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Even borderline pulmonary hypertension was associated with poorer survival in the long run, according to a large single-center study.

Unadjusted 5-year survival rates among those with normal mean pulmonary arterial pressure (mPAP), borderline pulmonary hypertension, and pulmonary hypertension were 83%, 75%, and 59%, respectively, among those who got routine right heart catheterization at Vanderbilt University School of Medicine in Nashville from 1998 to 2014.

Every incremental increase in mPAP was associated with greater likelihood of mortality, reported Evan Brittain, MD, MSc, of Vanderbilt, and colleagues in a study published online in JAMA Cardiology.

Compared with normal mPAP in the 18 mm Hg or less range, patients with borderline pulmonary hypertension of 19 to 24 mm Hg had (adjusted HR 1.31, 95% CI 1.04-1.65). Patients with overt pulmonary hypertension of at least 25 mm Hg had the highest risk of all (adjusted HR 1.70, 95% CI 1.37-2.10).

Moreover, 61% of the patients with borderline pulmonary hypertension who got a repeat right heart catheterization had developed overt pulmonary hypertension by then. They saw a median increase in mPAP of 5 mm Hg (P<0.001).

"Most patients with borderline pulmonary hypertension who progressed to pulmonary hypertension developed postcapillary physiology with relatively low pulmonary vascular resistance, suggesting that early pulmonary arterial hypertension-directed therapy would not improve outcomes in these patients," Brittain's group noted.

"Our findings suggest that borderline pulmonary hypertension is an early and intermediate pulmonary vascular phenotype in patients with exposure to numerous pulmonary hypertension risk factors," they concluded. "The clinical profile of our cohort suggests most patients with borderline pulmonary hypertension have existing or early left heart failure, rather than early pulmonary arterial hypertension."

"Additional studies are needed to determine whether the mortality risk in patients with borderline pulmonary hypertension can be modified, for example, by aggressive treatment of left heart disease and the attendant clinical risk factors."

A total of 4,343 individuals were included in Brittain and collaborators' study (mean age 59 years, 51% women, 86% white). The cohort largely had pulmonary hypertension (62%), with another 18% presenting with borderline pulmonary hypertension.

Those with borderline pulmonary hypertension were older and had more comorbidities than the normal mPAP group at baseline.

Statistical adjustment accounted for 34 variables, including left ventricular function and medication exposure.

The analysis of those who progressed to overt pulmonary hypertension upon repeat right heart catheterization was subject to selection bias, Brittain's group admitted, since decompensating patients may be more likely to undergo repeated invasive testing than stable patients.

Furthermore, "mPAP is a surrogate that integrates the complex cardiopulmonary physiology of the patient," they added. "While mPAP is independently associated with mortality on a population level, it lacks sufficient discrimination to predict outcomes for an individual patient."

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