Impact of the COVID-19 pandemic: a perspective from industry

The global COVID-19 pandemic has led to unprecedented change throughout society.1 As the articles in this supplement outline, all segments of the broader cardiovascular community have been forced to adapt, to change models of care delivery, and to evolve and innovate in order to deliver optimal management for cardiovascular patients. The medtech/device industry has not been exempt from such change and has been forced to navigate direct and indirect COVID-associated disruption, with effects felt from supply chain logistics to the entire product lifecycle, from the running of clinical trials to new device approvals and managing training, proctoring and congresses in an increasingly-online world. This sea-change in circumstances itself has enforced the industry, in effect, to disrupt its own processes, models and activities. Whilst some of these changes may be temporary, many will endure for some time and some will doubtless become permanent; one thing is for sure: the healthcare ecosystem, including the medical device industry, will never look quite the same again. Although the pandemic has brought a short- to medium-term medical crisis to many countries, its role as a powerful disruptor cannot be underestimated, and may indeed prove to be a force for long-term good, given the accelerated innovation and rapid adaptation that it has cultivated.

Standardized Definition of Structural Valve Degeneration for Surgical and Transcatheter Bioprosthetic Aortic Valves

Bioprostheses are prone to structural valve degeneration, resulting in limited long-term durability. A significant challenge when comparing the durability of different types of bioprostheses is the lack of a standardized terminology for the definition of a degenerated valve. This issue becomes especially important when we try to compare the degeneration rate of surgically inserted and transcatheter bioprosthetic valves. This document, by the VIVID (Valve-in-Valve International Data), proposes practical and standardized definitions of valve degeneration and provides recommendations for the timing of clinical and imaging follow-up assessments accordingly. Its goal is to improve the quality of research and clinical care for patients with deteriorated bioprostheses by providing objective and strict criteria that can be utilized in future clinical trials. We hope that the adoption of these criteria by both the cardiological and surgical communities will lead to improved comparability and interpretation of durability analyses.

Novel United Kingdom prognostic model for 30-day mortality following transcatheter aortic valve implantation

OBJECTIVE

Existing clinical prediction models (CPM) for short-term mortality after transcatheter aortic valve implantation (TAVI) have limited applicability in the UK due to moderate predictive performance and inconsistent recording practices across registries. The aim of this study was to derive a UK-TAVI CPM to predict 30-day mortality risk for benchmarking purposes.

METHODS

A two-step modelling strategy was undertaken: first, data from the UK-TAVI Registry between 2009 and 2014 were used to develop a multivariable logistic regression CPM using backwards stepwise regression. Second, model-updating techniques were applied using the 2013-2014 data, thereby leveraging new approaches to include frailty and to ensure the model was reflective of contemporary practice. Internal validation was performed by bootstrapping to estimate in-sample optimism-corrected performance.

RESULTS

Between 2009 and 2014, up to 6339 patients were included across 34 centres in the UK-TAVI Registry (mean age, 81.3; 2927 female (46.2%)). The observed 30-day mortality rate was 5.14%. The final UK-TAVI CPM included 15 risk factors, which included two variables associated with frailty. After correction for in-sample optimism, the model was well calibrated, with a calibration intercept of 0.02 (95% CI -0.17 to 0.20) and calibration slope of 0.79 (95% CI 0.55 to 1.03). The area under the receiver operating characteristic curve, after adjustment for in-sample optimism, was 0.66.

CONCLUSION

The UK-TAVI CPM demonstrated strong calibration and moderate discrimination in UK-TAVI patients. This model shows potential for benchmarking, but even the inclusion of frailty did not overcome the need for more wide-ranging data and other outcomes might usefully be explored.

Relative Survival After Transcatheter Aortic Valve Implantation: How Do Patients Undergoing Transcatheter Aortic Valve Implantation Fare Relative to the General Population?

Background

Transcatheter aortic valve implantation (TAVI) is indicated for patients with aortic stenosis who are intermediate‐high surgical risk. Although all‐cause mortality rates after TAVI are established, survival attributable to the procedure is unclear because of competing causes of mortality. The aim was to report relative survival (RS) after TAVI, which accounts for background mortality risks in a matched general population.

Methods and Results

National cohort data (n=6420) from the 2007 to 2014 UK TAVI registry were matched by age, sex, and year to mortality rates for England and Wales (population, 57.9 million). The Ederer II method related observed patient survival to that expected from the matched general population. We modelled RS using a flexible parametric approach that modelled the log cumulative hazard using restricted cubic splines. RS of the TAVI cohort was 95.4%, 90.2%, and 83.8% at 30 days, 1 year, and 3 years, respectively. By 1‐year follow‐up, mortality hazards in the >85 years age group were not significantly different from those of the matched general population; by 3 years, survival rates were comparable. The flexible parametric RS model indicated that increasing age was associated with significantly lower excess hazards after the procedure; for example, by 2 years, a 5‐year increase in age was associated with 20% lower excess mortality over the general population.

Conclusions

RS after TAVI was high, and survival rates in those aged >85 years approximated those of a matched general population within 3 years. High rates of RS indicate that patients selected for TAVI tolerate the risks of the procedure well.

Inadequacy of existing clinical prediction models for predicting mortality after transcatheter aortic valve implantation

BACKGROUND

The performance of emerging transcatheter aortic valve implantation (TAVI) clinical prediction models (CPMs) in national TAVI cohorts distinct from those where they have been derived is unknown. This study aimed to investigate the performance of the German Aortic Valve, FRANCE-2, OBSERVANT and American College of Cardiology (ACC) TAVI CPMs compared with the performance of historic cardiac CPMs such as the EuroSCORE and STS-PROM, in a large national TAVI registry.

METHODS

The calibration and discrimination of each CPM were analyzed in 6676 patients from the UK TAVI registry, as a whole cohort and across several subgroups. Strata included gender, diabetes status, access route, and valve type. Furthermore, the amount of agreement in risk classification between each of the considered CPMs was analyzed at an individual patient level.

