Transcatheter aortic valve replacement: historical perspectives, current evidence, and future directions

Pathogenesis and Molecular Immune Mechanism of Calcified Aortic Valve Disease

Calcified aortic valve disease (CAVD) was previously regarded as a passive process associated with valve degeneration and calcium deposition. However, recent studies have shown that the occurrence of CAVD is an active process involving complex changes such as endothelial injury, chronic inflammation, matrix remodeling, and neovascularization. CAVD is the ectopic accumulation of calcium nodules on the surface of the aortic valve, which leads to aortic valve thickening, functional stenosis, and ultimately hemodynamic disorders. CAVD has become an important cause of death from cardiovascular disease. The discovery of therapeutic targets to delay or block the progression of CAVD and the clinical application of transcatheter aortic valve implantation (TAVI) provide new ideas for the prevention and treatment of CAVD. This article summarizes the pathogenesis of CAVD and provides insight into the future directions of CAVD diagnosis and treatment.

Insulin like growth factor binding protein 2 (IGFBP-2) for risk prediction in patients with severe aortic stenosis undergoing Transcatheter Aortic Valve Implantation (TAVI)

INTRODUCTION

Severe aortic stenosis (AS) caused by degenerative calcification is the most frequent acquired valvular heart disease worldwide and mortality rates are considerably high. Transcatheter Aortic Valve Implantation (TAVI) is a well-established method for valve replacement in high risk patients with AS. However, there is a lack of reliable predictors for patients undergoing TAVI since commonly used scores were developed for surgical populations.

MATERIALS AND METHODS

208 patients subjected to TAVI were included in this study. Plasma samples were obtained before TAVI and were evaluated for IGFBP-2 using commercially available ELISA kits. IGFBP-2 levels were analyzed for their ability for risk prediction after TAVI.

RESULTS

IGFBP-2 levels measured before TAVI correlated significantly with left ventricular ejection fraction, EUROSCORE and other functional and prognostic parameters like the 6-minute walking test. When patients were retrospectively divided in two groups with a cut-off of serum IGFBP-2 levels of 275 ng/ml, IGFBP-2 was a strong predictor for 30-day and one-year mortality (3% vs. 11%, p = 0.05 and 18.2% vs. 46.2%; p < 0.001 respectively). Compared to an EUROSCORE above 20 or an STS score cut-off above 8, IGFBP-2 plasma levels above 275 ng/ml outperformed the established risk score for prediction of one-year mortality as assessed by NRI (0.65 95% CI 0.37-0.94; p < 0.001 and 0.54 95% CI 0.25-0.82; p < 0.001, respectively).

CONCLUSIONS

Our results indicate that IGFBP-2 could serve as new outcome predictor for patients undergoing TAVI procedure. By providing additional information to the commonly used EUROSCORE, IGFPB-2 analysis could further assist Heart Team decision making.

Timing and Outcomes of PCI in the TAVR Era

PURPOSE OF REVIEW

Transcatheter aortic valve replacement (TAVR) has become an established therapy for patients with symptomatic severe aortic stenosis (AS). As the number of patients referred for TAVR increases, so does the prevalence of untreated obstructive coronary artery disease (CAD) in the population under evaluation. Despite the high prevalence of CAD in patients treated with TAVR, the management strategy of concomitant CAD in these patients remains an area of considerable uncertainty.

RECENT FINDINGS

Percutaneous coronary intervention (PCI) in patients with CAD and severe AS has been shown to be feasible and safe. Whether revascularization before, during, or after TAVR is optimal remains a subject of debate. All three approaches represent valid strategies with advantages and disadvantages that need to be carefully weighed on an individual basis. Current expert opinions recommend that PCI should be performed before or at the time of TAVR as long as the risk of the procedure does not outweigh the potential benefits. The results of large clinical trials evaluating the optimal revascularization time are closely awaited.

