Thoracic and cardiovascular surgery in Japan during 2014

The Japanese Association for Thoracic Surgery has conducted annual surveys of thoracic surgery throughout Japan since 1986 to determine the statistics regarding the number of procedures according to operative category. Here, we have summarized the results from our annual survey of thoracic surgery performed during 2014.

The Japanese Association for Thoracic Surgery has conducted annual surveys of thoracic surgery throughout Japan since 1986 to determine the statistics regarding the number of procedures according to operative category. Here, we have summarized the results from our annual survey of thoracic surgery performed during 2014.
Thoracic surgery was classified into three categoriescardiovascular, general thoracic, and esophageal surgeryand the patient data were examined and analyzed for each group. Access to the computerized data is offered to all members of this Association. We honor and value all member's continued kind support and contributions (Tables 1, 2).
The incidence of hospital mortality was added to the survey to determine the nationwide status, which has contributed to the Japanese surgeons to understand the present status of thoracic surgery in Japan and to make progress to improve operative results by comparing their work with those of others. The Association was able to gain a better understanding of the present problems as well as the future prospects, which has been reflected to its activity including education of its members. Thirty-day mortality (so-called ''operative mortality'') is defined as death within 30 days of operation regardless of the patient's geographic location and even though the patient had been discharged from the hospital.
Hospital mortality is defined as death within any time interval after an operation if the patient had not been discharged from the hospital. Hospital-to-hospital transfer is not considered discharge in the categories of cardiovascular surgery and esophageal surgery: transfer to a nursing home or a rehabilitation unit is considered hospital discharge unless the patient subsequently dies of complications of the operation. While hospital-to-hospital transfer after 30 days of operation is considered discharge in the categories of general thoracic surgery, because data of national clinical database (NCD) 2014 were used in this category, and hospital-to-hospital transfer after 30 days of operation is considered discharge in NCD.

Abstract of the survey
We sent out survey questionnaire forms to the departments of each category in all 1039 institutions (578 cardiovascular, 762 general thoracic, and 626 esophageal) nationwide in early April 2014. The response rates in each category by the end of December 2015 were 97.1, 96.1, and 96.0 %, respectively. This high response rate has been keep throughout recent survey, and more than 96 % response rate in all fields in 2014 survey has to be congratulated.

Final report (A) Cardiovascular surgery
First, we are very pleased with the high response rate to our survey of cardiovascular surgery (97.1 %), which definitely enhances the quality of this annual report. We very much appreciate the enormous effort put into completing the survey at each participating institution. Figure 1 shows the development of cardiovascular surgery in Japan over the last 28 years. Aneurysm surgery includes only operations for thoracic and thoracoabdominal aortic aneurysm. Pacemaker implantation includes only transthoracic implantation, and transvenous implantation is excluded. The number of pacemaker and assist device implantation operations is not included in the total number of surgical operations. A total of 66,453 cardiovascular operations were performed at 561 institutions during 2014 alone and included 30 heart transplantations, which were restarted in 1999.
The number of operations for congenital heart disease (9269 cases) decreased slightly (1.0 %) compared with that of 2013 (9366 cases), and 2.9 % decrease when compared with the data of 10 years ago (9545 cases in 2004). The number of operations for adult cardiac disease (21,939 cases in valvular heart disease, 17,498 cases in thoracic aortic aneurysm, and 2118 cases for other procedures) increased compared with those of 2013 (0.8, 11.0, and 13.2 %, respectively) except for ischemic heart disease (15,629 cases), which decreased 5.6 % of that in 2013. During the last 10 years, the numbers of operations for adult heart disease increased constantly except for that for ischemic heart disease (73.8 % increase in valvular heart disease, 26.5 % decrease in ischemic heart disease, 114.5 % increase in thoracic aortic aneurysm, and 56.5 % increase in other procedures compared those of 2004). The concomitant coronary artery bypass grafting procedure (CABG) is not included in ischemic heart disease but included in other categories, such as valvular heart disease and thoracic aneurysm in our study, and then, the number of CABG still remained over 20,000 cases per year (20,991 cases) in 2014. Data for individual categories are summarized in tables through 3 to 9.
