Cardiol Res

Cardiology Research, ISSN 1923-2829 print, 1923-2837 online, Open Access

Article copyright, the authors; Journal compilation copyright, Cardiol Res and Elmer Press Inc

Journal website http://www.cardiologyres.org

Original Article

Volume 10, Number 2, April 2019, pages 74-82

Optimal Duration for Clopidogrel Suspension Prior to Coronary Artery Bypass Grafting

Figure 1. Test of variance. There were no outliers in the data, as assessed by inspection of a boxplot for values greater than 1.5 box-lengths from the edge of the box.

**Table 1.** Characteristics of Our Patient Population
Group (clopidogrel stopped)	Total number	Sex (male)	Average LVEF	Age (mean)	HTN	DM	CHF	HLD	Smoking	PRBC
HTN: hypertension; DM: diabetes mellitus; CHF: congestive heart failure; HLD: hyperlipidemia; PRBC: packed red blood cells.
3 days or less	25	22 (88%)	45%	67	25 (100%)	14 (56%)	1 (4%)	20 (80%)	10 (40%)	4 (16%)
5 days	17	8 (47%)	46%	76	17 (100%)	9 (53%)	2 (11%)	16 (94%)	3 (18%)	5 (29%)
Not on clopidogrel	40	31 (78%)	44%	68	34 (85%)	21 (53%)	1 (3%)	26 (65%)	7 (18%)	9 (23%)
4 days	8	4 (50%)	45%	72	8 (100%)	5 (63%)	1 (13%)	5 (63%)	2 (25%)	3 (38%)
Total	90	65 (72%)	45%	71	72 (80%)	49 (54%)	5 (6%)	67 (74%)	22 (24%)	21 (23%)

Table 1. Characteristics of Our Patient Population

Group (clopidogrel stopped)

Total number

Sex (male)

Average LVEF

Age (mean)

HTN

CHF

HLD

Smoking

PRBC

HTN: hypertension; DM: diabetes mellitus; CHF: congestive heart failure; HLD: hyperlipidemia; PRBC: packed red blood cells.

3 days or less

22 (88%)

45%

25 (100%)

14 (56%)

1 (4%)

20 (80%)

10 (40%)

4 (16%)

5 days

8 (47%)

46%

17 (100%)

9 (53%)

2 (11%)

16 (94%)

3 (18%)

5 (29%)

Not on clopidogrel

31 (78%)

44%

34 (85%)

21 (53%)

1 (3%)

26 (65%)

7 (18%)

9 (23%)

4 days

4 (50%)

45%

8 (100%)

5 (63%)

1 (13%)

5 (63%)

2 (25%)

3 (38%)

Total

65 (72%)

45%

72 (80%)

49 (54%)

5 (6%)

67 (74%)

22 (24%)

21 (23%)

**Table 2.** Patient Population Divided Into Four Groups
	Frequency	Percent	Valid percent	Cumulative percent
Clopidogrel stopped 3 days or less	25	27.8	27.8	27.8
Clopidogrel stopped 5 days	17	18.9	18.9	46.7
Not on clopidogrel	40	44.4	44.4	91.1
Clopidogrel stopped 4 days before	8	8.9	8.9	100.0
Total	90	100.0	100.0

Table 2. Patient Population Divided Into Four Groups

Frequency

Percent

Valid percent

Cumulative percent

Clopidogrel stopped 3 days or less

27.8

Clopidogrel stopped 5 days

18.9

46.7

Not on clopidogrel

44.4

91.1

Clopidogrel stopped 4 days before

8.9

100.0

Total

100.0

**Table 3.** Test of Normality
Clopidogrel stopped	Kolmogorov-Smirnov	Shapiro-Wilk
The fall in hemoglobin was normally distributed for all the groups, as assessed by Shapiro-Wilk’s test (P > 0.05)
Clopidogrel stopped 3 days	0.188	25	0.02	0.885	25	0.09
Clopidogrel stopped 5 days	0.094	17	0.20	0.972	17	0.855
No clopidogrel	0.066	40	0.20	0.973	40	0.435
Clopidogrel stopped 4 days	0.178	8	0.20	0.962	8	0.832

Table 3. Test of Normality

Clopidogrel stopped

Kolmogorov-Smirnov

Shapiro-Wilk

Statistic

Sig.

Statistic

Sig.

The fall in hemoglobin was normally distributed for all the groups, as assessed by Shapiro-Wilk’s test (P > 0.05)

Clopidogrel stopped 3 days

0.188

0.02

0.885

0.09

Clopidogrel stopped 5 days

0.094

0.20

0.972

0.855

No clopidogrel

0.066

0.20

0.973

0.435

Clopidogrel stopped 4 days

0.178

0.20

0.962

0.832

**Table 4.** Test of Homogeneity of Variances for Hemoglobin Drop
	Levene statistic	df1	df2	Sig.
There was homogeneity of variances, as assessed by Levene’s test for equality of variances (P > 0.05).
Based on mean	0.214	3	86	0.886
Based on median	0.314	3	86	0.815
Based on median and with adjusted df	0.314	3	84.115	0.815
Based on trimmed mean	0.268	3	86	0.848

Table 4. Test of Homogeneity of Variances for Hemoglobin Drop

Levene statistic

df1

df2

Sig.

