Acute kidney injury (AKI) is associated with a poor prognosis after transcatheter aortic valve replacement (TAVR). A paucity of data exists regarding the incidence and effect of AKI after TAVR using the new recommended Valve Academic Research Consortium criteria. At Columbia University Medical Center, 218 TAVR procedures (64.2% transfemoral, 35.8% transapical) were performed from 2008 to July 2011. The creatinine level was evaluated daily until discharge. Using the Valve Academic Research Consortium definitions, the 30-day and 1-year outcomes were compared between patients with significant AKI (AKI stage 2 or 3) and those without significant AKI (AKI stage 0 or 1). Significant AKI occurred in 18 patients (8.3%). Of these 18 patients, 10 (55.6%) had AKI stage 3 and 9 (50%) required dialysis. AKI was associated with a lower baseline mean transvalvular gradient (37.6 ± 11.4 vs 45.6 ± 14.8 mm Hg for no AKI, p = 0.03). After TAVR, the AKI group had a greater hemoglobin decrease (3.6 ± 2.0 vs 2.4 ± 1.3 g/dl, p = 0.01), greater white blood cell elevation at 72 hours (21.09 ± 12.99 vs 13.18 ± 4.82 × 10 3 /μl, p = 0.001), a more severe platelet decrease (118 ± 40 vs 75 ± 43 × 10 3 /μl, p <0.0001), and longer hospitalization (10.7 ± 6.4 vs 7.7 ± 8.5 days, p <0.001). One stroke (5.6%) occurred in the AKI group compared with 3 (1.5%) in the group without AKI (p = 0.29). The 30-day and 1-year rates of death were significantly greater in the AKI group than in the no-AKI group (44.4% vs 3.0%, hazard ratio 18.1, 95% confidence interval 6.25 to 52.20, p <0.0001; and 55.6% vs 16.0%, hazard ratio 6.32, 95% confidence interval 3.06 to 13.10, p <0.0001, respectively). Periprocedural life-threatening bleeding was the strongest predictor of AKI after TAVR. In conclusion, the occurrence of AKI, as defined by the Valve Academic Research Consortium criteria, is associated with periprocedural complications and a poor prognosis after TAVR.
In an effort to improve the quality of clinical research and enable meaningful comparisons among studies, the Valve Academic Research Consortium (VARC) has proposed standardized consensus definitions for important clinical end points after transcatheter aortic valve replacement (TAVR). For acute kidney injury (AKI), The VARC has suggested adopting the serum creatinine criteria from the modified Risk, Injury, Failure, Loss, End-stage kidney disease (RIFLE) classification. In published studies, a paucity of data exists regarding the occurrence and effect of AKI after TAVR using the new recommended VARC criteria. Therefore, we sought to determine the incidence, effect, and predictors of AKI after TAVR using the new VARC definitions and to characterize its temporal pattern.
Methods
We prospectively studied consecutive high-risk patients who presented to the Valve Center at Columbia University Medical Center/New York-Presbyterian Hospital with severe aortic stenosis and received TAVR as a part of the Placement of AoRTic traNscathetER valve (PARTNER) trial ( Clinicaltrials.gov trial no. NCT00530894 ) from July 2008 to July 2011. The subjects were ≥60 years old and had severe, calcific aortic stenosis (aortic valve area <0.8 cm 2 and mean gradient >40 mm Hg or jet velocity >4.0 m/s). All subjects had cardiac symptoms of advanced aortic valve disease. According to iliac and femoral vessel diameter suitability, TAVR was performed using either the transfemoral (22F or 24F sheath) or transapical (29F dedicated system) approach. The Columbia University Medical Center institutional review board approved the study protocol, and all participants provided written informed consent.
