Natural course and risk factors for impaired renal function during the first year after heart transplantation

Background

Post-operative renal failure is a common and potentially hazardous complication after heart transplantation (HTx). In this study we characterized pre- and post-operative risk factors for acute renal failure requiring renal replacement therapy (RRT).

Methods

Ninety-three patients underwent orthotopic HTx between 2000 and 2007. The risk factors for RRT during the early post-operative period and predictors contributing to impaired renal function within the first post-transplant year were analyzed by regression analysis. The impact of pre-operative renal failure and early post-operative RRT on renal function within 1 year were studied.

Results

Before HTx, 55% of patients (51 of 93) had normal renal function or mild renal failure (glomerular filtration rate [GFR] >60 ml/min/1.73 m²). Before discharge from the hospital, 25% (23 of 93) developed acute renal failure and required RRT. Of these, 16% (8 of 51) had pre-operatively normal renal function or mild renal failure, and 36% (15 of 42) had moderate or severe renal failure (GFR <60 ml/min/1.73 m²; p = 0.02). The prognosticators for early RRT were prolonged graft dysfunction, re-admission to the operating room due to post-operative bleeding, poor diuresis during surgery (<1,000 ml), pre-operative pacemaker implantation, intubation time >24 hours, pre-operative GFR <60 ml/min/1.73 m², post-operative troponin T >6 μg/liter and pre-operative use of angiotensin receptor blocker.

Conclusions

Pre-operative renal failure is a significant risk factor for RRT during the immediate post-operative period and requires aggressive treatment. Patients with pre-operative renal failure secondary to severe heart failure and acute post-operative renal failure requiring RRT tend to recover within the first year post-HTx.

Keywords: heart transplantation, renal function, immunosuppression, glomerular filtration rate, 4-MDRD equation