RESULTS

The observed 30-day mortality rate was 5.4%. In the whole cohort, the majority of CPMs over-estimated the risk of 30-day mortality, although the mean ACC score (5.2%) approximately matched the observed mortality rate. The areas under ROC curve were between 0.57 for OBSERVANT and 0.64 for ACC. Risk classification agreement was low across all models, with Fleiss's kappa values between 0.17 and 0.50.

CONCLUSIONS

Although the FRANCE-2 and ACC models outperformed all other CPMs, the performance of current TAVI-CPMs was low when applied to an independent cohort of TAVI patients. Hence, TAVI specific CPMs need to be derived outside populations previously used for model derivation, either by adapting existing CPMs or developing new risk scores in large national registries.

Impact of left ventricular function and transaortic gradient on outcomes from transcatheter aortic valve implantation: data from the UK TAVI Registry

AIMS

Aortic valve surgery in the presence of reduced ejection fraction (EF) or low transaortic gradient is associated with adverse outcome. Low gradient (LG) may be associated with reduced EF, known as low EF-low gradient (LEF-LG), or "paradoxically" low with normal EF (P-LG). Our aim was to investigate the impact of EF and transaortic gradient on outcome following transcatheter aortic valve implantation (TAVI).

METHODS AND RESULTS

We retrospectively analysed the UK TAVI Registry from 2007 to 2011 (n=2,535 consecutive patients, mean age 81.3±7.5, logistic EuroSCORE 21.8±14). Thirty-day mortality was 7.8%, low EF (<50%) was present in 39%, low gradient (<64 mmHg) was present in 27%, LEF-LG in 15% and P-LG in 12% of patients, respectively. LEF-LG patients had the highest risk profile vs. the other groups (EuroSCORE 30±16 vs. 20±12, p<0.001). Neither EF nor gradient impacted on procedural outcome or 30-day mortality. Mortality at two years was significantly higher in LEF-LG patients (34.7%), whereas, in patients with low EF/high gradient (27.8%) or normal EF/low gradient (23%), mortality was not significantly different from that of normal EF/high gradient (23%) patients. LEF-LG independently predicted reduced survival, HR 1.7 (1.4-2.1).

CONCLUSIONS

Neither low EF nor low gradient affected procedural success or 30-day mortality. Long-term survival was reduced in LEF-LG patients but not in those with low EF and high gradient or P-LG with normal EF.

Prevalence and Prognostic Significance of Right Ventricular Systolic Dysfunction in Patients Undergoing Transcatheter Aortic Valve Implantation

Background—

Cardiovascular magnetic resonance (CMR) can provide important structural information in patients undergoing transcatheter aortic valve implantation. Although CMR is considered the standard of reference for measuring ventricular volumes and mass, the relationship between CMR findings of right ventricular (RV) function and outcomes after transcatheter aortic valve implantation has not previously been reported.

Methods and Results—

A total of 190 patients underwent 1.5 Tesla CMR before transcatheter aortic valve implantation. Steady-state free precession sequences were used for aortic valve planimetry and to assess ventricular volumes and mass. Semiautomated image analysis was performed by 2 specialist reviewers blinded to patient treatment. Patient follow-up was obtained from the Office of National Statistics mortality database. The median age was 81.0 (interquartile range, 74.9–85.5) years; 50.0% were women. Impaired RV function (RV ejection fraction ≤50%) was present in 45 (23.7%) patients. Patients with RV dysfunction had poorer left ventricular ejection fractions (42% versus 69%), higher indexed left ventricular end-systolic volumes (96 versus 40 mL), and greater indexed left ventricular mass (101 versus 85 g/m 2 ; P <0.01 for all) than those with normal RV function. Median follow-up was 850 days; 21 of 45 (46.7%) patients with RV dysfunction died, compared with 43 of 145 (29.7%) patients with normal RV function ( P =0.035). After adjustment for significant baseline variables, both RV ejection fraction ≤50% (hazard ratio, 2.12; P =0.017) and indexed aortic valve area (hazard ratio, 4.16; P =0.025) were independently associated with survival.

Conclusions—

RV function, measured on preprocedural CMR, is an independent predictor of mortality after transcatheter aortic valve implantation. CMR assessment of RV function may be important in the risk stratification of patients undergoing transcatheter aortic valve implantation.

Comparative survival after transapical, direct aortic, and subclavian transcatheter aortic valve implantation (data from the UK TAVI registry)

Many patients have iliofemoral vessel anatomy unsuitable for conventional transfemoral (TF) transcatheter aortic valve implantation (TAVI). Safe and practical alternatives to the TF approach are, therefore, needed. This study compared outcomes of alternative nonfemoral routes, transapical (TA), direct aortic (DA), and subclavian (SC), with standard femoral access. In this retrospective study, data from 3,962 patients in the UK TAVI registry were analyzed. All patients who received TAVI through a femoral, subclavian, TA, or DA approach were eligible for inclusion. The primary outcome measure was survival up to 2 years. Median Logistic EuroSCORE was similar for SC, DA, and TA but significantly lower in the TF cohort (22.1% vs 20.3% vs 21.2% vs 17.0%, respectively, p <0.0001). Estimated 1-year survival rate was similar for TF (84.6 ± 0.7%) and SC (80.5 ± 3%, p = 0.27) but significantly worse for TA (74.7 ± 1.6%, p <0.001) and DA (75.2 ± 3.3%, p <0.001). A Cox proportional hazard model was used to analyze survival up to 2 years. Survival in the SC group was not significantly different from the TF group (hazard ratio [HR] 1.22, 95% confidence interval [CI] 0.88 to 1.70, p = 0.24). In contrast, survival in the TA (HR 1.74, 95% CI 1.43 to 2.11; p <0.001) and DA (HR 1.55, 95% CI 1.13 to 2.14; p <0.01) cohorts was significantly reduced compared with TF. In conclusion, TA and DA TAVI were associated with similar survival, both significantly worse than with the TF route. In contrast, subclavian access was not significantly different from TF and may represent the safest nonfemoral access route for TAVI.

