Propensity matched comparison of TAVI and SAVR in intermediate-risk patients with severe aortic stenosis and moderate-to-severe chronic kidney disease: a subgroup analysis from the German Aortic Valve Registry

Matched comparisons [11,12,13,14] of the impact of CKD on clinical outcomes after TAVI vs. SAVR in patients with severe AS have shown mixed results, but two meta-analyses have suggested overall results to be favourable to TAVI [15, 16]. However, to our knowledge, this is the first study with selection criteria based on recently defined CKD risk thresholds for TAVI and SAVR [10] in which clinical outcomes after TAVI vs. SAVR have been compared using a propensity score adjustment method in patients in which both TAVI and SAVR could possibly be considered according to recent studies. To avoid further artificial subgroup analysis, we used a propensity score weighting method [23, 24].

In our population of patients with moderate-to-severe CKD, TAVI and SAVR therapies showed essentially similar survival results at 1-year follow-up. Thus, our results based on real-world data from a large representative European registry in this subpopulation confirm the appropriateness of recent international recommendations. However, some differences were found regarding the most common complications between both therapies. Specifically, significant bleeding, and myocardial infarction were more common with SAVR, whereas pacemaker need was more common with TAVI. As expected, vascular complications were more common with TAVI and hospital stay was longer with SAVR. These differences in complication rates may be of interest when discussing the options with the patient and to inform the future selection of therapeutic approaches by heart teams when considering specific comorbidities and risks.

Acute kidney injury (AKI) is a matter of concern after SAVR and also after TAVI since the introduction of transcatheter procedures [25]. Some large studies [13, 26, 27] and meta-analyses [28,29,30] have shown a lower risk of postprocedural AKI with TAVI. In our analysis, although a significantly higher need for acute newly onset dialysis with SAVR was confirmed, the need for long-term dialysis was very low and similar with TAVI and SAVR.

Apart from the specific recommendations for patients with particular comorbidities or specific anatomic or procedural characteristics, recent 2021 ESC guidelines suggest a decision on TAVI vs. SAVR by a heart team, based on individual factors and after a discussion with the patient, in those patients younger than 75 years with intermediate surgical risk (4–8 score in STS-PROM/EuroScore II) [7]. Current 2020 ACC/AHA guidelines also provide some specific orientation for the low and intermediate risk (STS ≤ 8) group and suggest considering either SAVR or TAVI in 65-to-80-years-old symptomatic patients after shared decision-making, which requires taking into account expected longevity, valve durability, and individual factors [8].

The impact of CKD on TAVI and SAVR results has been widely recognized and studied. Leaving aside patients with very severe CKD (stage 5) that were not included in our analysis, most real-world data suggest that mild (stage 2) CKD has no prognostic effect, whereas moderate-to-severe CKD (stages 3–4) is a consistent risk factor [10, 11, 31,32,33]. Previous direct comparisons of TAVI vs. SAVR in patients with more-than-mild CKD are scarce and usually include all treated patients, not just those eligible for both therapies according to guidelines. A meta-analysis by Cheng et al. suggested TAVI could be better than SAVR in CKD patients [15]; however, 4 out of 10 studies exclusively included patients on dialysis, and other 4 studies included patients with end-stage renal disease or CKD 5 stage. Similar results have been found in another meta-analysis [16]. D’Errigo et al. reported slightly better results with SAVR, not reaching significance, in 170 propensity score matched pairs of patients in CKD 3b-5 stages from the Italian OBSERVANT registry [11]. On the contrary, Shavit et al., in a small not matched study in mostly very old patients [22], and Kumar et al. in a propensity score-matched study of all-age and all-CKD level patients [34], found better results with TAVI. However, these studies were previous to current guidelines and did not select patients eligible for both TAVI and SAVR based on current age and surgical risk criteria.

The main strengths of our study include the use of a large and representative real-world database at a national level, the selection of patients essentially based on most recent international guidelines; and the statistical meaningful comparison of TAVI and SAVR using modern propensity matched analyses. Moreover, since American and European guidelines are not fully consistent when defining patients who are candidates to TAVI and SAVR, we managed to select a population for which recent American guidelines recommend either TAVI or SAVR, and confirmed the same results in an equivalent population based on European guidelines. Some limitations must also be acknowledged. First, the initial cohorts were not comparable in terms of clinical parameters and a detailed propensity matching procedure was needed to allow meaningful comparisons. As in any observational registry study, even with a very large sample and a prospective follow-up as used in GARY, some unidentified confounding factors could remain in spite of the thorough adjustment, and the results must be interpreted cautiously. Specific randomized controlled trials will be needed to definitely address this important issue, and some ongoing trials are currently comparing SAVR vs TAVI in low/intermediary risk patients (e.g., DEDICATE study [35]). However, properly adjusted analyses from large registries do have a role. They can provide us with some insights on the topic when making therapeutic decisions on our current patients, while waiting for clinical trials’ results. Furthermore, ongoing trials are not specifically focused on our target population (intermediate risk plus moderate-to-severe CKD); conclusions based on trial’s sub-analyses will be highly informative, but will also require caution in interpretation because they do not reflect a truly randomized comparison. Both American and European guidelines have been recently issued; it will take some time to have trials results available for such specific cohorts that are of particular interest for clinicians. Moreover, real-world data have an additional complementary role. Even though clinical trials are the only way to prove an effect, they include highly selected patients that are carefully controlled and are not fully representative for the real patients being treated in daily clinical practice. Our observational results, based on data from the vast majority of procedures performed at a national level, do reflect the real world results in patients undergoing either TAVI or SAVR. Second, our data do not include a substantial proportion of the most recent prosthetic valve devices; however, at the moment there are no reasons to expect different results in CKD patients with the latest devices. Third, using estimated glomerular filtration rates based on creatinine levels is also a limitation. Fourth, our findings are based on short- and mid-term (1-year mortality) outcomes and do not necessarily reflect longer-term results. Fifth, our conclusions are not applicable to CKD 5 patients frequently receiving dialysis, because such patients were excluded from analyses. GARY results for patients on dialysis have been reported separately [20]. And sixth, complications were not reported according to current BARC and VARC criteria, as currently recommended, because such criteria were not yet in common use when GARY registry was started. Despite not using such categorization, our description of complications appears to be, however, fully illustrative.

In conclusion, we performed a propensity score-matched study based on a large nation-wide registry (GARY) in a selected subcohort of intermediate-risk patients for whom both TAVI and SAVR could possibly be considered. Our results confirm that good and similar results are obtained with both therapies in patients with moderate-to-severe CKD and intermediate-risk. These findings can be considered by heart teams and will provide an additional tool for personalized decision-making in severe AS.

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