Modeling the Volume-Outcome Relationship for TAVR

Transfemoral aortic valve implantation: procedural hospital volume and mortality in Germany

AIMS

Studies assessing transfemoral transcatheter aortic valve implantation (TF-TAVI) showed lower rates of in-hospital mortality at high-volume hospitals and minimum caseloads were recommended to assure quality standards.

METHODS AND RESULTS

All patients in the German mandatory quality assurance registry with elective or urgent TF-TAVI procedures in 2018 and 2019 at 81 and 82 hospitals, respectively, were analysed. Observed in-hospital mortality was adjusted to expected mortality by the German AKL-KATH score (O/E) as well as by the EuroScore II (O/E2). Hospital volume and O/E were correlated by regression analyses and volume quartiles. 18 763 patients (age: 81.1 ± 1.0 years, mean EuroSCORE II: 6.9 ± 1.8%) and 22 137 patients (mean age: 80.7 ± 3.5 years, mean EuroSCORE II: 6.5 ± 1.6%) were analysed in 2018 and 2019, respectively. The average observed in-hospital mortality was 2.57 ± 1.83% and 2.36 ± 1.60%, respectively. Unadjusted in-hospital mortality was significantly inversely related to hospital volume by linear regression in both years. After risk adjustment, the association between hospital volume and O/E was statistically significant in 2019 (R2 = 0.049; P = 0.046), but not in 2018 (R2 = 0.027; P = 0.14). The variance of O/E explained by the number of cases in 2019 was low (4.9%). Differences in O/E outcome between the first and the fourth quartile were not statistically significant in both years (1.10 ± 1.02 vs. 0.82 ± 0.46; P = 0.26 in 2018; 1.16 0 .97 vs. 0.74 ± 0.39; P = 0.084 in 2019). Any chosen volume cut-off could not precisely differentiate between hospitals with not acceptable quality (>95th percentile O/E of all hospitals) and those with acceptable (O/E ≤95th percentile) or above-average (O/E < 1) quality. For example, in 2019 a cut-off value of 150 would only exclude one of two hospitals with not acceptable quality, while 20 hospitals with acceptable or above-average quality (25% of all hospitals) would be excluded.

CONCLUSION

The association between hospital volume and in-hospital mortality in patients undergoing elective TF-TAVI in Germany in 2018 and 2019 was weak and not consistent throughout various analytical approaches, indicating no clinical relevance of hospital volume for the outcome. However, these data were derived from a healthcare system with restricted access to hospitals to perform TAVI and overall high TAVI volumes. Instead of the unprecise surrogate hospital volume, the quality of hospitals performing TF-TAVI should be directly assessed by real achieved risk-adjusted mortality.

The Use and Outcomes of Cerebral Protection Devices for Patients Undergoing Transfemoral Transcatheter Aortic Valve Replacement in Clinical Practice

OBJECTIVES

This study hypothesized that cerebral protection prevents strokes in patients undergoing transfemoral transcatheter aortic valve replacement (TAVR) in clinical practice.

BACKGROUND

Preventing strokes is an important aim in TAVR procedures. Embolic protection devices may protect against cardiac embolism during TAVR, but their use and outcomes in clinical practice remain controversial.

METHODS

Isolated transfemoral TAVR procedures performed in Germany with or without cerebral protection devices were extracted from a comprehensive nationwide billing dataset.

RESULTS

A total of 41,654 TAVR procedures performed between 2015 and 2017 were analyzed. The overall share of procedures incorporating cerebral protection devices was 3.8%. Patients receiving cerebral protection devices were at increased operative risk (European System for Cardiac Operative Risk Evaluation score 13.8 vs. 14.7; p < 0.001) but of lower age (81.1 vs. 80.6 years; p = 0.001). To compare outcomes that may be related to the use of cerebral protection devices, a propensity score comparison was performed. The use of a cerebral protection device did not reduce the risk for stroke (adjusted risk difference [aRD]: +0.88%; 95% confidence interval [CI]: -0.07% to 1.83%; p = 0.069) or the risk for developing delirium (aRD: +1.31%; 95% CI: -0.28% to 2.89%; p = 0.106) as a sign of acute brain failure. Although brain damage could not be prevented, in-hospital mortality was lower in the group receiving a cerebral protection device (aRD: -0.76%; 95% CI: -1.46% to -0.06%; p = 0.034).

CONCLUSIONS

In this large national database, cerebral embolic protection devices were infrequently used during TAVR procedures. Device use was associated with lower mortality but not a reduction in stroke or delirium. Future studies are needed to confirm these findings.

Outcomes of transcatheter aortic valve implantations in high-volume or low-volume centres in Germany

Objective

Transcatheter aortic valve implantation (TAVI) is the most common aortic valve replacement in Germany. Since 2015, to ensure high-quality procedures, hospitals in Germany and other countries that meet the minimum requirement of 50 interventions per centre are being certified to perform TAVI. This study analyses the impact of these requirements on case number and in-hospital outcomes.

Methods

All isolated TAVI procedures and in-hospital outcomes between 2008 and 2016 were identified by International Classification of Diseases (ICD) and the German Operation and Procedure Classification codes.

Results

73 467 isolated transfemoral and transapical TAVI procedures were performed in Germany between 2008 and 2016. During this period, the number of TAVI procedures per year rose steeply, whereas the overall rates of hospital mortality and complications declined. In 2008, the majority of procedures were performed in hospitals with fewer than 50 cases per year (54.63%). Until 2014, the share of patients treated in low-volume centres constantly decreased to 5.35%. After the revision of recommendations, it further declined to 1.99%. In the 2 years after the introduction of the minimum requirements on case numbers, patients were at decreased risk for in-hospital mortality when treated in a high-volume centre (risk-adjusted OR 0.62, p=0.012). The risk for other in-hospital outcomes (stroke, permanent pacemaker implantation and bleeding events) did not differ after risk adjustment (p=0.346, p=0.142 and p=0.633).

Conclusion

A minimum volume of 50 procedures per centre and year appears suitable to allow for sufficient routine and thus better in-hospital outcomes, while ensuring nationwide coverage of TAVI procedures.