Quality control and the learning curve of transcatheter aortic valve implantation

Volume-outcome relationship in transcatheter aortic valve implantations in Germany 2008-2014: a secondary data analysis of electronic health records

OBJECTIVES

We examine the volume-outcome relationship in isolated transcatheter aortic valve implantations (TAVI). Our interest was whether the volume-outcome relationship for TAVI exists on the centre level, whether it occurs equally for different outcomes and how it develops over time.

DESIGN

Secondary data analysis of electronic health records. The comprehensive German Federal Bureau of Statistics Diagnosis Related Groups database was queried for data on all isolated TAVI procedures performed in Germany between 2008 and 2014. Logistic and linear regression analyses were carried out. Risk adjustment was applied using a predefined set of patient characteristics to account for differences in the risk factor composition of the patient populations between centres and over time. Centres performing TAVI were stratified into groups performing <50, 50-99 and ≥100 procedures per year.

SETTING

Germany 2008-2014.

PARTICIPANTS

All patients undergoing isolated TAVI in the observation period.

INTERVENTIONS

None.

PRIMARY AND SECONDARY OUTCOME MEASURES

In-hospital mortality, bleeding, stroke, probability of ventilation >48 hours, length of hospital stay and reimbursement.

RESULTS

Between 2008 and 2014, a total of 43 996 TAVI procedures were performed in 113 different centres in Germany with a total of 2532 cases of in-hospital mortality. Risk-adjusted in-hospital mortality decreases over the years and is lower the higher the annual procedure volume at the centre is. The magnitude of the latter effect declines over the observation period. Our results indicate a ceiling effect in the volume-outcome relationship: the volume-outcome relationship is eminent in circumstances of relatively unfavourable outcomes. Alongside improving outcomes, however, the volume-outcome relationship decreases. Also, a volume-outcome relationship seems to be absent in circumstances of constantly low event rates.

CONCLUSIONS

The hypothesised volume-outcome relationship for TAVI exists but diminishes and may disappear over time. This should be taken into account when considering mandatory minimum thresholds.

Learning Curves Among All Patients Undergoing Transcatheter Aortic Valve Implantation in Germany: A Retrospective Observational Study

BACKGROUND

Transcatheter aortic valve implantation (TAVI) is a rapidly evolving technique for therapy of aortic stenosis. Previous studies report learning curves with respect to in-hospital mortality and clinical complications. We aim to determine whether observed improvements of in-hospital outcomes after TAVI are the result of improvements in procedures or due to a change in the patient population, and whether improvements differ between the transfemoral (TF) and the transapical (TA) approach.

METHODS

Data was analyzed using risk-adjusted regression analyses in order to track the development of clinical outcomes of all isolated TAVI procedures performed in Germany from 2008 to 2013 (N=32.436) in all German hospitals performing TAVI. Measurements include in-hospital mortality, stroke, bleeding, and mechanical ventilation.

RESULTS

Unadjusted mortality rates decrease over time for both TA-TAVI and TF-TAVI. Reductions in mortality were smaller for TA-TAVI than for TF-TAVI. These trends could also be observed for risk-adjusted (standardized) mortality rates, indicating that time trends and differences between TA-TAVI (around 7% in 2013) and TF-TAVI (around 4% in 2013) cannot be explained by changes in the risk factor composition of the patient populations. Bleeding complications decreased for both access routes. Both unadjusted and standardized bleeding rates were substantially higher for TA-TAVI. In addition, TA-TAVI procedures were associated with an increased likelihood of requiring >48h of mechanical ventilation.

CONCLUSIONS

Observed improvements in TAVI-related in-hospital mortality are not due to a change in patient population. The results indicate the superiority of a TF-first approach.

Clinical outcomes of transcatheter aortic valve implantation: from learning curve to proficiency

Objective

The use of transcatheter aortic valve implantation (TAVI) is growing rapidly in countries with a predominantly elderly population, posing a huge challenge to healthcare systems worldwide. The increment of human and economic resource consumption imposes a careful monitoring of clinical outcomes and cost-benefit balance, and this article is aimed at analysing clinical outcomes related to the TAVI learning curve.

Methods

Outcomes of 177 consecutive transfemoral TAVI procedures performed in 5 years by a single team were analysed by the Cumulative Sum of failures method (CUSUM) according to the clinical events comprised in the Valve Academic Research Consortium (VARC-2) safety end point and the VARC-2 definition of device success. Margins for events acceptance were extrapolated from landmark trials that tested both balloon or self-expandable percutaneous valves.

Results

30-day and 1-year survival rates were 97.2% and 89.9%, respectively. Achievement of the primary end point (number of cases needed to provide the acceptable margin of the composite end point of any death, stroke, myocardial infarction, life-threatening bleeding, major vascular complications, stage 2–3 acute kidney injury and valve-related dysfunction requiring a repeat procedure) required the performance of 54 cases, while the learning curve to achieve ‘device success’ identified 32 cases to reach the expected proficiency. In this experience, the baseline clinical risk as assessed by the Society of Thoracic Surgeons (STS) score determined the long-term survival rather than the adverse events related to the learning curve.

Conclusions

A relatively large number of cases are required to achieve clinical outcomes comparable to those reported in high-volume centres and controlled trials. According to our national workload standards, this represents more than 2 years of continuous activity.