SNOWMASS, COLO. (FRONTLINE MEDICAL NEWS)Differentiating constrictive pericarditis from restrictive cardiomyopathy in patients with right heart failure with a normal ejection fraction is “one of the most difficult diagnostic challenges in cardiology today,” but reliable results can be achieved using a careful step-by-step approach, Dr. Rick A. Nishimura said at the Annual Cardiovascular Conference at Snowmass.

Under current terminology for heart failure, cardiologists speak of HFrEF, or heart failure with reduced ejection fraction, and HFpEF, or heart failure with preserved ejection fraction. But there is a third group of patients who are often mistakenly thought to have HFpEF: those with severe right heart failure and a normal ejection fraction, classically caused by constrictive pericarditis or restrictive cardiomyopathy.

Unlike patients with HFpEF, these people are not hypertensive and they don’t have pulmonary congestion. Instead, they present predominantly with ascites, peripheral edema, fatigue, and marked elevation in jugular venous pressure, noted Dr. Nishimura, professor of medicine at the Mayo Clinic in Rochester, Minn.

Before elaborating on his own tried-and-true, step-by-step approach, he highlighted several diagnostic procedures he considers less than reliable. One is advanced imaging with CT or MRI looking for the pericardial thickening that is widely viewed as an anatomic hallmark of constrictive pericarditis.

“Remember, 22% of patients with proven constrictive pericarditis actually have a normal pericardium on CT or MRI, because it’s their fibrotic epicardium that’s causing the constrictive pericarditis. And roughly 70% of patients are going to have some thickened pericardium after radiation therapy or coronary artery bypass graft surgery without having constrictive pericarditis. So CT and MRI are helpful, but they’re not going to be diagnostic,” according to the cardiologist.

Similarly, while it’s often been said that constrictive pericarditis can be diagnosed based upon a classic trio of hemodynamic findings obtained through heart catheterization – namely, early rapid filling with a left ventricular end-diastolic pressure equal to the right ventricular end-diastolic pressure, a right ventricular end-diastolic pressure greater than one-third of the right ventricular systolic pressure, and a pulmonary artery pressure below 50 mm Hg – these criteria didn’t reliably separate the last 100 patients who came to the catheterization lab at the Mayo Clinic with either constrictive pericarditis or restrictive cardiomyopathy, he continued.

Dr. Nishimura’s approach to the work-up of patients with unexplained right heart failure and a normal ejection begins with the history and physical examination. The history in a patient with constrictive pericarditis is classically one of radiation therapy years earlier for a malignancy, or prior CABG surgery. And the physical exam has to reveal the presence of high neck veins.

“If you don’t see high neck veins due to elevated jugular venous pressure with rapid x and y descents, the patient doesn’t have constrictive pericarditis, no matter what the echocardiogram shows,” Dr. Nishimura asserted.

If those findings are present, however, then on 2-D echocardiography he’s looking for three things that point to constrictive pericarditis: a brisk septal shudder due to rapid filling in early diastole with every heart beat; an early diastolic posterior motion of the intraventricular septum, known as the septal bounce, that occurs as a consequence of the less compliant ventricular walls; and dilation of the inferior vena cava indicative of increased right atrial pressure.

When all three findings are present on 2-D echo, he turns to Doppler echo for hemodynamic information. If Doppler shows a reduction in transmitral driving pressure from the lungs to the heart during inspiration, as the intrathoracic pressure drops but the left ventricular pressure does not, the work-up is done. That patient has constrictive pericarditis and needs to be referred to surgery for pericardiectomy, which will bring rapid improvement.

In roughly one-quarter of patients with constrictive pericarditis, however, that full constellation of 2-D and Doppler echocardiographic findings isn’t present. It then becomes necessary to move on to cardiac catheterization. The first two things to look for in the cath lab are elevated end-equalization of diastolic pressures and low cardiac output.

“If they’re in the cath lab and they’ve got normal filling pressures and a normal cardiac output, they do not have clinically significant constrictive pericarditis, no matter what the echo shows. So those two things are necessary to see, but of course they’re not diagnostic. So we go further,” Dr. Nishimura said.

A patient with constrictive pericarditis will have enhanced ventricular interaction arising from the restraint imposed by a rigid, diseased pericardium. That’s crucial. This increased ventricular interaction is manifest as an increase in the size of the right ventricle during inspiration while the area of the left ventricle is getting smaller.

In contrast, during inspiration and expiration in a patient with restrictive cardiomyopathy, as the right ventricle gets smaller, so does the left ventricle.

“The ratio of the right ventricle to left ventricle area under the curve during inspiration versus expiration gives a very nice distinction between constrictive pericarditis and restrictive cardiomyopathy. Enhanced ventricular interaction is the most sensitive and specific finding for constrictive pericarditis,” according to Dr. Nishimura.

He added that, in addition to constrictive pericarditis and restrictive cardiomyopathy, there is a third and underappreciated cause of right heart failure with a normal ejection fraction: severe tricuspid regurgitation. This abnormality may not be readily apparent upon echocardiography in a patient with a pacemaker lead or automatic implantable cardioverter-defibrillator lead, which can cause acoustic shadowing that results in underestimation of the severity of tricuspid regurgitation. The clue here is the observation of hepatic vein systolic flow reversal, which can only be caused by severe tricuspid regurgitation.

“Think tricuspid regurgitation in patients who have a pacemaker lead or AICD, and also in older women with longstanding atrial fibrillation who dilate their tricuspid annulus and develop more and more tricuspid regurgitation. Take those patients to the cath lab and do a right ventriculogram, which will show tricuspid regurgitation,” Dr. Nishimura advised.

He reported having no financial conflicts.