Abstract
Background
Baseline comorbidities including renal dysfunction are frequently found in patients treated with transcatheter aortic valve replacement (TAVR) and may increase the risks of acute kidney injury (AKI), although some of them may actually improve renal function. We aimed to evaluate the potential of TAVR to acutely improve post-procedure renal function.
Methods
This is a prospective single-center registry of consecutive patients with severe symptomatic aortic stenosis treated by transfemoral TAVR. Creatinine levels were determined at baseline and daily until hospital discharge. AKI was defined according to VARC-2 criteria. Patients who had improvement of creatinine levels >25% were classified as having TAVR induced renal function improvement (TIRFI).
Results
A total of 69 patients undergoing TAVR were included, with a mean age of 83.0±7.4 years, being 24.6% diabetics, with a median STS score of 9.2 (5.1–21.6). Using the VARC-2 criteria, the majority of patients (64.6%) did not have renal impairment, while AKI was detected in 35.4% of the patients. Importantly, in those with prior severe renal dysfunction (clearance <30 mL/min/1.73 m 2 ) or diabetes, AKI reached up to 50% and 56.3% of the patients, respectively. Conversely, acute kidney recovery (TIRFI) occurred in 12 patients (18.5%) being >50% in 1 patient (1.5%), and at hospital discharge the majority of the patients (88.6%) left the hospital in their original or better renal function categories.
Conclusion
Despite multiple comorbidities in a selected TAVR-population and the use of contrast media, TAVR did not impair renal function in a majority of patients, with a significant proportion of them rather having acute renal function improvement.
1
Introduction
Radiological diagnostic and therapeutic procedures using intravascular iodinated contrast media injections are increasingly used in the daily practice, with a significant impact in the incidence of procedure-related acute kidney injury (AKI) . Overall, the risk of renal function impairment associated with such procedures is low (0.6%–2.3%), yet in some high-risk patient subgroups it may be as high as 50% . A number of risk factors have been argued to accrue the incidence of AKI, including pre-existing renal impairment, diabetes mellitus and various cardiac conditions such as heart failure, coronary artery or valvular heart disease . Importantly, the combination of such risk factor may heighten the risks for developing AKI .
There is a subgroup of patients where such combination of risk factors may be of particular importance, such as those older patients with high-risk severe aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) . Previous renal function impairment (30%–50% of this population) together with other clinical comorbidities and the pharmacological treatment of severe AS (e.g. diuretic administration) may increase the risk of developing AKI and compromise renal function in such patients. Of note, renal impairment at baseline as well as post-intervention renal function deterioration has been shown to be relatively frequent in patients treated with TAVR, and to adversely affect both the short- and long-term prognosis .
Paradoxically, to what might be expected, and unlike non-TAVR catheter-based interventions, TAVR may also lead to rapid improvements in the overall clinical condition and hemodynamic status, which may ultimately help post-procedure kidney recovery. Thus far, the apparent contradictory benign effects of TAVR on renal function have been poorly described. The aim of the present study was therefore to evaluate the potential of TAVR to acutely improve renal function in a consecutive cohort of patients with high-risk severe symptomatic AS.
2
Methods
2.1
Study design and patient population
A total of 69 consecutive patients who underwent transfemoral TAVR were included, with both self-expandable and balloon-expandable valves. One patient who died during the procedure and 3 patients on chronic dialysis were excluded from the present analysis, so that the final population comprised 65 patients. Eligibility for TAVR, valve type and access were determined as previously reported . Clinical, procedural and echocardiography data were prospectively gathered into a pre-set TAVR database. Outcomes were defined according to the Valve Academic Research Consortium 2 (VARC-2) criteria . The registry design and procedures complied with the principles of good clinical practice and the Declaration of Helsinki. Ethics committee approved the study and written informed consent was given for the procedures.
2.2
Evaluation of renal function
Serum creatinine was collected at baseline and daily after the procedure until hospital discharge. Creatinine clearance was estimated by the Modified Diet on Renal Disease (MDRD) formula [(eGFR =186 × SCr − 1.154 × Age − 0.203 × (1.212 if black) × (0.742 if female)] . Based on clearance estimation the renal function was classified according to the Kidney Disease Quality Outcome Initiative (KDQOI) , as follows: normal–mild renal dysfunction: eGFR ≥60 mL/min/1.73 m 2 ; moderate renal dysfunction: eGFR =30–59 mL/min/1.73 m 2 ; severe renal dysfunction: eGFR <30 mL/min/1.73 m 2 .