Effect of gender on results of percutaneous edge-to-edge mitral valve repair with MitraClip system

Knowledge regarding gender-specific results of percutaneous edge-to-edge mitral valve repair is scarce. The aim of this study was to investigate gender differences in outcomes in a cohort of patients treated with MitraClip implantation. A multicenter registry of 173 patients treated with MitraClip prostheses from 2009 to 2012 at 3 experienced centers was performed. One hundred nine patients (63%) were men. Men were younger (mean age 73 ± 10 vs 79 ± 9 years, p = 0.001) and had a higher prevalence of previous coronary bypass graft surgery (34% vs 13%, p = 0.002), previous myocardial infarction (46% vs 20%, p = 0.001), and diabetes mellitus (26% vs 11%, p = 0.020). There were no differences regarding New York Heart Association (NYHA) functional class before the intervention (NYHA class III or IV in 95% of men vs 97% of women, p = 0.472) or the cause of mitral regurgitation (MR) (functional in 58% of men vs 48% of women, p = 0.233). Men exhibited significantly larger ventricles (mean indexed left ventricular end-systolic diameter 2.4 ± 0.8 vs 2.0 ± 1.6 cm/m(2), p = 0.002, and mean indexed left ventricular end-diastolic volume 92.7 ± 46.1 vs 59.9 ± 24.6 ml/m(2), p <0.001). At 1 month, there were no differences between groups in the reduction of MR or NYHA functional class (MR grade ≤2+ in 98.2% of men vs 96.8% of women, p = 0.586, and NYHA class ≤II in 78.3% of men vs 77% of women, p = 0.851). At 6 months, results were maintained (MR grade ≤2+ in 89.5% of men vs 96.8% of women, p = 0.414, and NYHA class ≤II in 73.1% of men vs 74.2% of women, p = 0.912). After a mean follow-up period of 16.1 ± 11.1 months, no difference was found between groups in the incidence of death or admission for heart failure (log-rank p = 0.798). In conclusion, MitraClip implantation seems to be an equally safe and effective treatment of MR in men and women.

Management of concomitant coronary artery disease in patients undergoing transcatheter aortic valve implantation: the United Kingdom TAVI Registry

BACKGROUND

The management and impact of concomitant coronary artery disease in patients referred for TAVI remains contentious. We describe the prevalence, clinical impact and management of coronary artery disease (CAD) in patients in the United Kingdom TAVI Registry.

METHODS

All-inclusive study of patients undergoing TAVI in the United Kingdom (excluding Northern Ireland) from January 2007 to December 2011. Coronary artery disease at the time of TAVI was demonstrated on invasive angiography.

RESULTS

2588 consecutive patients were entered in the U.K. TAVI Registry. CAD was reported in 1171 pts with left main stem involvement in 12.4% of this cohort (n=145). Most patients were free of chest pain, but limited by dyspnoea (NYHA Class III & IV 81.9%). Angina was however more prevalent in those patients with CAD (p<0.0001). Hybrid PCI was uncommon, performed in only 14.7% of the CAD cohort (n=172). Survival at 30days, 1year, and 4years was 93.7%, 81.4% and 72.0% respectively. Adjusting for confounders in a multivariate model the presence and extent of CAD was not associated with early (30-days, p=0.36) or late (4years, p=0.10) survival.

CONCLUSIONS

This contemporary study of coronary artery disease management in an "all-comers" patient population undergoing TAVI demonstrates that whilst often an indicator of significant underlying comorbidity coronary artery disease is not associated with decreased short or long-term survival. The majority of patients with aortic stenosis and concomitant CAD can be managed effectively by TAVI alone. However, the importance of the Heart Team in making decisions on individual patients must not be underestimated.

Effect of advanced chronic kidney disease in clinical and echocardiographic outcomes of patients treated with MitraClip system

BACKGROUND

Data regarding the influence of different levels of renal dysfunction on clinical and echocardiographic results of MitraClip therapy are scarce. We aimed to evaluate the impact of baseline advance renal failure in the outcomes of a cohort of patients treated with MitraClip.

METHODS AND RESULTS

We analyzed data from a multicenter registry of 173 patients treated with MitraClip between 2009 and 2012. Patients were classified as advanced chronic kidney disease (CKD, creatinine clearance [CrCl] <30 ml/min, group 1, n=20), moderate CKD (CrCl 30-60 ml/min, group 2, n=78) and normal renal function (CrCl >60 ml/min, group 3, n=75). Twenty patients (11.5%) presented advanced CKD. Procedural success was equal in the 3 groups (95.0% group 1, 100% in group 2 and 96.0% in group 3, p=0.180). Post-procedural MR and NYHA class at 1 month (MR ≥ 3+5.0% vs. 0% vs. 4.0% p=0.190 and NYHA>II 40.0% vs. 21.0% vs. 18.3%, p=0.101) and 6 months (MR ≥ 3+0% vs. 13.0% vs. 2.7%, p=0.330; and NYHA class>II 54.5% vs. 26.9% vs. 25.6%, p=0.298) did not differ between groups. However, patients in group 1 experienced higher frequency of the composite end-point of mortality or readmission at 16.2 ± 11.1 months of follow-up (HR 4.8, CI 95% 1.1-21.3).

CONCLUSION

Advanced CKD is linked to an excess of cardiac adverse events. This should be judiciously taken into account when selecting patients for MitraClip.