There was homogeneity of variances, as assessed by Levene’s test for equality of variances (P > 0.05).

Based on mean

0.214

0.886

Based on median

0.314

0.815

Based on median and with adjusted df

0.314

84.115

0.815

Based on trimmed mean

0.268

0.848

**Table 5.** Fall in Hemoglobin for the Four Different Groups
	N	Mean	Std. deviation	Std. error	95% Confidence interval for mean
Data are presented as mean ± standard deviation. The fall in hemoglobin (g/dL) in group 1 (stopped clopidogrel 3 days or less before CABG) was 2.36 ± 1.24 (n = 25); the fall in group 2 (stopped clopidogrel 5 days prior to CABG) was 2.89 ± 1.22 (n = 17); the fall in hemoglobin in group 3 (patients not on clopidogrel) was 2.54 ± 1.35 (n = 40); and the fall in hemoglobin in group 4 (patients stopped clopidogrel 4 days prior to CABG) was 2.02 ± 1.31 (n = 8).
Clopidogrel stopped 3 days or less	25	2.3560	1.23628	0.24726	1.8457	2.8663
Clopidogrel stopped 5 days	17	2.8824	1.22384	0.29683	2.2531	3.5116
Not on clopidogrel	40	2.5400	1.34904	0.21330	2.1086	2.9714
Clopidogrel stopped 4 days ago	8	2.0250	1.30903	0.46281	0.9306	3.1194
Total	90	2.5078	1.29165	0.13615	2.2372	2.7783

Table 5. Fall in Hemoglobin for the Four Different Groups

Mean

Std. deviation

Std. error

95% Confidence interval for mean

Lower bound

Upper bound

Data are presented as mean ± standard deviation. The fall in hemoglobin (g/dL) in group 1 (stopped clopidogrel 3 days or less before CABG) was 2.36 ± 1.24 (n = 25); the fall in group 2 (stopped clopidogrel 5 days prior to CABG) was 2.89 ± 1.22 (n = 17); the fall in hemoglobin in group 3 (patients not on clopidogrel) was 2.54 ± 1.35 (n = 40); and the fall in hemoglobin in group 4 (patients stopped clopidogrel 4 days prior to CABG) was 2.02 ± 1.31 (n = 8).

Clopidogrel stopped 3 days or less

2.3560

1.23628

0.24726

1.8457

2.8663

Clopidogrel stopped 5 days

2.8824

1.22384

0.29683

2.2531

3.5116

Not on clopidogrel

2.5400

1.34904

0.21330

2.1086

2.9714

Clopidogrel stopped 4 days ago

2.0250

1.30903

0.46281

0.9306

3.1194

Total

2.5078

1.29165

0.13615

2.2372

2.7783

**Table 6.** Fall in Hemoglobin on ANOVA in All the Different Groups
	Sum of squares	df	Mean square	F	Sig.
There were no statistically significant differences in fall in hemoglobin on ANOVA in all the different groups. F(3, 86) = 0.972, P = 0.410.
Between groups	4.867	3	1.622	0.972	0.410
Within groups	143.617	86	1.670
Total	148.485	89

Table 6. Fall in Hemoglobin on ANOVA in All the Different Groups

Sum of squares

Mean square

Sig.

There were no statistically significant differences in fall in hemoglobin on ANOVA in all the different groups. F(3, 86) = 0.972, P = 0.410.

Between groups

4.867

1.622

0.972

0.410

Within groups

143.617

1.670

Total

148.485

**Table 7.** Fall in Hemoglobin During the Surgery Between Any Group When Compared to the Other Groups
(J) Clopidogrel stop day	Mean difference (I-J)	Std. error	Sig.	95% Confidence interval
There was no statistically significant difference between any groups when compared to the other groups regarding the fall in hemoglobin during the surgery. This is demonstrated in the table for multiple outcomes (^aComparison with group 1; ^bComparison with group 2; ^cComparison with group 3; ^dComparison with group 4).
Clopidogrel stopped 5days^a	-0.52635	0.40624	0.568	-1.5907	0.5380
Not on clopidogrel^a	-0.18400	0.32947	0.944	-1.0472	0.6792
Clopidogrel stopped 4 days ago^a	0.33100	0.52492	0.922	-1.0443	1.7063
Clopidogrel stopped 3 days or less^b	0.52635	0.40624	0.568	-0.5380	1.5907
Not on clopidogrel^b	0.34235	0.37414	0.797	-0.6379	1.3226
Clopidogrel stopped 4 days ago^b	0.85735	0.55406	0.414	-0.5943	2.3090
Clopidogrel stopped 3 days or less^c	0.18400	0.32947	0.944	-0.6792	1.0472
Clopidogrel stopped 5 days^c	-0.34235	0.37414	0.797	-1.3226	0.6379
Clopidogrel stopped 4 days ago^c	0.51500	0.50050	0.733	-0.7963	1.8263
Clopidogrel stopped 3 days or less^d	-0.33100	0.52492	0.922	-1.7063	1.0443
Clopidogrel stopped 5 days^d	-0.85735	0.55406	0.414	-2.3090	0.5943
Not on clopidogrel^d	-0.51500	0.50050	0.733	-1.8263	0.7963

