization Methods Adults with equivocal symptoms and severe AS (1-aortic valve area [AVA] ≤ 1.0 cm2 or AVA index ≤ 0.6 cm2/m2, 2-peak aortic jet velocity ≥ 4.0 m/sec, 3-mean transvalvular pressure gradient ≥ 40 mm Hg by rest or dobutamine stress echocardiography, or 4-aortic valve calcification ≥ 1200 in women or ≥ 2000 AU in men) were studied. All participants completed both a 6MWT and symptom-limited progressive bicycle exercise testing. Breath-by-breath gas analysis and 12-lead electrocardiography were completed during 6MWT and CPET. Results: Eleven patients were studied. Patients walked on average 330 ± 75 m during the 6MWT and achieved a maximal workload of 48 ± 14 watts during the CPET. During the 6MWT, peak maximal oxygen uptake (O2peak) was 12.8 ± 2.5 vs 10.8 ± 4.2 mL/kg/min during the CPET. Respiratory exchange ratio exceeded 1.1 in both the 6MWT and CPET indicating similarly high exertion. Compared with the CPET, a larger proportion of the 6MWT was performed at a high intensity level (78% ± 28% vs 33% ± 24% at > 85% V̇O2peak; P = 0.004). Conclusions The 6MWT with breath-by-breath gas analysis was well tolerated and able to achieve a physiological intense RER and O2peak that are similar to symptom-limited CPET in patients with severe AS.Introduction La prise en charge de la sténose aortique (SA) dépend des symptômes. L’épreuve d’effort est recommandée aux patients asymptomatiques qui ont une SA significative, mais elle est souvent perçue comme dangereuse et/ou théoriquement irréaliste chez ces patients qui sont souvent fragiles, en mauvaise forme et craintifs par l’épreuve d’effort. Nous avons comparé le fardeau physiologique calculé par la consommation maximale de l’oxygène (O2max) et le quotient respiratoire (QR) d’un test de marche de 6 minutes (TM6) et d'une épreuve d’effort maximal chez des patients avec une SA sévère. Méthodes Tous les patients présentaient une SA symptomatique et sévère (1-aire valvulaire aortique [AVA] ≤ 1,0 cm2 ouAVA ≤ 0,6 cm2/m2, 2-une vélocité maximale du flux aortique ≥ 4,0 m/sec, 3-un gradient de pression transvalvulaire moyen ≥ 40 mmHg au repos ou à l’échocardiographie à l’effort sous dobutamine ou 4-une calcification valvulaire aortique (AU) ≥ 1200 chez les femmes ou ≥ 2000 AU chez les hommes). Les participants ont effectué un TM6 et une ’épreuve d’effort maximal de type rampe sur vélo. L’analyse des échanges gazeux respiration par respiration et un électrocardiogramme à 12 dérivations ont été effectués durant le TM6 et l'épreuve d'effort maximal. Résultats Un total de 11 patients ont participé à l'étude. Les patients ont marché en moyenne 330 ± 75 m durant le TM6 et ont atteint une charge de travail maximale de 48 ± 14 watts durant l’épreuve d'effort maximal. Durant le TM6, le O2max était de 12,8 ± 2,5 vs 10,8 ± 4,2 ml/kg/min durant l’épreuve d'effort maximal. Le QR était supérieur à 1,1 au TM6 ainsi qu'à l’épreuve d'effort maximal. Comparativement à l’épreuve d'effort maximal, un pourcentage plus important au TM6 a été réalisée à une intensité élevée (78 % ± 28 % vs 33 % ± 24 % à > 85 % V̇O2max; P = 0,004). Conclusions Le TM6 avec mesure directe des échanges gazeux était bien toléré et susceptible d’atteindre des valeurs physiologiques d'intensité élevée pour le QR et le O2max. Les valeurs atteintes au TM6 étaient semblables à celles de l'épreuve d'effort maximal chez les patients avec une SA sévère

Transcatheter aortic valve implantation for the treatment of patients with severe symptomatic aortic stenosis

