Nonperturbative theory of weak pre- and post-selected measurements

This paper starts with a brief review of the topic of strong and weak pre- and post-selected (PPS) quantum measurements, as well as weak values, and afterwards presents original work. In particular, we develop a nonperturbative theory of weak PPS measurements of an arbitrary system with an arbitrary meter, for arbitrary initial states. New and simple analytical formulas are obtained for the average and the distribution of the meter pointer variable, which hold to all orders in the weak value. In the case of a mixed preselected state, in addition to the standard weak value, an associated weak value is required to describe weak PPS measurements. In the linear regime, the theory provides the generalized Aharonov-Albert-Vaidman formula. Moreover, we reveal two new regimes of weak PPS measurements: the strongly-nonlinear regime and the inverted region, where the system-dependent contribution to the pointer deflection decreases with increasing the measurement strength. The optimal conditions for weak PPS measurements are achieved in the strongly-nonlinear regime, where the magnitude of the average pointer deflection is equal or close to the maximum. This maximum is independent of the measurement strength, being typically of the order of the pointer uncertainty. We show that the amplification in the weak PPS measurements is a product of two qualitatively different quantities: proper amplification and enhancement. The effects of the free system and meter Hamiltonians are discussed. We also identify optimal meters for weak measurements. Exact solutions are obtained for a certain class of the measured observables. These solutions are used for numerical calculations, the results of which agree with the theory. Moreover, the theory is extended to allow for a completely general post-selection measurement. We also discuss time-symmetry properties of PPS measurements of any strength.Comment: The final version, corrected and expanded; 107 pages, 13 figure

Clinical and hemodynamic outcomes of "all-comers" undergoing transapical aortic valve implantation: Results from the Italian Registry of Trans-Apical Aortic Valve Implantation (I-TA)

ObjectiveThe aim of this study was to assess clinical and hemodynamic outcomes of transapical aortic valve implantation (TA-TAVI) in patients enrolled in the Italian Registry of Trans-Apical Aortic Valve Implantation (I-TA).MethodsFrom April 2008 until November 2010, 504 patients from 20 Italian centers were enrolled in the I-TA registry. Mean logistic EuroSCORE and Society of Thoracic Surgeons score were 24% ± 16% and 11% ± 4%, respectively. Mean follow-up was 9.2 ± 6.5 months (range, 1-26 months). Outcomes were analyzed according to intraoperative complications, procedural volume (high-volume centers, >20 cases; low-volume centers, < 20 cases) and learning curve (first 50% cases vs second 50% cases of each center).ResultsAll-cause overall mortality was 8.3% (42 patients). Device success was 99% (500/504 patients). Intraoperative severe complications occurred in 24 (4.8%) patients. Overall 2-year survival was 71.5% ± 6.2%. At discharge, peak and mean gradients were 16.4 ± 11.2 and 8.7 ± 4.1 mm Hg, respectively, and effective orifice area was 1.67 cm2. These values remained stable at 3, 6, and 12 months after surgery. Independent risk factors for mortality after TA-TAVI were as follows: New York Heart Association class III and IV (odds ratio [OR], 4.43; 95% confidence intervals [CI], 1.28-15.40; P = .02); logistic EuroSCORE greater than 20 (OR, 1.83; 95% CI, 1.02-3.29; P = .04); creatinine concentration greater than 200 μmol/L (OR, 2.56; 95% CI, 1.07-6.15; P = .03), and intraoperative complications (OR, 5.80; 95% CI, 2.68-12.55; P < .001). There were no significant differences in outcomes between high- and low-volume centers and between the first and the second 50% of cases.ConclusionsTA-TAVI represents a safe and effective alternative treatment for patients who are inoperable or at high risk for surgery. The occurrence of an intraoperative complication significantly affects survival. Procedural volume and learning curve have no impact on patient survival

Clinical and hemodynamic outcomes of "all-comers" undergoing transapical aortic valve implantation: results from the Italian Registry of Trans-Apical Aortic Valve Implantation (I-TA).

