CABG Tied to Lower Death Rate in MI Complicated by Cardiogenic Shock

By Will Boggs MD

April 07, 2020

NEW YORK (Reuters Health) - Coronary-artery-bypass grafting (CABG) is associated with lower in-hospital mortality in myocardial infarction (MI) complicated by cardiogenic shock, compared with percutaneous coronary intervention (PCI), according to a database study.

"Patients who underwent coronary-bypass grafting in the original SHOCK trial had similar outcomes to patients who underwent angioplasty but were more likely to have diabetes mellitus and severe coronary-artery disease in multiple vessels," said Dr. Nathaniel R. Smilowitz of New York University School of Medicine, New York.

"In the current study, patients with MI and cardiogenic shock undergoing bypass surgery actually had lower mortality than those undergoing stent placement - overall, in key subgroups by type of myocardial infarction, and in analyses in which patients with similar characteristics were matched to one another," he told Reuters Health by email.

Dr. Smilowitz and colleagues used data from the National Inpatient Sample covering 2002 through 2014 to compare outcomes of CABG and PCI in more than 386,000 patients hospitalized for acute MI complicated by cardiogenic shock.

Overall, PCI was performed in 44.9% of cases, CABG was performed in 14.1% of cases, and a hybrid approach of PCI and CABG was used in 3.4% of cases.

During the study interval, the frequency of coronary revascularization for these patients increased from 51.5% to 67.4%; the frequency of PCI increased from 34.0% to 50.7%, while the frequency of CABG declined slightly from 14.2% to 13.9%, the researchers report in the American Heart Journal.

In-hospital mortality from all causes was 36.9% overall, 35.0% among patients presenting with non-ST-elevation MI (NSTEMI) and 37.9% among those with STEMI.

Mortality was significantly lower among patients who underwent coronary revascularization than among those who did not (26.1% vs. 54.9%). In the former group, significantly fewer died during the follow-up after CABG than after PCI (18.9% vs. 29.0%).

Results were similar in a propensity-matched analysis and in subgroup analyses of matched patients with STEMI versus NSTEMI, after excluding patients who died within 24 hours of admission, and among patients who presented in the era of second-generation drug-eluting stents.

"These findings, derived from analyses of a large national observational dataset of hospital admissions, are hypothesis generating and should be confirmed in prospective registries and, ultimately, tested in a large randomized clinical trial," Dr. Smilowitz said. "In the meantime, bypass surgery may be appropriate for select patients with MI, cardiogenic shock, and coronary disease in multiple territories - but this decision should be guided based on the clinical history, anatomy of the coronary arteries, and local surgical expertise."

"We do not have evidence from trials to support many of the interventions for patients with MI and cardiogenic shock (other than urgently restoring blood flow to the heart in the culprit vessel causing the infarction)," he said. "Clinical trials are urgently needed to define best practices for these complex patients."

Dr. Holger Thiele of Heart Center Leipzig, in Germany, who co-authored the European Society of Cardiology's position statement for the diagnosis and treatment of patients with acute MI complicated by cardiogenic shock, told Reuters Health by email, "The mortality difference in favor of CABG in comparison to PCI is really interesting. However, the mortality difference is huge, and there is for sure a selection bias which cannot be accounted for even by propensity matching."

"The results of this registry are also contradictory to all other previous registries which showed similar outcome of CABG versus PCI," he said. "Thus, this registry and this analysis is hypothesis generating and would need to be confirmed in a randomized clinical trial."

"Based on this registry, I am concerned that only 62% of the patients underwent revascularization," added Dr. Thiele, who was not involved in the research. "This clearly shows that we need more efforts to convince physicians to perform guideline-recommended treatment. Revascularization is currently the only way to improve the survival of these patients, and this is currently a class-1 recommendation in guidelines!"

SOURCE: American Heart Journal, online March 12, 2020.