Surgical Outcomes following Complex and High Risk Cardiac Surgery in Australia

The population presenting for cardiac surgery today is more elderly and high risk. The objective of this thesis was to identify the outcomes following complex and high risk cardiac surgery and determine its feasibility, safety and reproducibility. Methods used were retrospective database studies (unadjusted and propensity matched studies), systematic review and meta-analysis as well as literature review. The main outcomes studied were perioperative mortality, stroke and long term survival. This dissertation discusses off pump (OPCAB) versus on pump (ONCAB) coronary revascularisation surgery; mitral valve (MV) repair versus replacement; surgical aortic valve replacement (sAVR) versus transcatheter aortic valve implantation (TAVI); aortic root replacement and valve-sparing aortic root reconstruction. On pump coronary artery bypass and OPCAB had similar postoperative mortality and stroke rates but there was a non-significant trend towards improved long term survival following OPCAB. Significant mortality benefit in patients with diabetes, left main disease and peripheral vascular disease and significant stroke benefit in patients with diabetes and peripheral vascular disease was seen post OPCAB. Overall, MV repair is superior to MV replacement, especially in the elective setting. In degenerative MR, there was a non significant trend towards improved short and long term outcomes following repair. In ischaemic MR, the outcomes were equivalent. The literature review on management of aortic stenosis suggest that in inoperable patients with symptomatic aortic stenosis, TAVI is superior to standard medical treatment. In the high surgical risk cohort, TAVI was comparable to sAVR. Our studies show that patients undergoing aortic root replacement and valve-sparing aortic root reconstruction in Australia have outcomes on par with international institutions. Perioperative mortality, stroke and long term survival is good, especially in the elective setting. In summary, this dissertation has provided a better understanding regarding complex and high risk cardiac surgeries, especially in Australia. The dissertation has established feasibility of such procedures in the elderly and high risk patients and highlights the excellent outcomes that are being achieved with increasing experience

Outcomes of On-Pump versus Off-Pump Coronary Artery Bypass Graft Surgery in the High Risk (AusSCORE > 5)

Background: Coronary artery bypass graft surgery (CABG) has been established as the preferred intervention for coronary revascularisation in the high-risk population. OPCAB may further reduce mortality and morbidity in this population subgroup. This study presents the largest series of high-risk (AusSCORE > 5) OPCAB patients in Australia and New Zealand. Methods: We reviewed the Australian and New Zealand Society of Cardiac and Thoracic Surgeons' (ANZSCTS) database for high-risk patients (n=7822) undergoing isolated CABG surgery and compared the ONCAB (n=7277) with the OPCAB (n=545) technique. Preoperative and intraoperative risk factors, and postoperative outcomes were analysed. Survival analysis was performed after cross-matching the database with the national death registry to identify long-term mortality. Results: The ONCAB and OPCAB groups had similar risk profiles based on the AusSCORE. Thirty-day mortality (ONCAB vs OPCAB 3.9% vs 2.4%, p=0.067) and stroke (ONCAB vs OPCAB 2.4% vs 1.3%, p=0.104) were similar between the two groups. OPCAB patients received fewer distal anastomoses than ONCAB patients (2.5±1.2 vs 3.3±1.0, p<0.001). The rates of new postoperative atrial arrhythmia (28.3% vs 33.3%, p=0.017) and blood transfusion requirements (52.1% vs 59.5%, p=0.001) were lower in the OPCAB group, while duration of ICU stay in hours (97.4±187.8 vs 70.2±152.8, p<0.001) was longer. There was a non-significant trend towards improved 10-year survival in OPCAB patients (74.7% vs. 71.7%, p=0.133). Conclusions: In the high-risk population, CABG surgery has a low rate of mortality and morbidity suggesting that surgery is a safe option for coronary revascularisation. OPCAB reduces postoperative morbidity and is a safe procedure for 30-day mortality, stroke and long-term survival in high-risk patients

Comparison of the Safety and Efficacy of On-Pump (ONCAB) versus Off-Pump (OPCAB) Coronary Artery Bypass Graft Surgery in the Elderly: A Review of the ANZSCTS database

Background: The elderly population (age >70 years) incurs greater mortality and morbidity following CABG. OPCAB may mitigate these otucomes. A retrospective analysis of the results of OPCAB in this population was performed. Methods: We reviewed the Australian and New Zealand Society of Cardiac and Thoracic Surgeons’ (ANZSCTS) database for elderly patients (n=12697) undergoing isolated CABG surgery and compared the ONCAB (n=11676) with OPCAB (n=1021) technique. Preoperative and intraoperative risk factors, and postoperative outcomes were analysed. Survival analyses was performed after cross-matching the database with the national death registry to identify long-term mortality. Results: High-risk patients were more prevalent in the ONCAB group (p<0.05). OPCAB patients received fewer distal anastomoses than ONCAB patients (2.4±1.1 vs 3.3±1.0, p<0.001). Thirty-day mortality and stroke rates between OPCAB and ONCAB were not significantly different (2% vs 2.5% and 1.1% vs 1.8%, respectively). There was a non-significant trend towards improved 10-year survival in OPCAB patients using multivariate analysis (78.8% vs. 73.3%, p=0.076, HR 0.83; 95% CI 0.67-1.02). Conclusions: Mortality and stroke rates following CABG surgery are extremely low in the elderly suggesting that surgery is a safe management option for coronary artery disease in this population. OPCAB did not offer a significant advantage over ONCAB with regards to 30-day mortality, stroke and long-term survival. Further prospective randomised trials will be necessary to clarify risks or benefits in the elderly