Patients with elevated pulmonary arterial pressure, but not high enough to be diagnosed with pulmonary hypertension (PH), have a poorer prognosis compared to those with lower pulmonary arterial pressure.
According to the findings of the study, “Prognostic Effect and Longitudinal Hemodynamic Assessment of Borderline Pulmonary Hypertension,” featured in the journal JAMA Cardiology, this particular subset of patients has a high incidence of secondary diseases and higher mortality rates.
PH is currently defined by the mean values of pulmonary arterial pressure (mPAP). All patients who have clinically determined mPAP higher than 25 mmHg are diagnosed with PH. This definition was established in 1973.
This mPAP PH-associated value is, however, much higher than that observed in healthy individuals, which is between 10.7 and 17.3 mmHg. This has led many researchers to investigate the characteristics of those patients who present mPAP values ranging between the healthy and PH diagnosis values, referred to as borderline PH.
Recognition of clinical profile, prognosis, and the natural history of patients with borderline PH may help identify clinical risks associated with pulmonary arterial pressures in clinical practice.
Led by Dr. Tufik R. Assad, MD, from the Vanderbilt University School of Medicine in Nashville, Tennessee, a team of researchers conducted a retrospective study that involved 4,343 patients indicated for routine right heart catheterization (RHC), a diagnostic procedure typically used to assess the pressure and blood flow in the heart.
All participants were followed from 1998 to 2014 at Vanderbilt University Medical Center.
Of all participants, 62% had mPAP values of at least 25 mmHg (PH diagnosis), 18% had values between 19 and 24 mmHg (borderline PH), and 20% of the patients had mPAP values equal or below 18 mmHg (the control group).
The team found that older patients, those with a higher body mass index (BMI), and patients who had chronic heart and lung disease were more susceptible to have borderline PH.
Analysis of all-cause mortality rates showed that patients with PH had a 1.7 times higher risk of death, and patients with borderline PH had a 1.31 times higher risk of dying than the individuals in the control group. In addition, the researchers found that increments on mPAP values starting from 11 mmHg were already associated with increased risk of mortality.
Seventy of the borderline PH patients repeated the RHC; of these, 61% developed overt PH, with a median increase in mPAP of 5 mmHg.
Overall, the researchers concluded that “borderline PH is common in patients undergoing RHC and is associated with significant comorbidities, progression to overt PH, and decreased survival. Small increases in mPAP, even at values currently considered normal, are independently associated with increased mortality.”
“This work builds on an evolving body of literature that suggests borderline PH is clinically important and reconsideration of the diagnostic classification of PH may be warranted,” the team added.