Thoracic and cardiovascular surgery in Japan during 2012

The Japanese Association for Thoracic Surgery has conducted annual surveys of thoracic surgery throughout Japan since 1987 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 2012. 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 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: transfer to a nursing home or a rehabilitation unit is considered hospital discharge unless the patient subsequently dies of complications of the operation. The definitions of the Ad Hoc Liaison Committee for Standardizing Definitions of Prosthetic Heart Valve Morbidity of the Society of Thoracic Surgeons and Annual report by The Japanese Association for Thoracic Surgery: Committee for Scientific Affair

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).

Abstract of the survey
We sent out survey questionnaire forms to the departments of each category in all 1,986 institutions (601 cardiovascular, 802 general thoracic and 582 esophageal) nationwide in early April 2013. The response rates in each category by the end of December 2013 were 97.0, 96.8, and 95.2 %, respectively. This high response rate has been keep throughout recent survey, and more than 95 % response rate in all fields in 2012 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 (97.0 %), 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 26 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 63,800 cardiovascular operations were performed at 583 institutions during 2012 alone and included 28 heart transplantations, which were restarted in 1999.
The number of operations for congenital heart disease (9,558 cases) decreased slightly (3.1 %) compared with that of 2011 (9,859 cases), while there was 3.9 % increase when compared with the data of 10 years ago (9,202 cases in 2002). The number of operations for adult cardiac disease (20,913 cases in valvular heart disease, 16,752 cases in ischemic heart disease, 14,944 cases in thoracic aortic aneurysm and 1,663 cases for other procedures) increased compared with those of 2011 in all categories (9.1, 7.5, 5.8 and 5.1 %, respectively). During the last 10 years, the  numbers of operations for adult heart disease increased constantly except for that of ischemic heart disease (81.0 % increase in valvular heart disease, 26.6 % decrease in ischemic heart disease, 112.4 % increase in thoracic aortic aneurysm, and 40.7 % increase in other procedures compared those of 2002). 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 in our study, then, the number of CABG still remained over 20,000 cases per year (21,569 cases) in 2012, which is 89.4 % of that in 2002 (24,135 cases). Data for individual categories are summarized in tables through 1 to 7.
In 2012, 7,171 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 3.6 % in 2002. In detail, the most common disease was atrial septal defect (1,331 cases), however, its number deceased to 71.7 % of that in 2002, which might be due to the recent development of catheter closure of atrial septal defect in Japan. Hospital mortality for complex congenital heart disease improved dramatically in the last 10 years such as interrupted aortic arch with ventricular septal defect (13.9 % in 2002 to 3.6 % in 2012), complete atrio-septal defect (4.2 to 3.2 %), Tetralogy of Fallot (3.8 to 1.1 %), transposition of the great arteries with and without ventricular septal defect (14.0 to 3.2 % and 7.4 to 2.6 %, respectively), single ventricle and tricuspid atresia (9.2 to 5.5 % and 3.9 to 0 %, respectively), and hypoplastic left heart syndrome (37.9 to 10.2 %). Right heart bypass surgery is now commonly performed (375 bidirectional Glenn procedures and 438 Fontan type procedures including total cavopulmonary connection) with acceptable hospital mortality (2.1 % in each procedure). Norwood type I procedure was performed in 130 cases with relatively low hospital mortality rate of 15.4 %.
As previously mentioned, the number of operations for valvular heart disease increased by 81 % in the last 10 years, and the hospital mortality associated with primary single valve replacement was 3.0 and 4.5 % for the aortic and the mitral position, while that for primary mitral valve repair was 1.3 %. However, hospital mortality rate for redo valve surgery was still high and was 9.3 and 6.7 % for aortic and mitral procedure, respectively. Finally, overall hospital mortality did not show any improvement during the last 10 years (3.1 % in 2002 and 3.2 % in 2012), which might be partially due to the recent progression of age of the patients. Repair of the valve became popular procedure (484 cases in the aortic, 6,002 cases in the mitral, and 4,947 case in the tricuspid), and mitral valve repair constituted 28.7 % of all valvular heart disease operation and 57.6 % of all mitral valve procedure (10,425 procedures), which are similar to those of the last 4 years and increased compared with those of 2002 (19.5 and 34.9 %, respectively). Aortic and mitral valve replacement with bioprosthesis were performed in 8,926 cases and 3,002 cases, respectively, with the number consistently increasing. The ratio of prostheses changed dramatically during the last 10 years, and the usage of bioprosthesis is 74.3 % at the aortic position (37.3 % in 2002) and 61.0 % at the mitral position (24.2 % in 2002). CABG as a concomitant procedure increased gradually to 23.9 % of operations for all valvular heart disease (12.1 % in 2002).
