Shrunken Pore Syndrome is associated with a sharp rise in mortality in patients undergoing elective coronary artery bypass grafting

Figures & data

Table I. Preoperative characteristics of the study cohort (n = 1638).

Variable	Mean (±SD)/ No. (%)
Age (year)	67.4 (± 9.6)
Female gender	343 (21%)
Body Mass Index (kg/m^2)	27.5 (± 3.8)
Diabetes	405 (25%)
COPD	180 (11%)
eGFR (mL/min/1.73 m^2) according to: CAPA LMrev CKD-EPIcystatin C CKD-EPIcreatinine Anemia	67 (± 19)70 (± 17)68 (± 22)78 (± 19)142 (9%)
Previous vascular surgery	81 (5%)
Peripheral vascular disease	212 (13%)
History of cerebrovascular injury	150 (9%)
LVEF 30–50%	338 (21%)
LVEF < 30%	115 (7%)
Previous myocardial infarction	798 (49%)
Euro score – additive	4.3 (±3.1)
NYHA class
I	522 (32%)
II	527 (32%)
III	472 (29%)
IV	117 (7%)
CCS class
I	201 (12%)
II	750 (46%)
III	525 (32%)
IV	162 (10%)
IABP before surgery	21 (1%)
Preoperative hemoglobin (g/L)	136.4 (± 15.0)

Presented as either mean (± standard deviation) for continuous variables or number (percent) for dichotomous variables. CCS, Canadian Cardiovascular Society; COPD, chronic obstructive pulmonary disease; IABP, intra-aortic balloon pump; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association.

Table II. Postoperative characteristics of the study cohort (n = 1638).

Outcomes	Mean (± SD)/No. (%)
Use of CBP	1638 (100%)
Perfusion time (min)	77.2 (± 26.2)
Cross clamp time (min)	46.1 (± 17.8)
IABP after surgery	23 (0.014%)
Time in the ICU (h)	23 (20–27)*
Sepsis	10 (0.6%)
Myocardial infarction	8 (0.5%)
Permanent stroke	4 (0.2)%
Pneumonia	18 (1.1%)
RRT	10 (0.6%)
Atrial fibrillation	321 (19.6%)
Time in ventilator (min)	300 (210–430)*
Re-operated for bleeding	33 (2.0%)
Re-operated for mediastinitis	14 (0.9%)
Erythrocytes transfused (units)	1.2 (± 2.6)
Plasma transfused (units)	0.51 (± 2.4)
Platelets transfused (units)	0.22 (± 0.84)

Presented as either mean (± standard deviation) for continuous variables, number (percent) for dichotomous variables, or as median (interquartile range) for outcome variables that are skewed*. CBP, cardiopulmonary bypass; IABP, intra-aortic balloon pump; ICU, Intensive care unit; RRT, renal replacement therapy.

Table III. Cox multivariate analysis of patients with and without Shrunken Pore Syndrome. (A) Defined by the equation pair CKD-EPI_{cystatin C} and CKD-EPI_creatinine with a cut-off of 60% (i.e. eGFR_{cystatin C} ≤ 0.6 eGFR_creatinine). (B) Defined by the equation pair CAPA and LMrev with a cut-off of 60% (i.e. eGFR_{cystatin C} ≤ 0.6 eGFR_creatinine). (C) Defined by the equation pair CAPA and LMrev with a cut-off of 70% (i.e. eGFR_{cystatin C} ≤ 0.7 eGFR_creatinine).

	(A) CKD-EPI, cut-off 0.6			(B) CAPA-LMrev, cut-off 0.6			(C) CAPA-LMrev, cut-off 0.7
	p-value	HR	95% CI	p-value	HR	95% CI	p-value	HR	95% CI
Age (per year)	0.004588	1.036	1.011–1.062	0.001181	1.042	1.016–1.068	0.000745	1.044	1.018–1.070
Peripheral vascular disease	0.004756	1.825	1.202–2.771	0.008423	1.751	1.154–2.657	0.003787	1.852	1.220–2.811
LVEF< 30%	0.110203	1.487	0.914–2.419	0.077655	1.552	0.952–2.530	0.155834	1.426	0.873–2.329
Hours in ICU	0.004740	1.003	1.001–1.005	0.012124	1.002	1.001–1.004	0.004223	1.003	1.001–1.005
Preoperative Hemoglobin (g/L)	0.004137	0.981	0.969–0.994	0.001112	0.979	0.966–0.991	0.004042	0.981	0.968–0.994
Log units of plasma given	0.000009	1.701	1.345–2.151	0.000001	1.826	1.448–2.302	0.000002	1.763	1.399–2.221
Preoperative eGFRmean (mL/min/1.73 m^2)	0.000003	0.975	0.965–0.985	0.000018	0.975	0.963–0.986	0.000024	0.975	0.963–0.986
Shrunken Pore Syndrome	0.000016	2.742	1.733–4.339	0.000166	3.445	1.810–6.557	0.000006	2.941	1.842–4.694

HR, hazard ratio; CI, confidence interval; LVEF, left ventricle ejection fraction; ICU, Intensive care unit.

Figure 1. Calculations using the CKD-EPI formulas based on cystatin C or creatinine. Survival after coronary artery bypass surgery for patients with eGFR > 60 mL/min/1.73 m² (A) with Shrunken Pore Syndrome (SPS, red broken line) and without (blue solid line). Patients with eGFR< 60 mL/min/1.73 m² are seen in (B). The cut-off level for SPS was 0.6. For both levels of eGFR: p < 0.001 with log-rank test.

Figure 2. Calculations using the CAPA and LMrev formulas based on cystatin C or creatinine. Survival after coronary artery bypass surgery for patients with eGFR > 60 mL/min/1.73 m² (A) with Shrunken Pore Syndrome (SPS, red broken line) and without (blue solid line). Patients with eGFR < 60 mL/min/1.73 m² are seen in (B). The cut-off level for SPS was 0.6. For both levels of eGFR: p < 0.001 with log-rank test.

Figure 3. Calculations using the CAPA and LMrev formulas based on cystatin C or creatinine. Survival after coronary artery bypass surgery for patients with eGFR > 60 mL/min/1.73 m² (A) with Shrunken Pore Syndrome (SPS, red broken line) and without (blue solid line). Patients with eGFR < 60 mL/min/1.73 m² are seen in (B). The cut-off level for SPS was 0.7. For both levels of eGFR: p < 0.001 with log-rank test.

Table IV. Number of patients defined as suffering from ‘Shrunken Pore Syndrome’ by different GFR-estimating equation constellations.

Estimating equation constellation	Number of patients with Shrunken Pore Syndrome
(I) CKD-EPIcystatin C ≤ 60% of CKD-EPIcreatinine	93, of which 82 were also identified by equation constellation III
(II) CAPA ≤ 60% of LMrev	34, of which 33 and 34 were also identified by equation constellations I and III, respectively
(III) CAPA ≤ 70% of LMrev	106, of which 82 were also identified by equation constellation I