Survival was not significantly improved by the administration of intravenous sodium nitrite by paramedics during resuscitation in patients who suffered a cardiac arrest out of the hospital, according to the results of a Late-Breaking Clinical trial presented March 29 during ACC.20/WCC .

Some 400,000 people in the U.S. have out-of-hospital cardiac arrest each year. Cardiopulmonary resuscitation and early defibrillation are the only treatments shown to improve survival after cardiac arrest, which is fatal in over 80% of cases. To date, no new medications have been shown to improve long-term survival, says Francis Kim, MD, FACC, the study’s lead author.

Findings from animal studies suggested that when blood flow and oxygen is blocked, the body can convert sodium nitrite into nitric oxide. In animal models of cardiac arrest, the use of sodium nitrite during resuscitation increased survival by almost 50%. In a previous first-in-human study, Kim and his research team found that intravenous sodium nitrite could be safely given to out-of-hospital cardiac arrest patients.

Kim, et al., studied 1,502 patients who had an out-of-hospital cardiac arrest and randomly assigned them either a low dose or a high dose of sodium nitrite or a placebo. The drug was in an unmarked syringe and injected by a paramedic during active resuscitation in the field.

“Sodium nitrite did not harm the patients who suffered out-of-hospital cardiac arrest, but it didn’t help them either,” Kim says.

Patients’ average age was around 64 years and 66% were male; 22% had ventricular fibrillation, 43% had asystole and 29% experienced pulseless electrical activity. The primary endpoint was the proportion of patients who survived to hospital admission and the secondary endpoint was the proportion who survived to hospital discharge. Safety data were also collected to determine whether sodium nitrite had harmful effects on blood pressure.

Kim concludes, “Many treatments that work in animal models don’t translate to effectiveness in humans, and we now know that sodium nitrite is in this category. Although we are very disappointed with these results, they do close a chapter on the potential of sodium nitrite as a treatment for out-of-hospital cardiac arrest, which is in itself a contribution to scientific knowledge. The majority of patients who suffer out-of-hospital cardiac arrest do not survive and new treatments are urgently needed, so it’s an important area of research.”

Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, SCD/Ventricular Arrhythmias, Acute Heart Failure

Keywords: ACC Annual Scientific Session, acc20, Ventricular Fibrillation, Resuscitation, Acute Coronary Syndrome, Heart Failure

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