Specialist outlines treatment strategies for mitral stenosis in pregnancy

SAN FRANCISCO — At TCT 2013, Linda D. Gillam, MD, MPH, outlined the most recent treatment strategies for pregnant patients with varying degrees of mitral stenosis.

According to Gillam, of Morristown Medical Center in Morristown, N.J., a heart team approach is essential for treating this patient population.

“In patients with significant mitral stenosis, pre-pregnancy planning is imperative,” she said during a session.

Treatment options

Gillam outlined the various treatment modalities at different stages or severity of mitral stenosis. Patients with severe mitral stenosis should have an elective intervention, ideally balloon valvuloplasty. In those with moderate mitral stenosis, the team will need to assess patient risk based on symptoms, with exercise testing being enormously helpful. If patients do poorly on stress testing, they should be considered for an elective intervention. If they do well, they should receive medical therapy, and patients with mild mitral stenosis can be treated with medical therapy alone.

“During pregnancy for patients with severe mitral stenosis, maximal medical therapy should be tried, and if despite maximal medical therapy the patient remains symptomatic with symptoms of heart failure and reduced exercise tolerance, yes, you must bite the bullet and go ahead and do what you hope will be elective balloon valvuloplasty,” Gillam said. “You do not want to carry them through pregnancy and get them into the middle of labor and delivery with that extra boost of cardiac output and be forced to do any kind of intervention on a truly emergent basis. The heart team is absolutely essential for these patients.”

Medical team essential

She also stressed the importance of a medical team for these patients made up of cardiologists, imaging specialists, noninvasive clinical cardiologists, interventional cardiologists, as well as cardiac surgeons, anesthesiologists and obstetricians.

Gillam explained special circumstances in pregnancy that can create stress on the heart. “First blood volume goes up by at least 40%. Reductions in both systemic and pulmonary vascular resistance occur and the heart rate goes up. As an end result cardiac output goes up roughly 30%,” she said.

During labor and delivery cardiac output goes up an additional 60% to 80%. Heart rate and BP tend to increase during uterine contractions. Rapid volume changes occur with uterine contractions. Blood volume increases as there is increased venous return.

“One of the take-home messages should be that you are not out of the woods if your pregnant patient has delivered,” Gillam said. “In fact these patients need to be closely monitored for at least 24 hours after delivery because of ongoing volume and hemodynamic changes.”

Risk predictors

Important risk predictor factors in a patient with mitral stenosis are a prior history of HF, transient ischemic attack, stroke or arrhythmia, baseline NYHA functional class II or higher and a mitral valve area of less than 2 cm2, she said.

“Very importantly, echocardiography has to be performed pre-pregnancy,” she said.

Pre-pregnancy echocardiography allows the team to assess the severity of the obstruction giving measures of both the mitral valve area and mean gradient. It also allows an assessment of the patient for valvuloplasty using the Wilkins and Padial scores. An assessment of the patient’s functional capacity can be done with exercise stress echocardiography.

In regard to medical management, she said the beta-blocker of choice is metoprolol, because it is a beta-1 selective and avoids beta-2 effects on uterine relaxation, and has less effect on fetal growth than atenolol.

“The threshold for catheter-based or surgical intervention in pregnant patients is limited to those patients who have refractory symptoms despite the best medical management.”

Valvuloplasty should be performed at between 20 and 24 weeks of the pregnancy. The surgical window is between 20 and 28 weeks, but there is a 30% to 40% chance of fetal mortality and up to a 9% chance of maternal mortality.

For more information:

Gillam LD. Management of pregnancy in mitral stenosis. Presented at: TCT 2013; Oct. 27-Nov. 1, 2013; San Francisco.

Disclosure:Gillam reports receiving research/grant support from Coherex, Edwards Lifesciences and Medtronic.