Institutional volume affects long-term survival following lung transplantation in the USA

OBJECTIVES

The aim of this study was to evaluate the impact of institutional volume on long-term outcomes following lung transplantation (LTx) in the USA.

METHODS

Adults undergoing LTx were identified in the United Network for Organ Sharing registry. Patients were divided into equal size tertiles according to the institutional volume. All-cause mortality following LTx was evaluated using the risk-adjusted multivariable Cox regression and the Kaplan-Meier analyses, and compared between these volume cohorts at 3 points: 90 days, 1 year (excluding 90-day deaths) and 10 years (excluding 1-year deaths). Lowess smoothing plots and receiver-operating characteristic analyses were performed to identify optimal volume thresholds associated with long-term survival.

RESULTS

A total of 13 370 adult LTx recipients were identified. The mean annual centre volume was 33.6 ± 20.1. After risk adjustment, low-volume centres were found to be at increased risk for 90-day mortality, [hazard ratio (HR) 1.56, P < 0.001], 1-year mortality excluding 90-day deaths (HR 1.46, P < 0.001) and 10-year mortality excluding 1-year deaths (HR 1.22, P < 0.001). These findings persisted when the centre volume was modelled as a continuous variable. The Kaplan-Meier analysis also demonstrated significant reductions in survival at each of these time points for low-volume centres (each P < 0.001). The 10-year survival conditional on 1-year survival was 37.4% in high-volume centres vs 28.0% in low-volume centres (P < 0.001). The optimal annual volume threshold for long-term survival was 26 LTx/year.

CONCLUSIONS

The institutional volume impacts long-term survival following LTx, even after excluding deaths within the first post-transplant year. Identifying the processes of care that lead to longer survival in high-volume centres is prudent.

Acute aortic dissections with entry tear in the arch: A report from the International Registry of Acute Aortic Dissection

OBJECTIVE

To analyze presentation, management, and outcomes of acute aortic dissections with proximal entry tear in the arch.

METHODS

Patients enrolled in the International Registry of Acute Aortic Dissection and entry tear in the arch were classified into 2 groups: arch A (retrograde extension into the ascending aorta with or without antegrade extension) and arch B (only antegrade extension into the descending aorta or further distally). Presentation, management, and in-hospital outcomes of the 2 groups were compared.

RESULTS

The arch A (n = 228) and arch B (n = 140) groups were similar concerning the presence of any preoperative complication (68.4% vs 60.0%; P = .115), but the types of complication were different. Arch A presented more commonly with shock, neurologic complications, cardiac tamponade, and grade 3 or 4 aortic valve insufficiency and less frequently with refractory hypertension, visceral ischemia, extension of dissection, and aortic rupture. Management for both groups were open surgery (77.6% vs 18.6%; P < .001), endovascular treatment (3.5% vs 25.0%; P < .001), and medical management (16.2% vs 51.4%; P < .001). Overall in-hospital mortality was similar (16.7% vs 19.3%; P = .574), but mortality tended to be lower in the arch A group after open surgery (15.3% vs 30.8%; P = .090), and higher after endovascular (25.0% vs 14.3%; P = .597) or medical treatment (24.3% vs 13.9%; P = .191), although the differences were not significant.

CONCLUSIONS

Acute aortic dissection patients with primary entry tear in the arch are currently managed by a patient-specific approach. In choosing the management type of these patients, it may be advisable to stratify them based on retrograde or only antegrade extension of the dissection.

Causes of death in intermediate-risk patients: The Randomized Surgical Replacement and Transcatheter Aortic Valve Implantation Trial

OBJECTIVES

Examine the causes and timing of death in the Surgical Replacement and Transcatheter Aortic Valve Implantation intermediate-risk randomized trial for transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR).

METHODS

Causes of death were adjudicated by an independent clinical event committee and by post-hoc hierarchical classification. Causes of death were evaluated and characteristics and procedural parameters compared between patients who died and survivors for 3 time periods: early (0-30 days), recovery (31-120 days), and late (121-365 days).

RESULTS

All-cause mortality at 1 year was 6.5% after TAVR and 6.7% after SAVR. There were no differences in mortality rates between TAVR and SAVR for any of the 3 time periods. Early mortality was primarily due to technical, procedure-related problems in TAVR and due to complications in SAVR. For TAVR and SAVR, most deaths during recovery were caused by complications. Other causes, including comorbid conditions, accounted for most late deaths.

