Dr LA Hodsdon

Amiodarone Been first-line drug for the treatment of stable ventricular tachycardia (VT) in recent years. 1 Reason for preference: repeated demonstration that Lignocaine (prev drug of choice) is effective in terminating < 25% of cases of VT; another was that Procainamide is very slow to work. 1) Amiodarone Is Poorly Effective for the Acute Termination of Ventricular Tachycardia Marill KA, deSouza IS, Nishijima DK, et al. Ann Emerg Med 2006;47:  Set out to assess how effect Amiodarone is at terminating VF

Amiodarone Is Poorly Effective for the Acute Termination of Ventricular Tachycardia Marill KA, deSouza IS, Nishijima DK, et al. Ann Emerg Med 2006;47:  Retrospective analysis of VT cases – 4 Urban University Hospitals (1996 – 2005).  Standard AHA-recommended 150 mg Amiodarone bolus + infusion for sustained monomorphic VT (formal criteria to define and prove VT included).  Endpoint: % cases of VT terminated within 20 minutes of initiation of Amiodarone therapy.  Small study group & retrospective nature.

 33 VT patients  5 required electrical treatment within 20 minutes of initiation of Amiodarone (due to presyncope, hypotension, or other adverse effects which seemed related to the amiodarone).  Only 8 (29%) of remaining 28 pts successfully converted.  18 of the 33 patients (55%) required electrical therapy (overdrive pacing, cardioversion or defibrillation) because of worsening symptoms or failure to respond.  5 (18%) of pts that did not respond to amiodarone did respond to another antidysrhythmic.  Direct current cardioversion with sedation is still the most effective means of terminating VT and should be the preferred treatment in the emergency setting. Amiodarone is probably not as effective as previously thought; be wary of side effects & have electricity on hand!

2) The Quest for a Terminator Cummins RO, Hazinski MF. Ann Emerge Med 2006;47: (editorial accompanying above article – AHA & ACLS editorial team)  Evidence for study was weak, but that for amiodarone as one of the drugs of choice for stable VT was a bit suspect as well (Small, old studies were used, and most of the prior evidence also suggested that amiodarone was far from perfect, with termination rates of 40-60%).  Procainamide and Sotalol have better efficacy rates, but procainamide is very slow to work and sotalol is not readily available for ED use.  They admit that electrical cardioversion is the most effective therapy for stable VT and it should be in place for rapid use even if a trial of amiodarone is chosen as a first treatment.

3) Intravenous Amiodarone for the Pharmacological Termination of Haemodynamically-Tolerated Sustained Ventricular Tachycardia: Is Bolus Dose Amiodarone an Appropriate First- Line Treatment? Tomlinson DR, Cherian P, Betts TR, et al. Emerg Med J 2008:25:  Retrospective analysis of 41 consecutive EU admissions for VT  Patient with sustained, haemodynamically stable VT that was treated according to current UK advanced life support practice guidelines: bolus dose IV amiodarone 300 mg.  Pharmacological termination of VT occurred within 20 minutes in only 6/41 patients (15%) and within 1 hour in only 12/41 patients (29%).  Hemodynamic deterioration requiring emergency direct current cardioversion occurred in 7/41 patients (17%).

Amiodarone Amiodarone’s success rate in converting stable VT is only 29%. (1) The inclusion of amiodarone in the AHA Guidelines was based on small, old studies indicating that amiodarone was only 40-60% successful in terminating VT. (2) Procainamide appears to have a longer history of success, with conversion rates as high as 80% in a randomized study. (3) Pharmacological termination of VT occurs within 20 minutes in only 15% and within 1 hour in only 29% patients; while hemodynamic deterioration requiring emergency direct current cardioversion occurred in 17% of patients questioning its purported haemodynamic stability. (4)

SOURCES 1. Marill KA, deSouza IS, Nishijima DK, et al. Amiodarone is poorly effective for the acute termination of ventricular tachycardia. Ann Emerg Med 2006;47: Cummins RO, Hazinski MF. The quest for a terminator. Ann Emerg Med 2006;47: Gorgels AP, van den Dool A, Hofs A, et al. Comparison of procainamide and lidocaine in terminating sustained monomorphic ventricular tachycardia. Am J Cardiol 1996;78: Intravenous Amiodarone for the Pharmacological Termination of Haemodynamically-Tolerated Sustained Ventricular Tachycardia: Is Bolus Dose Amiodarone an Appropriate First-Line Treatment? Tomlinson DR, Cherian P, Betts TR, et al. Emerg Med J 2008:25:

ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death — Executive Summary (many authors) Circulation 2006;114:

ACC, AHA, and the European Society of Cardiology (ESC) Consensus Appear to be less keen to turn emergency physicians into Cardiologists: Wide complex tachycardia with uncertain origin should be treated as a VT In ACS patients, the use of beta blockers is encouraged unless there is a contraindication - the purpose of the beta blockers is NOT to just slow the heart, but rather to decrease the incidence of VF arrest.

