M Ruel, V Chan, M Boodhwani, B McDonald, X Ni, G Gill, K Lam, F Rubens, P Hendry,

R Masters, T Mesana

Ottawa, Canada

How Detrimental is Re-Exploration for Bleeding after Cardiac Surgery?

Analysis from 16,793 Cases

University of Ottawa Heart Institute

DISCLOSURES: none

Introduction & Objectives

- Re-exploration for bleeding (REFB) rates are ~2-6%- Previous groups suggest mortality due to transfusions not REFB (Ranucci et al, Ann Thorac Surg 2008)

- Others promote earlier re-intervention as less risky (Karthik et al, Ann Thorac Surg 2004; Haneya et al, Thorac Cardiovasc Surg 2015)

- No large single-center series encompasses all cases- How intrinsically detrimental is REFB?

Elective priority(N=9,162)

Discharged to ICU (N=16,749)

Discharged home (N=16,254)

Adult Cardiac Surgical Procedure(N=16,793)

CABG* Valve* Valve+CABG Arrhythmia* Heart Failure § Congenital AorticOthers† (N=9,214) (N=3,906) (N=2,198) (N=48) (N=335) (N=157)

(N=627) (N=308)

Not discharged to ICU (N=44)

In-hospital death(N=539)

* Denotes isolated CABG, isolated valve replacement/repair, or isolated arrhythmia surgery § Denotes heart transplantation, mechanical heart assistance, or other operations for cardiomyopathy† Denotes pericardiectomy, cardiac tumor resection, pulmonary thromboendarterctomy or embolectomy, or other non-categorized operations

Urgent priority(N=6,302)

Emergency priority(N=1,329)

July

200

2 -

Sep

tem

ber

2014

Not re-explored for bleeding (N=16,132) or

Re-explored for bleeding (N=661)

Not readmitted to hospital (N=15,196)

Readmitted to hospital (N=1,058)

Methods: Study Flow Chart

Methods: Definitions

Patients were operated on CPB unless notedCrystalloid cardioplegia until June 2005LV grades 1, 2, 3 and 4 = LVEF ≥50%, 35-49%, 20-34%, and <20Increase in serum creatinine defined as highest serum creatinine value minus preoperativeMortality defined as hospital mortality at any time prior to discharge Surgical site infections monitored during hospitalization and after discharge by dedicated staff

• Comparisons between patients who were not REFB and REFB with T test/Mann-Whitney U test for continuous variables; Chi-square with Yate’s for categorical

• For clinical outcomes logistic (REFB, mortality, other morbidity and readmission) and linear (increases in creatinine and length of stay) models included: • age• gender • body surface area • preoperative atrial fibrillation • preoperative LV grade • preoperative serum creatinine • operative priority • redo status • type of operation • lowest hematocrit on CPB • aortic cross-clamp and CPB durations • number of blood product units transfused • postoperative increase in serum creatinine • new onset atrial fibrillation

• Regression models underwent 50 bootstrap resampling estimations • Optimal cut-off values set by receiver operating characteristics

Methods: Statistical Analyses

Re-exploration after the index procedure occurred in 710 (4.2%) patients

The first episode of REFB occurred on pod 0 in 358 (54.2%), on pod 1 in 169 (25.6%), on pod 2 in 19 (2.9%), on pod 3-7 in 47 (7.1%), later in 68 (10.3%)

Thirteen patients (2.0% of REFB patients) were re-explored for bleeding more than once

Results: REFB Occurrences

Of these, 661 (3.9%) were REFB

Results: Independent determinants of REFB

Coefficient [95% CI] P value

Body surface area (per m2) 0.6±0.1 [0.4, 0.9] 0.02

Emergency status 1.7±0.4 [1.1, 2.6] 0.03

Redo status 1.5±0.3 [1.1, 2.1] 0.02

On-pump vs. off-pump CABG 1.7±0.1 [1.1, 2.5] 0.01

Aortic dissection repair 3.0±1.0 [1.6, 5.6] 0.001

Tricuspid valve repair 2.6±0.1 [1.9, 3.6] <0.001

Lowest CPB hematocrit (per %) 0.97±0.01 [0.94, 0.99] 0.02

Ao clamp duration (per min) 1.003±0.001 [1.000, 1.006] 0.04

CPB duration (per min) 1.005±0.001 [1.003, 1.006] <0.001

• ROC curves revealed the best cut-off of lowest CPB hematocrit to be 27% (c-statistic=0.614)