The baseline demographic, clinical, and echocardiographic information was collected for all patients according to the PARTNER trial protocol recommendations. The echocardiographic measurements were adjudicated by an independant echocardiographic core laboratory. The left ventricular (LV) volumes and LV ejection fraction were measured using the biplane Simpson volumetric method combining apical 4- and 2-chamber views. A visual LV ejection fraction assessment was also performed. The stroke volume and cardiac output were calculated using the LV volumes measured using the biplane Simpson method and Doppler methods. The atrioventricular peak and mean gradients were obtained using the view showing the maximal velocity. The atrioventricular area or effective orifice area was calculated according to the continuity equation. Using these data, the Society of Thoracic Surgeons risk score for an isolated aortic valve replacement was computed for each subject and is reported as the predicted mortality at 30 days. The creatinine level was evaluated the day before TAVR and daily after TAVR until discharge. Significant AKI was defined as stage 2 or 3 kidney injury, and no significant AKI was defined as stage 0 or 1, according to the VARC recommended modified Risk, Injury, Failure, Loss, End-stage kidney disease criteria ( Table 1 ). The glomerular filtration rate (GFR) was estimated at baseline and then on each day after TAVR using the Cockcroft-Gault equation. The intervals to the peak creatinine level and lowest GFR were recorded.
| Change in serum creatinine (≤72 h) compared to baseline |
| Stage 1: increase in serum creatinine to 150–200% (1.5–2.0 times increase compared to baseline) or increase of >0.3 mg/dl (>26.4 mmol/L) |
| Stage 2: increase in serum creatinine to 200–300% (2.0–3.0 times increase compared to baseline) or increase of >0.3 mg/dl (>26.4 mmol/L) but <4.0 mg/dl (<354 mmol/L) |
| Stage 3 ∗ : increase in serum creatinine to ≥300% (>3 times increase compared to baseline) or serum creatinine of ≥4.0 mg/dl (≥354 mmol/L), with acute increase of ≥0.5 mg/dl (44 mmol/L) |
∗ Patients receiving renal replacement therapy were considered to meet stage 3 criteria, irrespective of other criteria.
All-cause mortality and procedural outcomes were prospectively assessed and adjudicated. The procedural outcomes included in-hospital bleeding, in-hospital stroke, in-hospital vascular complications, and 30-day mortality. Bleeding, vascular complications, and stroke were assessed according to the VARC criteria. One-year mortality was assessed at semiannual follow-up visits or by telephone calls by trained research personnel when follow-up visits were not feasible.
The baseline characteristics between the AKI group (AKI stage 2-3) and no-AKI group (AKI stage 0-1) were compared using the Student t test, chi-square test, or Fisher exact test, as appropriate. The univariate and multivariate predictors of AKI were identified using logistic regression analysis. The association of AKI with clinical outcomes was evaluated using Cox proportional hazards models and tabulated according to the Kaplan-Meier method. All analyses were performed using SAS, version 9.2 (SAS Institute, Cary, North Carolina). p Values <0.05 were considered statistically significant.
Results
From July 2008 to July 2011, 218 consecutive suitable patients with severe symptomatic aortic stenosis underwent TAVR using a 23- or 26-mm Edwards SAPIEN transcatheter valve. The transfemoral approach was used in 140 patients (64.2%) and the transapical approach in 78 patients (35.8%). Of the total population, AKI occurred in 18 patients (8.3%) and no AKI (stage 0-1) in 200 (91.7%; Figure 1 ). Of the 18 AKIs, 12 occurred in the first half (12 of 109; 11.0%) and 6 in the second half (6 of 109; 5.5%) of our experience. In the AKI group, 10 patients (55.6%) had AKI stage 3, 9 of whom (50% of 18) required dialysis. No differences were seen in the baseline characteristics between the 2 groups, except for a lower baseline transvalvular mean gradient (37.6 ± 11.4 vs 45.6 ± 14.8 mm Hg, p = 0.03) in the AKI group ( Table 2 ).