L'implantation de valve aortique par cathéter (IVAC) a émergé comme une alternative thérapeutique pour les patients avec une sténose aortique (SA) sévère symptomatique considérée à haut risque pour le remplacement de valve aortique (RVA) chirurgicale. Nos objectifs étaient les suivants: 1) Déterminer l'incidence, les facteurs prédictifs et la valeur pronostique de l'insuffisance rénale aiguë (IRA) suite à l'IVAC, et de comparer l'incidence d'IRA chez les patients atteints d'insuffisance rénale chronique (IRC) pré-procédurale par rapport à un groupe ayant subi un RVA. 2) Évaluer l'utilité de l'échocardiographie transoesophagienne (ETO) pour guider l'IVAC par voie transapicale comme modalité d'imagerie primaire. 3) Comparer l'incidence et les facteurs prédictifs du bloc auriculo-ventriculaire (BAV) complet et d'implantation d'un pacemaker permanent (IPP) après l'IVAC par rapport au RVA. 4) Évaluer la faisabilité et la sécurité du test de marche de 6 minutes (6MWT) comme une mesure de la capacité d'exercice avant et après l'IVAC. 5) Évaluer le "Duke Activity Status Index" (DASI) comme une mesure de l'état fonctionnel/qualité de vie (QDV) pré-et post-IVAC, et de comparer l'état fonctionnel évalué par le DASI et la classification fonctionnelle de la "New York Heart Association" (NYHA) avec la capacité d'exercice, telle qu'évaluée par le 6MWT chez ces patients. Les résultats de notre premier travail ont montré que l'IRA s'est produite chez 11.7% des patients suite à l'IVAC et a été associée à un risque 4 fois supérieur de mortalité postopératoire. L'hypertension, la maladie pulmonaire obstructive chronique et les transfusions sanguines péri-opératoires étaient les facteurs prédictifs d'IRA. Chez les patients atteints d'IRC pré-procédurale, l'IVAC a été associée à une réduction significative d'IRA par rapport au RVA. Nous avons montré que l'ETO a été associée à une réduction significative de la quantité de produit de durant l'IVAC par voie transapicale. Suite à cela, nous avons démontré que l'IVAC avec la valve expansible par ballonnet a été associé à un taux plus élevé de BAV complet et IPP par rapport à le RVA. La présence du bloc de branche droite de base a montré une corrélation avec l'IPP dans le groupe IVAC. Nous avons démontré que l'IVAC a été associée à une amélioration significative de l'état fonctionnel/QDV ainsi que dans la distance parcourue lors du 6MWT après l'IVAC. Toutefois, une proportion substantielle de patients n'ont pas amélioré ou a même ont diminué leurs évaluations fonctionnelles après l'IVAC

Transcatheter aortic valve implantation in patients with severe aortic stenosis and small aortic annulus

Objectives: Valve hemodynamics and clinical outcomes among patients with a small aortic annulus who underwent transcatheter aortic valve implantation (TAVI) were examined. Background: The presence of a small aortic annulus may complicate the surgical management of patients with severe aortic stenosis (AS). TAVI is an alternative to aortic valve replacement (AVR) in high-risk patients, but few data exist on the results of TAVI in patients with a small aortic annulus. Methods: Between 2007 and 2010, 35 patients (mean age 79.2 ± 9.4 years) with severe AS and an aortic annulus diameter <20 mm (mean 18.5 ± 0.9 mm) underwent TAVI with a 23-mm Edwards SAPIEN bioprosthesis (Edwards Lifesciences, Inc., Irvine, California). Echocardiographic parameters and clinical outcomes were assessed prior to discharge and at 6, 12, and 24 months. Results: Procedural success was achieved in 34 patients (97.1%). There was 1 in-hospital death. Peak and mean transaortic gradients decreased from 76.3 ± 33.0 mm Hg and 45.2 ± 20.6 mm Hg at baseline to 21.8 ± 8.4 mm Hg and 11.7 ± 4.8 mm Hg post-procedure, respectively, both p < 0.0001. Mean indexed effective orifice area (IEOA) increased from 0.35 ± 0.10 cm2/m2 at baseline to 0.90 ± 0.18 cm2/m2 post-procedure, p < 0.0001. Severe prosthesis–patient mismatch (IEOA <0.65 cm2/m2) occurred in 2 patients (5.9%). At a mean follow-up of 14 ± 11 months, gradients remained low and 30 of the 31 remaining survivors were in New York Heart Association functional class I or II. Conclusions: In high-risk patients with severe AS and a small aortic annulus, TAVI is associated with good post-procedural valve hemodynamics and clinical outcomes. TAVI may provide a reasonable alternative to conventional AVR in elderly patients with a small aortic annulus

