Statistics of OPCAB in Japan

Abstract

This chapter focuses on the status and outcome of coronary artery surgery performed in Japan between January 1 and December 31, 2012. A total of 14,999 patients underwent coronary artery bypass grafting (CABG), 10,658 (71 %) of which received isolated CABG. During this period, the operative mortality rate for patients who underwent isolated CABG was 1.49 %, while the mortality for initial elective CABG was 0.72 %. These are the best results obtained since this survey was initially established in 1996. The number of off-pump CABG (OPCAB) cases has since remarkably increased on an annual basis. This less invasive procedure was performed on 5,865 patients in 2012, which is 65.0 % of the total number of initial elective CABG cases (8,983). The mortality rate of complete OPCAB patients was 0.45 %, which is approximately one-fifth of that in the previous year (2011), indicating quality improvement. More than half (58.9 %) of patients with 4 or more grafting underwent OPCAB, which was a higher rate than 56.9 % in 2011. Vein grafts were utilized in 42 %, which had gradually increased over the previous 8 years. The complicated rate of cerebral-vascular stroke in complete OPCAB was significantly lower than those in on-pump beating CABG and conversion cases from off- to on-pump CABG. This less invasive procedure demonstrated a reduction in adverse cerebral-vascular events.

1 Introduction

The Japanese Association for Coronary Artery Surgery (JACAS) has been conducting surveys of the status of coronary artery surgery since 1970 [1–11]. The most recent survey was conducted from January 1 to December 31, 2012. Questionnaires were completed and returned by 326 (71.1 %) out of a total of 459 institutions with departments of cardiac surgery. This report summarizes the advances in coronary artery surgery with special focus on the current status of off-pump coronary artery bypass (OPCAB) in Japan. Results of the status of coronary artery surgery from the previous year as well as from previous surveys were reviewed and considered in the present report.

Operative mortality is defined as any death within 30 days after the day of surgery. Patient characteristics were examined by X ² statistics with regard to operative mortality.

2 Total Number of Coronary Artery Surgeries and Off-Pump CABG Rate

A total of 14,999 patients underwent coronary artery bypass surgery in 2012, with 10,658 (71 %) of which receiving coronary artery bypass grafting (CABG) only. The remaining 4,341 patients underwent additional procedures for myocardial infarction or other complications at the same time. Of those who received CABG alone, initial elective surgery was performed in 8,983 patients, and 5,865 (65 %) of those underwent off-pump CABG (OPCAB). Other than those who received initial elective surgery (emergency and/or redo cases: 1,675), OPCAB was performed in 880 patients (53 %) (Table 2.1).

Table 2.1 Total number of coronary artery surgery and off-pump CABG rate

3 Changes in OPCAB Rate of Initial Elective Isolated CABG

Figure 2.1 shows the changes in OPCAB rates over the previous 17 years from 1996 to 2012. Since 1996, the number of OPCAB cases had remarkably increased annually until 2004, reaching 62 %. Although there was a slight decrease in 2005, 65 % of patients who underwent initial elective isolated CABG received OPCAB in 2012, indicating a persistently high rate.

Fig. 2.1

Changes in OPCAB rate of initial elective isolated CABG

4 Surgical Procedures of Initial Elective Isolated CABG

Regarding initial elective isolated CABG, a total of 2,038 patients (22.7 %) underwent on-pump CABG with cardiac arrest, 1,080 patients underwent on pump with cardiac beating (12.0 %), and OPCAB was performed in 5,865 cases (65.3 %). In those OPCAB cases, 5,718 patients (97.5 %) underwent off pump until the end of operation, and the remaining 147 cases required conversion from off-pump to on-pump CABG. This conversion rate was 2.5 %, which was lower than 3.8 % in 2011 as shown in Table 2.2.

Table 2.2 Surgical procedures of initial elective isolated CABG

5 Outcome According to Procedures

The mortality rate in patients who underwent isolated CABG was 1.49 %, which was much lower than that in 2011, and that for isolated initial elective CABG cases was 0.72 %, achieving the best result since the survey was first conducted. The mortality rate for complete OPCAB was 0.45 %, which is the lowest since this less invasive procedure was introduced. In addition, the mortality rate for conversion from off- to on-pump cases was 2.72 %, which is lower than those of previous years (Table 2.3).

Table 2.3 Outcome according to procedures

6 Changes in Mortality of CABG

The changes in mortality since 1996 are shown in Fig. 2.2. The clinical results improved remarkably annually; the operative mortality rate of isolated CABG cases decreased to 1.49 % and that of initial elective patients decreased to 0.72 % in 2012. These are the best results obtained since the surveys were introduced 30 years previously.

Fig. 2.2

Changes in mortality of CABG

7 Changes in Mortality According to Procedures: Isolated Initial Elective CABG

Figure 2.3 shows the changes in mortality according to procedures since 2004. Generally, the mortality rate of off- to on-pump conversion cases was high. In contrast, the mortalities of on pump (arrest) and off pump (complete) were lower, with the lowest rate of 0.45 % in complete OPCAB in 2012.

Fig. 2.3

Changes in mortality according to procedures: isolated initial elective CABG

8 Number of Grafts According to Surgical Procedures

Figure 2.4 shows the number of grafts according to surgical procedures. The mean number of grafts of total initial elective CABG cases was 2.97/patient, which is approximately the same as that in 2011 (2.96). The mean number of grafts of on pump (cardiac arrest) was 3.22/patient, that of on pump (cardiac beating) was 3.01/patient, that of off- to on-pump conversion cases was 3.17/patient, and that of complete off pump was 2.87/patient.

