To Protect or Not to Protect: Mitigating the Potential Risk That Surgical Ineligibility Poses in High-Risk PCI

Percutaneous coronary intervention nowadays is a routine cardiac procedure carrying low risk aided by resurgence of the radial approach, advancement in techniques and use of more potent antiplatelet agents making same day discharges achievable in high volume centers.¹ On the other end of the spectrum of procedural risk lies the performance of PCI in reduced left ventricular function, severe multivessel CAD including unprotected left main lesions, and acute MI with cardiogenic shock.² A recent report by Wayangakar et al on the contemporary invasive management of acute MI in CS patients chronicles the continued rise in in-hospital mortality in CS despite the widespread adoption of early invasive percutaneous intervention and use of mechanical support.³ Setting these disheartening findings aside, the results suggest that improved targeted time-sensitive therapies coupled with a better understanding of risks encountered may improve outcomes. Objective risk score calculators including the NCDR CathPCI score, Mayo Clinic score, and SYNTAX score can assist in predicting risk; however, continued poor outcomes in the high-risk subset begs the question of whether other unmeasured variables such as surgical ineligibility, frailty, or patient preference are significantly impacting outcomes without being included in standard databases or PCI risk models.⁴

The report by Shavelle et al⁵ in this issue of the Journal of Invasive Cardiology sets out with a two-fold aim to prove (1) whether surgical ineligibility is a true predictor of poorer outcomes in high risk PCI, and (2) does protected PCI lessen that perceived risk? To examine a cohort of the highest risk patients, they reviewed subjects of the PROTECT II trial, arguably the most contemporary randomized representation of the highest risk patients undergoing complex PCI.⁶ The PROTECT II trial investigated the outcomes of patients undergoing high risk PCI randomized to mechanical support with either IABP or Impella device. Patients enrolled in the trial were defined as high risk by virtue of having reduced LVEF, multivessel CAD including unprotected left main disease, and lone remaining conduits or circulation as culprit lesions. In studying patients who underwent pre-PCI surgical consultation to those who did not, Shavelle et al found that there was no difference in the primary endpoint, a composite of 90-day major adverse cardiac and cerebrovascular events (MACCE). 

Although the PROTECT II protocol prompted all eligible patients to undergo surgical consultation, curiously less than half (47%) of the enrolled patients actually received surgical evaluation; patients without surgical consultation were essentially protocol deviations. Thus, albeit confusing, the report compared the surgically evaluated “presumed surgically ineligible” to the non-surgically evaluated “CABG clinically unattractive.”⁶ Not surprisingly, patients with de novo disease, prior CVA, and insulin-requiring diabetes mellitus were more inclined to undergo surgical consultation, whereas those with prior PCI or surgical revascularization, and specifically with an SVG lesion, did not. The authors note that PROTECT II was conducted before the present-day adoption of the heart team approach; as such, it is unclear whether use of the heart team would change the results of this study. The importance of shared decision making via knowledge transfer between heart team and the patient was not in place at the time.⁷ The reasons for surgical turn-down in this study were co-morbid conditions (83%) and patient preference (17%). The latter cohort of patients probably consist of lower-risk patients and would have received more firm recommendations for surgical revascularization especially if they were diabetic patients since PROTECT II was conducted prior to the release of the FREEDOM trial results.⁸

With respect to angiographic findings, patients receiving surgical consultation were more inclined to have lesions with moderate/severe calcification with higher SYNTAX scores, and subsequently underwent lengthier index procedures, and required >3 hours of device support. In the PROTECT II trial, total device support was significantly longer in the IABP group vs the Impella group, suggesting that patients receiving surgical consultation likely received IABP support and left the cath lab receiving continued device support although this is not specified in either report. Whether IABP versus Impella may more effectively diminish the importance of surgical ineligibility is unknown as the authors do not include the proportion of each type of support in the two studied groups. Additionally, the difference in complete revascularization attained in the two arms, ie, the residual SYNTAX score associated with surgical ineligibility, was not specified either. Lastly, multivariate analysis was not done, however, since there was no difference in their group’s primary outcomes, this would not likely add much. Although this study sheds more light on surgical ineligibility and PCI risk, it could not determine whether device supported PCI reduced risk in surgically ineligible patients. 

So where do we place surgical ineligibility in the spectrum of PCI risk? As an unmeasured confounder, it truly confounds risk modeling in high-risk PCI. In previous reports by Waldo and McNulty, surgical ineligibility significantly affected outcomes leading both investigators to recommend inclusion of surgical ineligibility in standard risk-adjustment models.^9,10 The current report by Shavelle et al, although derived from subgroup analysis, serves as the only available RCT data to infer that mechanical hemodynamic support during high-risk PCI may blunt the potential for increased risk associated with surgical ineligibility. 

References

1.    Jabara R, Gadesam R, Pendyala L, et al. Ambulatory discharge after transradial coronary intervention: preliminary US single-center experience (Same-day TransRadial Intervention and Discharge Evaluation, the STRIDE Study). Am Heart J. 2008;156:1141-1146. Epub 2008 Oct 9.

2.    Brennan JM, Curtis JP, Dai D, et al. Enhanced mortality risk prediction with a focus on high-risk percutaneous intervention: results from 1,208,137 procedures in the NCDR. JACC Cardiovasc Interv. 2013;6:790-799.

3.    Wayangankar SA, Bangalore S, McCoy LA, et al. Temporal trends and outcomes of patients undergoing percutaneous coronary interventions for cardiogenic shock in the setting of acute myocardial infarction: a report from the CathPCI registry. JACC Cardiovasc Interv. 2016 Jan 16 (Epub ahead of print).

4.    Garratt K. Challenges and Importance of finding hidden confounders when conducting comparative effectiveness studies using registry data: The impact of surgical turn-down on percutaneous coronary intervention mortality. Circulation. 2014;130:2269-2271. 

5.    Shavelle D, Kirtane A, Schreiber T, et al. Impact of surgical consultation on outcomes in hemodynamically supported high risk percutaneous coronary intervention: insights From PROTECT II randomized study. J Invasive Cardiol. 2016:28:187-192. Epub 2016 February 15. 

6.    O’Neill WW, Kleiman NS, Moses J, et al. A prospective, randomized clinical trial of hemodynamic support with Impella 2.5 versus intra-aortic balloon pump in patients undergoing high-risk percutaneous coronary intervention: the PROTECT II study. Circulation. 2012; 126:1717-1727. 

7.    Head SJ, Kaul S, Mack MJ, et al. The rationale for heart team decision-making for patients with stable, complex coronary artery disease. Eur Heart J. 2013;34:2510-2518.

8.    Farkouh ME, Domanski M, Sleeper LA, et al. Strategies for multivessel revascularization in patients with diabetes. N Engl J Med. 2012;367:2375-2384. Epub 2012 Nov 4.

9.    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;130:2295-2301. 

10.    McNulty EJ, Ng W, Spertus JA, et al. Surgical candidacy and selection biases in nonemergent left main stenting: implications for observational studies. JACC Cardiovasc Interv. 2011;4:1020-1027.