Heart failure patients at increased risk during non-cardiac surgery

Patients with heart failure undergoing major non-cardiac surgical procedures are almost twice as likely to die as other patients, according to researchers at the Duke Clinical Research Institute (DCRI).

In their analysis of Medicare data, the researchers also found, to their surprise, that the outcomes after major non-cardiac surgery were similar in patients with coronary artery disease and those with no heart disease.

The findings about heart failure patients are significant, the researchers continued, because very little is known about how these patients fare when they undergo surgery. With the aging of the American population and the increase in the number of surgeries being performed, the researchers said it is crucial to understand why such a disparity in outcomes exist. “While the risks of coronary artery disease on patients undergoing surgery have always been considered in assessing risk, there is very little data on which to base guidelines for treating patients with heart failure,” said Duke cardiologist Adrian Hernandez, M.D., lead author of a study whose results will be published Oct. 6, 2004, in the Journal of the American College of Cardiology.

“The results of our analysis show that heart failure patients, especially those over the age of 65, suffer significant adverse events after undergoing major non-cardiac surgery,” Hernandez continued. “More research is needed first to better understand why heart failure patients do not do as well, and secondly to develop strategies for reducing risks and improving outcomes after non-cardiac surgery.”

Heart failure is a condition marked by the inability of the heart muscles to pump enough oxygen and nutrients in the blood to the body’s tissues. Also known as congestive heart failure, its many causes include infections of the heart, coronary artery disease, high blood pressure, previous heart attacks and valve problems.

An estimated 5 million Americans suffer from the condition, with 550,000 new cases reported each year; and according to the researchers, it is the only cardiovascular disease that is rising in incidence. About 75 percent of heart failure patients are over the age of 65. Once diagnosed with heart failure, about half of patients will die within five years.

“The markedly higher rates of post-operative mortality and complication seen in heart failure patients is quite concerning,” said Duke cardiologist James Jollis, M.D., senior member of the research team. “These result point out the need for a disease management approach to heart failure patients, where a team of specialists take care of patients before, during and after surgery.”

Despite the growing incidence of heart failure, there have been very few studies that address the risk factors associated with heart failure and non-cardiac surgery, Hernandez said. Those studies tended to be small, or included patients at only one or a handful of other centers. For this reason, the Duke team analyzed Medicare data from 1997-1998 on patients who underwent non-cardiac surgery to get a more “real-world” understanding of the situation.

For their analysis, the team found that 1,532 of 23,340 heart failure patients underwent major non-cardiac surgery, compared to 1,757 of 28,710 patients with coronary artery disease. As a control, there were 44,512 patients without heart disease who underwent major non-cardiac surgery. The surgeries included vascular, abdominal, thoracic and orthopedic cases.

The Duke analysis found that the mortality rates for heart failure patients was 11.7 percent, compared to 6.6 percent for coronary artery disease patients and 6.2 percent for patients without heart disease. In terms of readmission rates after surgery, heart failure patients had a 20 percent rate, compared to 14.2 percent for coronary artery disease patients and 11 percent for patients with out heart disease.

“When it comes to surgery, these patients are at very high risk for death, for further complications and for readmission to the hospital,” Hernandez said. “Twenty-five years ago, the situation was similar for coronary artery disease. During the intervening time, we have taken steps to improve outcome for those patients. We need to do the same now for heart failure patients.”

Hernandez said that the similar mortality rates seen among coronary artery disease patients and those without heart disease shows that over time, the medical community has been quite effective in reducing the risks for patients with coronary artery disease. With more research, he believes the same advances can be made for heart failure patients.

Future research will be carried out on a number of fronts. One avenue is to better understand the underlying biology of heart failure and how the bodies of these patients respond to the stresses of surgery. Hernandez said that researchers will also look at the treatments these patients receive prior to surgery to see if the treatments have any impact on the outcome. The team will also study what happens during the post-operative phase of care.