Monomorphic VT Procainamide is back in favour! For stable monomorphic VT, procainamide is listed as a class IIa intervention with a higher level of evidence than amiodarone (Class IIa, level of evidence B; amio — Class IIa, level of evidence C). IV amiodarone is most reasonable for patients with sustained monomorphic VT that are hemodynamically unstable despite DC shocks or VT that is persistent / recurrent despite procainamide or other agents. Lignocaine is considered reasonable and effective when VT is thought to be related to myocardial ischemia or infarction. In cases of repetitive monomorphic VT in the setting of ACS, add beta blockers to your list of treatment options.

Polymorphic VT (PVT) DC cardioversion is probably the best, and often the only, choice if the rhythm is persistent. For intermittent or recurrent PVT, consider IV Beta Blockers or IV amiodarone (ONLY if the patient has a normal QTs). Procainamide is also probably useful, and Lignocaine can be used especially if in the setting of suspected ACS. If ACS is suspected or “can’t be excluded” urgent angiography should be considered. Magnesium is not likely to be effective in these patients (normal QT patients).

Torsades de Pointes type of PVT TdP is a PVT associated with a prolonged QT interval. Thus drugs that prolong the QT interval (including the sodium channel blocking antiarrhythmics - amiodarone, procainamide, probably lignocaine also) are best avoided. Magnesium is the first line drug (unlikely to be effective if the QT interval is normal - i.e. generic PVT). Other options include (overdrive) pacing and isoproterenol. Immediate withdrawal of any offending drugs or correction of electrolyte abnormalities (hypo-K, hypo-Mg, hypo-Ca) is very important.

Arrhythmic Complications of Electrical Cardioversion: Relationship to Shock Energy Gallagher MM, Yap YG, Padula M, et al. Int J Cardiol 2008;123: Guidelines for electrical cardioversion (ECV) of patients with atrial dysrhythmias have recommended starting with low energy (e.g. 50J- 100J) and increasing in increments if the initial shocks fail. This recommendation is based on fears that high-energy shocks might induce myocardial damage or induce ventricular fibrillation.  Authors proposed that higher energy levels may be safe and more effective.

 Retrospective analysis.  Data on shocks delivered to 1896 patients who underwent thransthoracic ECV for various atrial dysrhythmias.  In 2522 attempts at ECV, 6398 shocks were delivered.  1243 shocks delivered for atrial flutter (AFlut) or atrial tachycardia’s and the others for atrial fibrillation (AFib).  Ventricular fibrillation (VFib) was more common after shocks of 200 J, p<0.05).  Conversion of AFlut or atrial tachycardia to AFib was also more common at 200 J, p<0.05).

Sinus bradycardia or sinus arrest was an extremely rare complication (0.95%), unrelated to the energy used, and in no cases required emergency pacing. Embolic complications occurred in 14 patients and were not related to the energy used either. The energy levels used above relate to monophasic defibrillators. For biphasic defibrillators, the Guidelines for ECV of AFib (1) suggest starting at 200 J, which is equivalent to monophasic shocks of 360 J. Since the authors caution against using monophasic shocks < 200J, they correspondingly caution against using biphasic shocks of < 100J.

In the discussion, the authors make an interesting point, stating that “It has been shown (2) that the initial use of a higher energy setting reduces the number of shocks required to effect [successful] cardioversion and in many cases [actually] reduces the total energy delivered.” So it appears that higher energy levels are more effective and associated with slightly fewer complications. 1. Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 Guidelines for the management of patients with atrial fibrillation. Eur Heart J 2006;27: Gallagher MM, Guo X, Ploneicki J, et al. Initial energy setting, outcome and efficiency in direct current cardioversion of atrial fibrillation and flutter. J Am Coll Cardiol 2001;38:

Sources A. Mattu. Emergency Cardiology 2009: The articles you’ve got to know!! ACC/AHA website and publications:  ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death – Executive Summary  AHA ACLS Tachycardia Algorithm1  AHA ACLS Bradycardia Algorithm  ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation – Executive summary Best Bets Website / Google