Jun 6 2005
A simple blood test can quickly identify what type of congestive heart failure (CHF) a patient has, improving diagnostic accuracy; eliminating the need for extensive diagnostic tests, such as heart muscle biopsy or exploratory surgery; and enabling the patient to be treated sooner, according to a study published in the June 7 Journal of the American College of Cardiology. After blood is drawn, the test results are ready in 15 minutes.
In the study, researchers at Loyola University Health System found significantly higher levels of the cardiac hormone, brain natriuretic peptide (BNP), in the blood of patients with one type of CHF, restrictive cardiomyopathy (RCMP), versus another type of CHF, constrictive pericarditis (CP).
“This is an important discovery because, while the symptoms are similar for both types of heart failure, the diagnosis, treatment and prognosis are very different,” said lead author Dr. Fred Leya, professor of medicine/cardiology, Loyola University Chicago Stritch School of Medicine; and director, interventional cardiology and director, cardiac catheterization lab, Loyola University Health System, Maywood, Ill. “By examining the BNP level in congestive heart failure patients, we can quickly determine whether they have RCMP or CP. As a result, we can provide the appropriate treatment much sooner.”
Five million people in the U.S. have CHF, where the heart weakens and becomes unable to pump adequate amounts of blood. When blood returning from the body to the heart is not pumped fast enough, it starts to back up into the lungs. CHF symptoms include shortness of breath, swollen legs, swollen liver and fatigue, which could also be signs of other conditions. Some CHF may go undetected for months, even years.
All people have some level of BNP, but the heart muscle releases excessive amounts of the hormone in response to heart failure. Therefore, as expected, CP and RCMP patients had higher levels of BNP than patients with a normal heart. Yet, RCMP patients had significantly elevated BNP levels compared to CP patients.
“The reason for this is because CP patients have a rigid or scarred pericardium – the sac-like membrane covering the heart,” said Leya. “As a result, the chambers of the heart are “restrained,” and cannot expand and fill with blood to function normally. When this happens, the heart muscle wall cannot stretch as much and release BNP.” Left untreated, CP can be life-threatening, and a surgical procedure to remove part of the pericardium may be necessary.
With RCMP, the heart muscle stiffens so that not enough blood can enter the ventricles, the lower chambers of the heart. However, unlike with CP patients, the pericardium is not rigid or scarred. Therefore, higher levels of BNP can be more easily released. In some cases, early diagnosis and treatment can prevent further damage. In other cases, treatment is aimed at decreasing the workload of the heart. Eventually, a heart transplant may be necessary.
For the study, Dr. Leya and colleagues measured BNP levels in 11 patients suspected of having CP or RCMP. Five patients had RCMP and six had CP, as confirmed by hemodynamic assessment. “The mean plasma BNP levels of the RCMP group were four times that of the CP group,” said Leya, who is developing a registry of patients to further expand the study.
Co-authors of the study with Leya are Dr. Dinesh Arab, Dr. Dominique Joyal, Krystyna M. Shioura, Dr. Bruce E. Lewis, Dr. Lowell H. Steen and Dr. Leslie Cho.