Transcatheter Aortic Valve Implantation in Lower-Risk Patients With Aortic Stenosis

A Machine Learning Model for the Accurate Prediction of 1-Year Survival in TAVI Patients: A Retrospective Observational Cohort Study

BACKGROUND

predicting the 1-year survival of patients undergoing transcatheter aortic valve implantation (TAVI) is indispensable for managing safe early discharge strategies and resource optimization.

METHODS

Routinely acquired data (134 variables) were used from 629 patients, who underwent transfemoral TAVI from 2012 up to 2018. Support vector machines, neuronal networks, random forests, nearest neighbour and Bayes models were used with new, previously unseen patients to predict 1-year mortality in TAVI patients. A genetic variable selection algorithm identified a set of predictor variables with high predictive power.

RESULTS

Univariate analyses revealed 19 variables (clinical, laboratory, echocardiographic, computed tomographic and ECG) that significantly influence 1-year survival. Before applying the reject option, the model performances in terms of negative predictive value (NPV) and positive predictive value (PPV) were similar between all models. After applying the reject option, the random forest model identified a subcohort showing a negative predictive value of 96% (positive predictive value = 92%, accuracy = 96%).

CONCLUSIONS

Our model can predict the 1-year survival with very high negative and sufficiently high positive predictive value, with very high accuracy. The "reject option" allows a high performance and harmonic integration of machine learning in the clinical decision process.

Transcatheter aortic valve thrombosis: incidence, clinical presentation and long-term outcomes

Aims

To assess the incidence, management and long-term outcomes of transcatheter heart valve thrombosis (THVT).

Methods and results

Between August 2007 and February 2016, 1396 patients were included in the Bern TAVI Registry and prospectively followed-up through echocardiographic and clinical evaluation. THVT was suspected in case of: (i) a mean transvalvular pressure gradient greater than 20 mmHg at transthoracic echocardiography, or (ii) an increase of more than 50% of the mean transvalvular pressure gradient compared with previous measurements or (iii) new symptoms or signs of heart failure with the presence of thrombus documented by transoesophageal echocardiography or multi-slice computed tomography. THVT occurred in 10 patients (0.71%) at variable time points after TAVI. Increased transvalvular pressure gradients were recorded in all patients and 7 out of 10 patients were symptomatic. Oral anticoagulant therapy (with vitamin K antagonists or non-Vitamin K antagonists) was initiated in all but two patients and resulted in normalization of transvalvular pressure gradients and amelioration of clinical status within 1 month. At long-term follow-up (between 10 and 25 months after valve thrombosis), echocardiographic findings were stable and no adverse events were reported.

Conclusion

THVT is rarely detected at routine clinical and echocardiographic evaluation after TAVI. Oral anticoagulation appears effective to normalize transvalvular gradients in the majority of cases with stable clinical and haemodynamic evolution during long-term follow-up.

Pre-procedural risk models for patients undergoing transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) has emerged as the standard treatment option for patients with symptomatic aortic stenosis who are considered intermediate to high surgical risk. Nonetheless, optimal clinical outcomes following the procedure require careful consideration of procedural risk by the Heart Team. While this decision-making could be supported through the development of TAVI-specific clinical prediction models (CPMs), current models remain suboptimal. In this review paper, we aimed to outline the performance of several recently derived TAVI CPMs that predict mortality and present some future research directions. We discuss how the existing risk models have achieved only moderate discrimination but highlight that some of the models are well calibrated across multiple populations, indicating the feasibility of using them to aid benchmarking analyses. Moreover, we suggest that future work should focus on the development of CPMs in cohorts of patients with aortic stenosis that include multiple treatment modalities. Supported by appropriate modelling of 'what if' scenarios, this would allow the Heart Teams to predict and compare outcomes across surgical aortic valve replacement, medical management and TAVI, thereby allowing one to personalise treatment decisions to the individual patient. Such a goal could be facilitated by considering novel risk factors, shifting the focus to endpoints other than mortality, and through collaborative efforts to combine the evidence base and existing models across wider populations.

The Role of Quantitative Aortographic Assessment of Aortic Regurgitation by Videodensitometry in the Guidance of Transcatheter Aortic Valve Implantation

Background

Balloon post-dilatation (BPD) is often needed for optimizing transcatheter heart valve (THV) implantation, since paravalvular leak (PVL) after transcatheter aortic valve implantation is associated with poor outcome and mortality. Quantitative assessment of PVL severity before and after BPD is mandatory to properly assess PVL, thus improving implantation results and outcomes.

Objective

To investigate a quantitative angiographic assessment of aortic regurgitation (AR) by videodensitometry before and after BPD.

Methods

Videodensitometric-AR assessments (VD-AR) before and after BPD were analysed in 61 cases.

Results

VD-AR decreased significantly from 24.0[18.0-30.5]% to 12.0[5.5-19.0]% (p < 0.001, a two-tailed p < 0.05 defined the statistical significance). The relative delta of VD-AR after BPD ranged from -100% (improvement) to +40% (deterioration) and its median value was -46.2%. The frequency of improvement, no change, and deterioration were 70% (n = 43), 25% (n = 15) and 5% (n = 3), respectively. Significant AR (VD-AR > 17%) was observed in 47 patients (77%) before and in 19 patients (31%) after BPD.

Conclusions

VD-AR after THV implantation provides a quantitative assessment of post-TAVI regurgitation and can help in the decision-making process on performing BPD and in determining its efficacy.