Postprocedural Changes of Tricuspid Regurgitation After MitraClip Therapy for Mitral Regurgitation

The effect of percutaneous mitral valve repair using the MitraClip system on tricuspid regurgitation (TR) has not been well investigated. We retrospectively analyzed 102 consecutive patients who underwent the successful MitraClip procedure, and who also had a preprocedural and 1-year follow-up transthoracic echocardiography. TR severity was graded by standard guideline-recommended criteria. At 1 year after the MitraClip procedure, the degree of TR regressed (at least 1 grade) in 23% of the patients, was unchanged in 62% of the patients, and progressed in 16% of the patients. Compared with patients in the other groups, the patients with TR regression had a greater severity of TR at baseline. The TR regression group showed a significant reduction in the systolic pulmonary artery pressure (sPAP) (49 ± 13 to 37 ± 11 mm Hg, p <0.05), a right-sided cardiac reverse remodeling (right ventricular diameter: 41 ± 7 to 39 ± 7 mm, tricuspid annular diameter: 48 ± 8 to 46 ± 9 mm, both p <0.05), and an increase in the right ventricular fractional area change (38 ± 7 to 40 ± 7%, p <0.05). In the multivariate analysis, the decrease in sPAP was the only independent parameter change associated with TR regression. In conclusion, TR regression was observed in 23% of the patients after the successful MitraClip procedures, and favorable echocardiographic parameter changes were detected in this group. Only a reduction in sPAP was independently associated with TR regression.

Comparison of Frequency of Referral to Cardiothoracic Surgery for Aortic Valve Disease in Blacks, Hispanics, and Whites

Racial differences in prevalence and in intervention rate of those with severe aortic stenosis have been reported. Our objective was to evaluate health disparities in referral to cardiothoracic surgery (CTS) for aortic stenosis in black and Hispanic compared with white patients before the transcatheter aortic valve replacement program was started in our community. Using a retrospective cohort design, we identified all patients >40 years, who had been captured with aortic valve disease from January 2011 to June 2016. Clinical and echocardiographic data were collected manually. Exposure was race/ethnicity; outcome was referral to CTS. Multivariable logistic regression analysis was conducted with variables that had significance of p <0.20 in univariate model. We included 952 patients in the final analysis (423 white, 376 black, and 153 Hispanic). Compared with whites, black subjects were significantly younger, had more advanced degrees of kidney disease, were more likely to have Medicaid as payer, and had more atherogenic co-morbidities. Black patients had significantly higher aortic valve area indexed for body surface area, more aortic regurgitation, lower peak velocities, lower transvalvular gradients, less calcified valves, and fewer patients in aortic stenosis stage D. The adjusted odds ratio for CTS referral was 0.48 for blacks (p <0.001) and 0.86 for Hispanics (p = 0.73) compared with whites. In conclusion, after adjusting for clinical and echocardiographic variables, black patients were less likely to be referred to CTS for treatment of aortic valve disease. We found no difference in the referral pattern of Hispanic compared with white patients.

Soluble ST2 predicts 1-year outcome in patients undergoing transcatheter aortic valve implantation

BACKGROUND

Soluble ST2 (sST2) has been introduced as a novel biomarker in patients suffering from heart failure for risk stratification. In this study, we sought to investigate whether sST2 is useful for risk stratification and prediction of mortality in patients undergoing transcatheter aortic valve implantation (TAVI).

MATERIALS AND METHODS

A total of 274 patients undergoing TAVI were included in this study (149 female; age 81 ± 1 years; EUROSCORE 25 ± 1; STS score 3·8 ± 0·2). Plasma samples were obtained preinterventional and analysed for sST2. Patients were followed up 1 month and 1 year after TAVI.

RESULTS

In a Cox regression analysis, sST2 plasma concentration was associated with increased mortality (changes per pg/mL sST2 concentration; HR 1·00006 95% (1·00004-1·00009); P < 0·001). A cut-off by means of the Youden Index was calculated (10 070·27 pg/mL), and patients were retrospectively divided into two cohorts, in those above (31·3%) and those below (68·7%) this value. These two groups were then compared regarding mortality both after 30 days and 1 year: whereas 1-month mortality did not differ (7·0% vs. 10·3%, OR 1·50 95% CI (0·60-3·79; P = 0·46)), patients with a sST2 concentration above the cut-off of 10 070·27 pg/mL showed a significantly worse outcome after 1 year (49·2% vs. 23·2%; OR 3·21 95% CI (1·70-6·04); P < 0·001). After correction for confounders in a multivariate Cox regression analysis, sST2 (1·0002 95% CI (1·0001-1·0003); P = 0·001) concentration remained associated with mortality.

