New Orleans, LA, Nov. 9, 2004 The pulmonary artery catheter (PAC), a device that measures pressures and flows in the heart, is frequently used to diagnose, monitor, and guide treatment of congestive heart failure and other conditions. However, use of the PAC has been controversial with varying opinions as to its risk and benefits. New findings from a multi-center study supported by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health show that the PAC did not significantly increase or decrease deaths or the number of days hospitalized in patients with severe heart failure.
The results of the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) Trial are being presented today in the late-breaking clinical trials section of the American Heart Association's Scientific Sessions 2004.
"Heart failure affects about 5 million Americans and the numbers are growing. So it is important to find out the best way to diagnose and treat this serious condition. The ESCAPE study lays to rest concerns that use of a pulmonary artery catheter in patients with advanced heart failure is associated with increased death and hospitalization. At the same time, the study suggests that PAC should not be used routinely to guide therapy. This is an invasive procedure with potentially serious complications and, without a definite survival benefit, its use should be carefully evaluated," said NHLBI Acting Director Barbara Alving, M.D.
About 4 percent of the patients undergoing pulmonary artery catheterization experienced complications, including cardiac arrest and infection but there were no PAC-related deaths. Patients in both groups studied those who received a PAC and those whose therapy was guided by clinical assessment spent about 8 days in the hospital.
ESCAPE was a randomized clinical trial of 433 patients at 26 sites in the U.S. and Canada. The primary goal of the study was to evaluate whether the increased precision that a PAC offers regarding heart and lung pressures translates to improved patient survival and reduced time spent in the hospital over 6 months compared with therapy primarily guided by clinical assessment of physical signs and symptoms. Other study objectives included comparisons of quality of life, ability to exercise, and changes in the heart's structure and function as measured by echocardiograms. The study also sought to evaluate costs and resources associated with the PAC. These results are not yet available.
Study patients had "Class 4" advanced heart failure (severe physical limits, symptoms at rest, and low 2-year survival rate). The average patient age was 56 years. Seventy-four percent of the participants were male and 40 percent were minority. About half (215) of the patients were randomly assigned to receive PACs and 218 patients were assigned to the clinical assessment group. Patients could receive any of the other standard therapies and medications for heart failure.
The PAC is a thin catheter that is inserted via a neck vein and passed through the right side of the heart into the pulmonary artery. Once the catheter is in place, pressures and flows can be measured from the right side of the heart and the lungs. A tiny balloon is inflated to allow measurement of pressures from the left side of the heart. Excess pressure can build up in the heart when it is not pumping effectively. This can further weaken the heart and lead to the hallmark symptoms of heart failure, which are shortness of breath and fluid buildup in the lungs, ankles, and legs.
The PAC, which is used in 3 to 5 percent of heart failure hospitalizations, is used not only to diagnose the specific part of the heart that is not functioning or pumping properly but also to gauge the effect of medications on heart function and symptoms. Physicians can use the PAC to individualize medications for each patient.
The ESCAPE trial was led by Dr. Lynne Stevenson of the Brigham and Women's Hospital in Boston and coordinated by the Duke Clinical Research Institute (DCRI). Dr. Robert Califf, director of the DCRI, noted that this study demonstrates a critical principle of technology assessment at a time when many new technologies are being introduced in the hopes of improving health. "A diagnostic technology, even if it provides accurate information, can be beneficial, neutral, or detrimental, and the PAC is neutral," said Califf.
Pulmonary artery catheterization, also called Swan Ganz catheterization, was introduced for use in 1970 to provide bedside assessment and management of circulation and blood flow at a higher level of precision than has been available from other tests. The device was quickly embraced by the medical community and its use expanded beyond acutely ill cardiac patients, before its benefits were actually proven. There was no consensus regarding the risks and benefits of a PAC-based strategy. In fact, by 1996 the controversy over excessive risks was so high that several professional societies held a consensus conference to review the literature and available data on clinical benefit and safety. The consensus report, endorsed by several organizations including the Society of Critical Care Medicine, called for a clinical trial on the use of the PAC. In response to continued concerns, the NHLBI and FDA convened a workshop on the PAC in 1997 and the resulting report recommended a randomized clinical trial to test its safety and effectiveness.
ESCAPE provided important information about the effect of the PAC on patients' quality of life, although it was not the primary outcome tested.
"It was encouraging that patients in both groups had major improvement in their symptoms and their ability to exercise. Patients whose therapy was guided by the PAC reported a greater improvement in the value they placed on their own daily lives than the other group of patients," said ESCAPE principal investigator Stevenson, who is co-director of the cardiomyopathy/heart failure program at Brigham and Women's Hospital. "While we don't know exactly how to interpret this information yet, the ESCAPE trial emphasizes that we need to learn more about what matters most to our patients as they face disabling symptoms," she said.
"We know that patients who received a PAC felt better, but then why didn't they have fewer deaths or hospitalizations?" asked Stevenson, who presented the ESCAPE results at the American Heart Association meeting.
According to Stevenson, the answer may lie in the fact that there was a big variation in how PAC information was used to treat patients. The study did not specify which medications or other types of therapy would be used, she noted.
George Sopko, M.D., project officer for the ESCAPE trial and Medical Officer with NHLBI's Division of Heart and Vascular Diseases, said that "ideally, another study would compare specific choices of therapy."
"We also need to find out how therapies could be adjusted using non-invasive tests, such as echocardiograms, to provide similar information to PAC but without risks. In-depth analysis now underway of the ESCAPE echocardiogram data should provide clues about these next steps," said Sopko.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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