• However, specificity was increased in patients with lowest CPB hematocrit < 24%, in whom the risk of re-exploration was independently increased by two-thirds (odds ratio 1.7±0.2; P<0.001)

Impact of Lowest CPB Hematocrit on REFB

• Perioperative mortality was 458/16,132 (2.8%) in those who did not undergo REFB versus 81/661 (12.0%) in those who had REFB

• 4.1±0.5 odds ratio (P<.001) for perioperative death, which was additive to other mortality determinants, including the number of blood products unit transfused

• Timing of REFB did not significantly impact mortality in patients who had REFB: within REFB patients, the OR for death was 1.06±0.4 (P=0.1) per incremental day after the index surgical procedure

Results: Mortality

Results: MortalityCoefficient [95% CI] P value

Female gender 1.6±0.1 [1.4, 1.8] <0.001

Age (per year) 1.04±0.04 [1.03, 1.05] <0.001

Left ventricular grade (per grade) 1.6±0.1 [1.4, 1.8] <0.001

Creatinine (preoperative, /umol/L) 1.002±0.0006 [1.001, 1.003] 0.001

Emergency status 4.3±0.8 [3.1, 6.2] <0.001

Redo status 1.5±0.3 [1.1, 2.1] 0.02

Aortic dissection 9.9±5.3 [3.5, 28.0] <0.001

Mitral valve repair 0.6±0.1 [0.4, 0.9] 0.007

Tricuspid valve repair 1.9±0.4 [1.3, 2.8] 0.001

Lowest CPB hematocrit (per %) 0.97±0.01 [0.94, 0.99] 0.02

Ao clamp duration (per min) 1.01±0.002 [1.01, 1.02] <0.001

CPB duration (per min) 1.01±0.002 [1.01, 1.02] <0.001

Total blood products transfused (/u) 1.04±0.003 [1.03, 1.04] <0.001

Re-exploration for bleeding 4.1±0.5 [3.2, 5.3] <0.001

Results: Morbidity

 

Not REFB(N=16,132)

REFB(N=661)

Multivariablecoefficient (Coef) or

odds ratio (OR)*P value

ICU LOS, median days [IQR] 1 [1] 3 [5] Coef: 6.1±1.1 <0.001

ICU readmission, n (%) 453 (2.8%) 80 (12.1%) OR: 3.6±0.8 <0.001

New atrial fibrillation, n (%) 4,194 (26.0%) 240 (36.3%) OR: 1.5±0.2 0.006†

Increase in creatinine, umol/L 25.9±48.5 51.0±49.6 Coef: 17.9±3.2 <0.001

Hospital LOS, median days [IQR] 7 [6] 12 [20] Coef: 6.8±0.8 <0.001

Hospital readmission, n (%) 1,011 (6.3%) 47 (7.1%) OR: 1.02±0.3 0.9

Surgical site infection, n (%) 1,055 (6.5%) 84 (12.7%) OR: 2.0±0.4 0.001

Limitations

Single center experience

No economic analysis

No perioperative medications

effect

No individual surgeon associationNo differentiation between surgical and medical bleeding

Re-exploration for bleeding (REFB) is a: • non-infrequent • lethal • potentially modifiable complication of cardiac surgery

In a large contemporary series: • the impact of REFB adds to that of other well known risk

factors for mortality and morbidity, including transfusions• avoiding nadir hematocrits of less than 24% during CPB

may help avoid REFB • the present findings strongly justify continued quality

improvement and research efforts to minimize the occurrence and negative impacts of REFB.