Fig. 2.4

Number of grafts according to surgical procedures

9 Surgical Procedures According to Number of Grafts

Figure 2.5 shows surgical procedures according to the number of grafts. Eighty-seven percent of single-vessel grafting patients underwent OPCAB. The rate of on-pump cardiac arrest CABG increased with increasing numbers of grafts. More than half (58.9 %) of 4 or more grafts underwent OPCAB, which was higher than 56.9 % in 2011.

Fig. 2.5

Surgical procedures according to number of grafts

10 Comparison of On-Pump Arrest and Off-Pump According to Anastomosis Site of Coronary Artery: Initial Elective Surgery

There are almost no differences in the anastomosis rate of the right coronary artery and left ascending artery between on-pump arrest and off-pump procedures. However, in the left circumflex coronary artery, the anastomosis rate of on-pump arrest is higher than that of the off pump (Fig. 2.6).

Fig. 2.6

Comparison of on-pump arrest and off pump according to anastomosis site of coronary artery: initial elective surgery

11 Graft Selection: Isolated CABG Cases

The total number of grafts was 28,489 in the isolated CABG cases. Of those, the left internal thoracic artery was most commonly used, accounting for 35.9 %, followed by the saphenous vein. The utilization rate of arterial grafts was 58 % of isolated CABG (Fig. 2.7).

Fig. 2.7

Graft selection: isolated CABG cases

12 Complication Rate of Cerebral-Vascular Stroke According to Surgical Procedures: Isolated CABG Cases

Cerebral-vascular stroke is defined as central neurological deficiency persisting for more than 72 h with physical disability. Of all isolated CABG cases (10,658), 112 patients were defined as having a cerebral-vascular stroke, indicating a complication rate of 1.05 %. The complication rate of complete off-pump procedure was 0.81 %, which was significantly lower than that of the on-pump (cardiac beating) cases and off- to on-pump conversion surgery (Fig. 2.8). This result demonstrated that the less invasive complete off-pump procedure is effective against adverse cerebral-vascular events.

Fig. 2.8

Complication rate of cerebral-vascular stroke according to surgical procedures: isolated CABG

13 Special Survey for OPCAB in 2012

In 2012, the Japanese Association for Coronary Artery Surgery (JACAS) made an additional special survey concerning OPCAB. The questions were regarding the following ten items:

• 1. First choice of CABG procedure

• 2. Countermeasures against hypotension during OPCAB

• 3. How to overturn a heart

• 4. How to stabilize a heart

• 5. Choice of composite graft type

• 6. Frequency of use of harmonic scalpel to skeletonize a graft

• 7. Use of endoscopy for graft harvesting

• 8. Implementation of coronary artery endarterectomy

• 9. Procedure of proximal anastomosis for OPCAB

• 10. How to evaluate intraoperative graft flow

Figure 2.9 shows the occupancy rate of the first choice for CABG procedure, where 63.5 % of patients underwent OPCAB, indicating the highest rate. On-pump arrest was performed in 28.5 %, followed by on-pump beating CABG. As a countermeasure against hypotension during OPCAB, inotropic drugs were administered in 54.2 %, and volume loading was performed in 43.1 % (Fig. 2.10).

Fig. 2.9

First choice of procedure for CABG

Fig. 2.10

Countermeasures against hypotension during OPCAB

How to overturn a heart is shown in Figs. 2.11 and 2.12. A heart positioner was utilized in 87 %, demonstrating a high rate. The remaining 13 % of the total cases adopted other procedures, of which LIMA suture was utilized in 80 %.

Fig. 2.11

How to overturn a heart (1)

Fig. 2.12

How to overturn a heart (2)

Tissue stabilizer was used to stabilize a heart in all cases (Fig. 2.13). Figure 2.14 shows the frequency of the use of composite graft type. Although almost half of all institutes did not use any type of composite graft, I-composite graft was used in 25.5 % and Y-composite graft in 22.3 %.

Fig. 2.13

How to stabilize a heart

Fig. 2.14

Frequency of use of composite graft type

The frequency of harmonic scalpel usage for skeletonizing a graft is shown in Fig. 2.15. The frequency was high in most cases (82.3 %), followed by occasional use in 8.4 % and no usage in 9.3 %. Figure 2.16 shows the use of endoscopy for graft harvesting. 87.4 % of the institutes did not use an endoscope to harvest grafts.

Fig. 2.15

Frequency of use of harmonic scalpel to skeletonize graft

Fig. 2.16

Usage of endoscope for graft harvesting

During OPCAB, coronary artery endarterectomy was performed in only 26 % of all cases (Fig. 2.17). Procedures of proximal anastomosis for OPCAB are shown in Fig. 2.18. Seventy percent of OPCAB were carried out with the application of the aorta non-touch technique, using assistive devices.

Fig. 2.17

Operation of coronary artery endarterectomy

Fig. 2.18

Procedure of proximal anastomosis for OPCAB

Figure 2.19 shows how to evaluate intraoperative graft flow. A transit time flow meter was used in 73.8 % of all patients, followed by SPY in 6.2 % and ultrasonic echogram in 4.9 %. On the other hand, 12.3 % of all cases did not evaluate graft flow during surgery.

Fig. 2.19

How to evaluate intraoperative graft flow