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 Table of Contents  
ORIGINAL RESEARCH
Year : 2020  |  Volume : 4  |  Issue : 1  |  Page : 7-10

Effect of Off-pump Coronary Artery Bypass Graft Surgery on Transthoracic Echocardiographic Right Ventricular Function in Indian Patients


1 Department of Cardiology, Cauvery Heart and Multispeciality Hospital, Mysore, Karnataka, India
2 Department of Cardiothoracic Surgery, Cauvery Heart and Multispeciality Hospital, Mysore, Karnataka, India

Date of Submission19-Jun-2019
Date of Decision03-Nov-2019
Date of Acceptance05-Jan-2020
Date of Web Publication11-Apr-2020

Correspondence Address:
Dr. Veenu John
Department of Cardiology, Cauvery Heart and Multispeciality Hospital, College Circle, Siddarthnagar, Mysore - 570 029, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiae.jiae_31_19

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  Abstract 

Background: The importance of the right ventricle as a determinant of exercise capacity and its significant prognostic value in the evaluation of surgical outcomes has been largely proven. In this study, we sought to explore the effect of off-pump coronary artery bypass surgery (OPCAB) on right ventricular (RV) function by the different methods of RV functional assessment on transthoracic echocardiography. Materials and Methods: This is a prospective cohort study. All patients undergoing elective OPCAB were included in the study from July 1, 2016, to October 1, 2016 after an informed consent. Their preoperative, postoperative day 4, and postoperative 2-month transthoracic echocardiographic RV and left ventricular functions were evaluated and analyzed. Results: A total of 48 patients undergoing OPCAB were included in this study. The mean age of the cohort was 57.2 ± 8 years. About 85.4% (41) were males. Overall, there is a significant time effect observed in RV ejection fraction (RVEF), with a significant decline from preoperative to postoperative value and a significant increase from postoperative day 4 to postoperative 2-month value. Although RVEF was lower throughout the study in patients with events than those without events, this difference was not statistically significant. Conclusion: In this Indian cohort of patients undergoing OPCAB, there is a significant drop in RVEF, RV tissue Doppler, tricuspid annular peak systolic excursion on postoperative day 4, and also a significant increase in these values over the next 2 months though not reaching the basal value. Hence, suggesting that the drop in RV function is temporary and recovers over time in patients undergoing OPCAB. Patients with events had a lower RVEF when compared to those without events suggesting prognostication.

Keywords: Left ventricular diastolic dysfunction, off-pump coronary artery bypass surgery, right ventricular function


How to cite this article:
John V, Thomas A, Chikkamadegowda MS, Jambunathan R. Effect of Off-pump Coronary Artery Bypass Graft Surgery on Transthoracic Echocardiographic Right Ventricular Function in Indian Patients. J Indian Acad Echocardiogr Cardiovasc Imaging 2020;4:7-10

How to cite this URL:
John V, Thomas A, Chikkamadegowda MS, Jambunathan R. Effect of Off-pump Coronary Artery Bypass Graft Surgery on Transthoracic Echocardiographic Right Ventricular Function in Indian Patients. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2020 [cited 2020 Aug 4];4:7-10. Available from: http://www.jiaecho.org/text.asp?2020/4/1/7/282201




  Introduction Top


The importance of the right ventricle (RV) as a determinant of exercise capacity and its significant prognostic value in the evaluation of surgical outcomes have been largely proven.[1],[2] The effect of coronary artery bypass graft surgery (CABG) on RV function has been proven by various studies.[3],[4] Most of these studies are done on CABG, which were on pump and many reasons have been considered. To mention a few, it may be intraoperative ischemia, intraoperative myocardial damage, cardioplegia, or pericardial disruption.[5],[6],[7],[8],[9] In this study, we sought to explore the effect of off-pump coronary artery bypass surgery (OPCAB) on RV function by the different methods of RV functional assessment on transthoracic echocardiography.


  Materials and Methods Top


This is a prospective cohort study conducted in a tertiary care hospital catering to patients from Mysuru, Karnataka, India. All patients undergoing elective OPCAB were included in the study from July 1, 2016, to October 1, 2016 after an informed consent. Patient's preoperative left ventricular ejection fraction (LVEF), left ventricular diastolic dysfunction (LVDD), right ventricular ejection fraction (RVEF), tricuspid annular peak systolic excursion (TAPSE), RV tissue Doppler (RVTDI), RV diastolic dysfunction, and RV e/e' were calculated on transthoracic echocardiography. The views used were apical four-chamber and two-chamber views. RVEF and LVEF were calculated by biplane Simpson's method. The same parameters were evaluated at postoperative day 4 and 2 months (January 1, 2017) post OPCAB. These patients were followed up either on outpatient basis or telephonic basis for cardiac events and mortality for 1-year duration up to January 1, 2018.

