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Literature Review

Health Status Benefits of Transcatheter vs Surgical Aortic Valve Replacement in Patients With Severe Aortic Stenosis at Intermediate Surgical Risk: Results From the PARTNER 2 Randomized Clinical Trial

Baron SJ, Arnold SV, Wang K, et al. JAMA Cardiol. [Published online ahead of print June 28, 2017.] doi:10.1001/jamacardio.2017.2039.

Reviewers: Scott R. Coleman, DO1; Henry Liu, MD2

  1. Resident, Department of Anesthesiology and Perioperative Medicine, Drexel University College of Medicine, Hahnemann University Hospital, Philadelphia, PA
  2. Faculty, Department of Anesthesiology and Perioperative Medicine, Drexel University College of Medicine, Hahnemann University Hospital, Philadelphia, PA
Background

Aortic valve repair offers improved morbidity and mortality in severe, symptomatic aortic stenosis (AS). The technological advancement of transcatheter aortic valve replacement (TAVR) has provided an option for patients not suitable for traditional surgical aortic valve replacement (SAVR). Although TAVR is being used more frequently in lower-risk patients, SAVR achieves better outcomes and does not warrant further investigations. For intermediate-risk patients, the 2-year survival is similar for TAVR and SAVR, but the quality of life alterations during this 2-year window are unknown. In addition, the differences in outcomes between transfemoral and transthoracic catheter repairs also need further illumination.

Methods

Design

The authors analyzed data from 2032 patients in the PARTNER 2 trial with severe AS and intermediate surgical risk. Severe AS was determined as valve area 0.8 cm2 or less, aortic valve area index 0.5 cm2/m2 or less, mean aortic valve gradient greater than 30 mmHg, or peak aortic jet velocity greater than 4 m/s. Intermediate risk of surgery meant that the predicted 30-day surgical mortality of the patient was 4%–8%, according to the Society of Thoracic Surgeons mortality risk model. Exclusion criteria included congenital bicuspid aortic valve, severe renal disease, predominant aortic regurgitation, or left ventricular ejection fraction less than 20%. All patients in the study were assessed to determine suitability for transfemoral or transthoracic access and were then stratified and randomized to TAVR or SAVR.

Measurement

Quality of life was derived from questionnaires measuring health status. This information was collected at 1 month, 1 year, and 2 years after surgery via multiple questionnaires. The primary endpoint was the Kansas City Cardiomyopathy Questionnaire overall summary score (KCCQ-OS), which correlates well with clinical outcomes in heart failure. Secondary outcomes were scores on the Medical Outcomes Study Short-Form 36 (SF-36) and the EuroQOL-5D (EQ-5D). These 2 questionnaires assess health status but are not disease-specific.

Statistical Analysis

Baseline characteristics between the TAVR and SAVR groups were analyzed for potential differences. Baseline health status scores for each patient were compared to scores at each time point using a paired t test. In addition, differences in health status scores between TAVR and SAVR groups were compared at each time point. Improvements in the KCCQ-OS also were converted into categorical data based on known, clinically relevant changes. This categorized data was compared between TAVR and SAVR groups using logistic regression.

Results

Data for 1833 patients (950 TAVR and 883 SAVR) were available. Analysis of baseline characteristics showed no significant differences between the TAVR and SAVR cohorts. The majority of patients (76%, n=1393) were eligible for transfemoral TAVR, and the remaining 440 (24%) patients required a transthoracic approach. Patients requiring transthoracic access did have higher rates of peripheral artery disease, prior coronary artery bypass surgery, and prior history of stroke. However, there were no significant differences between the TAVR and SAVR groups even when subdivided by site of access evaluation.

Health status improved significantly by 1 year and 2 years after TAVR and SAVR, regardless of access location, by a mean increase of 16–22 points on the KCCQ-OS scale. When comparing the 2 groups, a difference was noted at 1 month for patients who had transfemoral repair. Their improvement was significantly higher than the SAVR group at this time interval (CI 3.7-5.5; P<.01). However, at 1 and 2 years, this difference was no longer statistically significant (CI -1.4-8.4; P>.01). Outcomes between the TAVR transthoracic and SAVR patients were not statistically significant at any time point.

Conclusions

During a 2-year follow-up for patients with severe, symptomatic AS at intermediate surgical risk, TAVR and SAVR had comparable and noteworthy improvements in health status. Additionally, TAVR showed a statistically significant improvement in health status at 1 month after surgery when the transfemoral approach was used compared to transthoracic TAVR and SAVR.

Comments

A strength of this study is the number of patients included. The authors did suggest the smaller number of patients requiring transthoracic approach (n=440) might have limited the power to find a significant difference between this technique and SAVR. However, overall, the large sample size lends to a study likely to find even modest differences. The decision to subdivide patients based on transfemoral versus transthoracic TAVR eligibility was shrewd and helped minimize an obvious confounding variable.

The primary endpoint of the KCCQ-OS seems apt. First of all, this questionnaire correlates well with clinical outcomes such as rehospitalization, healthcare cost, and death from heart failure. Secondly, the scores on this scale have been correlated with the New York Heart Association functional classes. Lastly, changes in the score over time already have been correlated to increments of clinical improvement in prior research. This is a thoroughly studied questionnaire that is relevant for the patient population of this trial.1

Of note, these results do not represent patients with significant heart failure (ejection fraction <20%), severe renal disease, concomitant severe aortic regurgitation, and bicuspid valve, as these patients were excluded from the study.

One limitation of this study the authors discussed was its unblinded nature. Although this was obviously difficult to accomplish, the lack of blinding does increase the chance of bias because the data are patient reported. Response rates for the study were relatively high (84% in SAVR; 88% in TAVR). However, the lack of complete data also creates the possibility of responder bias.

Since the completion of this trial, a newer device has become available for TAVR. This new device (Sapien 3) has been shown to have better outcomes than the device used in this study (Sapien XT). Primarily, the amount of aortic regurgitation is reduced with the newest model.2 As the authors discussed, this may lead to even further improvements for TAVR vs SAVR.

The results from this study imply that quality of life improvements for TAVR patients of intermediate surgical risk are equal to or better than SAVR patients over a 2-year period. This information can help clinicians and patients make a more informed decision when discussing TAVR and SAVR options. This study provides a template for additional studies to further elucidate which patients will benefit more from TAVR or SAVR. This could include assessment between 1 month and 1 year to determine where the difference in health measures declines, longer follow-up, assessing low-risk surgical patients, and measurement of different postoperative metrics such as length of stay.

References

  1. Arnold SV, Spertus JA, Lei Y, et al. Use of the Kansas City Cardiomyopathy Questionnaire for monitoring health status in patients with aortic stenosis. Circ Heart Fail. 2013;6(1):61-67.
  2. Amat-Santos IJ, Dahou A, Webb J, et al. Comparison of hemodynamic performance of the balloon-expandable SAPIEN 3 versus SAPIEN XT transcatheter valve. Am J Cardiol. 2014;114(7):1075-1082.

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