In 2014, 6894 open-heart operations for congenital heart disease were performed with overall hospital mortality of 2.3 %. The number of operations for congenital heart disease was quite steady throughout these 10 years (maximum 7,386 cases in 2006), while overall hospital mortality decreased gradually from that of 3.9 % in 2004. In detail, the most common disease was atrial septal defect (1,248 cases); however, its number deceased to 64.3 % of that in 2004, which might be partially due to the recent development of catheter closure of atrial septal defect in Japan. In the last 10 years, hospital mortality for complex congenital heart disease improved in some anomalies such as, complete atrioventricular septal defect (5.4-1.7 %), tetralogy of Fallot (2.5-1.1 %), transposition of the great arteries with and without ventricular septal defect (9.8-3.9 and 7.1-6.6 %, respectively), single ventricle (8.5-4.3 %), and hypoplastic left heart syndrome (27.7-9.8 %). Right heart bypass surgery is now commonly performed (351 bidirectional Glenn procedures excluding 56 Damus-Kaye-Stansel procedures and 397 Fontan-type procedures including total cavopulmonary connection) with acceptable hospital mortality (1.2 and 1.0 %). Norwood type I procedure was performed in 125 cases with relatively low hospital mortality rate of 15.2 %.
As previously mentioned, the number of operations for valvular heart disease increased by 73.8 % in the last 10 years, and the hospital mortality associated with primary single valve replacement was 2.4 and 5.9 % for the aortic and the mitral position, while that for primary mitral valve repair was 1.1 %. However, hospital mortality rate for redo valve surgery was still high and was 9.4 and 7.8 % for aortic and mitral procedure, respectively. Finally, overall hospital mortality did not show dramatic improvement during the last 10 years (3.8 % in 2004 and 3.1 % in 2014), which might be partially due to the recent progression of age of the patients. Repair of the valve became popular procedure (397 cases in the aortic, 6527 cases in the mitral, and 5066 cases in the tricuspid), and mitral valve repair constituted 29.8 % of all valvular heart disease operation and 59.6 % of all mitral valve procedure (10,957 procedures), which are similar to those of the last 5 years and increased compared with those of 2004 (23.6 and 42.8 %, respectively). Aortic and mitral valve replacements with bioprosthesis were performed in 10,220 cases and 2,765 cases, respectively, with the number consistently increasing in the aortic position. The ratio of prostheses changed dramatically during the last 10 years and the usage of bioprosthesis is 77.5 % at the aortic position (36.7 % in 2004) and 25.2 % at the mitral position (14.8 % in 2004). CABG as a concomitant procedure performed in 17.3 % of operations for all valvular heart disease (13.3 % in 2004).
Isolated CABG was performed in 14,454 cases which were only 72.5 % of that of 10 years ago (2004). Among these 14,454 cases, off-pump CABG was intended in 9,006 cases (62.3 %) with a success rate of 98.3 %, so final success rate of off-pump CABG was 61.2 %. The percentage of intended off-pump CABG reached 60.3 % in 2004, and then was kept over 60 % until now. In 14,454 isolated CABG patients, 95.4 % of them received at least one arterial graft, while all arterial graft CABG was performed only 21.4 % of them.
The operative and hospital mortality rates associated with primary elective CABG procedures in 12335 cases were 0.8 and 1.3 %, respectively. Similar data analysis of CABG, including primary/redo and elective/emergency data, was begun in 2003, and the operative and hospital mortality rates associated with primary elective CABG procedures in 2003 were 1.0 and 1.5 %, respectively, so operative results of primary CABG has been stable, while hospital mortality of primary emergency CABG in 1,959 cases was still high and was 7.9 %. During these 10 years, the results of conversion from off-pump CABG improved both in conversion rate (3.1-1.7 %) and in hospital mortality (10.4-4.5 %).