CONCLUSIONS

Mortality rates were similar for patients treated with TAVR or SAVR at any time period including at 1 year. Early cause of death was more commonly technical failure after TAVR and due to complications after SAVR. Recovery phase cause of death was dominated by complications from TAVR and SAVR. Late cause of death appeared to be independent of the procedure in both groups.

Predissection-derived geometric and distensibility indices reveal increased peak longitudinal stress and stiffness in patients sustaining acute type A aortic dissection: Implications for predicting dissection

OBJECTIVE

To assess ascending aortic distensibility and build geometry and distensibility-based patient-specific stress distribution maps in patients sustaining type A aortic dissection (TAAD) using predissection noninvasive imaging.

METHODS

Review of charts from patients undergoing surgical repair of TAAD (n = 351) led to the selection of a subset population (n = 7) with 2 or more predissection computed tomography angiography scans and echocardiograms at least 1 year before dissection. Ascending aortic wall biomechanical properties (aortic strain, distensibility, and stiffness) were compared with age- and size-matched nondissected nonaneurysmal controls. Patient-specific aortic strain served as an input in aortic geometry-based simulated 3-dimensional reconstructions to generate longitudinal and circumferential wall stress maps. Inspection of perioperative dissection scans and intraoperative visual examination confirmed primary tear locations.

RESULTS

Predissection echocardiography revealed ascending aortas of patients sustaining TAAD to exhibit decreased aortic wall strain (14.50 ± 1.13% vs 8.49 ± 1.08%; P < .01), decreased distensibility (4.26 ± 0.44 vs 2.39 ± 0.33 10^-6 cm²·dyne^-1; P < .01), increased stiffness (3.84 ± 0.24 vs 7.48 ± 1.05; P < .001), and increased longitudinal wall stress (246 ± 22 vs 172 ± 37 kPa; P < .01). There was no significant difference in circumferential wall stress. Predissection computed tomography angiography models revealed overlap between regions of increased longitudinal wall stress and primary tear sites.

CONCLUSIONS

Using predissection imaging, we identified increased stiffness and longitudinal wall stress in ascending aortas of patients with dissection. Patient-specific imaging-derived biomechanical property maps like these may be instrumental toward designing better prediction models of aortic dissection potential.

Clinical Outcomes of Mitral Valve Reoperations in the United States: An Analysis of The Society of Thoracic Surgeons National Database

BACKGROUND

This study evaluated outcomes of reoperative mitral valve surgery (MVS) in the United States.

METHODS

Adults undergoing isolated MVS with prior open-heart operation in The Society of Thoracic Surgeons (STS) National Database between July 2011 and September 2016 were included. Urgent or emergent operations as well as all indications and causes for MVS were included. Primary outcomes were operative mortality and morbidity. Multivariable models were used for risk-adjustment, incorporating variables from the STS Valve Risk Model as well as type of prior operation and reoperative approach.

RESULTS

A total of 17,195 patients underwent isolated reoperative MVS at 962 centers. The STS predicted risk of mortality was 8.0%, with 20% having an STS predicted risk of mortality greater than 10%. Prior cardiac operations included previous MVS (61%), coronary artery bypass (39%), aortic valve surgery (18%), and tricuspid valve surgery (6%). Operative mortality for the overall study cohort was 6.6%, and postoperative stroke occurred in 2.4%. Observed-to-expected mortality for the overall cohort was 0.82. The strongest independent predictors of operative mortality included salvage operation, preoperative dialysis dependence, congestive heart failure, recent myocardial infarction, and active endocarditis. Prior aortic valve replacement was associated with increased mortality risk, whereas prior MVS reduced mortality risk. Surgical approach did not affect mortality. For patients with prior MVS undergoing elective, non-endocarditis operations, the operative mortality was 3.4%.

CONCLUSIONS

Despite a high-risk patient profile, surgical outcomes of reoperative MVS were acceptable, particularly in patients with prior MVS and without endocarditis undergoing elective operations.

Outcomes of mitral valve surgery during concomitant aortic valve replacement

BACKGROUND

This study evaluates outcomes of mitral valve surgery (MVS), replacement (MVR), and repair (MVr), during concomitant aortic valve replacement (AVR).

