[Emergency Care Journal 2016; 12:6097] [page 67] Esmolol for the treatment of recurrent ventricular tachycardia Simone Savastano, Alessandra Greco, Benedetta Matrone Cardiology Department, San Matteo Hospital, Pavia, Italy Abstract Cardiac arrest and electrical storm are two major emergencies. The use of beta blockers in these clinical conditions has been proposed; however, definite data about the emergency use of beta blockers in recurrent ventricular tachycardia with pulse have never been pub- lished. We report two cases of recurrent ven- tricular tachycardia, which were unresponsive to the standard pharmacological treatment but successfully responsive to esmolol infusion. Both cases showed a reduced left ventricle ejection fraction due to an acute myocardial infarction and to an idiopathic dilated car- diomyopathy respectively. Nevertheless, the use of esmolol was shown to be both safe and effective without inducing low output syn- drome. Introduction The protective role against ventricular arrhythmias of oral administration of beta blockers in patients with catecholaminergic polymorphic ventricular tachycardia 1 or with ST-segment elevation myocardial infarction (STEMI) 2 has been shown, however there is very little evidence about the use of intra- venous beta blockers for the treatment of recurrent ventricular tachycardias. In this regard we report two cases of recurrent ven- tricular tachycardia effectively solved by intra- venous administration of esmolol. Pharmacology of esmolol Esmolol is an ultra-short-acting b1-selective adrenergic blocker (mean elimination half-life [t½]=9 minutes) with rapid onset and offset of effects that provided an element of safety. When esmolol is administered as a bolus fol- lowed by continuous infusion, onset of activity occurs within 2 minutes, with 90% of b-block- ade at 5 minutes. Full recovery from its effect takes 18–30 minutes after stopping the infu- sion. Generally, a loading dose of 500 mcg/kg over one minute is administered prior to a maintenance infusion dose of 50–300 mg/kg/min. Esmolol is metabolized by red blood cells’ esterases to an acid metabolite (ASL-8123) and methanol. It makes esmolol safe even for those patients with renal or hepatic dysfunction. Pharmacokinetic interac- tions of esmolol with other cardiovascular drugs have been studied without finding any of clinical interest. The most common adverse effect with esmolol is hypotension. The inci- dence of hypotension (0–50%) increases with bolus doses of 100 mg (25%) to 200 mg (33%) or continuous infusions exceeding 150 mg/kg/min. Hypotension can be easily man- aged by decreasing the dose or stopping the infusion. Due to its characteristics esmolol is suitable for emergency rooms, critical care units and surgical settings where rapid control of heart rate or blood pressure is often needed. Case Report The first case is about a 47-year-old woman, who came to our attention for anterior myocar- dial infarction (STEMI). A primary percuta- neous coronary intervention on the left anteri- or descendant artery was performed in a single vassel disease. Circulation was supported by an intra-aortic balloon pump (IABP) and epi- nephrine infusion. The left ventricular func- tion was depressed (LVEF 30% at echo). The patient was then stabilized; IABP was removed and epinephrine infusion was stopped. Eight days later, she suffered an episode of sus- tained monomorphic VT at 220/min perceived as simple palpitations; blood pressure was 73/49 mmHg (85/50 mmHg during sinus rhythm). Lidocaine 100 mg was administered unsuccessfully, so she was sedated and con- verted to sinus rhythm with 200J synchronized DC shock. From that moment on six other arrhythmic relapses occurred, for a total of seven DC shocks, despite the infusion of amio- daron (20 mcg/kg/min) and lidocaine (20 mcg/kg/min). After the last cardioversion an infusion of esmolol 50 mcg/kg/min was started and the patient stabilized, without any other relapse. There was no mechanical cause for the arrhythmia (Figure 1A) The second case is about a 71-year-old man with an idiopathic dilated cardiomyopathy (LVEF 28% at echo) and normal coronary arter- ies. He was admitted because of an appropri- ate ICD intervention. During the hospitaliza- tion he suffered another episode of VT refrac- tory to antitachycardia pacing (ATP) and evolv- ing into ventricular flutter treated with DC shock. In the following hours he had incessant episodes of haemodynamically well-tolerated VT, not responding to medical treatment with intravenous lidocaine (100 mg bolus and then infusion 20 mcg/kg/min), intravenous fle- cainide (1 mg/kg), amiodarone (150 mg plus 300 mg bolus), and several attempts of ATP. The patient was cardioverted eight times with external and internal DC shock. The arrhyth- mias stopped when esmolol therapy was insti- tuted, with an initial bolus of 40 mg followed by an infusion of 50 mcg/kg/min for two hours. No relapse of ventricular arrhythmia was observed and in the following days (Figure 1B). Discussion Cardiac arrest (CA) and electrical storm (ES) are two major and often fatal emergen- cies. During ventricular tachycardia (VT) or ventricular fibrillation (VF) a marked increase of plasma concentration of epinephrine has been demonstrated 3,4 and this may play an important role in sustaining arrhythmias. Moreover a denervation supersensitivity to cat- echolamine has been described after myocar- dial infarction 5 and this may have been one of the mechanisms involved in the first case pre- sented. From here the hypothesis of using beta blockers on top of antiarrhythmic therapies was formulated. Esmolol is a cardio-selective beta1-receptor blocking agent with a rapid onset and a short duration of action (t1/2=9 minutes). 6 The efficacy of esmolol has been successfully tested both during CA due to refractory VF 7-11 increasing ROSC and survival and during pulseless ES 12 overcoming ACLS drugs. However the efficacy of esmolol in treat- ing hemodynamically tolerated ventricular arrhythmias has never been described and so we reported these two cases. Notably we used esmolol in two patients with a significantly reduced left ventricle ejection fraction without inducing a low output syndrome Emergency Care Journal 2016; volume 12:6097 Correspondence: Simone Savastano, Cardiology Department, San Matteo Hospital, piazzale Golgi, 27100 Pavia, Italy. Tel: +39.0382.501590 - Fax: +39.0382.501279. E-mail: s.savastano@smatteo.pv.it Key words: Esmolol; Ventricular tachycardia; Electric storm. Contributions: the authors contributed equally. Received for publication: 17 June 2016. Revision received: 4 September 2016. Accepted for publication: 6 September 2016. This work is licensed under a Creative Commons Attribution 4.0 License (by-nc 4.0). ©Copyright S. Savastano et al., 2016 Licensee PAGEPress, Italy Emergency Care Journal 2016; 12:6097 doi:10.4081/ecj.2016.6097 Non commercial use only