Exercise capacity in patients with severe symptomatic aortic stenosis before and six months after transcatheter aortic valve implantation

Few data exist on the use of the 6-minute walk test (6MWT) to measure the exercise capacity of patients with severe symptomatic aortic stenosis considered at very high surgical risk. The objectives of the present prospective study were (1) to determine the feasibility and safety of the 6MWT as a measure of exercise capacity before and after transcatheter aortic valve implantation (TAVI), and (2) to determine the clinical and hemodynamic parameters associated with the exercise capacity changes in such patients. A total of 64 patients (age 80 8 years, logistic European System for Cardiac Operative Risk Evaluation score 21 15%, Society of Thoracic Surgeons’ score 7.5 3.9%) who had undergone successful TAVI were included. The 6MWT was performed within the month before TAVI and at the 6-month follow-up visit. The mean distance walked increased from 165.3 79.7 to 231.7 88.9 m (p <0.0001); however, up to 25% of the patients did not improve or even decreased their exercise capacity. After adjustment for the baseline distance walked, multilinear regression analysis showed that a greater degree of renal dysfunction, as evaluated by the serum creatinine levels (r 2 0.05, p 0.03), lower postprocedural hemoglobin values (r 2 0.13, p 0.0012), and a longer hospitalization length (r 2 0.08, p 0.007) were associated with lower improvement in exercise capacity. In conclusion, exercise capacity, as evaluated by the 6MWT, was very poor in patients with severe symptomatic aortic stenosis considered at very high surgical risk. TAVI was associated with a significant increase in exercise capacity, although no improvement was observed in 1/4 of the patients. A greater degree in renal dysfunction, lower postprocedural hemoglobin values, and longer hospitalization stay were predictors of lower improvement in exercise capacity after TAVI. These results suggest that the 6MWT might become an important tool as a part of the evaluation process for TAVI candidates. © 2011 Elsevier Inc. All rights reserved. (Am J Cardiol 2011;108:258–264

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 (EOA1), LVOT diameter (LVOTd) entered in the continuity equation was measured at the base of prosthesis cusps whereas, in Method #2 (EOA2), LVOTd was measured immediately proximal to the prosthesis stent.Results : The average EOA2 (1.57 ± 0.41 cm2) was larger (p 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 patient's annulus size and these valves provide excellent hemodynamics even in patients with a small aortic annulus

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

Incidence, predictive factors, and prognostic value of myocardial injury following uncomplicated transcatheter aortic valve implantation.

OBJECTIVES: This study sought to: 1) determine the incidence, degree, and timing of the rise in serum cardiac markers of myocardial injury associated with uncomplicated transcatheter aortic valve implantation (TAVI); and 2) evaluate the predictive factors and prognostic value of myocardial injury associated with TAVI. BACKGROUND: Very few data exist on the occurrence and clinical relevance of myocardial injury during TAVI procedures. METHODS: A total of 101 patients who underwent successful TAVI (transfemoral [TF] approach, n = 38; transapical [TA] approach, n = 63) were included. Creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT) levels were determined at baseline and at 6 to 12, 24, 48, and 72 h following TAVI. RESULTS: TAVI was associated with some degree of myocardial injury in 99% of the patients (TF: 97%, TA: 100%) as determined by a rise in cTnT (maximal value, 0.48 µg/l, interquartile range [IQR]: 0.24 to 0.82 µg/l) and in 77% of the patients (TF: 47%, TA: 95%) as determined by a rise in CK-MB (maximal value, 18.6 µg/l; IQR: 11.0 to 27.4 µg/l). TA approach and baseline renal dysfunction were associated with a higher increase in biomarkers of myocardial injury (p < 0.01 for both). A larger myocardial injury was associated with a smaller improvement of left ventricular ejection fraction (LVEF) (p < 0.01). The degree of rise in cTnT was an independent predictor of cardiac mortality at 9 ± 10 months of follow-up (hazard ratio: 1.14 per each increase of 0.1 µg/l, 95% confidence interval: 1.02 to 1.28, p = 0.028). CONCLUSIONS: TAVI was systematically associated with some degree of myocardial injury, with TA approach and baseline renal dysfunction determining a higher increase in biomarkers of myocardial injury. A greater degree of myocardial injury was associated with less improvement in LVEF and a higher cardiac mortality at follow-up

Performance-based functional assessment of patients undergoing transcatheter aortic valve implantation