METHODS

Patients undergoing MVS with concomitant AVR between 2011 and 2017 at a single center were reviewed. Patients were stratified into MVR versus MVr with concomitant AVR. Outcomes included early and midterm mortality, hospital re-admissions, re-operations, and complications. Multivariable Cox regression analysis was used for risk-adjustment.

RESULTS

Four hundred twenty-four patients underwent MVS with concomitant AVR: 247 (58.3%) MVr and 177 (41.7%) MVR. In unadjusted analysis, there was a non-significant increase in 30-day mortality with MVR, with no differences in 1- and 5-year mortality (30-day: 5.6% vs 10.1%, P = 0.081; 1-year: 14% vs 18.2%, P = 0.181; 5-year: 35.1% vs 37.8%, P = 0.232). Freedom from re-admission and mitral reoperation were comparable. Freedom from at least moderate mitral regurgitation at 5 years was 78% in MVr patients. Those undergoing MVR had increased postoperative blood transfusions, acute renal failure, and pleural effusions requiring drainage (P each <0.05).

CONCLUSIONS

MVr can be performed during concomitant AVR without an adverse impact on longer-term outcomes, including mortality, re-admissions, and mitral reoperations. The majority of patients have durable repairs at 5 years although durability is less than that reported in isolated MVS.

Medial Hypoxia and Adventitial Vasa Vasorum Remodeling in Human Ascending Aortic Aneurysm

Human ascending aortic aneurysms characteristically exhibit cystic medial degeneration of the aortic wall encompassing elastin degeneration, proteoglycan accumulation and smooth muscle cell loss. Most studies have focused on the aortic media and there is a limited understanding of the importance of the adventitial layer in the setting of human aneurysmal disease. We recently demonstrated that the adventitial ECM contains key angiogenic factors that are downregulated in aneurysmal aortic specimens. In this study, we investigated the adventitial microvascular network (vasa vasorum) of aneurysmal aortic specimens of different etiology and hypothesized that the vasa vasorum is disrupted in patients with ascending aortic aneurysm. Morphometric analyses of hematoxylin and eosin-stained human aortic cross-sections revealed evidence of vasa vasorum remodeling in aneurysmal specimens, including reduced density of vessels, increased lumen area and thickening of smooth muscle actin-positive layers. These alterations were inconsistently observed in specimens of bicuspid aortic valve (BAV)-associated aortopathy, while vasa vasorum remodeling was typically observed in aneurysms arising in patients with the morphologically normal tricuspid aortic valve (TAV). Gene expression of hypoxia-inducible factor 1α and its downstream targets, metallothionein 1A and the pro-angiogenic factor vascular endothelial growth factor, were down-regulated in the adventitia of aneurysmal specimens when compared with non-aneurysmal specimens, while the level of the anti-angiogenic factor thrombospondin-1 was elevated. Immunodetection of glucose transporter 1 (GLUT1), a marker of chronic tissue hypoxia, was minimal in non-aneurysmal medial specimens, and locally accumulated within regions of elastin degeneration, particularly in TAV-associated aneurysms. Quantification of GLUT1 revealed elevated levels in the aortic media of TAV-associated aneurysms when compared to non-aneurysmal counterparts. We detected evidence of chronic inflammation as infiltration of lymphoplasmacytic cells in aneurysmal specimens, with a higher prevalence of lymphoplasmacytic infiltrates in aneurysmal specimens from patients with TAV compared to that of patients with BAV. These data highlight differences in vasa vasorum remodeling and associated medial chronic hypoxia markers between aneurysms of different etiology. These aberrations could contribute to malnourishment of the aortic media and could conceivably participate in the pathogenesis of thoracic aortic aneurysm.

Outcomes in the Randomized CoreValve US Pivotal High Risk Trial in Patients With a Society of Thoracic Surgeons Risk Score of 7% or Less

Importance

Transcatheter aortic valve replacement (TAVR) is now a well-accepted alternative to surgical AVR (SAVR) for patients with symptomatic aortic stenosis at increased operative risk. There is interest in whether TAVR would benefit patients at lower risk.

