When PCI Becomes the Backup for Coronary Bypass Surgery

Patrice Wendling

February 01, 2019

A surprising number of patients undergoing coronary artery bypass graft (CABG) surgery will require postprocedure coronary angiography and emergent percutaneous coronary intervention (PCI) before discharge — a scenario that carries substantial morbidity, mortality, and costs — according to a large nationwide study.

"There are a lot of studies talking about emergent CABG after failed PCI or complications, but there is really a very limited number of studies, small single centers, talking about the opposite — how often we go and do PCI after CABG," senior author Mohamad Alkhouli, MD, West Virginia Heart and Vascular Institute, Morgantown, told theheart.org | Medscape Cardiology.

The vast majority of patients do well after CAGB and go home without routine postoperative coronary angiography, he noted. Yet throughout his training, there have been patients who experience coronary ischemia after CABG. The Society of Thoracic Surgeons (STS) database has only one field on postoperative MI but lacks details about the outcomes and does not track post-CABG angiography or PCI.

"There really is no perfect registry to address this question at the current time, so we tried to at least to acknowledge that there is a problem," Alkhouli said.

After identifying 554,987 patients who had CABG surgery between January 2003 and December 2014 in the National Inpatient Sample, the investigators found that 4.4% of patients had in-hospital angiography postoperatively and 2.6% underwent PCI. Most PCI procedures (71.4%) were performed in the first 24 hours after CABG.

"When you ask surgeons how often you need to do an emergent PCI or send a patient for emergent cath after CABG, they say less than 1%," Alkhouli said. "These data show that in a nationwide sample it is 4.4%, and then what is striking here is that we actually see in practice that these patients do worse even if you do a PCI."

Treated but Poorer for It

Compared with patients discharged after CABG alone, patients who underwent post-CABG PCI experienced higher rates of stroke (2.1% vs 1.6%), acute kidney injury (16.0% vs 12.3%), and infectious complications, including sepsis (3.4% vs 1.7%).

They also averaged longer hospitalizations (12 vs 10 days), were more likely to be discharged to an immediate-care facility (20.1% vs 19.5%), and racked up almost 50% more in-hospital costs (mean, $62,080 vs $44,080; P < .001 for all comparisons). This translated into an estimated $1.4 billion in added CABG care costs during the 12-year study period, without accounting for the added costs of out-of-hospital resources.

Moreover, post-CABG PCI during the same hospitalization confers more than a 100% increase in crude and risk-adjusted in-hospital mortality, the authors reported January 28 in the Journal of the American College of Cardiology.

Unadjusted in-hospital mortality was 5.1% in patients who underwent urgent PCI and 2.7% in those who did not (<.001). In logistic regression, adjusted odds ratios (ORs) for in-hospital mortality with post-CABG PCI ranged from 1.71 to 2.02, depending on which of the four models were used (P < .001 for all).

In-hospital mortality remained significantly higher in the PCI than in non-PCI group in sensitivity analyses that excluded patients who underwent off-pump CABG (5.3% vs 2.6%) or excluded those who underwent redo CABG during the same hospitalization (5.2% vs 2.7%; < .001 for both).

"Clearly this is something that people have thought about for a long time, but this is the first study of any magnitude that I think really tells us what's going on out there," Frederick S. Ling, MD, director of the cardiac catheterization laboratory and professor of medicine, University of Rochester Medical Center, New York, said in an interview.

"The value of this is that it gives you a huge patient sample that has never been looked at before and gives you some hard data in terms of outcomes," he said. "The disadvantage is, now that we have this information, how can we prevent it? How can we decide also what is the best therapy?"

In multivariate analyses, the team found that the strongest predictors of the need for PCI after CABG were nonelective admission (OR, 3.45; 95% CI, 3.30 - 3.60) and off-pump surgery (OR, 1.85; 95% CI, 1.78 -1.92). CABG volume was also an independent predictor, with ORs of 1.31 and 1.14 for low and intermediate volume, respectively.

"Mirroring the average rate of post-PCI emergency CABG of 3% in the pre-stent era in the early 1990s, this report demonstrates an inversion of the paradigm, where PCI has become the backup procedure of CABG," Paul Guedeney, MD, and Gilles Montalescot, MD, PhD, Sorbonne University, Paris, say in an accompanying editorial.

"The present study provides a powerful statement for the need to identify and address modifiable risk factors of early coronary compromise following CABG. In this regard, low annual CABG volume may be one of the most important risk factors, which other identified risk factors may stem from," they say.

Nevertheless, the editorialists point out that the study lacks information on the exact diagnosis behind the post-CABG PCI and did not include patients undergoing post-CABG PCI during a subsequent early readmission. Further, no conclusions can be drawn regarding the optimal revascularization strategy to adopt.

"This only answers a small piece of the puzzle," Alkhouli acknowledged. "There's much more to be addressed, but at least it's increasing awareness."

Although they did not know what led surgeons to send patients to the catheterization lab after CABG, the finding of higher mortality in the PCI group would suggest there was a suspicion of acute coronary ischemia, he said. Still, data were not available for several other factors that might have contributed, including operative time and ejection fraction. It's also likely that there is a proportion of patients who have ischemia but never make it to the cath lab.

"I think the predictors are good to look at and are provocative or theory-generating, but I wouldn't say we have answered the question," said Alkhouli.

Concerns about coronary ischemia led the investigators to conduct a similar analysis in patients requiring early PCI after isolated aortic or mitral valve surgery, with their report last year showing even more dismal results.

"This paper is mainly meant to show that this problem does exist much more than what we commonly think and it is not as pretty as we think," Alkhouli said of the current study.

"I'd like to see a collaborative database from a couple high-volume surgical centers looking at their data and their patients who had ischemia after CABG in the hospital — and actually several months after they get out of the hospital — to see how we might prevent this, knowing now that ischemia after CABG is problematic," he said.

Ling commented that clinical databases like the STS and National Cardiovascular Data Registry (NCDR)–Cath PCI database don't specifically look at this population, but can collect the needed information.

"The fact that we have this study now would give us good cause to, say, whether it's STS or NCDR, add a field so we can determine much more richly, especially the angiographic variables, how to treat this population," he said.

The authors, Ling, and Guedeney reported having no relevant financial relationships. Montalescot has received institutional research grants or consulting/lecture fees from Abbott, Amgen, Actelion, AstraZeneca, Bayer, Boehringer Ingelheim, Boston Scientific, Bristol-Myers Squibb, Beth Israel Deaconess Medical, Brigham Women's Hospital, Cardiovascular Research Foundation, Daiichi-Sankyo, Idorsia, Lilly, Europa, Elsevier, Fédération Française de Cardiologie, ICAN, Medtronic, Journal of the American College of Cardiology, Lead-Up, Menarini, MSD, Novo Nordisk, Pfizer, Sanofi, Servier, The Mount Sinai School, TIMI Study Group, and WebMD, the parent company of Medscape.

J Am Coll Cardiol. 2019;73:415-423, 424-426. Abstract, Editorial

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org | Medscape Cardiology, follow us on Twitter and Facebook.

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