Mitral valve surgery and acute renal injury: port access versus median sternotomy

Background Many outcomes and complications of minimally invasive and conventional cardiac surgery await comparison. Patients undergoing mitral valve surgery commonly sustain renal injury. Using peak postoperative fractional change of serum creatinine as a marker of renal injury, we tested the hypothesis that mitral valve surgery with port access minithoracotomy (Port) and conventional surgery with a median sternotomy (MS) incision are associated with different degrees of acute renal injury. Methods We evaluated data from all isolated mitral valve operations by a single surgeon between 1990 and 2000 (MS = 90, Port = 227). We also performed a secondary analysis of mitral valve surgeries performed by both MS and Port approaches in a concurrent period from 1996 to 2002 (MS = 93, Port = 240). Univariable and multivariable tests were used to determine the association of surgical technique with peak postoperative creatinine (CrmaxPost) and peak postoperative fractional change in creatinine (%ΔCr); p less than 0.05 was considered significant. Results In our analysis that accounted for the date of surgery, we observed a highly significant independent association between surgical approach and %ΔCr, indicating a greater risk of acute renal injury in the MS group (F value 13.33; p = 0.0003). Similar findings were noted in the secondary (time-concurrent) analysis of %ΔCr (F value 12.65; p = 0.0176). Conclusions We present retrospective evidence of reduced acute renal injury associated with the port access technique in mitral valve surgery patients. Our findings suggest that a port access minithoracotomy approach to mitral valve surgery may be preferable to conventional methods for patients with high renal risk.