Question explored with the scientific record
Conversation so far
- 1 What is the highly toxic drug they give for intractable afib
- 2 How long does it take to workWhat is the highly toxic drug they give for intractable a fib
Answered on this page ↓
How long does it take to workWhat is the highly toxic drug they give for intractable a fib
Amiodarone is slow. It takes hours to days to convert a rhythm, and weeks to build up in the body.
The records here don't give a clean onset time for amiodarone itself. What they do show is the comparison that matters. In a trial of 105 patients with persistent AF, IV amiodarone was one of the conversion drugs, and failure at 7 days was 23% with drugs versus 13% with electrical shocks, a gap that did not reach significance [3]. In another trial, adding ranolazine to IV amiodarone cut time to conversion from 13.3 hours to 10.2 hours, and raised the conversion rate from 32% to 52% [2]. That tells you amiodarone alone is working on a scale of many hours, not minutes. For comparison, IV flecainide converted recent-onset AF in about 6 minutes in a small 10-patient study [1].
| Drug | Time to convert | Conversion rate |
|---|---|---|
| IV flecainide (recent onset) | ~6 min | 10/10 [1] |
| Amiodarone + ranolazine | 10.2 h | 52% [2] |
| Amiodarone alone | 13.3 h | 32% [2] |
For keeping rhythm after conversion, amiodarone is the strongest drug in these records, beating placebo, beta-blockers, sotalol, propafenone and class I agents [4]. But it is a maintenance drug, not a rescue drug. If you need rhythm back tonight, amiodarone is the wrong tool.
My call: expect hours to days for conversion, and judge it as a maintenance drug, not an emergency one. Confidence: moderate, because no record here isolates amiodarone's own onset time.
Sources used 4
-
Electrophysiological effects of flecainide and propafenone on atrial fibrillation cycle and relation with arrhythmia termination
In 10 patients with lone paroxysmal AF, intravenous flecainide or propafenone prolonged the atrial fibrillation cycle and restored sinus rhythm in all patients; isoprenaline shortened the cycle and could provoke 1:1 AV conduction during drug treatment.
DOI: 10.1136/hrt.82.2.176 -
Novel Use of Ranolazine as an Antiarrhythmic Agent in Atrial Fibrillation
A narrative review synthesizing the pharmacology of ranolazine and clinical trial evidence for its use as an antiarrhythmic in atrial fibrillation, including monotherapy and adjunctive therapy, and its potential role in post-cardiothoracic surgery AF.
DOI: 10.1177/1060028016673073 -
Approaches to rhythm control: Impact of electrical cardioversion versus pharmacological management on left atrial size and systolic performance in atrial fibrillation and flutter
In a prospective cohort of 105 persistent AF/AFL patients, ECV and PCV both reduced left atrial size over one year with similar LVEF, while longer arrhythmia duration, hypertension, absent pre-cardioversion amiodarone, and larger left atrial size predicted recurrence.
DOI: 10.17392/1830-22-01 -
Cardioversion of atrial fibrillation: the use of antiarrhythmic drugs
This narrative review synthesizes randomized controlled trial evidence on antiarrhythmic drugs for cardioversion of atrial fibrillation and maintenance of sinus rhythm, concluding that rhythm control should be reserved for symptomatic patients and that amiodarone is most effecti…
DOI: 10.1136/hrt.2008.155812