[Impact of metoprolol use in the treatment of patients with electrical-storm after cardioverter defibrillators implantation].

OBJECTIVE: To explore the effectiveness of the metoprolol dosage adjustment on reducing the incidence of electrical-storm (ES) in patients with Implantable Cardioverter Defibrillators (ICDs). METHODS: Data from patients with ICD implantation between Jan, 2003 and Jun, 2006 in our hospital were retrospectively analyzed. ES was defined as either ≥ 3 times of ventricular tachyarrhythmias (VTAs) resulting in ICD therapy or VTAs lasting more than 30 s detected by ICD without any therapy within 24 hours. RESULTS: During a follow-up period of (27.5 ± 21.2) months, ES was recorded in 39 cases [34 males, average age (52.0 ± 13.1) years] out of 119 patients (32.8%) and 9 patients died after ES. During the period of storm attack, ES was successfully controlled in 25/30 patients by various interventions, including predisposing factors corrected in 5 cases, ICD reprogramming and antiarrhythmic drugs therapy optimized in 16 cases (one received intravenous injection of metoprolol), and VTAs eliminated by catheter ablation in 4 cases. ES was spontaneously resolved in the remaining 5 cases. In the chronic phase, 2 patients with Brugada syndrome were treated with Quinidine mono-therapy while the dosage of metoprolol was adjusted in the remaining 23 patients and the dosage of metoprolol was increased gradually from (26.8 ± 13.9) mg/d to (88.9 ± 53.5) mg/d without any adverse effects (9 patients received also oral amiodarone 200 mg/d). Post dosage adjustment, the total VTA episodes [(1.9 ± 1.7) times/month vs. (0.8 ± 0.6) times/month, P = 0.004], incidence of antitachycardia pacing therapies [(4.2 ± 3.8) runs/month vs. (2.3 ± 2.0) runs/month, P = 0.003], as well as electrical cardioversion or defibrillation [(1.1 ± 0.9) times/month vs. (0.4 ± 0.2) times/month, P = 0.001] were significantly decreased. ES was not controlled until a extremely high dosage [225 - 300 (255.3 ± 41.7) mg/d] of metoprolol was reached in the remaining 5 patients. CONCLUSIONS: Metoprolol use is essential and its dosage should be individualized in the majority of ICD recipients with ES. In approximately 1/6 patients, the dosage of metoprolol should be higher than 200 mg/d.