The mortality increase in cardiac surgery patients associated with shrunken pore syndrome correlates with the eGFR_{cystatin C}/eGFR_creatinine-ratio

Abstract

Shrunken pore syndrome (SPS) is a condition in which estimated glomerular filtration rate (eGFR) based upon cystatin C is lower than eGFR based upon creatinine. It has been associated with increased mortality even in the presence of normal GFR in both a cardiac surgical population and a general population. No systematic studies of the variation in eGFR_{cystatin C}/eGFR_creatinine-ratio used for SPS diagnosis have been published. This study aims to evaluate whether early and midterm mortality following elective cardiac surgery varies with the ratio used to identify SPS. Preoperative levels of cystatin C and creatinine were analysed in 4007 patients undergoing elective coronary artery bypass grafting (CABG) and/or surgical aortic valve replacement (sAVR). The eGFR_{cystatin C}/eGFR_creatinine-ratio was calculated based on the equation pairs CKD-EPI_{cystatin C}/CKD-EPI_creatinine and CAPA/LMrev. The overall 1- and 3-year all-cause mortality was 2.9 and 6.8%, respectively. Mean follow-up time was 3.6 years. Mortality markedly and progressively increased with a decrease in the eGFR_{cystatin C}/eGFR_creatinine-ratio for both equation pairs. An increase in mortality was noted already when the ratio decreased from 1.0 to 0.90. To facilitate the clinical decisions based upon the SPS-defining eGFR_{cystatin C}/eGFR_creatinine-ratio, we calculated both the ratios defining the highest combined sensitivity and specificity and the ratios producing a high specificity of 95%, finding different cut-off for these scenarios.

Keywords:

• Cardiac surgery
• coronary artery bypass
• aortic valve replacement
• creatinine
• cystatin C
• glomerular filtration rate
• shrunken pore syndrome

Disclosure statement

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the article.

Additional information

Funding

The investigation was supported by grants from Skåne University Hospital Funds and the Medical Faculty of Lund University.