Certain antiarrhythmic drugs improve the chances of patient survival when administered by paramedics to patients with out-of-hospital cardiac arrest who had failed electric shock treatment, a study published in the New England Journal of Medicine has found.

Previous data have shown that only ~10% of patients who suffer an out-of-hospital cardiac arrest survive. Treatments such as CPR and defibrillation can increase a patient’s chance of survival, and now the study’s findings add the possibility of added benefit from some antiarrhythmics.

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For the study, Peter Kudenchuk, MD, the principal study author, and colleagues followed the patients from hospital admission to discharge. A total of 3,026 patients with out-of-hospital cardiac arrest caused by ventricular fibrillation and ventricular tachycardia were randomized in the 3-year study. Patients were assigned amiodarone, lidocaine, or placebo by rapid injection along with all the other standard resuscitation treatments.

Among the 1,900 patients whose cardiac arrest was bystander-witnessed, survival improved significantly from about 23% to 28% by either drug. This finding suggests that “treating patients as soon as possible after their collapse might be a critical determinant of whether drugs like amiodarone or lidocaine will have a significant clinical effect,” Dr. Kudenchuk noted.

The two study drugs, amiodarone and lidocaine, did not statistically significantly improve overall rate of survival to hospital discharge though amiodarone demonstrated a favorable trend in that direction (3%). Survival to discharge was defined as the point at which a patient is discharged from the hospital.

The study was conducted by the Resuscitation Outcomes Consortium.

For more information visit NIH.gov.