NEW YORK (Reuters Health) – The incidence of acute kidney injury after transcatheter aortic valve implantation (TAVI) is higher than 10%, a Canadian study shows. As reported in an early online issue of the European Heart Journal, these injuries increase the risk of postprocedural death by a factor of 4.
Still, in patients with chronic kidney disease at baseline, acute kidney injury is less common with a transcatheter approach than with open surgery, the authors found.
"Acute kidney injury is one of the most serious complications following cardiac surgery," senior author Dr. Josep Rodes-Cabau, from Laval University, Quebec City, commented to Reuters Health. "In patients with severe aortic stenosis, TAVI has emerged as an alternative to surgery for those patients considered at very high or prohibitive surgical risk, but very few data were available on the occurrence and prognosis of acute kidney injury following TAVI."
The need for contrast media, short periods of extreme hypotension, and manipulation of large catheters in the aorta all add to the risk for kidney injury after TAVI, he and his colleagues point out.
Their analysis included data on 213 patients (mean age 82 years) who underwent TAVI for severe aortic stenosis between 2005 and 2009. One hundred nineteen of these patients had pre-existing chronic kidney disease; this group was compared with a control group of 104 chronic kidney disease patients who had isolated surgical aortic valve replacement.
Acute kidney injury was defined as a drop in estimated glomerular filtration rate (EGFR) of 25% or more in the 48 hours following the procedure, or a need for hemodialysis during that hospitalization.
This endpoint occurred in 25 patients (11.7%), with 1.4% requiring dialysis. Independent predictors of acute kidney injury following TAVI were hypertension, chronic obstructive pulmonary disease, and red blood cell transfusion.
In-hospital mortality was 28% in patients with kidney injury, versus 7.4% among those with no kidney injury (p = 0.005), according to the researchers.
When the two cohorts with baseline chronic kidney disease were compared, the transcatheter group was older, with more comorbidities and a lower mean EGFR, than the surgical group (p < 0.0001 for each).
But despite its higher risk profile, the TAVI group had a lower rate of acute kidney injury than the surgery group (9.2% vs 25.9%, odds ratio 0.29, p = 0.001).
"In patients undergoing TAVI, optimal pre- and post-procedural hydration is very important, and our results suggest that efforts should be made to avoid unnecessary blood transfusions," Dr. Rodes-Cabau commented.
He added, "Continued efforts to minimize the amount of contrast media in these procedures (contrast dilution, contrast hand injections, echocardiography guidance for valve positioning) are also important in further reducing the risk of acute kidney injury following TAVI."
Because acute kidney injury nearly quadrupled the risk of death, the researchers recommend assessment of kidney function within 48 hours.
The authors caution that their results may not apply to lower volume hospitals, "especially at the beginning of the learning curve" for the transcatheter approach. Also, they consider their findings hypothesis generating and in need of confirmation by prospective randomized trials.
Eur Heart J 2009.