Pulmonary Hypertension Increases Risk of Poor Outcomes After Transcatheter Mitral Valve Repair

Transcatheter mitral valve repair with the MitraClip system is approved by the FDA for patients with symptomatic, severe primary mitral regurgitation who are perceived to have prohibitive surgical risk. Pulmonary hypertension (pHTN) is common in such patients, but there are little data on how it affects the outcomes of valve repair.

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In a large retrospective study, reported in JAMA Cardiology, Rasha Al-Bawardy, MD, MSc, interventional cardiology fellow, Sammy Elmariah, MD, MPH, interventional cardiologist in the Division of Cardiology at Massachusetts General Hospital, and colleagues documented increased mortality and readmission for heart failure after transcatheter mitral valve repair. However, even in patients with severe pHTN, the repair was safe and effective.

Study Methods

The researchers identified 4,071 patients across 232 centers from the Society of Thoracic Surgery/American College of Cardiology Transcatheter Valve Therapy registry who underwent nonemergent mitral valve repair using the MitraClip system between November 4, 2013 and March 31, 2017.

They were classified based on the following severity of pHTN:

• Group 1 — No pHTN: mean pulmonary arterial pressure (mPAP) < 25 mm Hg (27% of patients)
• Group 2 — Mild pHTN: mPAP of 25–34 mm Hg (34%)
• Group 3 — Moderate pHTN: mPAP of 35–44 mm Hg (25%)
• Group 4 — Severe pHTN: mPAP ≥ 45mm Hg (14%)

30-Day Outcomes

• After multivariable adjustment, pHTN was independently associated with the composite outcome of 30-day all-cause mortality or heart failure-related readmission (HR for group 4 vs. group 1, 1.56; 95% CI, 0.99–2.42; P = .05)
• When those outcomes were analyzed separately, 30-day mortality was associated with more severe pHTN (HR for group 4 vs. group 1, 2.81; 95% CI, 1.28–6.16; P = .01), but 30-day readmission rates did not differ significantly between groups
• Robust improvements in New York Heart Association functional class were observed in all groups

One-Year Outcomes

• The primary outcome, the composite of one-year mortality or readmission, occurred in 34% of all patients. Higher rates were noted with worsening pHTN (group 1, 28%; group 2, 32%; group 3, 36%; group 4, 45%; P < .001)
• When analyzed separately, one-year mortality and readmission rates demonstrated similar patterns, with statistically significant differences between group 1 and group 4
• The association of severe pHTN with increased incidence of the composite outcome persisted despite multivariable adjustment for potential confounders (HR for group 4 vs. 1, 1.44; 95% CI, 1.16–1.79; P < .001) and when modeled in a continuous manner (HR per 5-mm Hg increase in mPAP, 1.04; 95% CI, 1.01–1.07; P = .01)

A Hypothesis for Future Research

The relationships between severity of pHTN and adverse outcomes of mitral regurgitation suggest that treatment of mitral regurgitation occurred late in the disease course. Earlier intervention, before pulmonary hypertension develops, may result in improved outcomes.

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