A total of 1175 patients underwent surgery for complications of myocardial infarction, including 329 operations for a left ventricular aneurysm or ventricular septal perforation or cardiac rupture and 261 operations for ischemic mitral regurgitation.
Operations for arrhythmia were performed mainly as a concomitant procedure in 3855 cases with satisfactory mortality (1.6 % hospital mortality) including 3,486 MAZE procedures. MAZE procedure has become quite popular procedure when compared with that in 2004 (1837 cases).
Operations for thoracic aortic dissection were performed in 7733 cases. For 4953 Stanford type A acute aortic dissections, hospital mortality remained high and was 10.6 %. Operations for a non-dissected thoracic aneurysm were carried out in 9765 cases, with overall hospital mortality of 4.7 %. The hospital mortality associated with unruptured aneurysm was 3.3 %, and that of ruptured aneurysm was 21.2 %, which remains markedly high.
The number of stent graft procedures remarkably increased recently. A total of 1,625 patients with aortic dissection underwent stent graft placement: thoracic endovascular aortic repair (TEVAR) in 1,382 cases and open stent grafting in 243 cases. The number of TEVAR for type B chronic aortic dissections increased from 69 cases in 2004 to 835 cases in 2014. The hospital mortality rates associated with TEVAR for type B aortic dissection were 5.5 % in acute cases and 2.9 % for chronic cases, respectively.
A total of 3922 patients with non-dissected aortic aneurysm underwent stent graft placement; TEVAR in 3521 cases (12.4 % increase compared with that in 2013) and open stent grafting in 401 cases (145 % increase compared with that in 2013). The reason of dramatic increase in open stent grafting might be due to commercially availability since 2014. The hospital mortality rates for TEVAR were 2.4 and 17.1 % for non-ruptured and ruptured aneurysm, respectively.
Surgery for benign pulmonary tumor was 2171 in 2014 (Table 11).
Further information of primary malignant pulmonary tumors is shown in Tables 12 and 13. Among lung cancer subtypes, adenocarcinoma comprises an overwhelming percentage of 69.2 % of the total lung cancer surgery, followed by squamous cell carcinoma of 19.3 %. Limited resection by wedge resection or segmentectomy was performed in 9581 lung cancer patients, which is 25.2 % of the entire cases. Lobectomy was performed in 27,584 patients, which is 72.4 % of the entire cases. Sleeve lobectomy was done in 471 patients. Pneumonectomy was done in 521 patients which is 1.4 % of the entire cases.
There were 103 patients who died without discharge within 30 days after lung cancer surgery, and 59 patients who were discharged from hospital but died within 30 days after lung cancer surgery, indicating that 162 patients died within 30 days after lung cancer surgery (30-day mortality rate; 0.42 %). There were 266 patients died without discharge (hospital mortality rate; 0.70 %). 30-day mortality rate in regard to procedures is 0.12 % in segmentectomy, 0.48 % in lobectomy, and 1.53 % in pneumonectomy. Interstitial pneumonia was the leading cause of death after lung cancer surgery, followed by pneumonia, respiratory failure, cardiovascular event, and bronchopleural fistula.
Surgery for metastatic pulmonary tumors is denoted in Table 14. The number of patients undergoing operations for metastatic pulmonary tumor was 8057 in 2014 with steady increase similarly to lung cancer surgery (6248; 2009, 6748: 2010, 7210; 2011, 7403; 2012, 7829; 2013). Colorectal cancer was by far the leading primary malignancy indicated for resection of metastatic tumors, which comprises 48.4 % of the entire cases.
118 tracheal tumors were operated in 2014 (Table 15). Squamous cell carcinoma and adenoid cystic carcinoma were frequent primary tracheal tumor. 673 tumors of the pleural origin were operated in 2014 (Table 16). Diffuse malignant pleural mesothelioma was the most frequent histology. Total pleurectomy was performed in 73 patents and surpassed extrapleural pneumonectomy which was the most frequently chosen operative method in 2013. Hospital mortality rate was 4.1 % after total pleurectomy and 4.3 % after extrapleural pneumonectomy in 2014.