Clinical and economic consequences of non-cardiac incidental findings detected on cardiovascular computed tomography performed prior to transcatheter aortic valve implantation (TAVI)

Transcatheter aortic valve implantation (TAVI) is an effective treatment option for patients with severe degenerative aortic valve stenosis who are high risk for conventional surgery. Computed tomography (CT) performed prior to TAVI can detect pathologies that could influence outcomes following the procedure, however the incidence, cost, and clinical impact of incidental findings has not previously been investigated. 279 patients underwent CT; 188 subsequently had TAVI and 91 were declined. Incidental findings were classified as clinically significant (requiring treatment), indeterminate (requiring further assessment), or clinically insignificant. The primary outcome measure was all-cause mortality up to 3 years. Costs incurred by additional investigations resultant to incidental findings were estimated using the UK Department of Health Payment Tariff. Incidental findings were common in both the TAVI and medical therapy cohorts (54.8 vs. 70.3%; P = 0.014). Subsequently, 45 extra investigations were recommended for the TAVI cohort, at an overall average cost of £32.69 per TAVI patient. In a univariate model, survival was significantly associated with the presence of a clinically significant or indeterminate finding (HR 1.61; P = 0.021). However, on multivariate analysis outcomes after TAVI were not influenced by any category of incidental finding. Incidental findings are common on CT scans performed prior to TAVI. However, the total cost involved in investigating these findings is low, and incidental findings do not independently identify patients with poorer outcomes after TAVI. The discovery of an incidental finding on CT should not necessarily influence or delay the decision to perform TAVI.

Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

IMPORTANCE

Owing to a considerable shift toward bioprosthesis implantation rather than mechanical valves, it is expected that patients will increasingly present with degenerated bioprostheses in the next few years. Transcatheter aortic valve-in-valve implantation is a less invasive approach for patients with structural valve deterioration; however, a comprehensive evaluation of survival after the procedure has not yet been performed.

OBJECTIVE

To determine the survival of patients after transcatheter valve-in-valve implantation inside failed surgical bioprosthetic valves.

DESIGN, SETTING, AND PARTICIPANTS

Correlates for survival were evaluated using a multinational valve-in-valve registry that included 459 patients with degenerated bioprosthetic valves undergoing valve-in-valve implantation between 2007 and May 2013 in 55 centers (mean age, 77.6 [SD, 9.8] years; 56% men; median Society of Thoracic Surgeons mortality prediction score, 9.8% [interquartile range, 7.7%-16%]). Surgical valves were classified as small (≤21 mm; 29.7%), intermediate (>21 and <25 mm; 39.3%), and large (≥25 mm; 31%). Implanted devices included both balloon- and self-expandable valves.

MAIN OUTCOMES AND MEASURES

Survival, stroke, and New York Heart Association functional class.

RESULTS

Modes of bioprosthesis failure were stenosis (n = 181 [39.4%]), regurgitation (n = 139 [30.3%]), and combined (n = 139 [30.3%]). The stenosis group had a higher percentage of small valves (37% vs 20.9% and 26.6% in the regurgitation and combined groups, respectively; P = .005). Within 1 month following valve-in-valve implantation, 35 (7.6%) patients died, 8 (1.7%) had major stroke, and 313 (92.6%) of surviving patients had good functional status (New York Heart Association class I/II). The overall 1-year Kaplan-Meier survival rate was 83.2% (95% CI, 80.8%-84.7%; 62 death events; 228 survivors). Patients in the stenosis group had worse 1-year survival (76.6%; 95% CI, 68.9%-83.1%; 34 deaths; 86 survivors) in comparison with the regurgitation group (91.2%; 95% CI, 85.7%-96.7%; 10 deaths; 76 survivors) and the combined group (83.9%; 95% CI, 76.8%-91%; 18 deaths; 66 survivors) (P = .01). Similarly, patients with small valves had worse 1-year survival (74.8% [95% CI, 66.2%-83.4%]; 27 deaths; 57 survivors) vs with intermediate-sized valves (81.8%; 95% CI, 75.3%-88.3%; 26 deaths; 92 survivors) and with large valves (93.3%; 95% CI, 85.7%-96.7%; 7 deaths; 73 survivors) (P = .001). Factors associated with mortality within 1 year included having small surgical bioprosthesis (≤21 mm; hazard ratio, 2.04; 95% CI, 1.14-3.67; P = .02) and baseline stenosis (vs regurgitation; hazard ratio, 3.07; 95% CI, 1.33-7.08; P = .008).

CONCLUSIONS AND RELEVANCE

In this registry of patients who underwent transcatheter valve-in-valve implantation for degenerated bioprosthetic aortic valves, overall 1-year survival was 83.2%. Survival was lower among patients with small bioprostheses and those with predominant surgical valve stenosis.

Do outcomes from transcatheter aortic valve implantation vary according to access route and valve type? The UK TAVI Registry

OBJECTIVES

To determine whether outcomes from transcatheter aortic valve implantation (TAVI) vary according to access route and valve type in a real-world population.

BACKGROUND

Registry and uncontrolled trial data have found that patients undergoing nonfemoral TAVI have higher early and late mortality. It is not clear whether worse outcomes relate directly to access route. There have been no direct comparisons of outcomes according to valve type.

METHODS

Data were collected prospectively on 1,620 patients undergoing TAVI in the UK and compared in 4 groups: SAPIEN transfemoral (TF); SAPIEN transapical (TA); CoreValve TF, CoreValve subclavian. Univariable and multivariable regression analysis was performed to identify independent predictors of mortality.

RESULTS

Mortality in patients undergoing SAPIEN TAVI via a TA approach was higher than with TF at 30 days (11.2% vs. 4.4%, P < 0.01), 1 year (28.7% vs. 18.1%, P = 0.01), and 2 years (56.0% vs. 43.5%, P = 0.01). Logistic EuroSCORE was higher in TA patients (22.5 ± 12.9% vs. 17.7 ± 11.1%, P < 0.0001). After multivariable analysis TA access was associated with increased mortality at 30 days (OR 2.56, 95% CI 1.46-4.48, P < 0.01) and 2 years (OR 1.75, 1.08-2.74, P = 0.02). There was no significant difference in mortality at any time-point between patients treated with SAPIEN (n = 812) and CoreValve (n = 808) prostheses. CoreValve-treated patients had a higher rate of permanent pacemaker implantation (23.1% vs. 7.2%, P < 0.0001), and grade ≥2 aortic regurgitation on postprocedure echocardiography (13.0% vs. 7.3%, P < 0.01).