| Variable | AKI 0-1 (n = 200) | AKI 2-3 (n = 18) | Combined (n = 218) | p Value |
|---|---|---|---|---|
| Age (yrs) | 85.5 ± 7.7 | 84.0 ± 7.4 | 85.4 ± 7.7 | 0.39 |
| Women | 49% (97) | 50% (9) | 48% (106) | 0.90 |
| Society of Thoracic Surgeons score | 11.65 ± 4.74 | 12.84 ± 4.32 | 11.75 ± 4.71 | 0.23 |
| Weight (kg) | 67.5 ± 16.6 | 67.9 ± 17.5 | 67.5 ± 16.6 | 0.91 |
| Height (cm) | 163.6 ± 12.0 | 163.3 ± 9.8 | 163.6 ± 11.8 | 0.96 |
| Body surface area (m 2 ) | 1.72 ± 0.27 | 1.72 ± 0.24 | 1.72 ± 0.27 | 0.84 |
| Body mass index (kg/m 2 ) | 25.15 ± 5.40 | 25.35 ± 5.94 | 25.16 ± 5.44 | 0.89 |
| Diabetes | 28% (55) | 38% (7) | 29% (62) | 0.31 |
| Hypertension | 83% (165) | 83% (15) | 83% (180) | 1.00 |
| Dyslipidemia | 63% (125) | 67% (12) | 63% (137) | 0.73 |
| Atrial fibrillation/flutter | 41% (82) | 44% (8) | 41% (90) | 0.78 |
| Previous percutaneous coronary intervention | 40% (80) | 44% (8) | 40% (88) | 0.71 |
| Previous coronary artery bypass grafting | 40% (80) | 50% (9) | 40% (89) | 0.41 |
| Previous pacemaker placement | 30% (59) | 44% (8) | 31% (67) | 0.19 |
| Previous stroke | 10% (19) | 11% (2) | 10% (21) | 0.69 |
| Peripheral vascular disease | 24% (47) | 33% (6) | 24% (53) | 0.39 |
| Tobacco use | 9% (18) | 17% (3) | 10% (21) | 0.39 |
| Severe chronic obstructive pulmonary disease | 29% (57) | 39% (7) | 29% (64) | 0.35 |
| Ejection fraction (%) | 48.2 ± 15.8 | 49.5 ± 16.4 | 48.3 ± 15.8 | 0.63 |
| Mean gradient (mm Hg) | 45.6 ± 14.8 | 37.6 ± 11.4 | 44.9 ± 14.7 | 0.03 |
| Aortic valve area (cm 2 ) | 0.58 ± 0.17 | 0.55 ± 0.18 | 0.58 ± 0.17 | 0.72 |
| Annulus size (mm) | 22.8 ± 1.9 | 23.0 ± 2.1 | 22.8 ± 1.9 | 0.80 |
| Approach | ||||
| Transfemoral | 65% (131) | 50% (9) | 64% (140) | 0.19 |
| Transapical | 35% (69) | 50% (9) | 36% (78) | 0.19 |
| Valve size (mm) | 0.41 | |||
| 23 | 38 (75) | 44% (8) | 38% (83) | |
| 26 | 63% (125) | 56% (10) | 62% (135) | |
The absolute and relative changes in renal function after TAVR compared to baseline are listed in Table 3 . No differences were seen in the baseline creatinine or amount of contrast used between the 2 groups. Of the total population, 96 patients (44.0%) had improved renal function (lower creatinine and greater GFR) from baseline to discharge. The laboratory findings before and after TAVR for both groups are listed in Table 4 . The hemoglobin decrease, platelet decrease, and white blood cell elevation at 72 hours after procedure were more pronounced in the AKI group.