OBJECTIVE: The aim of this study was to assess clinical and hemodynamic outcomes of transapical aortic valve implantation (TA-TAVI) in patients enrolled in the Italian Registry of Trans-Apical Aortic Valve Implantation (I-TA). METHODS: From April 2008 until November 2010, 504 patients from 20 Italian centers were enrolled in the I-TA registry. Mean logistic EuroSCORE and Society of Thoracic Surgeons score were 24% \ub1 16% and 11% \ub1 4%, respectively. Mean follow-up was 9.2 \ub1 6.5 months (range, 1-26 months). Outcomes were analyzed according to intraoperative complications, procedural volume (high-volume centers, >20 cases; low-volume centers, < 20 cases) and learning curve (first 50% cases vs second 50% cases of each center). RESULTS: All-cause overall mortality was 8.3% (42 patients). Device success was 99% (500/504 patients). Intraoperative severe complications occurred in 24 (4.8%) patients. Overall 2-year survival was 71.5% \ub1 6.2%. At discharge, peak and mean gradients were 16.4 \ub1 11.2 and 8.7 \ub1 4.1 mm Hg, respectively, and effective orifice area was 1.67 cm(2). These values remained stable at 3, 6, and 12 months after surgery. Independent risk factors for mortality after TA-TAVI were as follows: New York Heart Association class III and IV (odds ratio [OR], 4.43; 95% confidence intervals [CI], 1.28-15.40; P = .02); logistic EuroSCORE greater than 20 (OR, 1.83; 95% CI, 1.02-3.29; P = .04); creatinine concentration greater than 200 \u3bcmol/L (OR, 2.56; 95% CI, 1.07-6.15; P = .03), and intraoperative complications (OR, 5.80; 95% CI, 2.68-12.55; P < .001). There were no significant differences in outcomes between high- and low-volume centers and between the first and the second 50% of cases. CONCLUSIONS: TA-TAVI represents a safe and effective alternative treatment for patients who are inoperable or at high risk for surgery. The occurrence of an intraoperative complication significantly affects survival. Procedural volume and learning curve have no impact on patient survival

Clinical and hemodynamic outcomes of "all-comers" undergoing transapical aortic valve implantation: results from the Italian Registry of Trans-Apical Aortic Valve Implantation (I-TA).

OBJECTIVE: The aim of this study was to assess clinical and hemodynamic outcomes of transapical aortic valve implantation (TA-TAVI) in patients enrolled in the Italian Registry of Trans-Apical Aortic Valve Implantation (I-TA). METHODS: From April 2008 until November 2010, 504 patients from 20 Italian centers were enrolled in the I-TA registry. Mean logistic EuroSCORE and Society of Thoracic Surgeons score were 24% ± 16% and 11% ± 4%, respectively. Mean follow-up was 9.2 ± 6.5 months (range, 1-26 months). Outcomes were analyzed according to intraoperative complications, procedural volume (high-volume centers, >20 cases; low-volume centers, < 20 cases) and learning curve (first 50% cases vs second 50% cases of each center). RESULTS: All-cause overall mortality was 8.3% (42 patients). Device success was 99% (500/504 patients). Intraoperative severe complications occurred in 24 (4.8%) patients. Overall 2-year survival was 71.5% ± 6.2%. At discharge, peak and mean gradients were 16.4 ± 11.2 and 8.7 ± 4.1 mm Hg, respectively, and effective orifice area was 1.67 cm(2). These values remained stable at 3, 6, and 12 months after surgery. Independent risk factors for mortality after TA-TAVI were as follows: New York Heart Association class III and IV (odds ratio [OR], 4.43; 95% confidence intervals [CI], 1.28-15.40; P = .02); logistic EuroSCORE greater than 20 (OR, 1.83; 95% CI, 1.02-3.29; P = .04); creatinine concentration greater than 200 μmol/L (OR, 2.56; 95% CI, 1.07-6.15; P = .03), and intraoperative complications (OR, 5.80; 95% CI, 2.68-12.55; P < .001). There were no significant differences in outcomes between high- and low-volume centers and between the first and the second 50% of cases. CONCLUSIONS: TA-TAVI represents a safe and effective alternative treatment for patients who are inoperable or at high risk for surgery. The occurrence of an intraoperative complication significantly affects survival. Procedural volume and learning curve have no impact on patient survival

When does transapical aortic valve replacement become a futile procedure? An analysis from a national registry