CONCLUSIONS

Patients undergoing TA TAVI experienced increased early and late mortality compared to a TF approach. Survival was not influenced by valve type.

Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

Background—

Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry.

Methods and Results—

The Global Valve-in-Valve Registry included 202 patients with degenerated bioprosthetic valves (aged 77.7±10.4 years; 52.5% men) from 38 cardiac centers. Bioprosthesis mode of failure was stenosis (n=85; 42%), regurgitation (n=68; 34%), or combined stenosis and regurgitation (n=49; 24%). Implanted devices included CoreValve (n=124) and Edwards SAPIEN (n=78). Procedural success was achieved in 93.1% of cases. Adverse procedural outcomes included initial device malposition in 15.3% of cases and ostial coronary obstruction in 3.5%. After the procedure, valve maximum/mean gradients were 28.4±14.1/15.9±8.6 mm Hg, and 95% of patients had ≤+1 degree of aortic regurgitation. At 30-day follow-up, all-cause mortality was 8.4%, and 84.1% of patients were at New York Heart Association functional class I/II. One-year follow-up was obtained in 87 patients, with 85.8% survival of treated patients.

Conclusions—

The valve-in-valve procedure is clinically effective in the vast majority of patients with degenerated bioprosthetic valves. Safety and efficacy concerns include device malposition, ostial coronary obstruction, and high gradients after the procedure.

Cardiovascular magnetic resonance imaging in assessment of intracaval and intracardiac extension of renal cell carcinoma

OBJECTIVES

About 1 in 5 patients with renal cell carcinoma have intravascular tumoral extension at presentation. Level of tumoral extension within inferior vena cava determines surgical approach, with higher extension requiring cardiopulmonary bypass. Tumoral invasion of inferior vena caval wall is associated with poor prognosis. We evaluated accuracy of magnetic resonance imaging (MRI) in assessing level of intravascular extension of renal cell carcinoma and predicting vessel wall invasion.

METHODS

MRIs and surgical database were reviewed from January 1999 to December 2008. Sixty-four patients with suspected intravascular extension of renal cell carcinoma underwent MRI. Forty-one underwent curative or palliative surgery at our institution and were included in final analysis. MRI scans were reviewed to determine intravascular extension and tumoral adherence to the vessel wall, as assessed by circumferential flow around the intravascular tumor and its mobility during different phases of cardiac cycle. MRI findings were correlated with surgical findings to assess accuracy.

RESULTS

There was 87.8% agreement (P < .001; κ = 0.82) between MRI and surgical findings regarding level of intravascular extension of tumor. MRI was highly sensitive and specific (93%) in assessing supradiaphragmatic extension (negative predictive value, 96%). Depending on sign used, sensitivities and negative predictive values in assessing tumoral adherence to vessel wall ranged from 86% to 95% and 81% to 91%, respectively.

CONCLUSIONS

MRI is highly accurate in staging intravascular and intracardiac extension, aiding in accurate preoperative surgical planning. MRI may help determine prognosis of renal cell carcinoma by accurately assessing tumoral adherence to the vessel wall.

Long-term outcomes after transcatheter aortic valve implantation in high-risk patients with severe aortic stenosis: the U.K. TAVI (United Kingdom Transcatheter Aortic Valve Implantation) Registry

OBJECTIVES

The objective was to define the characteristics of a real-world patient population treated with transcatheter aortic valve implantation (TAVI), regardless of technology or access route, and to evaluate their clinical outcome over the mid to long term.

BACKGROUND

Although a substantial body of data exists in relation to early clinical outcomes after TAVI, there are few data on outcomes beyond 1 year in any notable number of patients.

METHODS

The U.K. TAVI (United Kingdom Transcatheter Aortic Valve Implantation) Registry was established to report outcomes of all TAVI procedures performed within the United Kingdom. Data were collected prospectively on 870 patients undergoing 877 TAVI procedures up until December 31, 2009. Mortality tracking was achieved in 100% of patients with mortality status reported as of December 2010.

RESULTS

Survival at 30 days was 92.9%, and it was 78.6% and 73.7% at 1 year and 2 years, respectively. There was a marked attrition in survival between 30 days and 1 year. In a univariate model, survival was significantly adversely affected by renal dysfunction, the presence of coronary artery disease, and a nontransfemoral approach; whereas left ventricular function (ejection fraction <30%), the presence of moderate/severe aortic regurgitation, and chronic obstructive pulmonary disease remained the only independent predictors of mortality in the multivariate model.

CONCLUSIONS

Midterm to long-term survival after TAVI was encouraging in this high-risk patient population, although a substantial proportion of patients died within the first year.

Radial artery versus saphenous vein patency randomized trial: five-year angiographic follow-up

BACKGROUND

Graft patency is a fundamental predictor of long-term survival after coronary artery bypass surgery. Left and right internal thoracic artery (arterial) graft patency has been shown to be superior to that of saphenous vein grafts. More recently, the radial artery has been used as an aortocoronary graft, but little is known about the midterm and long-term patency of this conduit. We performed a single-center prospective randomized trial comparing the angiographic patency of radial artery and saphenous vein aortocoronary bypass grafts at 5 years after surgery.

METHODS AND RESULTS

We enrolled 142 patients randomized at a single center to have either the radial artery or saphenous vein grafted to a stenosed branch of the native left circumflex coronary artery. The primary end point was angiographic graft patency 5 years postoperatively. At 5 years, 134 patients were alive and eligible for reangiography (5-year survival, 94.4%). Angiography was performed in 103 patients (77%); 98.3% of radial artery grafts and 86.4% of saphenous vein grafts were patent (P=0.04). Graft narrowing occurred in 10% of patent radial artery grafts and 23% of patent saphenous vein grafts (P=0.01).

