Lidocaine or amiodarone in shockable arrest: no clear survival difference

Design

Target trial emulation from a prospective registry (2011 to 2015)

Population

2,451 adults with shockable out-of-hospital cardiac arrest and at least three shocks

Primary outcome

Survival to hospital discharge

Effect

26.2% vs 23.5%; adjusted difference 2.8% (95% CI -0.6 to 6.2)

This target trial emulation used the Resuscitation Outcomes Consortium cardiac arrest registry from 2011 to 2015. It included 2,451 adults with non-traumatic out-of-hospital cardiac arrest, an initial shockable rhythm and at least three defibrillation attempts. Of these, 987 received lidocaine and 1,464 amiodarone. Time zero was the first antiarrhythmic dose, and groups were adjusted by inverse probability weighting.

Survival to hospital discharge was 26.2% with lidocaine and 23.5% with amiodarone, an adjusted difference of 2.8 percentage points (95% CI -0.6 to 6.2). Favourable neurological outcome was 17.7% vs 16.2% (difference 1.5, -1.5 to 4.5).

Neither difference was statistically significant, but the wide intervals leave room for a clinically meaningful benefit with lidocaine. The authors note the findings are consistent with randomised trials, and residual confounding cannot be excluded.

• Either antiarrhythmic is a reasonable choice in refractory shockable arrest; neither showed superior survival.
• Use the drug your protocol and supply allow without delaying defibrillation or compressions.
• A possible small lidocaine advantage is not excluded, but it is not established either.
• Observational data, even with target trial methods, cannot settle the question.

Why it matters

It adds registry evidence to a choice that randomised trials left open.

Don't overread it

A registry emulation of a trial can still be confounded by who received which drug and when.

The statistics, in plain English

An interval of -0.6 to 6.2 percentage points spans no difference and a gain of up to 6 points. The data are compatible with both, so the result is inconclusive rather than negative.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.