Comment
This study was a retrospective, single-center report of early and long-term results from OPCAB for octogenarians under an OPCAB-first strategy and illustrated real-world clinical practice. Early results were good in terms of mortality and morbidity rates, with the exception of post-operative atrial fibrillation. Long-term results were also good.
As post-operative results for the old group were not inferior to those for the young group, we believe that the OPCAB-first strategy for all generation becomes a good therapeutic option for surgical revascularization in octogenarians.
For elderly patients, early extubation and early recovery from bed rest are very important to prevent disuse atrophy, which can lead to post-operative complications. In the present study, post-operative intubation time and intensive care unit stay did not differ significantly between young and old groups. We adjusted graft usage in elderly or ill patients to shorten operative time, and the old group displayed a shorter operative time than the young group (Table 2). Shorter operative time and OPCAB with multidisciplinary care, including anesthetic drug usage and intra-operative volume control could contribute to the achievement of early extubation and a short stay in the intensive care unit, even for old patients.
Some reports have demonstrated that bilateral ITA usage was associated with an increased frequency of post-operative mediastinitis16,17. In the present study, however, the overall incidence of mediastinitis was low, at 0.8%, despite bilateral ITAs were used in 79.8% of all cases. This might be because bilateral ITAs were harvested in skeletonized fashion with a harmonic scalpel in our institution18. Furthermore, the surgeons who harvested bilateral ITAs were very experienced due to our strategy, and bilateral ITAs were used in nearly 80% of all cases.
Concerning the graft design, the radial artery was attractive as the third arterial graft14. However, in the present study, nearly 14% of patients were receiving hemodialysis before the operation, and radial artery harvesting was thus avoided in consideration of the fact that many patients with coronary artery disease potentially have reduced renal function and even non-hemodialysis patients might require future shunt establishment. As a matter of fact, 6.3% of the old group required temporary post-operative hemodialysis, even though OPCAB can reportedly lower post-operative kidney injury compared to conventional CABG19,20.
The frequency of post-operative cerebral infarction did not differ between groups, but was 1.8% overall. Three of the 13 patients with post-operative cerebral infarction were considered to have intraoperative cerebral infarction, comprising two emergent cases, and one cases with carotid stenosis. The “intra-operative” cerebral infarction rate was low, at 0.4%, probably because OPCAB could avoid aortic cannulation or cross-clamping11. The remaining 10 cases suffered delayed cerebral infarction on POD3 or later, including 5 cases of paroxysmal atrial fibrillation, and 3 cases in hemodialysis patients. Methods to reduce “post-operative” cerebral infarction are needed. We adopted double anti-platelet therapy, with aspirin at 81 mg/day and clopidogrel at 75 mg/day, with the aims of not only reducing graft occlusion15, but also reducing the risk of cerebral infarction21,22. However, our results indicate that changes in this post-operative regimen may be warranted. Adjustment of antiplatelet/anti-coagulation therapy, including heparin administration or use of warfarin or direct oral anticoagulants, might be required. Not only care, but also prevention of atrial fibrillation are the rational approaches to reducing post-operative cerebral infarction. This needs to be taken into consideration, using approaches such as aggressive usage of beta-blockers23.
Long-term results were satisfactory considering the age of our patients, and were better than what has been reported elsewhere4,5. These findings were comparable with those from previous reports; once old patients survive the surgery, long-term prospects are good6. In the present study, the 7-year survival rate was 48.6%, meaning that nearly half of the patients reached their nineties. This was close to the life expectancy of the general population in Japanese at age 80, which is about 9 years for Japanese men and 12 years for Japanese women3.
The Clinical Frailty Scale is a simple tool to semi-quantitatively assess patient frailty24. This scale can predict late mortality in certain cases25,26. In the present study, as preoperative Clinical Frailty Scale scores differed significantly between groups, the mean score in the old group was relatively low, at 3.2. Despite our no-refusal policy, some degree of selection bias would have naturally been introduced by referring doctors, cardiologists or even surgeons. This speculation was supported by the fact that 85.1% of patients were able to return home from hospital directly, indicating that daily activity of octogenarian patients was well preserved in this study. From another perspective, our results implied that those patients with a Clinical Frailty Scale score around 3 would have a high possibility of overcoming OPCAB, even in octogenarians.
The present study had several limitations. First, the results in this study represent our clinical experience with a consecutive series of isolated surgical CABG. The number of patients was small and selection of surgical revascularization for patients introduced a huge selection bias. Nonetheless, our results encourage us to keep providing open-heart surgery to octogenarians with ischemic coronary disease where feasible.
A second limitation was the retrospective design of the study, with no comparisons between OPCAB and conventional CABG made within groups. Whether OPCAB provided more benefit to old patients than conventional CABG thus could not be assessed. However, as we chose OPCAB as the first-line procedure, nearly 97% of cases were accomplished using OPCAB. We believe that the more we become familiar with the procedure, the more the operative results that can be provided to elderly patients will stabilize11.
Lastly, we did not assess major adverse cardiac events over the long term. The long-term symptom-free rate was therefore unknown. Nevertheless, our OCPAB-first strategy could provide elderly patients with a comparable survival rate to Japanese octogenarians in the general population.