CONCLUSIONS

Radial artery aortocoronary bypass grafts to a stenosed branch of the circumflex coronary artery have an excellent patency rate at 5 years. This was significantly better than the patency rate for saphenous vein grafts and comparable to reported patency rates for internal thoracic artery grafts.

Comparison of flow characteristics and vascular reactivity of radial artery and long saphenous vein grafts [NCT00139399]

Background

The morphological and functional differences between arteries and veins may have implications on coronary artery bypass graft (CABG) survival. Although subjective differences have been observed between radial artery (RA) and long saphenous venous (LSV) grafts, these have not been quantified. This study assessed and compared the flow characteristics and in-vivo graft flow responses of RA and LSV aorto-coronary grafts.

Methods

Angiograms from 52 males taken 3.7 ± 1.0 months after CABG surgery were analyzed using adjusted Thrombolysis in Myocardial Infarction (TIMI) frame count. Graft and target coronary artery dimensions were measured using quantitative coronary angiography. Estimated TIMI velocity (V_E) and volume flow (F_E) were then calculated. A further 7 patients underwent in-vivo graft flow responses assessments to adenosine, acetylcholine and isosorbide dinitrate (ISDN) using intravascular Doppler.

Results

The V_E for RA grafts was significantly greater than LSV grafts (P = 0.002), however there was no difference in volume F_E (P = 0.20). RA grafts showed positive endothelium-dependent and -independent vasodilatation, and LSV grafts showed no statistically significant response to adenosine and acetylcholine. There was no difference in flow velocity or volume responses. Seven RA grafts (11%) had compromised patency (4 (6%) ≥ 50% stenosis in the proximal/distal anastomoses, and 3 (5%) diffuse narrowing). Thirty-seven (95%) LSV grafts achieved perfect patency and 2 (5%) were occluded.

Conclusion

The flow characteristics and flow responses of the RA graft suggest that it is a more physiological conduit than the LSV graft. The clinical relevance of the balance between imperfect patency versus the more physiological vascular function in the RA graft may be revealed by the 5-year angiographic follow-up of this trial.

Quantification of regurgitant fraction in mitral regurgitation by cardiovascular magnetic resonance: comparison of techniques

BACKGROUND AND AIM OF THE STUDY

Cardiovascular magnetic resonance (CMR) assessment of mitral regurgitant volume from the subtraction of the right ventricular stroke volume (RVSV) from left ventricular stroke volume (LVSV) has commonly been performed using volumetric techniques. This is sensitive to errors in RVSV visualization and regurgitation of other heart valves, and therefore subtracting aortic flow volume from LVSV may be preferable. The study aim was to compare both techniques in a single CMR examination.

METHODS

Twenty-eight patients with isolated mitral regurgitation underwent left ventricular (LV) and right ventricular (RV) volumetry and aortic flow volume measurements. Mitral regurgitant fraction (RF) was calculated as either RF(VOL) = [LVSV - RVSV] or RF(FLOW) = [LVSV - aortic flow volume], both expressed as a fraction of LVSV. The agreement of the measurements was assessed as a measure of robustness in clinical practice.

RESULTS

There was good agreement between aortic and pulmonary flow (mean +/- SD difference -0.8 +/- 8.1 ml), and aortic flow volume and RVSV by volumetry (mean difference -2.6 +/- 11.8 ml). Intra- and interobserver variability (SD) of aortic flow volume (+/-6.6 ml and +/-5.3 ml) was superior to that of the RVSV (+/-8.5 ml and +/-12 ml). The intra- and inter-observer variability (SD) of RF(FLOW) was lower (+/-4.8% and +/-7.7%) than by RF(VOL) (+/-6.7% and +/-8.8%).

CONCLUSION

The RF(FLOW) technique maximized intra- and inter-observer agreement, and is the optimal CMR technique to quantify mitral regurgitation. RF(FLOW) also has the advantage of allowing correction for aortic regurgitation when it is present, and is potentially independent of the effects of tricuspid and pulmonary regurgitation.

Effects of radial artery harvesting on forearm function and blood flow

BACKGROUND

There is little information on the effects of radial artery harvesting on postoperative forearm function and blood flow. We evaluated the early changes in forearm neural sensation, circumference, grip power, cyclical exercise fatigue, and blood flow after radial artery harvesting for coronary artery bypass graft (CABG) surgery.

METHODS

Twenty-three patients with negative Allen's test of the nondominant forearm were recruited preoperatively and underwent assessment of bilateral forearm function (soft touch and pin-prick neural sensation, circumference, handgrip power, cyclical exercise fatigue) and blood flow measurements (forearm plethysmography). All vasoactive drugs were stopped 24 hours before assessments. Identical follow-up assessments were conducted (mean +/- SEM) 3.4 +/- 0.4 months postoperatively.

RESULTS

At the time of postoperative assessment all harvested forearm wounds were healed. There was no reduction of postoperative soft touch sensation but in 3 patients objective pinprick sensation was reduced in the distribution of the lateral antebrachial cutaneous nerve of the harvested forearms. Postoperative forearm circumference (p < 0.05) and grip power (p < 0.05) were significantly reduced in both forearms, however cyclical exercise fatigue was improved in both forearms. Preoperative and postoperative forearm blood flow at rest and in exercise-induced ischemic reperfusion were not significantly different in both forearms.

CONCLUSIONS

In patients with a negative Allen's test, harvesting of the radial artery does not adversely affect subsequent forearm function or blood flow to a clinically significant degree.

Validation of a new intraoperative technique to evaluate load-independent indices of right ventricular performance in patients undergoing cardiac operations

BACKGROUND

Assessment of right ventricular performance in the perioperative period is difficult because there is no generally accepted method of measuring right ventricular volume. We set out to determine whether conductance technology could provide a valuable technique for the investigation of intraoperative right ventricular function.