Thymectomy for myasthenia gravis was done in 495 patients (Table 19). Among them, 307 patients were associated with thymoma, and the remaining 188 patients were not associated with thymoma.
Lung resection for inflammatory lung diseases were done in 2287 patients in 2014 (Table 20). Inflammatory pseudotumor comprised 24.7 % of the entire cases, followed by atypical mycobacterium infection (21.9 %) and fungal infections (15.1 %).
2,608 operations for empyema were reported in 2014 (Table 21). There were 1911 patients (73.3 %) with acute empyema and 698 patients with chronic empyema. Bronchopleural fistula was associated in 469 patients (24.5 %) with acute empyema and 345 patients (49.5 %) with chronic empyema. It should be noted that hospital mortality was as high as 15.1 % in patients of acute empyema with fistula.
Operation for descending necrotizing mediastinitis was done in 103 patients in 2014 (Table 22). Hospital mortality rate was 8.7 %.
Operation for bullous diseases was done in 415 patients in 2014 (Table 23). Lung volume reduction surgery was done in only 28 patients, while emphysematous bulla was the principal target of operation.
The number of operations for spontaneous pneumothorax was 11,948. Among them, 3410 patients (28.5 %) underwent bullectomy alone, while additional procedure was performed in 7625 patients (63.8 %).
The number of operations for secondary pneumothorax was 2624. COPD was by far the most prevalent associated disease (67.2 %). It should be noted that hospital mortality rate of operation for pneumothorax associated with tumorous disease was as high as 16.7 %.
217 cases of surgery for chest wall deformity were reported in 2014 survey (Table 25). This number might be underestimated compared with the real number of operations, because chest wall deformity is more likely to be treated in the institutes which are not associated with JATS.
Diaphragmatic hernia was treated by surgery in 55 patients in 2014 (Table 26).
Chest trauma was treated by surgery in 394 patients in 2014 (Table 27). Table 28 denotes operations for other diseases, including 77 arteriovenous malformations and 104 pulmonary sequestrations. Table 29 denotes lung transplantation in 2014. A total of 60 lung transplantations were performed in 2014. The number of patients undergoing lung transplantation from brain-dead donors and living-related donors was 40 and 20, respectively. The number of lung transplantation is almost constant these several years, and lung transplantation is still dependent on living-related donors in Japan.
Details of tracheabronchoplasty, pediatric surgery, and combined resection of neighboring organs are denoted in Tables 30, 31, 32, and 33.
Committee for Scientific Affairs in JATS changed the method of surveying general thoracic surgery in 2014. JATS had investigated the number of diseases and operative procedures based on questionnaires until 2013 surveys, but JATS started to collect the number of procedures in general thoracic surgery using the database in National Clinical Database (NCD) registry. There were some differences in definition in VATS procedure between surveys by JATS before 2013 and that using NCD after 2014. While the length of skin incision in definition of VATS procedure had been less than 8 cm by JATS survey before 2013 following Swanson et al's proposal [1], NCD registry did not limit the length of skin incision in VATS procedures. On the other hand, NCD required the surgeons to choose the approach among complete VATS procedure without thoracotomy, the procedure using both thoracotomy and VATS which includes hybrid approach, and conventional thoracotomy without VATS procedure. It is presumed that hybrid approach was included in VATS procedure as far as the skin incision was shorter than 8 cm in JATS survey before 2013, but this does not seem to apply to survey in 2014 based on NCD registry, suggesting possible inconsistency in comparison between JATS survey before 2013 and NCD 2014 registry. In this report, therefore, analysis with regard to VATS procedure was not conducted.             Values in parenthesis represent mortality %       (Fig. 3). Among benign esophageal diseases (Table 35), hiatal hernia, esophageal varices, esophagitis (including reflux  esophagitis) and achalasia were the most common conditions in Japan. On the other hand, spontaneous rupture of the esophagus, benign esophageal tumors and congenital esophageal atresia were common diseases which were surgically treated as well as the above-mentioned diseases. The thoracoscopic and/or laparoscopic procedures have been widely adopted for benign esophageal diseases, in particular achalasia, hiatal hernia and benign tumors. Open surgery was performed in 1072 patients with a benign esophageal disease, with 30-day mortality in 14 (1.3 %), while thoracoscopic and/or laparoscopic surgery was performed for 588 patients, with 1(0.2 %) of the 30-day mortality The difference in these death rates between open and scopic surgery seems to be related the conditions requiring open surgery. The majority of malignant diseases were carcinomas (Table 36). Among esophageal carcinomas, the incidence of squamous cell carcinoma was 90.5 %, while that of adenocarcinomas including Barrett cancer was 7.1 %. The resection rate for patients with a squamous cell carcinoma was 76.4 %, while that for patients with an adenocarcinoma was 88.3 %.