Inclusion criteria

  1. All patients undergoing OPCAB from July 1, 2016, to October 1, 2016.


Exclusion criteria

  1. Emergency patients in whom a proper preoperative transthoracic echocardiographic evaluation could not be done
  2. Patients not willing for study or follow-up.


Statistical methods

Descriptive statistics was reported as mean and standard deviation for the continuous variables and as number and percentages for the categorical variables. Paired t-test was used to compare the change in each clinical outcome from baseline to postoperative day 4 and 2 months postoperative. Repeated measures analysis of variance (ANOVA) was used to test the change in outcomes over time and its interaction with event. P < 0.05 was considered as statistically significant. All the analyses were done using SPSS version 2.0.


  Results Top


A total of 48 patients undergoing OPCAB were included in this study. The baseline characteristics, events, and mortality are given in [Table 1]. The mean age of the cohort was 57.2+/−8 years. About 85.4% (41) were males. Fifty percent (24) of patients had diabetes mellitus and 45.8% (22) had hypertension. About 22.9% (11) were smokers.
Table 1: Baseline characteristics

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Overtime none of the LV parameters showed a change except the diastolic dysfunction, the higher grades (Grade 2 and 3) improved consistently post operatively as shown in [Table 2].
Table 2: Left ventricular diastolic dysfunction over time

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Repeated measures ANOVA for the clinical outcomes is presented in [Table 3]. There was no significant (time effect) change in LVEF and RV e/e' over time. However, RVEF, TAPSE, and RVTDI had significant time effect over time and no significant interaction effect with respect to events. In RVEF and RVTDI, baseline to postoperative day 4 was significantly decreased, change from postoperative day 4 to postoperative 2 months was not significantly different. For TAPSE, there was a significant decline from baseline; but, from postoperative day 4 to postoperative 2 months, there was a significant increment.
Table 3: Distribution of clinical outcomes over time

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Overall, there was a significant time effect observed in RVEF, with a significant decline from preoperative to postoperative value and a significant increase from postoperative day 4 to postoperative 2 months value [Figure 1] and [Table 4]. This was more pronounced in patients with higher grades (Grade 2 and Grade 3) of LVDD.
Figure 1: Change in mean of right ventricular ejection fraction (RVEF) (Y axis) over time (X axis – 1 – preoperative, 2 – postoperative day 4, 3 – 2 months postoperative) with respect to left ventricular diastolic dysfunction (grade 0–1 – blue and grade 2–3 – green)

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Table 4: Time effect observed in right ventricular ejection fraction with respect to left ventricular diastolic dysfunction grades

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Graph 1 clearly demonstrates the significant drop in RVEF from preoperative level to postoperative day 4, more so in patients with higher LVDD (Grade 2, 3). Also to be noted is that RVEF is relatively lower in higher grades of LVDD (P = 0.08). Similar time effects were seen with TAPSE and RVTDI, but there was no significant interaction effect (P = 0.815 and P = 0.823, respectively).

The data were categorized into patients with low LVEF <40%, 40%–50%, and >50%. These categories were compared with TAPSE, RVEF, and RV TDI [Figure 2] and [Figure 3]. Clearly, LVEF <40% had a lower TAPSE, RVEF, and RVTDI throughout the study period but was not statistically significant (P = 0.882, P = 0.182, and P = 0.182, respectively).
Figure 2: Clearly shows that tricuspid annular peak systolic excursion (TAPSE) was lower throughout the study in patients with left ventricular ejection fraction <40 than those 40 and above

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Figure 3: Shows that right ventricular ejection fraction (RVEF) was lower throughout the study in patients with left ventricular ejection fraction <40 than those 40 and above

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Although RVEF was lower throughout the study in patients with events than those without events, this difference was not statistically significant [Figure 4].
Figure 4: Right ventricular ejection fraction (RVEF) was lower throughout the study in patients with events than those without events, but this difference was not statistically significant

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  Discussion Top


RV dysfunction is a possible cause of cardiac failure after coronary surgery.[1],[2] Initially, it was thought off as due to on-pump cardiac surgery due to various causes.[5],[6],[7],[8],[9] Later, Michaux et al. through their randomized trial of RV function in both on-pump and off-pump surgery showed that there was no difference.[10] In our study, we wanted to see the effect of OPCAB on RV function in Indian patients over a period of 2 months and tried correlating it with outcomes over a period of 1 year. Clearly, there is a significant drop in RVEF, RVTDI, and TAPSE on postoperative day 4 and also a significant increase in these values over the next 2 months though not reaching the basal value (P < 0.001).