METHODS AND RESULTS

Three validating studies were performed in 25 patients undergoing routine coronary revascularization. Study 1: The influence of conductance catheter position in the right ventricle was examined in 10 patients. Insertion of the conductance catheter through the outflow tract was associated with a larger gain constant and a smaller parallel conductance compared with insertion through the tricuspid valve. Study 2: The reproducibility of contractility measurements with the use of a conductance catheter was examined in 7 additional patients. Removal and reinsertion of the conductance catheter was not associated with any significant difference in right ventricular volume or contractile function. Study 3: Right ventricular performance before and after cardiopulmonary bypass was compared in 8 additional patients. There was a fall in the slope of the right ventricular preload recruitable stroke work from 15.6 (3.8) to 11.0 (5.1) mm Hg (P=.01) and an increase in the slope of the end-diastolic pressure-volume relations from 0.05 (0.02) to 0.11 (0.05) mm Hg/mL (P=.001).

CONCLUSIONS

The conductance technique can be used to study perioperative changes in right ventricular performance. Insertion of the conductance catheter through the outflow tract provides stable and reproducible data. There is significant impairment of right ventricular contractility in the early postoperative period.

Plasma brain natriuretic peptide concentrations in patients with chronic mitral regurgitation

BACKGROUND AND AIMS OF THE STUDY

Patients with chronic mitral regurgitation (MR) are often referred for surgery only after irreversible left ventricular (LV) dysfunction has developed. Our aim was to determine whether plasma brain natriuretic peptide (BNP) concentrations could serve as a marker for early LV dysfunction in this condition.

METHODS

Twenty-two patients with isolated chronic MR and echocardiographic evidence of at least moderate regurgitation were studied.

RESULTS

Plasma BNP concentrations were significantly higher in patients than in normal volunteers (20.85 +/- 16.9 versus 3.37 +/- 0.9 pmol/l; p = 0.007). Concentrations increased with increasing severity of symptoms and were highest in those in NYHA class IV, but did not correlate with LV dimensions, fractional shortening or left atrial size. Of note, two asymptomatic patients with high BNP concentrations were referred for surgery within the 12-month follow up period due to symptom progression.

CONCLUSIONS

Plasma BNP concentrations are elevated in most patients with isolated chronic MR, including those who are asymptomatic with normal LV dimensions. The significance of these findings is uncertain, but they suggest that changes in ventricular physiology occur early in the disease process and before they can be detected echocardiographically. Longitudinal studies are required to determine if patients with high BNP levels have an adverse prognosis and if this can be altered by earlier surgical intervention.

Pulmonary surfactant composition early in development of acute lung injury after cardiopulmonary bypass: prophylactic use of surfactant therapy

Cardiopulmonary bypass surgery (CPB) causes lung injury and at least 2% of adult patients and more children develop the most severe from acute respiratory distress syndrome (ARDS). Pulmonary surfactant deficiency contributes to the pathogenesis of ARDS. It has been proposed that surfactant therapy immediately after CPB might arrest progression to ARDS. However, many patients develop only mild lung injury after CPB. Thus early markers are needed to identify those patients at highest risk to guide selection for treatment. The aim of this study was to determine whether changes in surfactant phospholipids occur, and reflect severity of lung injury within the first few hours after bypass. Because of the relatively low incidence of ARDS in adult patients, this study was conducted using young pigs highly susceptible to bypass-induced lung injury. Eight pigs were given 2 hours bypass. Six controls underwent 'sham' bypass. At 3 h after bypass pulmonary vascular endothelial permeability was assessed by transcapillary leakage of radiolabelled transferrin. A 4 hour broncho-alveolar lavage (BAL) was used to assess intra-alveolar levels of surfactant, inflammatory cells and oedema protein. Bypass caused falls in arterial oxygenation and lung compliance (P < 0.01), but at this early stage in progression of lung injury BAL surfactant phospholipid and albumin levels were within the control range indicating that the alveolar epithelium had not yet suffered major damage. The main abnormalities were increases in vascular endothelial permeability (P < 0.01), BAL neutrophils (P < 0.01), total protein and sphingomyelin (SM) (P < 0.05). Lung histology showed that the main damage was interstitial oedema located around the bronchioles and their associated vessels. A single instilled dose of surfactant phospholipids in 5 animals caused excess in vivo supplementation and did not reduce the early pathophysiologic changes. Our findings suggest that surfactant phospholipid deficiency does not make a major contribution in the initial stages of lung injury after CPB, and that excessive phospholipid supplementation at this stage can be deleterious.

Humoral and cellular activation in a simulated extracorporeal circuit

Endothelial injury consequent upon widespread humoral and cellular activation is probably a major contributor to the phenomenon of cardiopulmonary bypass-induced organ dysfunction. This article reviews some of the mechanisms by which complement and neutrophil activation and interleukin-8 may be involved in this inflammatory response. In a model consisting of a simulated extracorporeal circulation we were able to demonstrate complement activation, profound and specific changes in neutrophil adhesion molecule expression, and interleukin-8 generation. The importance of these changes and their potential interactions are discussed.

Chelatable iron and copper can be released from extracorporeally circulated blood during cardiopulmonary bypass

During cardiopulmonary bypass surgery blood is extracorporeally oxygenated and circulated before returning to the systemic arterial circulation. Blood undergoing extracorporeal dilution and circulation is exposed to non-physiological surfaces, which cause the activation of several regulatory cascades. Cells are also subjected to damaging shear stresses. Under such conditions neutrophils can be 'activated' to release reactive oxygen intermediates such as O2- and H2O2, and other cells can release proteolytic enzymes and metalloproteins. Collectively, these events can result in the release of micromolar quantities of redox active iron and copper. Bleomycin-detectable iron and phenanthroline-detectable copper were found in two out of four mock bypass experiments. However, there was no correlation between the presence of chelatable iron and copper and the activation of neutrophils measured as elastase.

