Preoperative Hyponatremia Predicts Poorer Long-Term Survival in Patients Receiving LVADs

With the constant goal of improving treatment for patients with heart failure, clinical investigators at Texas Heart Institute and Baylor College of Medicine examined the possible role of preoperative sodium levels in the outcomes of patients who received a left ventricular assist device (LVAD). They found that patients’ sodium levels before surgery were predictive of their long-term survival after LVAD implantation, suggesting a need for further studies to determine whether correcting sodium levels preoperatively could improve outcomes.

For many people with cardiovascular disease, excessively high sodium levels can worsen their condition. But chronically low sodium levels can cause problems, too. This disorder, called hyponatremia, is found in up to 12% of cardiac surgical patients, and it has been associated with greater mortality and morbidity risk in patients with heart failure.

Because patients who are slated to receive an LVAD are generally those with the most severe heart failure, Baylor College of Medicine and Texas Heart Institute heart failure and transplantation specialists Harveen Lamba, MD, Andrew Civitello, MD, Subhasis Chatterjee, MD, and colleagues reviewed data from 332 patients who received an LVAD at Baylor St. Luke’s Medical Center between 2012 and 2017. Before undergoing the LVAD implantation procedure, nearly half of these patients (n=160) had hyponatremia, defined as a blood sodium concentration less than 135 mEq/L. The results were recently published in the journal Artificial Organs.

The patients with hyponatremia and those with normonatremia (that is, a serum sodium concentration of 135-145 mEq/L, which is considered the normal range) were otherwise largely similar in terms of their preoperative risk factors, and after the LVAD placement operation, they also had a similar 30-day mortality rate (7.5% vs 6.5%). However, 5-year mortality was significantly greater in the patients with preoperative hyponatremia: 61%, versus 44% for the patients with normonatremia. Also, when logistic regression was used to identify independent predictors of 5-year mortality, hyponatremia was among them, along with older age and an elevated mean right atrial pressure/pulmonary capillary wedge pressure ratio (an indicator of right-sided heart failure).

“What this tells us,” Dr. Chatterjee says, “is that hyponatremia should be taken into account when we are considering what kind of survival benefit a given patient will gain from receiving an LVAD. It also suggests that, maybe, correcting hyponatremia in a patient before they receive an LVAD would improve their chances of long-term survival. That would be worth testing with a controlled study.”

Lamba HK, Parikh UM, Vincent J, Civitello AB, Nair A, Bhardwaj A, Senussi MH, Loor G, Shafii AE, Liao KK, Chatterjee S.  Preoperative hyponatremia and survival after left ventricular assist device implantation. Artif Organs. 2022 May 7. doi: 10.1111/aor.14280.

News Story By Stephen N. Palmer, PhD, ELS