Isolated CABG was performed in 15,462 cases which were only 71.5 % of that of 10 years ago (2002), however, there was an increase of 8.5 % compared with that in 2011. Among these 15,462 cases, off-pump CABG was intended in 9,499 cases (61.4 %) with a success rate of 97.9 %, so final success rate of off-pump CABG was 60.2 %. The percentage of intended off-pump CABG was 55.2 % in 2003, and was increased to 60.3 % in 2004, then was kept over 60 % until now. Conversion rate from off-pump CABG to on-pump CABG of 2.1 % was just same as that in 2011. In 15,462 isolated CABG patients, 96.5 % of them received at least one arterial graft, while, all arterial graft CABG was performed in only 23.5 % of them.
The operative and hospital mortality rates associated with primary elective CABG procedures in 13,004 cases were 0.6 and 1.1 %, 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 have been improved. However, hospital mortality of primary emergency CABG in 2,224 cases was 7.4 %, which was still high in spite of slight improvement compared with 9.7 % of hospital mortality rate in 2003. In comparison with data in 2003, the results of conversion improved both conversion rate (3.1 to 2.1 %) and hospital mortality (8.5 to 5.1 %).
A total of 1,274 patients underwent surgery for complications of myocardial infarction, including 413 operations for a left ventricular aneurysm or ventricular septal perforation or cardiac rupture and 296 operations for ischemic mitral regurgitation.
Operations for arrhythmia were performed mainly as a concomitant procedure in 3,992 cases with satisfactory mortality (1.8 % hospital mortality) including 3,771 MAZE procedures. MAZE procedure has become quite popular procedure when compared with that in 2002 (1,141 cases).
Operations for thoracic aortic dissection were performed in 6,266 cases. For 4,186 Stanford type A acute aortic dissections, hospital mortality was 10.6 %, which was similar to that in 2011 (11.1 %) and better than that in 2002 (15.5 %). Operations for a non-dissected thoracic aneurysm were carried out in 8,678 cases, with overall hospital mortality of 5.4 %, which was better than that in 2011 (6.7 %). The hospital mortality associated with unruptured aneurysm was 4.0 %, and that of ruptured aneurysm was 22.2 %, which remains markedly high.
The number of stent graft procedures remarkably increased recently. A total of 835 patients with aortic dissection underwent stent graft placement: thoracic endovascular aortic repair (TEVAR) in 723 cases, open stent grafting in 109 cases, and unspecified in 3 cases. The number of TEVAR for type B chronic aortic dissections increased from 359 cases in 2011 to 492 cases in 2012. The hospital mortality rates associated with TEVAR for type B aortic dissection were 7.3 % in acute cases and 2.6 % for chronic cases, respectively.
A total of 3,236 patients with non-dissected aortic aneurysm underwent stent graft placement with 18.8 % increase compared with that in 2011 (2,725 cases); TEVAR in 3,006 cases (23.6 % increase compared with that in 2011), open stent grafting in 226 cases (20.8 % decrease compared with that in 2011), and unspecified in 4 cases. The hospital mortality rates for TEVAR were 2.5 and 16.1 % for non-ruptured and ruptured aneurysm, respectively.
In summary, the total cardiovascular operations increased during 2012 by 3,516 cases, with steadily improving results in almost all categories compared with those in 2011.                               Values in parenthesis represent mortality %   The total number of operations reported in 2012 in general thoracic surgery has reached 72,899, which means an increase of 3,676 cases compared with the number of operations in 2011. This is largely owing to the steady increase in lung cancer surgery (31,301; 2009, 32,801; 2010, 33,878:2011, 35,667:2012). Surgery for lung cancer consists more than 49 % of all the general thoracic surgery. Among lung cancer subtypes, adenocarcinoma comprises an overwhelming percentage of 69.4 % of the total lung cancer surgery, followed by squamous cell carcinoma of 19.0 %. Limited resection by wedge resection or segmentectomy was performed in 6,789 lung cancer patients, which is 19.0 % of the entire cases. Lobectomy was performed 26,079 patients, which is 73.1 % of the entire cases. Sleeve lobectomy was done in 429 patients. Pneumonectomy was done in 571 patients, which is only 1.6 % of the entire cases. VATS (video-assisted thoracic surgery) procedure is performed in 65.6 % among the total lung cancer surgeries in 2012. 123 patients died within 30 days after lung cancer surgery (30-day mortality rate 0.34 %), and 248 patients died without discharge (Hospital mortality rate 0.70 %). 30-day mortality rate in regard to procedures is 0.26 % in segmentectomy, 0.31 % in lobectomy, and 2.45 % in pneumonectomy.
Interstitial pneumonia was the leading cause of death after lung cancer surgery, followed by pneumonia, cardiovascular event, bronchopleural fistula, and respiratory failure. 7,403 patients with metastatic pulmonary tumor were operated in 2012 with steady increase similar to lung cancer surgery (6,248:2009, 6,748:2010, 7,210:2011). VATS was adopted in 5,828 cases, which comprises 78.7 % of the entire cases. Colorectal cancer was by far the leading primary malignancy indicated for resection of metastatic tumors. 73 tracheal tumors were operated in 2012. Adenoid cystic carcinoma and squamous cell carcinoma were frequent primary tracheal tumor. 409 tumors of pleural origin were operated in 2012. Diffuse malignant pleural mesothelioma was the most frequent histology. Extrapleural pneumonectomy was the most frequently chosen operative method (135 cases) with a hospital death of 6.7 %. 752 chest wall tumors were resected in 2012. 4,671 mediastinal tumors were operated in 2012. There were 2,151 thymic epithelial tumors (1,842 thymomas, 271 thymic carcinomas, and 38 thymic carcinoid), followed by 906 congenital cysts, 495 neurogenic tumors, and 231 germ cell tumors. 2,425 cases (51.9 %) were resected by VATS.
