Patients with a history of heart failure had higher rates of 30-day mortality and readmission for heart failure following CABG compared with those who had no history of heart failure, according to a population-based cohort study.

Among the patients without heart failure, their risk of early death after CABG more than doubled if they had reduced ejection fraction versus those with preserved ejection fraction.

Lead researcher Magnus Dalén, MD, of Karolinska University Hospital, Stockholm, Sweden, and colleagues published their results online in JAMA Cardiology on July 13.

The researchers used a registry to identify 41,906 patients who underwent primary isolated CABG at eight hospitals in Sweden between Jan. 1, 2001, and Dec. 31, 2013. The mean age was 67.4 years old, and 21.0 percent of patients were female.

Of the patients, 64.8 percent had no heart failure and preserved ejection fraction; 24.0 percent had no heart failure and reduced ejection fraction; 2.9 percent had heart failure with preserved ejection fraction; and 8.2 percent had heart failure with reduced ejection fraction.

Patients with heart failure were older, more often women and more likely to have diabetes, worse renal function and atrial fibrillation compared with patients who did not have heart failure.

After a mean follow-up period of 6 years. 19 percent of patients died, including 13.2 percent of patients with no heart failure and preserved ejection fraction; 24.6 percent of patients with no heart failure and reduced ejection fraction; 33.9 percent of patients with heart failure and preserved ejection fraction; and 42.9 percent of patients with heart failure and reduced ejection fraction.

After a mean follow-up period of 5.1 years, 20.9 percent of patients had a heart failure hospitalization or death, including 13.9 percent, 29.4 percent, 25.5 percent and 45.9 percent of patients, respectively.

The rates of hospital readmission for heart failure or mortality within 30 days of surgery were 2 percent, 6.5 percent, 8.1 percent and 8.6 percent, respectively.

After adjusting for multiple variables, the hazard ratios for all-cause mortality were 1.47 in patients with no heart failure and reduced ejection fraction; 1.62 in patients with heart failure and preserved ejection fraction; and 2.29 in patients with heart failure and reduced ejection fraction compared with patients with no heart failure and preserved ejection fraction.

Meanwhile, the hazard ratios for the combination of all-cause mortality and readmission for heart failure were 1.71, 1.64 and 2.44, respectively.

The researchers acknowledged a few limitations of the study, including the lack of a clear diagnostic criteria for heart failure with preserved ejection fraction. They also did not have information on medical treatment, and the study may also have had residual confounding.

“The syndrome of [heart failure] regardless of [ejection fraction] is an important risk factor for poor short-term and long-term outcomes,” the researchers wrote. “While [ejection fraction] adds prognostic information in preoperative risk stratification, the [heart failure] syndrome may be a stronger predictor of long-term outcomes and should be carefully considered in preoperative assessment and postoperative follow-up.”