According to location, cancer in the thoracic esophagus was the most common (Table 37). Of the 3950 patients (37.3 % of total esophageal malignancies) having superficial esophageal cancers within mucosal and submucosal layers, 1892 (47.9 %) patients underwent esophagectomy, while 1848 (46.8 %) patients underwent EMR or ESD. The 30-day mortality rate and hospital mortality rate after esophagectomy for patients with a superficial cancer were 0.5 and 1.2 % respectively. Advanced esophageal cancer invading deeper than the submucosal layer was observed in 6628 (62.6 %) patients. Of the 6628 patients with advanced esophageal cancer, 4344 (65.5 %) underwent esophagectomy, with 0.9 % of the 30-day mortality rate, and with 2.4 % of the hospital mortality rate.
Multiple primary cancers were observed in 1908 (18.0 %) of all the 10,584 patients with esophageal cancer. Synchronous cancer was found in 982 (51.5 %) patients, while metachronous cancer (found before esophageal cancer) was observed in 926 (48.5 %) patients. The stomach is the commonest site for both synchronous and metachronous malignancy followed by head and neck cancer (Table 37).
Among esophagectomy procedures, transthoracic esophagectomy through right thoracotomy was the most commonly adopted for patients with a superficial cancer as well as for those with an advanced cancer (Table 38). Transhiatal esophagectomy commonly performed in Western countries was adopted in only 2.8 % of patients having a superficial cancer who underwent esophagectomy and in 1.6 % of those having an advanced cancer in Japan. The thoracoscopic and/or laparoscopic esophagectomy were adopted for 1134 patients (59.9 %) with a superficial cancer, and for 1666 patients (38.3 %) with an advanced cancer. The number of cases of thoracoscopic and/or laparoscopic surgery for superficial or advanced cancer has been increasing for these several years (Fig. 4).
Combined resection of the neighboring organs during resection of an esophageal cancer was performed in 330 patients (Tables 38,39). Resection of the aorta together with the esophagectomy was performed in 2 cases. Tracheal and/or bronchial resection combined with esophagectomy was performed in 24 patients, with the 30-day mortality rate at 0 % and the hospital mortality rate at 4.2 %. Lung resection combined with esophagectomy was performed in 77 patients, with the 30-day mortality rate at 3.9 % and the hospital mortality rate at 7.8 %.
Salvage surgery after definitive (chemo-) radiotherapy was performed in 262 patients, with the 30-day mortality rate at 1.5 % and with the hospital mortality rate at 3.8 % (Table 38).
Last, in spite of the efforts of the Committee to cover wider patient populations to this annual survey, the majority of the institutions which responded to the questionnaire were the departments of thoracic or esophageal surgery. It should be noted that larger number of patients with esophageal diseases should have been treated medically and endoscopically. We should continue our effort for complete survey through more active collaboration with the Japan Esophageal Society and otherrelated societies.        (1) Transhiatal esophagectomy 53 1 (1.9) 1 (1.9) 2 (3.8) 4 0 0 0 (2) Transthoracic (rt.) esophagectomy and reconstruction (1) Aorta 2 0 0 0 (2) Trachea, bronchus 24 0 0 1 (4.2) (3) Lung 77 3 (3.9) 2 (2.6) 6 (7.8) Values in parenthesis represent mortality %