Table 7. Fall in Hemoglobin During the Surgery Between Any Group When Compared to the Other Groups

(J) Clopidogrel stop day

Mean difference (I-J)

Std. error

Sig.

95% Confidence interval

Lower bound

Upper bound

There was no statistically significant difference between any groups when compared to the other groups regarding the fall in hemoglobin during the surgery. This is demonstrated in the table for multiple outcomes (^aComparison with group 1; ^bComparison with group 2; ^cComparison with group 3; ^dComparison with group 4).

Clopidogrel stopped 5days^a

-0.52635

0.40624

0.568

-1.5907

0.5380

Not on clopidogrel^a

-0.18400

0.32947

0.944

-1.0472

0.6792

Clopidogrel stopped 4 days ago^a

0.33100

0.52492

0.922

-1.0443

1.7063

Clopidogrel stopped 3 days or less^b

0.52635

0.40624

0.568

-0.5380

1.5907

Not on clopidogrel^b

0.34235

0.37414

0.797

-0.6379

1.3226

Clopidogrel stopped 4 days ago^b

0.85735

0.55406

0.414

-0.5943

2.3090

Clopidogrel stopped 3 days or less^c

0.18400

0.32947

0.944

-0.6792

1.0472

Clopidogrel stopped 5 days^c

-0.34235

0.37414

0.797

-1.3226

0.6379

Clopidogrel stopped 4 days ago^c

0.51500

0.50050

0.733

-0.7963

1.8263

Clopidogrel stopped 3 days or less^d

-0.33100

0.52492

0.922

-1.7063

1.0443

Clopidogrel stopped 5 days^d

-0.85735

0.55406

0.414

-2.3090

0.5943

Not on clopidogrel^d

-0.51500

0.50050

0.733

-1.8263

0.7963

**Table 8.** Pre- and Post-CABG Hemoglobin Levels and the Mean Change in Hemoglobin
	Pre-operative	Post-operative	Delta
Overall	12.5	9.8	-2.4
Cases	11.8	9.3	-2.5
Controls	12.8	10.3	-2.5

Table 8. Pre- and Post-CABG Hemoglobin Levels and the Mean Change in Hemoglobin

Pre-operative

Post-operative

Delta

Overall

12.5

9.8

-2.4

Cases

11.8

9.3

-2.5

Controls

12.8

10.3

-2.5

**Table 9.** Difference of Mean Hemoglobin Drop With Respect to the Duration of Clopidogrel Termination Prior to CABG
Study group	Fall in hemoglobin (g/dL)
Clopidogrel stopped 3 days or less before surgery	n = 25, 2.36 ± 1.24
Clopidogrel stopped 5 days before surgery	n = 17, 2.89 ± 1.22
Clopidogrel stopped 4 days before surgery	n = 8, 2.02 ± 1.31
No clopidogrel	n = 40, 2.54 ± 1.35

Table 9. Difference of Mean Hemoglobin Drop With Respect to the Duration of Clopidogrel Termination Prior to CABG

Study group

Fall in hemoglobin (g/dL)

Clopidogrel stopped 3 days or less before surgery

n = 25, 2.36 ± 1.24

Clopidogrel stopped 5 days before surgery

n = 17, 2.89 ± 1.22

Clopidogrel stopped 4 days before surgery

n = 8, 2.02 ± 1.31

No clopidogrel

n = 40, 2.54 ± 1.35

**Table10.** Number of Patients Requiring PRBC Transfusions in the Different Population Group
Patient group	Total number of patients	Number requiring PRBC transfusion	Percentage requiring PRBC transfusion
Cases	n = 50	n = 12	24.00%
Controls	n = 40	n = 9	22.50%
Total	n = 90	n = 21	23.33%

Table10. Number of Patients Requiring PRBC Transfusions in the Different Population Group

Patient group

Total number of patients

Number requiring PRBC transfusion

Percentage requiring PRBC transfusion

Cases

n = 50

n = 12

24.00%

Controls

n = 40

n = 9

22.50%

Total

n = 90

n = 21

23.33%