Postoperative stroke in patients on oral anticoagulation undergoing coronary artery bypass surgery

Figures & data

Table I. Baseline characteristics and operative data on patients on preoperative warfarin treatment who underwent isolated coronary artery bypass surgery. Results of univariate and logistic regression in predicting postoperative stroke are reported as well.

	No. (%)	Univariate analysis p-value	Logistic regression analysis p-value, O.R. 95%CI
Age (years)	69.4 ± 8.6	0.74
Age ≥ 75 years	89 (32.9)	0.63
Females	45 (16.7)	0.38
Diabetes	97 (35.9)	0.34
Hypertension	149 (55.2)	1.00
History of stroke/transient ischemic attack	68 (25.2)	0.13
Extracardiac arteriopathy	61 (25.2)	0.60
Previous PCI	36 (13.3)	0.37
Previous CABG	10 (3.7)	1.00
Previous cardiac surgery	18 (6.7)	1.00
Unstable angina pectoris	89 (32.9)	0.24
Left main stenosis	102 (37.8)	0.51
Left ventricular ejection fraction <50%	131 (48.5)	1.00
Recent myocardial infarction	114 (42.2)	0.33
Indication for warfarin treatment
Atrial fibrillation	203 (75.2)	0.71
Stroke/transient ischemic attack	29 (10.7)	1.00
Deep vein thrombosis	14 (5.2)	0.09	0.025, 7.73, 12.92-3619.27
Prosthetic heart valve	10 (3.7)	1.00
Other reasons	14 (5.2)	0.42
Drug treatment
Warfarin until day of surgery	43 (15.9)	0.69
Enoxaparin	146 (54.1)	0.52
Enoxaparin until day of surgery	121 (44.8)	0.19
Aspirin	169 (62.6)	0.18
Clopidogrel	21 (7.8)	0.18
Glycoprotein inhibitors	12 (4.5)	0.37
Thrombolysis during same hospitalization	3 (1.1)	0.004	<0.0001, 216.25, 12.92-3619.27
Aprotinin	18 (6.7)	1.00
Aminocaproic acid	133 (49.3)	0.34
Hemoglobin (g/l)	138± 17	0.61
INR	1.9 ± 0.6	0.80
Platelets (10^9/l)	236 ± 82	0.21
Creatinine (micromol/l)	93 ±40	0.13
Emergency/urgent operation	147 (54.4)	0.76
Additive EuroSCORE	6.3 ±3.3	0.44
CHADS2 score	2.2 ± 1.3	0.27
CHADS2 score >2	95 (35.2)	0.17	0.036, 5.80, 1.12-30.02
Aortic cross-clamp time (min)	74 ± 29	0.62
Cardiopulmonary bypass time (min)	105 ±41	0.96
Length of operation (min)	241 ± 61	0.92
Beating heart surgery	121 (44.8)	1.00

Continuous variable are reported as mean ± standard deviation; Values in parentheses are percentages. O.R., odds ratio; CI, confidence interval; PCI, percutaneous coronary intervention; CABG, coronary artery bypass grafting; INR, International normalized ratio; *, Definition criteria for preoperative variables are according to EuroSCORE (6); CHADS₂, score for prediction of stroke in patients with atrial fibrillation (7).

Table II. Immediate outcome after isolated coronary artery bypass surgery in patients on preoperative warfarin treatment.

In-hospital adverse events	No. (%)
Mortality	10 (3.7)
Stroke	10 (3.7)
Transient ischemic attack	2 (0.7)
Reoperation	23 (8.5)
Prolonged need of inotropics	137 (50.7)
Blood loss at ICU (ml)	865 ± 682
Red blood cells units	2.2 ± 3.1
Fresh-frozen plasma units	2.1 ± 2.7
Platelet units	1.1 ± 2.8
ICU stay (days)	3.3 ± 4.1

Values in parentheses are percentages; continuous variables are reported as mean ± standard deviation.

Table III. Details on patients on chronic oral anticoagulation treatment who suffered stroke after coronary artery bypass surgery.

Patient no.	Indication for warfarin treatment	Preop. TT-INR	Preoperative warfarin discontinuation	Length of warfarin discontinuation (days)	LMWH until surgery	Aspirin use	History of stroke/TIA	Type of surgery	CHADS2 score	Additive EuroSCORE	Off-pump surgery	Diseased ascending aorta	Timing of postop. stroke (days)	LMWH treatment at the time of stroke	In-hospital outcome
1	AF	1.6	No pause	0	Yes	Yes	Yes	Emergency		15	Yes	NA	12	Yes	Dead
2	DVT	2.1	Pause	2	Yes	No	Yes	Elective	4	5	No	Yes	3	Yes	Dead
3	AF	1.7	No pause	0	Yes	No	Yes	Urgent	2	7	No	NA	12	Yes	Dead
4	AF	3.3	Pause	1	No	No	No	Elective	3	4	No	Yes	1	No	Alive
5	AF	1.4	Pause	5	No	No	Yes	Elective	4	1	Yes	Yes	2	Yes	Alive
6	DCM	1.0	Pause	15	No	Yes	No	Elective	1	4	No	NA	3	No	Alive
7	AF	1.3	Pause	4	Yes	Yes	Yes	Urgent	3	8	Yes	No	8	Yes	Alive
8	DVT	2.4	Pause	2	Yes	No	No	Emergency	4	14	No	NA	15	No	Alive
9	AF	3.5	Pause	1	Yes	No	No	Urgent	0	6	Yes	No	13	Yes	Alive
10	AF	1.6	Pause	4	No	Yes	No	Urgent	1	10	No	NA	3	Yes	Alive

AF, atrial fibrillation; DVT, deep vein thrombosis; DCM, dilated cardiomyopathy; LMWH, low molecular weight heparin; TIA, transient ischemic attack; NA, not assessed.

Figure 1. Classification and regression tree summarizing independent predictors of postoperative stroke after coronary artery bypass surgery in patients on chronic oral anticoagulation. Rates of postoperative stroke are reported in percentages and absolute values in parentheses. The improvement values are reported at the splitting of the parent node. CABG, coronary artery bypass grafting; TIA, transient ischemic attack; LMWH, low molecular weight heparin.

Figure 2. Independent variable importance in predicting in-hospital stroke after coronary artery bypass surgery in patient on oral anticoagulation. LMWH, low molecular weight heparin.

Figure 3. Classification and regression tree including preoperative use of aspirin and/or clopidogrel and summarizing independent predictors of postoperative stroke after coronary artery bypass surgery in patients on chronic oral anticoagulation. Rates of postoperative stroke are reported in percentages and absolute values in parentheses. The improvement values are reported at the splitting of the parent node. CABG, coronary artery bypass grafting; TIA, transient ischemic attack; Aspirin/clopid., aspirin and/or clopidogrel; LMWH, low molecular weight heparin.