Thymectomy for myasthenia gravis was done in 446 patients, and 302 among them were associated with thymoma, indicating that thymectomy for non-thymomatous myasthenia gravis was done only in 144 patients. Advancement in medical control of myasthenia gravis by immunosuppressants might reduce indication of extended thymectomy for non-thymomatous myasthenia gravis. This possibility should be further examined.
2,250 operations for empyema were reported in 2012. There were 1,710 patients (76 %) with acute empyema and 540 patients with chronic empyema. Bronchopleural fistula was associated in 348 patients (20.4 %) with acute empyema and 274 patients (50.7 %) with chronic empyema. It should be noted that hospital mortality was as high as 12.1 % in patients of acute empyema with fistula.
14,410 operations for pneumothorax were reported in 2012. 13,555 operations (94.1 %) were performed by VATS, similarly to cases in 2011.
44 lung transplantations were reported in 2012. The number of the brain-dead donors is slightly increasing after revision of the law on organ transplantation.
The number of lung transplantation operation is still small compared to those in North America and European countries because of shortage of donors, but the number of brain-dead donors is increasing slowly in Japan after revision of the law of organ transplantation in 2010.                  Values in parenthesis represent mortality %               (Fig. 1). Among benign esophageal diseases (Table 2), esophageal varices, hiatal hernia, achalasia and esophagitis (including reflux esophagitis) 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. 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 828 patients with a benign esophageal disease with 30-day mortality in 5 (0.6 %), while thoracoscopic and/or laparoscopic surgery was performed for 233 patients with 0 (0.0 %) of the 30-day mortality The difference in these death rates between open and scopic surgery seems to be related to the conditions requiring open surgery.
The majority of malignant diseases were carcinomas (Table 3). Among esophageal carcinomas, the incidence of squamous cell carcinoma was 91.8 %, while that of adenocarcinomas including Barrett cancer was 5.7 %. The resection rate for patients with a squamous cell carcinoma was 77.6 %, while that for patients with an adenocarcinoma was 91.5 %.
According to location, cancer in the thoracic esophagus was the most common (Table 4). Of the 3,793 patients (37.8 % of total esophageal malignancies) having superficial esophageal cancers within mucosal and submucosal layers, 1,759 (46.3 %) patients underwent esophagectomy, while 1,802 (47.5 %) patients underwent EMR or ESD. The 30-day mortality rate and hospital mortality rate after esophagectomy for patients with a superficial cancer were 0.6 and 1.5 %, respectively. There was no EMR or ESD-related death. Advanced esophageal cancer invading deeper than the submucosal layer was observed in 6,231 (62.1 %) patients. Of the 6,231 patients with advanced esophageal cancer, 4,288 (68.8 %) underwent esophagectomy, with 0.8 % of the 30-day mortality rate, and with 2.4 % of the hospital mortality rate.
Multiple primary cancers were observed in 1,644 (16.4 %) of all the 10,034 patients with esophageal cancer. Synchronous cancer was found in 868 (52.9 %) patients, while metachronous cancer (found before esophageal cancer) was observed in 772 (47.0 %) patients. The stomach is the commonest site for both synchronous and metachronous malignancy followed by head & neck cancer (Table 4).
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 5). Transhiatal esophagectomy commonly performed in Western countries was adopted in only 4.4 % of patients having a superficial cancer who underwent esophagectomy, and in 2.0 % of those having an advanced cancer in Japan. The thoracoscopic and/or laparoscopic esophagectomy were adopted for 855 patients (48.6 %) with a superficial cancer, and for 1,193 patients (27.8 %) 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. 2).
Combined resection of the neighboring organs during resection of an esophageal cancer was performed in 334 patients (Tables 5, 6). Resection of the aorta together with the esophagectomy was performed in 2 cases. Tracheal and/or bronchial resection combined with esophagectomy was performed in 23 patients, with the 30-day mortality rate at 4.3 % and the hospital mortality rate at 13.0 %. Lung resection combined with esophagectomy was performed in 69 patients, with the 30-day mortality rate at 0 % and the hospital mortality rate at 1.4 %.
Salvage surgery after definitive (chemo-)radiotherapy was performed in 256 patients, with the 30-day mortality rate at 2.7 % and with the hospital mortality rate at 6.3 %. (Table 5).
Lastly, 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 other related societies.        Acknowledgments On behalf of The Japanese Association for Thoracic Surgery, the authors thank the Heads of the Affiliate and Satellite Institutes of Thoracic Surgery for their cooperation, and the Councilors of the Japan Esophageal Society.