Blood Sodium Level Gauge PAH Patients’ Mortality Risk: Study

PAH patients– ones experiencing chronically high blood pressure in the blood vessels of the lungs – and also measuring low on serum sodium levels have a greater risk of right-heart failure (RHF), thus having enhanced mortality rates, a new research from the University of Pennsylvania concludes.

PAH - Pulmonarydefine arterial hypertension – is a syndrome marked with an increase in the blood pressure in the arteries in the lungs. Typically characterized by symptoms like shortness of breath, dizziness and fainting, in severe cases it ends up with right-sided heart failure, as the right ventricledefine of the heart has to work much harder to pump blood into the lungs for re-oxygenation.

While, low blood sodium level - called hyponatremia (HN) - is already known to play havoc in left-sided heart failure, the current study is the first to demonstrate its links with right heart failure in patients with pulmonary arterial hypertension (PAH).

"This is the first study to show the powerful prognostic significance of low blood sodium in these patients," study's lead author, Paul R. Forfia, cardiologist in the Heart Failure/Transplant program and medical director of the Pulmonary Hypertension Program at the Hospital of the University of Pennsylvania stated.

For the study the researchers analyzed the blood sodium levels in 40 patients with PAH. Although comparable on the grounds of age, sex, ethnicity and body mass indexdefine, the patients were divided into two groups on the basis of their blood sodium levels - 13 had HN, or blood sodium lesser than 136 mEq/L, researchers noted.

On comparison to the World Health Organization standards, patients with lower HN had significantly poorer kidney function and were three times more likely to have lower extremity edema, with evidence on echocardiography of significantly worse right heart function, researchers found.

Moreover, during the two year follow up, HN patients were twice as likely to be hospitalized, specifically for right heart failure. A remarkable 11 of the 13 patients in the HN group died during the follow-up period, compared to only 19 percent in the other group.

Recommending routine measurement of the blood serum levels as the vital indicator for treating the syndrome, Forfia said, "Thus, serum sodium has important implications regarding right heart dysfunction, clinical right heart failure, and patient outcome, and should not be overlooked in the clinical assessment of patients with PAH."

The findings are published in a June issue of American Journal of Respiratory and Critical Care Medicine.