Hence, suggesting that the drop in RV function is temporary and recovers over time. Similarly, Khani et al. had found normalization of RV strain imaging at 3-month post-OPCAB.[11] The drop in RV function and the slow increase was significantly more pronounced in patients with higher Grades 2 and 3 of LVDD and in patients with LVEF lower than 40%. Shi et al. had studied LVDD in patients undergoing bypass surgery and found higher biventricular filling pressures post operatively in those patients with LVDD.[12] In our study, as higher grades of LVDD correlate with higher LV filling pressures, it shows a significant correlation with lower RVEF (P < 0.001). There was no mortality documented for the period of study. There were events such as heart failure and unstable angina in 10.8% of patients. These patients had a lower RVEF when compared to those with no events, but this difference was not statistically significant probably because of the smaller numbers (P = 0.08).


  Conclusion Top


In this Indian cohort of patients undergoing OPCAB, there is a significant drop in RVEF, RVTDI, and TAPSE on postoperative day 4 and also a significant increase in these values over the next 2 months though not reaching the basal value. Hence, suggesting that the drop in RV function is temporary and recovers over time in patients undergoing OPCAB. The drop-in RV function and the slow increase was significantly more pronounced in patients with higher grades 2 and 3 of LVDD and in patients with LVEF lower than 40%. Patients with events had a lower RVEF when compared to those without events suggesting prognostication.

Acknowledgments

The authors like to thank Dr. Sumithra, Biostatistician, St John's Research Institute, Bengaluru.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
de Groote P, Millaire A, Foucher-Hossein C, Nugue O, Marchandise X, Ducloux G, et al. Right ventricular ejection fraction is an independent predictor of survival in patients with moderate heart failure. J Am Coll Cardiol 1998;32:948-54.  Back to cited text no. 1
    
2.
Dávila-Román VG, Waggoner AD, Hopkins WE, Barzilai B. Right ventricular dysfunction in low output syndrome after cardiac operations: Assessment by transesophageal echocardiography. Ann Thorac Surg 1995;60:1081-6.  Back to cited text no. 2
    
3.
Stein KL, Breisblatt W, Wolfe C, Gasior T, Hardesty R. Depression and recovery of right ventricular function after cardiopulmonary bypass. Crit Care Med 1990;18:1197-200.  Back to cited text no. 3
    
4.
Hedman A, Alam M, Zuber E, Nordlander R, Samad BA. Decreased right ventricular function after coronary artery bypass grafting and its relation to exercise capacity: A tricuspid annular motion-based study. J Am Soc Echocardiogr 2004;17:126-31.  Back to cited text no. 4
    
5.
Honkonen EL, Kaukinen L, Pehkonen EJ, Kaukinen S. Right ventricle is protected better by warm continuous than by cold intermittent retrograde blood cardioplegia in patients with obstructed right coronary artery. Thorac Cardiovasc Surg 1997;45:182-9.  Back to cited text no. 5
    
6.
Kitano T, Hattori S, Miyakawa H, Yoshitake S, Iwasaka H, Noguchi T. Unwashed shed blood infusion causes deterioration in right ventricular function after coronary artery surgery. Anaesth Intensive Care 2000;28:642-5.  Back to cited text no. 6
    
7.
Wu ZK, Tarkka MR, Pehkonen E, Kaukinen L, Honkonen EL, Kaukinen S. Beneficial effects of ischemic preconditioning on right ventricular function after coronary artery bypass grafting. Ann Thorac Surg 2000;70:1551-7.  Back to cited text no. 7
    
8.
Schirmer U, Calzia E, Lindner KH, Hemmer W, Georgieff M. Right ventricular function after coronary artery bypass grafting in patients with and without revascularization of the right coronary artery. J Cardiothorac Vasc Anesth 1995;9:659-64.  Back to cited text no. 8
    
9.
Lindström L, Wigström L, Dahlin LG, Arén C, Wranne B. Lack of effect of synthetic pericardial substitute on right ventricular function after coronary artery bypass surgery. An echocardiographic and magnetic resonance imaging study. Scand Cardiovasc J 2000;34:331-8.  Back to cited text no. 9
    
10.
Michaux I, Filipovic M, Skarvan K, Schneiter S, Schumann R, Zerkowski HR, et al. Effects of on-pump versus off-pump coronary artery bypass graft surgery on right ventricular function. J Thorac Cardiovasc Surg 2006;131:1281-8.  Back to cited text no. 10
    
11.
Khani M, Hosseintash M, Foroughi M, Naderian M, Khaheshi I. Assessment of the effect of off-pump coronary artery bypass (OPCAB) surgery on right ventricle function using strain and strain rate imaging. Cardiovasc Diagn Ther 2016;6:138-43.  Back to cited text no. 11
    
12.
Shi Y, Denault AY, Couture P, Butnaru A, Carrier M, Tardif JC. Biventricular diastolic filling patterns after coronary artery bypass graft surgery. J Thorac Cardiovasc Surg 2006;131:1080-6.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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