Being Refused CABG a Sign of Extra Risk for PCI Patients With Left Main, Multivessel Disease
In patients with left main or multivessel disease undergoing percutaneous coronary intervention (PCI), not being a candidate for coronary artery bypass graft (CABG) surgery predicts higher mortality, even when accounting for other baseline differences. Yet surgical “turn down” has not been incorporated into standard risk adjustment models for PCI, say researchers of a registry study published online November 12, 2014, ahead of print in Circulation.
“These findings have important implications for comparative effectiveness research, evaluating hospital quality and procedural appropriateness, and the application of risk-prediction estimates to guide clinical decision making,” write Robert W. Yeh, MD, MSc, of Massachusetts General Hospital (Boston, MA), and colleagues.
| Methods |
| The investigators analyzed data from 1,013 patients undergoing nonemergent PCI for unprotected left main or multivessel CAD at 2 Massachusetts hospitals from 2009 to 2012. Electronic medical records were reviewed to assess documentation of surgical ineligibility. |
| In all, 218 patients (22%) were deemed ineligible for surgical revascularization by their treating clinician. Compared with those eligible for CABG, ineligible patients were older, more likely to be female, and had higher rates of concomitant cerebrovascular disease, chronic lung disease, congestive heart failure, diabetes, hypertension, peripheral artery disease, and prior MI. Additionally, their predicted in-hospital mortality was higher compared with that of patients who had not been denied CABG. |
During PCI, ineligible patients were more likely to undergo procedures via femoral access (81% vs 63%) and to have left main disease (33% vs 10%) and high complexity lesions (51% vs 34%) than those eligible for surgery (P < .001 for all). They also had a greater number of lesions and stents placed and longer stents (P < .001 for all). Surgery-eligible patients, however, had more vessels revascularized (P < .001).
Dramatic Increases for Both In-Hospital, Long-term Mortality Risk
Among those eligible for CABG, 81% did not have explicit documentation about surgical candidacy in their electronic medical record. The most commonly cited characteristics thought to significantly increase surgical risk were: poor surgical targets (24%), advanced age (16%), renal insufficiency (16%), severe lung disease (15%), and severe systolic dysfunction (14%).
After adjusting for known risk factors, documentation of surgical ineligibility remained independently associated with greater risk of both in-hospital and long-term mortality (table 1).
Furthermore, when surgical ineligibility was added to the previously validated NCDR model for risk adjustment, the capability of the model to predict mortality improved (c-statistic 0.753 for NCDR risk score vs 0.792 with inclusion of surgical ineligibility; P < .01).
Unmeasured Characteristics Can Undermine Research
Dr. Yeh and colleagues note that the results are topical given the fact that the optimal revascularization strategy for patients with multivessel CAD has been a topic of interest in comparative effectiveness research for many years.
“It is possible that surgical ineligibility in itself may represent a variety of other clinical characteristics that are poorly captured in administrative or clinical datasets, including general frailty or poor psychosocial support,” the study authors write. “Due to both their high prevalence and large effect size, these unmeasured characteristics have the potential to undermine the results of large observational studies comparing revascularization strategies, even those employing rigorous statistical methods to limit confounding.”
Additionally, they say, the findings “support the idea that documented surgical ineligibility may be an important variable to consider in risk-adjustment models used for hospital quality assessment, given its significant association with PCI outcomes and the likelihood that these patients would be concentrated at institutions that performed cardiac surgery.”
Despite the current revascularization guidelines recommending a heart team approach with input from both cardiac surgeons and interventional cardiologists, the study found that formal consultation and electronic documentation from cardiac surgeons was uncommon in this patient population, Dr. Yeh and colleagues point out. Instead, they hypothesize cardiologists may have used risk-prediction instruments such as the STS score or EuroSCORE—which do not include surgical ineligibility—to determine the potential morbidity of undergoing surgical revascularization.
Do More Confounders Exist?
In an editorial accompanying the study, Kirk N. Garratt, MSc, MD, of Northshore/LIJ Lenox Hill Hospital (New York, NY), writes that the new study questions the conclusions of the ASCERT trial—the largest registry-based analysis of comparative effectiveness for coronary revascularization ever conducted. In finding a mortality and cost-effectiveness advantage for CABG relative to PCI, ASCERT may have failed to account for surgical ineligibility, he says.
According to Dr. Garratt, the new study, coupled with a prior paper (McNulty EJ, et al. J Am Coll Cardiol Intv. 2011;4:1020-1027), provides substantial enough evidence to now ask whether surgical ineligibility is a “poison dart that threatens the validity of the many registry analyses,” including ASCERT.
Furthermore, Dr. Garratt suggests the possibility of other confounders, including cachexia and frailty, poor adherence to prescribed medications, aortic calcification, systemic infection, immunosuppression, and lack of patient acceptance of recommended treatment.
“As NCDR is now assembling a team to craft Version 5 of the CathPCI Registry, the Yeh publication is timely; this assembly will provide an opportunity to discuss changes in the structure and operation of the NCDR CathPCI Registry, as much as how to improve its data element list,” he writes. “Hopefully, STS will follow suit and look to make important changes to its Adult Cardiac Surgery Database as well.”
Sources:
1. Waldo SW, Secemsky EA, O’Brien C, et al. Surgical ineligibility and mortality among patients with unprotected left main or multivessel coronary artery disease undergoing percutaneous coronary intervention. Circulation. 2014;Epub ahead of print.
2. Garratt KN. The challenges and importance of finding hidden confounders when conducting comparative effectiveness studies using registry data: the impact of surgical turn-down on PCI mortality [editorial]. Circulation. 2014;Epub ahead of print.
Disclosures:
- Dr. Yeh reports no relevant conflicts of interest.
- Dr. Garratt reports receiving consultant fees from Abbott Vascular, Boston Scientific Corp, and The Medicines Company; research support from Boston Scientific, CeloNova , Daiichi-Sankyo/Lilly, The Mayo Foundation, and The Medicines Company; and holding equity in Guided Delivery Systems and Infarct Reduction Technologies.
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L.A. McKeown is a Senior Medical Journalist for TCTMD, the Section Editor of CV Team Forum, and Senior Medical…
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