Left ventricular function helps predict post-op mortality in HF patients

Heart failure (HF)—both symptomatic and asymptomatic—is associated with an up to 10 percent increased risk of 90-day postoperative mortality in patients undergoing noncardiac surgery, according to a study published Feb. 12 in the Journal of the American Medical Association.

“Heart failure has long been recognized as a risk factor for postoperative mortality,” senior author Sherry M. Wren, MD, of Stanford University in Palo Alto, California, and colleagues wrote. “However, most prior studies examining the relationship between HF and postoperative mortality have not accounted for the various subtypes of this disease. Because of heart failure’s importance as a risk factor for adverse surgical outcomes, it is common to include HF in operative risk prediction models, but most of these models were developed without accounting for the different subtypes of HF.”

A typical case of HF falls into one of two major categories, the authors explained—either HF with preserved ejection fraction or HF with reduced ejection fraction. Left ventricular ejection fraction (LVEF) itself can be an important predictor of long-term mortality, but Wren et al. said no work to date has sufficiently delineated a relationship between LVEF and post-op mortality in HF.

The authors studied the risk of postoperative mortality among 47,997 patients with heart failure and 561,738 without HF, looking specifically at 90-day postoperative mortality rates in patients with varying indications for the disease. All patients received elective noncardiac surgery between 2009 and 2016, and their outcomes and 1-year follow-up data were logged in the Veterans Affairs Surgical Quality Improvement Project Database.

Wren et al. found that compared to patients without heart failure, those with HF had a higher risk of 90-day post-op mortality (2,635 deaths compared to 6,881), which worked out to a crude mortality risk of 5.49 percent in HF patients and 1.22 percent in non-HF patients. Patients with symptomatic heart failure saw the highest risk of death—more than 10 percent compared to non-HF patients—while asymptomatic patients with HF saw a crude risk of 4.8 percent.

Even the subset of asymptomatic HF patients with preserved left ventricular systolic function experienced an elevated risk of death, the authors reported, seeing 1.46 times the odds of mortality. Other subgroups saw a good deal of variation, too—the crude 90-day post-op mortality rate for patients with HF increased from 4.6 percent for standard complexity operations to 10.3 percent for complex procedures, and for patients without HF, crude 90-day postoperative mortality increased from 0.7 percent to 6.2 percent for standard and complex operations, respectively.

“Low ejection fraction was associated with greater postoperative mortality with the mortality risk increasing as the ejection fraction decreased,” the authors wrote. “Multivariable regression greatly attenuated the apparent risk of heart failure on postoperative mortality, suggesting that HF is a marker for a constellation of comorbidities that patients with HF tend to have, all of which contribute to the elevated risk.

“Heart failure itself has a relatively small effect as an independent risk factor of postoperative mortality.”

In an editorial published simultaneously in JAMA Surgery, John S. Ikonomidis, MD, PhD, of the University of North Carolina at Chapel Hill, called Wren et al.’s study “well-written and well-reported,” but re-enforced the authors’ note that their dataset reflected an inherent selection bias. Since all patients analyzed were cleared for surgery, the study didn’t include patients who were considered for a procedure but didn’t go through with one.

Also, since data was drawn from a Veterans Affairs population, Ikonomidis said there was a paucity of female patients.

“However, the absolute number of female patients (52,563, of which 1,391 had heart failure) is considerable,” he wrote. “Overall, the data reported here is highly valuable and comprehensive information that practitioners can use for preoperative planning and also in discussions with patients.”