CONCLUSIONS

sST2 levels were associated with 1-year mortality after TAVI. Based on these results, we assume that sST2 might help to identify patients at high risk for death in whom conservative treatment should be considered.

Microparticles in patients undergoing transcatheter aortic valve implantation (TAVI)

Degenerative aortic stenosis (AS) is the most frequent form of acquired valvular heart disease. AS is known to entail endothelial dysfunction caused by increased mechanical shear stress leading to elevated circulatory levels of microparticles. Endothelial and platelet microparticles (EMP and PMP) are small vesicles that originate from activated cells and thrombocytes. We sought to evaluate whether transcatheter aortic valve implantation (TAVI) procedure would elicit effects on circulating EMP and PMP. 92 patients undergoing TAVI procedure for severe AS were included in this study. Samples were obtained at each visit before TAVI, 1 week post-procedure and at 1, 3 and after 6 months after TAVI and were evaluated using flow cytometry. A 12 month clinical follow-up was also performed. CD62E+ EMP concentration before TAVI was 21.11 % (±6.6 % SD) and declined to 20.99 % (±6.8 % SD) after 1 week, to 16.63 % (±5.4 % SD, p < 0.0001) after 1 month, to 17.08 % (±4.6 % SD, p < 0.0001) after 3 months and to 15.94 % (±5.4 % SD, p < 0.0001) after 6 months. CD31+/CD42b-, CD31+/Annexin+/- EMP remained unchanged. CD31+/CD41b+ PMP evidenced a slight, but statistically significant increase after TAVI and remained elevated during the entire follow-up. Apart from a procedure-related improvement in echocardiographic parameters, TAVI procedure led also to a decline in CD62E+ EMP. The reduction in pressure gradients with less hemodynamic shear stress seems also to have beneficially affected endothelial homeostasis.

Success rates and prognosis of heart valvuloplasty and valve replacement performed for elderly patients

Objective:

To analyze the success rates and prognosis of heart valvuloplasty and valve replacement for elderly patients, and to provide clinical evidence.

Methods:

A total of 1240 patients who received heart valve surgeries in our hospital from June 2004 to October 2014 were selected and retrospectively analyzed. They were divided into two groups based on age (60), and those older than 60 (Group B) suffered from rheumatic valvular heart disease and nonrheumatic valvular heart disease including degenerative valve disease. Mitral valve replacement (MVR), tricuspid valve replacement (TVR), aortic valve replacement (AVR), double valve replacement (DVR), mitral valvuloplasty (MVP) and tricuspid valvuloplasty (TVP) were performed by using bioprosthetic and mechanical valves. Before surgery, coronary angiography, coronary artery bypass grafting (CABG), left atrial thrombectomy, left atrial wall folding and radiofrequency ablation were conducted. For the patients younger than 60 (Group A) who had congenital heart disease, rheumatic valvular heart disease and valvular heart disease, MVR, AVR, DVR, MVP, TVP and closed cuspid commissurotomy were performed with bioprosthetic and mechanical valves. The two groups were then monitored.

Results:

The mortality rates of Group A and Group B were 2.7% (16 cases) and 3.1% (20 cases) respectively. They died mainly of malignant ventricular arrhythmias, multiple organ failure, left ventricular rupture, low cardiac output syndrome, acute renal failure, respiratory failure, upper gastrointestinal bleeding, mechanical valve failure and cerebrovascular accident. The two groups had significantly different application rates of bioprosthetic valve, times of auxiliary ventilation and hospitalization stay lengths (P<0.05), but left ventricular ejection fractions, left ventricular end-diastolic diameters (LVEDDs), mortality rates as well as times of aortic cross-clamping and cardiopulmonary bypass were similar (P>0.05). LVEDD, complicated coronary artery disease, CABG and grade of the New York Heart Association Functional Classification were independent risk factors for postoperative death.

Conclusion:

When heart valvuloplasty and valve replacement were performed for elderly patients, the success rate and prognosis could only be improved by optimizing preoperative preparation, shortening the times of cardiopulmonary bypass and aortic cross-clamping, and paying particular attention to myocardial protection and postoperative treatment.