The renal function after TAVR was analyzed according to 2 parameters: i) presence of renal failure after TAVR (VARC-II definition); ii) renal function at 72 h and at hospital discharge, comparing both levels in relation to the pre-TAVR. AKI was defined as an absolute reduction in kidney function within 72 h according to the modified RIFLE classification . AKI was classified as follows: mild — increase in serum creatinine 150% to 200% or increase of ≥0.3 mg/dl (≥26.4 mmol/l); moderate — increase in serum creatinine 200% to 300%; severe — increase in serum creatinine ≥300% or serum creatinine ≥4.0 mg/dL (≥353.6 mmol/l) with an acute increase of at least 0.5 mg/dL (44 mmol/l), or need for dialysis.
The renal function at 72 h and at hospital discharge was evaluated with respect to the creatinine levels of the baseline and it was classified as improved, neutral or worsened. Patients who had improvement of creatinine levels within 72 h > 25% were classified as having TAVR induced renal function improvement (TIRFI). These patients were further classified as follows: mild acute kidney recovery (serum creatinine 25% to 50% lower than baseline); and moderate or accentuate acute kidney recovery (serum creatinine >50% compared to baseline). Those patients with no change or improvement in creatinine levels up to 25% were considered as neutral.
2.3
Statistical analysis
Continuous variables are presented as mean (standard deviation) or median (25th to 75th interquartile range) depending on variable distribution. Statistical analysis was performed using SPSS 22.0 statistical software packages (SPSS Inc., Chicago, IL, USA). Group comparisons were analyzed using the Student t test or Wilcoxon rank sum test. The chi-square test and the Fisher exact test were performed for categorical variables.
2
Methods
2.1
Study design and patient population
A total of 69 consecutive patients who underwent transfemoral TAVR were included, with both self-expandable and balloon-expandable valves. One patient who died during the procedure and 3 patients on chronic dialysis were excluded from the present analysis, so that the final population comprised 65 patients. Eligibility for TAVR, valve type and access were determined as previously reported . Clinical, procedural and echocardiography data were prospectively gathered into a pre-set TAVR database. Outcomes were defined according to the Valve Academic Research Consortium 2 (VARC-2) criteria . The registry design and procedures complied with the principles of good clinical practice and the Declaration of Helsinki. Ethics committee approved the study and written informed consent was given for the procedures.
2.2
Evaluation of renal function
Serum creatinine was collected at baseline and daily after the procedure until hospital discharge. Creatinine clearance was estimated by the Modified Diet on Renal Disease (MDRD) formula [(eGFR =186 × SCr − 1.154 × Age − 0.203 × (1.212 if black) × (0.742 if female)] . Based on clearance estimation the renal function was classified according to the Kidney Disease Quality Outcome Initiative (KDQOI) , as follows: normal–mild renal dysfunction: eGFR ≥60 mL/min/1.73 m 2 ; moderate renal dysfunction: eGFR =30–59 mL/min/1.73 m 2 ; severe renal dysfunction: eGFR <30 mL/min/1.73 m 2 .
The renal function after TAVR was analyzed according to 2 parameters: i) presence of renal failure after TAVR (VARC-II definition); ii) renal function at 72 h and at hospital discharge, comparing both levels in relation to the pre-TAVR. AKI was defined as an absolute reduction in kidney function within 72 h according to the modified RIFLE classification . AKI was classified as follows: mild — increase in serum creatinine 150% to 200% or increase of ≥0.3 mg/dl (≥26.4 mmol/l); moderate — increase in serum creatinine 200% to 300%; severe — increase in serum creatinine ≥300% or serum creatinine ≥4.0 mg/dL (≥353.6 mmol/l) with an acute increase of at least 0.5 mg/dL (44 mmol/l), or need for dialysis.