Background: Very few data exist on the functional evaluation of patients with severe symptomatic aortic stenosis undergoing transcatheter aortic valve implantation (TAVI). The aims of this prospective study were (1) to evaluate the Duke Activity Status Index (DASI) as a measure of functional status pre-TAVI and post-TAVI, (2) to determine the clinical parameters associated with DASI changes after TAVI, and (3) to compare functional status as evaluated by DASI and the New York Heart Association (NYHA) class with exercise capacity as evaluated by the 6-minute walk test (6MWT) in such patients. Methods: A total of 76 patients (80 ± 8 years old) who underwent successful TAVI were included. All patients completed the DASI self-questionnaire at baseline and at 6 months after TAVI, and 46 patients also performed a 6MWT. Results: The mean DASI increased from 10.3 ± 5.4 to 16.3 ± 8.3 at 6 months after TAVI (P b .0001). However, the DASI did not change or even decreased to some extent in 30% of patients after TAVI. Renal dysfunction as evaluated by the estimated glomerular filtration rate was identified as the independent predictor of DASI impairment after TAVI (OR 1.7 for each decrease in estimated glomerular filtration rate of 10 mL/min/1.73 m2, 95% CI 1.3-2.3, P = .005). The mean distance walked increased from 165.9 ± 77.6 to 211.8 ± 78.7 m (P = .0001) at follow-up. The DASI showed a good correlation with the distance walked at baseline (r = 0.55, P b .0001) and at follow-up (r = 0.66, P b .0001). The NYHA class improved to some degree in all but 5 patients; however, the NYHA class did not correlate with the results of DASI and the 6MWT. Conclusions: Transcatheter aortic valve implantation was associated with a significant increase in functional status at 6-month follow-up as evaluated by the DASI, although no improvement was observed in about one third of patients. The presence of baseline renal dysfunction better determined this lack of improvement in functional status. The DASI, but not the NYHA class, correlated with distance walked in the 6MWT. These results suggest that the DASI might become a useful tool for evaluating both candidates for and the impact of TAVI procedures. (Am Heart J 2011;161:726-34.

Incidence, predictive factors, and prognostic value of new-onset atrial fibrillation following transcatheter aortic valve implantation

Objectives: This study sought to evaluate the incidence, predictive factors, and prognostic value of new-onset atrial fibrillation (NOAF) following transcatheter aortic valve implantation (TAVI). Background: Very few data exist on the occurrence of NOAF following TAVI. Methods: A total of 138 consecutive patients with no prior history of atrial fibrillation (AF) underwent TAVI with a balloon-expandable valve. Patients were on continuous electrocardiogram monitoring until hospital discharge, and NOAF was defined as any episode of AF lasting >30 s. All clinical, echocardiographic, procedural, and follow-up data were prospectively collected. Results: NOAF occurred in 44 patients (31.9%) at a median time of 48 h (interquartile range: 0 to 72 h) following TAVI. The predictive factors of NOAF were left atrial (LA) size (odds ratio [OR]: 1.21 for each increase in 1 mm/m2, 95% confidence interval [CI]: 1.09 to 1.34, p < 0.0001) and transapical approach (OR: 4.08, 95% CI: 1.35 to 12.31, p = 0.019). At 30-day follow-up, NOAF was associated with a higher rate of stroke/systemic embolism (13.6% vs. 3.2%, p = 0.021, p = 0.047 after adjustment for baseline differences between groups), with no differences in mortality rate between groups (NOAF: 9.1%, no-NOAF: 6.4%, p = 0.57). At a median follow-up of 12 months (interquartile range: 5 to 20 months), a total of 27 patients (19.6%) had died, with no differences between the NOAF (15.9%) and no-NOAF (21.3%) groups, p = 0.58. The cumulative rate of stroke and stroke/systemic embolism at follow-up were 13.6% and 15.9%, respectively, in the NOAF group versus 3.2% in the no-NOAF group (p = 0.039, adjusted p = 0.037 for stroke; p = 0.020, adjusted p = 0.023 for stroke/systemic embolism). Conclusions: NOAF occurred in about one-third of the patients with no prior history of AF undergoing TAVI and its incidence was increased in patients with larger LA size and those undergoing transapical TAVI. NOAF was associated with a higher rate of stroke/systemic embolism, but not a higher mortality, at 30 days and at 1-year follow-up