| Variable | AKI 0-1 (n = 200) | AKI 2-3 (n = 18) | Combined (n = 218) | p Value |
|---|---|---|---|---|
| Baseline creatinine (mg/dl) | 0.81 | |||
| Mean ± standard deviation | 1.3 ± 0.5 | 1.4 ± 0.6 | 1.3 ± 0.5 | |
| Range | 0.5–2.8 | 0.7–2.8 | 0.5–2.8 | |
| Baseline glomerular filtration rate (ml/min/1.73 m 2 ) | 0.59 | |||
| Mean ± standard deviation | 56.02 ± 21.77 | 52.97 ± 19.21 | 55.77 ± 21.55 | |
| Range | 17.76–175.23 | 22.69–97.89 | 17.76–175.23 | |
| Postoperative | ||||
| Peak creatinine (mg/dl) | 1.42 ± 0.57 | 2.97 ± 1.31 | 1.55 ± 0.78 | <0.0001 |
| Final glomerular filtration rate (ml/min/1.73 m 2 ) | 52.27 ± 22.98 | 22.24 ± 8.95 | 49.79 ± 23.65 | <0.0001 |
| Delta creatinine (peak − baseline) (mg/dl) | <0.0001 | |||
| Mean ± standard deviation | 0.12 ± 0.31 | 1.61 ± 1.21 | 0.25 ± 0.61 | |
| Range | −1.00–1.10 | 0.30–5.00 | −1.00–5.00 | |
| Change in creatinine (%) | <0.0001 | |||
| Mean ± standard deviation | 9.83 ± 22.89 | 131.77 ± 98.49 | 19.90 ± 48.70 | |
| Range | −40.00–88.89 | 10.71–454.55 | −40.00–454.55 | |
| Change in glomerular filtration rate (%) | <0.0001 | |||
| Mean ± standard deviation | −6.08 ± 21.77 | −55.40 ± 18.71 | −10.16 ± 25.44 | |
| Range | −54.69–80.33 | −86.15–11.11 | −86.15–80.33 | |
| Interval to peak creatinine postoperatively | <0.0001 | |||
| Median | 2.0 | 3.0 | 2.0 | |
| Interquartile range | 1.0–3.0 | 2.0–7.0 | 1.0–3.0 | |
| Mean ± standard deviation | 2.1 ± 1.5 | 4.0 ± 2.4 | 2.2 ± 1.7 | |
| Range | 1.0–7.0 | 1.0–8.0 | 1.0–8.0 | |
| Contrast volume (ml) | 103.84 ± 58.53 | 122.61 ± 96.79 | 105.39 ± 62.47 | 0.78 |
| Dialysis required (%) | 0.0% (0) | 50.0% (9) | 4.1% (9) | <0.0001 |
| Variable | AKI 0-1 (n = 200) | AKI 2-3 (n = 18) | Combined (n = 218) | p Value |
|---|---|---|---|---|
| Hemoglobin (g/dl) | ||||
| Baseline | 11.2 ± 1.5 | 11.3 ± 1.5 | 11.2 ± 1.5 | 0.71 |
| Postoperative nadir | 8.8 ± 1.4 | 7.8 ± 1.6 | 8.7 ± 1.5 | 0.01 |
| Decrease | 2.4 ± 1.3 | 3.6 ± 2.0 | 2.5 ± 1.4 | 0.01 |
| Transfusion received (n) | 0.60 ± 1.4 | 1.1 ± 1.4 | 0.64 ± 1.2 | 0.17 |
| Transfusion received (≥1) (%) | 26.5% (53) | 44.4% (8) | 28.0% (61) | 0.09 |
| White blood cell count (×10 3 /μL) | ||||
| Baseline | 7.37 ± 2.65 | 8.45 ± 3.04 | 7.46 ± 2.70 | 0.10 |
| Peak at 72 h | 13.18 ± 4.82 | 21.09 ± 12.99 | 13.83 ± 6.27 | 0.001 |
| Platelet count (×10 3 /μL) | ||||
| Baseline | 200 ± 65 | 226 ± 80 | 202 ± 66 | 0.22 |
| Postoperative nadir | 125 ± 50 | 107 ± 89 | 124 ± 54 | 0.11 |
| Decrease | 75 ± 43 | 118 ± 40 | 78 ± 44 | <0.0001 |
| Troponin (ng/ml) | ||||
| Baseline | 0.13 ± 0.23 | 0.04 ± 0.02 | 0.12 ± 0.22 | 0.65 |
| Peak | 3.64 ± 13.24 | 6.29 ± 11.25 | 3.90 ± 13.04 | 0.08 |
| Creatine kinase-MB (IU/L) | ||||
| Baseline | 2.99 ± 1.69 | 2.33 ± 1.30 | 2.94 ± 1.67 | 0.20 |
| Peak | 9.68 ± 12.97 | 3.80 ± 2.56 | 9.33 ± 12.67 | 0.10 |
| Brain natriuretic peptide (pg/ml) | ||||
| Baseline | 1,473.97 ± 1,634.93 | 1,250.54 ± 1,159.96 | 1,455.64 ± 1,600.11 | 0.67 |
| At discharge | 1,146.0 ± 1,429.9 | 1,386.4 ± 1,157.3 | 1,162.7 ± 1,410.6 | 0.27 |
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