ObjectivesPatient selection is crucial to achieve good outcomes and to avoid futile procedures in patients undergoing transcatheter aortic valve replacement. The aim of this multicenter retrospective study was to identify independent predictors of 1-year mortality in patients surviving after transapical transcatheter aortic valve replacement.MethodsWe analyzed data from the Italian registry of transapical transcatheter aortic valve replacement that includes patients undergoing operation in 21 centers from 2007 to 2012. Futility was defined as mortality within 1 year after transapical transcatheter aortic valve replacement in patients surviving at 30 days. Thirty-day survivors were divided in 2 groups: futility (group F) and nonfutility (group NF). Cox proportional hazard regression analysis was performed to identify independent predictors of futility.ResultsWe analyzed data from 645 patients with survival of 30 days or more after transapical transcatheter aortic valve replacement. Groups F and NF included 60 patients (10.8%) and 585 patients (89.2%), respectively. Patients in group F were more likely to have insulin-dependent diabetes (15% vs 7.2%, P = .03), creatinine 2.0 mg/dL or greater or dialysis (18.3% vs 8.2%, P = .01), logistic European System for Cardiac Operative Risk Evaluation greater than 20% (66.7% vs 50.3%, P = .02), preoperative rhythm disorders (40% vs 25.3%, P = .03), critical preoperative state (8.3% vs 1.8%, P = .002), and left ventricular ejection fraction less than 30% (15% vs 2.9%, P < .001). The multivariate analysis identified the following as independent predictors of futility: insulin-dependent diabetes (odds ratio, 3.1; P = .003), creatinine 2.0 mg/dL or greater or dialysis (odds ratio, 2.52; P = .012), preoperative rhythm disorders (odds ratio, 1.88; P = .04), and left ventricular ejection fraction less than 30% (odds ratio, 4.34; P = .001).ConclusionsAccording to our data, among patients undergoing transapical transcatheter aortic valve replacement, those with insulin-dependent diabetes, advanced chronic kidney disease, rhythm disorders, and low left ventricular ejection fraction have a higher risk to undergo futile procedures

Results of surgical aortic valve replacement and transapical transcatheter aortic valve replacement in patients with previous coronary artery bypass grafting

OBJECTIVES To evaluate the results of aortic valve replacement through sternotomic approach in redo scenarios (RAVR) vs transapical transcatheter aortic valve replacement (TAVR), in patients in the eighth decade of life or older already undergone previous coronary artery bypass grafting (CABG). METHODS One hundred and twenty-six patients undergoing RAVR were compared with 113 patients undergoing TaTAVR in terms of 30-day mortality and Valve Academic Research Consortium-2 outcomes. The two groups were also analysed after propensity-matching. RESULTS TaTAVR patients demonstrated a higher incidence of 30-day mortality (P = 0.03), stroke (P = 0.04), major bleeding (P = 0.03), worse 'early safety' (P = 0.04) and lower permanent pacemaker implantation (P = 0.03). TaTAVR had higher follow-up hazard in all-cause mortality [hazard ratio (HR) 3.15, 95% confidence interval (CI) 1.28-6.62; P < 0.01] and cardiovascular mortality (HR 1.66, 95% CI 1.02-4.88; P = 0.04). Propensity-matched patients showed comparable 30-day outcome in terms of survival, major morbidity and early safety, with only a lower incidence of transfusions after TaTAVR (10.7% vs RAVR: 57.1%; P < 0.01). A trend towards lower Acute Kidney Injury Network Classification 2/3 (3.6% vs RAVR 21.4%; P = 0.05) and towards a lower freedom from all-cause mortality at follow-up (TaTAVR: 44.3 \ub1 21.3% vs RAVR: 86.6 \ub1 9.3%; P =. 08) was demonstrated after TaTAVR, although cardiovascular mortality was comparable (TaTAVR: 86.5 \ub1 9.7% vs RAVR: 95.2 \ub1 4.6%; P = 0.52). Follow-up freedom from stroke, acute heart failure, reintervention on AVR and thrombo-embolisms were comparable (P = NS). EuroSCORE II (P = 0.02), perioperative stroke (P = 0.01) and length of hospitalization (P = 0.02) were the determinants of all-cause mortality at follow-up, whereas perioperative stroke (P = 0.03) and length of hospitalization (P = 0.04) impacted cardiovascular mortality at follow-up. CONCLUSIONS Reported differences in mortality and morbidity after TaTAVR and RAVR reflect differences in baseline risk profiles. Given the lower trend for renal complications, patients at higher perioperative renal risk might be better served by TaTAVR

Aortic Valve Replacement in Redo-Scenarios: A Comparison Between Traditional Aortic Valve Replacement (TAVR) and Transapical-TAVR from Two Real-World Multicenter Registries

The study aim was to compare the outcome of transapical transcatheter aortic valve replacement (TaTAVR) and traditional aortic valve replacement (AVR) in redo from two real-world registries