Organ dysfunction and cardiopulmonary bypass: the role of complement and complement regulatory proteins

Cardiopulmonary bypass-induced organ dysfunction remains a clinical problem in certain groups of patients. Although the pathogenesis is multifactorial, it is likely that a panendothelial injury consequent upon widespread humoral and cellular activation is a major contributor to this process. The biologically active products of complement activation are certainly capable of inducing many of the features of the post-perfusion syndrome. The complex interactions between complement and many of the other proposed mediators of this response also supports this contention. However, it is equally certain that many of the other proposed mediators have some role to play. Inhibition of one cell type or inflammatory cascade is therefore unlikely to abolish all the adverse effects of CPB but will, at least in experimental systems, permit a more precise determination of the pathogenesis of this problem. The temptation to simply measure elevated circulating levels of newly identified mediators must be resisted and more effort applied to examining the pathophysiological effects of specific inhibitors. This type of investigation should initially be effected in experimental models where reproducible conditions can be ensured. In conjunction with this, far more precise end-points are required in order to assess the effect of any potential therapeutic intervention in a clinical setting. In particular, new techniques of evaluating endothelial injury need to be developed. In clinical studies careful consideration must be given to the patient population studied. Whilst patients undergoing routine coronary artery surgery form a relatively homogeneous group, the magnitude of endothelial injury sustained is probably small and, especially in terms of lung function, the signal will be diluted by other non-bypass-related events. The study of high risk groups would seem more appropriate despite their heterogeneity. An important unanswered question is why certain sub-populations of patients are at increased risk of clinically relevant bypass-induced injury. The endothelium of these patients may be different: the neonatal pulmonary microcirculation is not the same as that of an adult (with increased fluid filtration pressure and a higher microvascular surface area per unit lung mass [5,6]), children with pulmonary hypertension have histological evidence of an altered/damaged endothelium (S.G. Haworth, Personal Communication) whilst pre-existing sepsis could clearly induce a degree of endothelial dysfunction. A further possibility is that the inflammatory response in these patients is already "primed". Some patients with heart failure have been shown to have elevated circulating TNF.(ABSTRACT TRUNCATED AT 400 WORDS)

Complex coronary arterial anatomy in transposition of the great arteries. Arterial switch procedure without coronary relocation

Translocation of the coronary arteries remains a technical problem in anatomic correction of transposition of the great arteries. Myocardial ischemia related to difficulties with coronary relocation is a significant factor in perioperative morbidity and mortality, particularly in those patients with complex coronary anatomy. Two neonates with transposition of the great arteries and intact ventricular septum are described in whom the coronary arteries arose from multiple ostia, all lying within sinus 1, with one of the ostia in each instance being severely eccentric. An anatomic switch of the great vessels was done without coronary relocation. This was achieved by means of an aortopulmonary fenestration with a bovine pericardial tunnel to allow coronary artery perfusion with blood from the neoaorta. An additional pericardial patch was placed to the contralateral wall of the proximal neopulmonary artery. Both infants had an uneventful postoperative recovery with no evidence of myocardial ischemia, although both have a mild gradient across the proximal pulmonary artery. This operative technique may be appropriate in those patients in whom there is concern over the feasibility of translocating the coronary arteries without producing myocardial ischemia.

Induced hypothermia in the management of refractory low cardiac output states following cardiac surgery in infants and children

Post-operative low cardiac output states remain a major cause of mortality following cardiac surgery in infants and children. Since 1979 we have used moderate induced whole-body hypothermia in the management of low-output states refractory to conventional modes of therapy. This is based not only upon the relationship between body temperature and oxygen consumption, but also on experimental work showing a beneficial effect of cooling upon myocardial contractility, particularly when there is pre-existing impairment of ventricular function. Between July 1986 and June 1990, 20 children with refractory low-output states were cooled by means of a thermostatically controlled water blanket to a rectal temperature of 32-33 degrees C. The median age was 12 months (1 week-11 years) with a median weight of 6 kg (3.5-33 kg). Ten children survived to leave hospital while a further two made a haemodynamic recovery. There was a marked reduction in heart rate (P < 0.001). The mean arterial pressure rose (P = 0.037) while there was a fall in mean atrial pressure (P < 0.001). There was a significant improvement in the urine output (P = 0.002). A fall in the platelet count (P < 0.001) was not accompanied by any change in the white cell count (P = 0.15). Although it is impossible to say whether cooling influenced the outcome in any of these children, it was usually effective in stabilising their clinical condition. The technique is simple and has a sound theoretical basis.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous hypoglycaemia and pleural fibroma: role of insulin like growth factors

Spontaneous hypoglycaemia was the presenting feature of a man with a large subpleural fibroma. Preoperative and postoperative studies support the view that the tumour induced hypoglycaemia was due to the secretion of peptide hormones by the tumour.

Circulatory support in infants with post-cardiopulmonary bypass left ventricular dysfunction using a left ventricular assist device

Extracorporeal membrane oxygenation has been advocated as the most appropriate mode of circulatory support in the paediatric age group for post-cardiopulmonary bypass ventricular dysfunction. The results in infants who have predominantly left ventricular failure, or who require such support in order to be weaned off bypass, have been disappointing. Three infants with severe left ventricular dysfunction following cardiopulmonary bypass for correction of congenital heart defects have been managed with a left ventricular assist device. Two required this form of circulatory support in order to be weaned from full bypass while in the third infant it was instituted for progressive left ventricular dysfunction postoperatively. All three were less than 10 kg in weight. Left atrial appendage to aortic bypass was effected using a closed loop circuit with a constrained vortex pump (Biomedicus). Duration of support ranged between 40 and 146 h. One infant made a complete recovery and was able to be discharged home 20 days postoperatively. Another made a circulatory recovery such that both mechanical and inotropic support could be discontinued but had sustained massive neurological damage. The third died of progressive left ventricular dysfunction. This experience with a left ventricular assist device demonstrates that it is technically feasible in small infants, and can be performed to good effect in infants with predominant left ventricular dysfunction following cardiac surgery. It may well be more appropriate than extracorporeal membrane oxygenation in this group of patients.