Objective

The Society of Thoracic Surgeons Predicted Risk of Mortality (STS PROM) has trended downward in US TAVR trials and the STS/American College of Cardiology Transcatheter Valve Therapy Registry. We hypothesized that if the Society of Thoracic Surgeons Predicted Risk of Mortality (STS PROM) alone is sufficient to define decreased risk, the contribution to survival based on the degree of invasiveness of the TAVR procedure will decrease, making it more difficult to show improved survival and benefit over SAVR.

Design, Setting, and Participants

The CoreValve US Pivotal High Risk Trial was a multicenter, randomized, noninferiority trial. This retrospective analysis evaluated patients who underwent an attempted implant and had an STS PROM of 7% or less. The trial was performed at 45 US sites. Patients had severe aortic stenosis and were at increased surgical risk based on their STS PROM score and other risk factors.

Interventions

Eligible patients were randomly assigned (1:1) to self-expanding TAVR or to SAVR.

Main Outcomes and Measures

We retrospectively stratified patients by the overall median STS PROM score (7%) and analyzed clinical outcomes and quality of life using the Kansas City Cardiomyopathy Questionnaire in patients with an STS PROM score of 7% or less.

Results

The mean (SD) ages were 81.5 (7.6) years for the TAVR group and 81.2 years (6.6) for the SAVR group. A little more than half were men (57.9% in the TAVR group and 55.8% in the SAVR group). Of 750 patients who underwent attempted implantation, 383 (202 TAVR and 181 SAVR) had an STS PROM of 7% or less (median [interquartile range]: TAVR, 5.3% [4.3%-6.1%]; SAVR, 5.3% [4.1%-5.9%]). Two-year all-cause mortality for TAVR vs SAVR was 15.0% (95% CI, 8.9-10.0) vs 26.3% (95% CI, 19.7-33.0) (log rank P = .01). The 2-year rate of stroke for TAVR vs SAVR was 11.3% vs 15.1% (log rank P = .50). Quality of life by the Kansas City Cardiomyopathy Questionnaire summary score showed significant and equivalent increases in both groups at 2 years (mean [SD] TAVR, 20.0 [25.0]; SAVR, 18.6 [23.6]; P = .71; both P < .001 compared with baseline). Medical benefit, defined as alive with a Kansas City Cardiomyopathy Questionnaire summary score of at least 60 and a less than 10-point decrease from baseline, was similar between groups at 2 years (TAVR, 51.0%; SAVR, 44.4%; P = .28).

Conclusions and Relevance

Self-expanding TAVR compares favorably with SAVR in high-risk patients with STS PROM scores traditionally considered intermediate risk.

Trial Registration

Clinicaltrials.gov Identifier: NCT01240902.

Right ventricle to pulmonary artery coupling in patients undergoing transcatheter aortic valve implantation

OBJECTIVES

To evaluate the prognostic value of the ratio between tricuspid annular plane systolic excursion (TAPSE)-pulmonary artery systolic pressure (PASP) as a determinant of right ventricular to pulmonary artery (RV-PA) coupling in patients undergoing transcatheter aortic valve replacement (TAVI).

BACKGROUND

RV function and pulmonary hypertension (PH) are both prognostically important in patients receiving TAVI. RV-PA coupling has been shown to be prognostic important in patients with heart failure but not previously evaluated in TAVI patients.

METHODS

Consecutive patients with severe aortic stenosis who received TAVI from July 2011 through January 2016 and with comprehensive baseline echocardiogram were included. All individual echocardiographic images and Doppler data were independently reviewed and blinded to the clinical information and outcomes. Cox models quantified the effect of TAPSE/PASP quartiles on subsequent all-cause mortality while adjusting for confounders.

RESULTS

A total of 457 patients were included with mean age of 82.8±7.2 years, left ventricular ejection fraction (LVEF) 54%±13%, PASP 44±17 mm Hg. TAPSE/PASP quartiles showed a dose-response relationship with survival. This remained significant (HR for lowest quartile vs highest quartile=2.21, 95% CI 1.07 to 4.57, p=0.03) after adjusting for age, atrial fibrillation, LVEF, stroke volume index, Society of Thoracic Surgeons Predicted Risk of Mortality.

CONCLUSION

Baseline TAPSE/PASP ratio is associated with all-cause mortality in TAVI patients as it evaluates RV systolic performance at a given degree of afterload. Incorporation of right-side unit into the risk stratification may improve optimal selection of patients for TAVI.