Interventional cardiologists and hospitals should re-evaluate the practice of using intra-aortic balloon pumps (IABP) in high-risk percutaneous coronary intervention (PCI) patients, advised authors of a study published online Dec. 6 in Circulation: Cardiovascular Quality and Outcomes. Researchers found wide variation in IABP use across hospitals with no supporting evidence that greater use of IABPs improves outcomes.
Jeptha P. Curtis, MD, of the Center for Outcomes Research and Evaluation at Yale University School of Medicine in New Haven, Conn., and colleagues noted that studies on IABP use for PCI have had conflicting results. Faced with insufficient evidence, guideline writers have declined to make specific recommendations, instead leaving the decision for use in high-risk patients to the discretion of operators.
In an attempt to fill that gap, they designed an observational study using data from the National Cardiovascular Data Registry CathPCI Registry, which includes clinical data and outcomes on cardiac catheterization and PCI from more than 600 hospitals in the U.S. From that database, they identified 181,599 patients who underwent a high-risk PCI at 681 hospitals between Jan. 1, 2005, and Dec. 31, 2007. To qualify as high risk, the PCI had to involve either an unprotected left main artery as the target vessel, cardiogenic shock, severely depressed left ventricular function or ST segment elevation myocardial infarction (STEMI).
Hospitals were categorized into quartiles based on their proportional use of IABP. Patient data included characteristics such as demographics, cardiac status, history and risk factors. The primary outcome was in-hospital mortality. Secondary outcomes included vascular complications, access artery occlusion, pseudoaneurysm, dissection and embolism.
They found variability in both the volume and use of IABP across hospitals, with the number of high-risk cases ranging from 30 to 1,337 and the number of IABP cases ranging from zero to 223.
“IABPs were used in slightly less than 10 percent of high-risk PCI, and hospital use varied such that there was a nearly two-fold difference in IABP use between hospital quartiles that used IABP more and less frequently,” the authors wrote. “These findings highlight the fact that much of IABP use is discretionary. The decision to insert an IABP is likely influenced by physician training, clinical experience and local practice patterns rather than high quality evidence from clinical studies.”
Hospital characteristics were similar in all quartiles but patient characteristics varied across hospital quartiles. Patients treated at hospitals with the highest proportional IABP use tended to be older, with a lower left ventricular ejection fraction, and have proportionally higher renal dysfunction, prior congestive heart failure, prior coronary artery bypass graft surgery, cardiogenic shock and diabetes.
After multivariable adjustments, in-hospital mortality and complication rates were found to be similar across all hospital quartiles. “Our findings provide no evidence to support the greater use of IABP at some hospitals and indicate a pressing need to further define the settings where this intervention provides a net benefit,” Curtis and colleagues argued.
They identified several potential reasons for the lack of high quality evidence and variation in practice. They noted that randomized trials have struggled with recruitment issues, making it difficult to provide robust results. In the absence of evidence, physicians and hospitals may establish their own standards and thresholds of use.
The authors cautioned that their study was retrospective and prone to weaknesses of a registry-based study, including potential confounding and lack of wanted variables and information.
“The results of this analysis highlight the variations in IABP use that exist across hospitals, and should prompt interventional cardiologists and PCI-capable hospitals to critically examine their practice patterns and, perhaps, consider adopting a more selective approach to IABP use in high-risk PCI,” they concluded.