This retrospective analysis of Medicare claims data provides evidence of three-year mortality and morbidity benefits of CABG in a large cohort of very elderly patients presenting with ACS and multivessel CAD. Rates of survival and freedom from composite morbidity are both initially higher for PCI recipients. Coronary artery bypass grafting provides enhanced survival and freedom from composite morbidity at 36 months relative to PCI. Comorbidities previously identified to negatively affect outcomes from CABG apply to this population as well; COPD, CHF, peripheral vascular disease, and STEMI. The size of the population studied, the availability of DES, and the broad demographic representation suggest that these findings are widely applicable in the current era. In appropriately selected very elderly ACS patients with multivessel CAD, CABG remains a viable strategy despite the availability of DES.
Given the improved survival and morbidity benefits over time for CABG versus PCI, an important question is whether the initial mortality risk of CABG, its postsurgical functional limitations, and its recovery period are worth the longer term survival advantage. Patients, especially persons over age 85, may be willing to discount additional months of life for the early benefits of PCI. Although this analysis prohibits an unambiguous recommendation for CABG versus PCI for any particular patient, the results provide evidence that CABG may be preferred and may provide improved outcomes for selected patients. Albeit speculative, the advantage of surgery may arise from a more complete revascularization strategy and (or) the durability advantages of left internal thoracic artery grafts. The Synergy between PCI with the Taxus and Cardiac Surgery (SYNTAX) trial published a higher risk of stroke with CABG compared with left main PCI [9
], and our results are consistent with this observation. The incidence of stroke was surprisingly high in both treatment groups with an increased incidence in CABG patients. It is possible that this analysis of very elderly patients has identified a particularly high-risk patient population that is highly vulnerable to cerebrovascular complications of coronary revascularization.
Interest in the elderly and the very elderly is growing, as they account for an increasing share of the US population. Unfortunately, prospective randomized controlled trials have excluded older patients, which limit insight into this vulnerable group. More recent trials such as the Trial of Invasive versus Medical therapy in Elderly (TIME) have enrolled a greater number of older patients [10
] but the over-80-year-old group remains underrepresented. Alexander and colleagues [11
] successfully used the National Cardiovascular Network to study cardiac surgery outcomes in octogenarians. This thoughtful analysis observed that appropriately selected octogenarians could successfully undergo cardiac surgery with acceptable risk. In a single-center review, Akins and colleagues [5
] identified 600 consecutive octogenarians undergoing cardiac operations. They not only demonstrated reasonable five-year survival but also observed that at five years, survival normalized with the general US octogenarian population. Extending beyond the single-center experience to a regional analysis, the Northern New England Cardiovascular Disease Study Group [7
] evaluated 1,693 octogenarians undergoing PCI or CABG for multivessel disease. They identified a short-term advantage with PCI at six months with a long-term benefit of CABG over the subsequent eight-year follow-up. This retrospective regional study was followed by a large meta-analysis published by the Mayo Clinic essentially confirming the above and advocating for prospective randomized controlled trials to provide enhanced evidence [6
]. Finally, the recently published SYNTAX trial is a prospective randomized controlled trial comparing CABG with multivessel PCI using exclusively DES [9
]. The SYNTAX population had a mean age of 65 years and excluded AMI patients, and therefore differed substantially from the current study. Moreover, the cohort analyzed presently is substantially larger, with two additional years of follow-up. No randomized trials of myocardial revascularization are currently planned in the 85-and-older population, which increases the importance of observational studies to provide data from real-world clinical practice to aid decision making.
Despite these strengths, this study has several limitations. It is a retrospective administrative analysis without clinical records such as ejection fraction. As medical record data were unavailable, the comorbidity data reflect only those codes included on the MedPAR claims and may underestimate the true prevalence of comorbid disease in the population due to missing data or important unobserved health status measures. Administrative data may also over-represent new conditions such as stroke. While propensity score adjustment of the treatment groups for comorbidities and other clinical and demographic characteristics improves the precision of these results, unmeasured differences may persist and result in significant confounding. Additional factors, including onset of comorbidities over time, socioeconomic status, support systems, premorbid functional status, and hospital and health care providers, may have influenced treatment selection beyond the controlling influence of the propensity adjustment methodology. Although unavailable, this study would also benefit from outcomes data specifying functionality (activities of daily living and self-report questionnaire) as well as a cost analysis.
In very elderly patients with ACS and multivessel CAD, CABG appears to offer an advantage over PCI of survival and freedom from composite endpoint at three years. To optimize the benefit of CABG in very elderly patients requires the absence of significant CHF, lung, and peripheral vascular disease. Despite improved safety of PCI and the development of drug-eluting stents, the advantage of CABG (albeit modest) over PCI appears to persist even after age 85. Improved patient selection, enhanced surgical techniques, and postprocedural care sensitive to the unique physiology in this vulnerable population will ensure that CABG remains an important therapeutic option for the treatment of multivessel CAD in this population.