Emergent CABG in Acute MI: Survival Better Despite Increasingly Risky Patients

Emergent CABG surgery has seen waning use over the past few decades among patients hospitalized for acute MI in the United States, a trend not likely to come as a surprise to cardiologists watching PCI’s ascendance. But nationwide data also show that even as the patients targeted for CABG therapy have grown sicker and higher-risk, their in-hospital mortality rates have decreased.

The data, encompassing more than 11 million acute MI admissions from 2000 to 2017, were released today during the virtual American College of Cardiology (ACC) 2021 Scientific Session and simultaneously published online in the Journal of the American Heart Association.

“There has been a near 90% reduction in the need for emergency CABG for acute myocardial infarction [over the years], primary due to the emergence of percutaneous coronary interventions and the associated outcomes,” Sri Harsha Patlolla, MBBS (Mayo Clinic, Rochester, MN), said when presenting the ACC abstract. Yet there still remains a role for CABG, he added, especially when it comes to NSTEMI.

Speaking with TCTMD, Saraschandra Vallabhajosyula, MD (Emory University School of Medicine, Atlanta, GA), senior author of the JAHA paper, observed that during the time frame they studied, “stent technologies and PCI technologies in general have gotten much better—from PTCA, to the bare-metal stent era, to first-generation and second-generation drug-eluting stents.”

The researchers wanted to look at how CABG usage and outcomes might have also changed in that evolving landscape, he said. As such, the finding that survival improved even in the face of more-challenging CABG cases “tells us that surgical techniques, postoperative care, and ICU care have all gotten better. So overall it’s a testament to the better quality of care that we’re delivering across the spectrum,” he said, adding, “We’re just doing a better job managing acute MI than we ever did before.”

Sharpest Drop Seen in STEMI

Led by Patlolla and Ardaas Kanwar, BA (University of Minnesota, Minneapolis), the researchers analyzed 11,622,528 acute MI admissions in the National Inpatient Sample over an 18-year period starting in 2000. Among these, only 9.2% involved emergent CABG. Surgery was more likely in patients younger than 75, men, white individuals, those with lower socioeconomic status, and those treated at large or urban teaching hospitals.

CABG use significantly decreased in all acute MIs from 10.5% in 2000 to 8.7% in 2017, as well as individually in STEMIs (from 10.2% to 5.2%) and in NSTEMIs (from 10.8% to 10.0%; P < 0.001 for all). The decreases were seen irrespective of sex and race/ethnicity. Stratified by age, CABG use increased slightly in 55- to 74-year-olds, but declined for other age groups. Concomitant PCI occurred in 9% to 12%.

Compared with patients who received emergent CABG in the first half of the study period, those who did so in 2012-2017 were more likely to have NSTEMI (80.5% vs 56.1%), have noncardiac multiorgan failure (26.1% vs 8.4%), experience cardiogenic shock (11.5% vs 6.4%), and receive mechanical circulatory support (MCS; 19.8% vs 18.7%; P < 0.001 for all). Despite this, in-hospital mortality for the CABG-treated acute MI patients decreased from 5.3% in 2000 to 3.6% in 2017 (adjusted OR 0.89; 95% CI 0.88-0.89).

Independent predictors of in-hospital mortality on multivariate analysis included older age, female sex, lower socioeconomic status, admission to small hospitals, STEMI, cardiogenic shock, cardiac arrest, acute noncardiac organ failure, MCS use, invasive mechanical ventilation, and acute hemodialysis.

Between 2000-2005 and 2012-2017, median hospital stay increased (from 9 to 10 days), as did median hospitalization costs (from $74,000 to $172,000). Over time, CABG-treated patients became less likely to be discharged to home (from 53.8% to 39.5%) and more likely to be discharged to skilled nursing facilities (from 18.7% to 26.1%; P < 0.001 for all).

“They’re sicker patients, so they stay longer [and] they cost more. But it’s also because we have more therapies to offer,” Vallabhajosyula pointed out, noting that in the early 2000s, extracorporeal membrane oxygenation and Impella (Abiomed) weren’t used to address cardiogenic shock in acute MI. “If they did bad postoperatively, even if we wanted to rescue them, we didn’t have options to rescue them,” he said.

As to who is still receiving CABG for acute indications, he described surgical revascularization as “almost like a bailout procedure” in STEMI patients, where time is of the essence. For NSTEMI patients, who tend to be stable, there’s more time to take a pause and discuss the options.

“For CABG, even though the referral rates are low, I think it always helps to have an early, quick, honest up-front discussion about the patient’s options after the diagnostic angiogram. It’s tough,” he said, “because it’s [in the] moment and the interventionalist is in the room, [but] you need to call the surgeon. But especially for the higher-risk patients, if we can coordinate a multidisciplinary call, kind of akin to the shock team model . . . , I think it would be really nice.”

For these patients, if there’s a chance “to decide where to go next and just get on with the plan, I suspect we can work on chipping away more of this mortality and morbidity that we see in this study,” Vallabhajosyula suggested. Interventional cardiologists and cardiac surgeons are working “hand in hand” in these cases, he said.