Reduced renal elimination of larger molecules is a strong predictor for mortality.

Renal dysfunction is a major risk factor for premature death and has been studied extensively. A new renal syndrome, shrunken pore syndrome (SPS), confers higher mortality in all studied populations. SPS is a condition in which cystatin C-based estimation of glomerular filtration rate (eGFRcystatin C) is ≥ 60% than creatinine-based estimation of glomerular filtration rate (eGFRcreatinine). We aimed to study the impact of SPS on mortality in a cohort of patients with follow up of up to 10 years. This was a retrospective single centre cohort study. We enrolled 3993 consecutive patients undergoing elective cardiac surgery. Outcome was evaluated using Kaplan Meier analysis and multivariable Cox regression. 1-, 5- and 10-year survival for patients with SPS was 90%, 59% and 45%, and without SPS 98%, 88% and 80% (p < 0.001). SPS was found to be an independent predictor for mortality with an HR of 1.96 (95% CI 1.63-2.36). SPS negatively affected survival regardless of pre-operative renal function. SPS is an independent predictor for mortality after elective cardiac surgery, equal to or greater than risk factors such as diabetes, impaired left ventricular function or renal dysfunction. SPS affected mortality even in patients with normal eGFR.Clinical registration number: ClinicalTrials.gov, ID NCT04141072.