Congestion, but not low cardiac output, is independently associated with acute kidney injury following contrast agent exposure.

AIM: Contrast-associated acute kidney injury (CA-AKI) is frequently associated with adverse outcomes. Renal perfusion gradient is central to glomerular filtration. While renal vasoconstriction can partially compensate low-output-associated impairment of the renal perfusion gradient, venous congestion cannot be compensated. We hypothesized that congestion is a stronger predictor of CA-AKI than low output in cardiovascular diseases.

METHODS AND

RESULTS

An all-comer single-center cohort of 3,126 cases undergoing coronary angiography with simultaneous right heart catheterization was analyzed. Patients were divided into four categories: congested [right atrial pressure (RAP) >10 mmHg and cardiac index (CI) >=2.2 L/min/m2], low output (RAP <= 10 mmHg and CI: <2.2 L/min/m2), combined (RAP > 10 mmHg and CI <2.2 L/min/m2), and control (CI >= 2.2 L/min/m2 and RAP <= 10 mmHg). The average age of patients was 74 years. CA-AKI occurred in 19% of patients overall. The incidence was highest among patients with congestion, who showed a significantly greater risk compared to controls (24% vs. 15%; Hazard Ratio (HR): 1.49, p = 0.001), whereas low-output patients showed only a trend towards increased risk (20% vs. 15%; HR: 1.22, p = 0.059). In multivariate analysis including the MEHRAN Score, only congestion but not low output was independently associated with AKI (HR for 5 mmHg increase in RAP: 1.07, p = 0.034; HR for CI: 1.00, p = 0.936).

CONCLUSIONS

Venous congestion is independently associated with CA-AKI and is a stronger predictor of CA-AKI than low cardiac output.