The renal function at 72 h and at hospital discharge was evaluated with respect to the creatinine levels of the baseline and it was classified as improved, neutral or worsened. Patients who had improvement of creatinine levels within 72 h > 25% were classified as having TAVR induced renal function improvement (TIRFI). These patients were further classified as follows: mild acute kidney recovery (serum creatinine 25% to 50% lower than baseline); and moderate or accentuate acute kidney recovery (serum creatinine >50% compared to baseline). Those patients with no change or improvement in creatinine levels up to 25% were considered as neutral.
2.3
Statistical analysis
Continuous variables are presented as mean (standard deviation) or median (25th to 75th interquartile range) depending on variable distribution. Statistical analysis was performed using SPSS 22.0 statistical software packages (SPSS Inc., Chicago, IL, USA). Group comparisons were analyzed using the Student t test or Wilcoxon rank sum test. The chi-square test and the Fisher exact test were performed for categorical variables.
3
Results
3.1
Baseline and procedural characteristics
The baseline clinical and echocardiographic characteristics overall and according to the presence of TIRFI are shown in Table 1 . The mean age was 83.0 ± 7.4 years, with 46.2% being male and 24.6% of diabetic patients. The median logistic EuroScore and STS-PROM were 13.3 [7.9–23.2] and 9.2 [5.1–20.9], respectively.
| All patients (n = 65) | TIRFI (n = 12) | No improvement (n = 53) | P value | |
|---|---|---|---|---|
| Clinical characteristics | ||||
| Age (years) | 83.0 ± 7.4 | 83.4 ± 7.1 | 82.0 ± 7.5 | 0.831 |
| Male gender | 30 (46.2) | 5 (41.7) | 25 (47.2) | 0.730 |
| Body mass index (kg/m 2 ) | 25.4 ± 4.5 | 25.3 ± 3.0 | 25.4 ± 4.8 | 0.933 |
| NYHA class | 0.467 | |||
| I–II | 15 (23.1) | 3 (25) | 12 (22.6) | |
| III–IV | 50 (76.9) | 9 (75) | 41 (77.3) | |
| Hypertension | 44 (67.7) | 8 (66.7) | 36 (67.9) | 0.933 |
| Diabetes | 16 (24.6) | 3 (25) | 13 (24.5) | 0.973 |
| Dyslipidemia | 24 (36.9) | 7 (58.3) | 17 (32.1) | 0.089 |
| COPD | 8 (12.3) | 2 (16.7) | 6 (11.3) | 0.611 |
| Chronic atrial fibrillation | 9 (13.8) | 3 (25.0) | 6 (11.3) | 0.349 |
| Coronary artery disease | 40 (61.5) | 10 (83.4) | 30 (56.6) | 0.197 |
| Prior MI | 12 (18.5) | 2 (16.7) | 10 (19.2) | 0.837 |
| Prior PCI | 17 (26.2) | 4 (33.3) | 13 (24.5) | 0.531 |
| Prior CABG | 19 (29.2) | 4 (33.3) | 15 (28.3) | 0.729 |
| Peripheral vascular disease | 17 (26.2) | 3 (25) | 14 (26.4) | 0.920 |
| Prior Stroke | 6 (9.2) | 0 (0) | 6 (11.3) | 0.221 |
| Logistic EuroScore (%) | 13.3 [7.9–23.2] | 22.4 [7.8–38.1] | 18.3 [7.9–22] | 0.493 |
| STS-PROM score (%) | 9.2 [5.1–20.9] | 10.1 [7–13.7] | 13.8 [4.9–22.2] | 0.493 |
| eGFR (ml/min) | 54 ± 19 | 40.3 ± 15.2 | 57.3 ± 18.8 | 0.037 |
| eGFR <60 ml/min | 44 (67.7) | 11 (91.7) | 33 (62.3) | 0.084 |
| Echocardiographic variables pre-TAVR | ||||
| Left ventricular ejection fraction (%) | 54.8 ± 14.2 | 62 ± 39 | 55.1 ± 13.9 | 0.784 |
| Mean aortic valve gradient (mmHg) | 47.0 ± 17.6 | 43 ± 34 | 48 ± 18.8 | 0.223 |
| Peak aortic valve gradient (mmHg) | 75.8 ± 27.6 | 75 ± 60 | 78 ± 28.4 | 0.153 |
| Aortic valve area (cm 2 ) | 0.74 ± 0.21 | 0.80 ± 0.60 | 0.73 ± 0.21 | 0.451 |
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