Influence of beta-blocker therapy on antitachycardia pacing effectiveness for monomorphic ventricular tachycardias occurring in implantable cardioverter-defibrillator patients: a dose-dependent effect.
OBJECTIVE
To determine, in a non-selected population of 282 implantable cardioverter-defibrillator (ICD) patients with left ventricular dysfunction, the influence of the dose of beta-blockers on antitachycardia pacing (ATP) effectiveness and on the incidence of shock due to monomorphic ventricular tachycardias (VT).


RESULTS
We followed 282 ICD patients along 26 +/- 19 months. Antitachycardia pacing and shock programming were standardized. We determined the indexed dose equivalent of beta-blockers (IDE-BB), using metoprolol as a reference, at each VT presentation. The median of IDE-BB was 55 mg/m(2)/day. We analysed 846 VT occurred in 100 patients. The ATP success rate was 84%. Upon classification of the events into three groups (IDE-BB = 0, IDE-BB < 55, and IDE-BB > or = 55), the frequency of effective ATP increased with the IDE-BB: 75 vs. 83 vs. 92% (P < 0.001). According to logistic regression, IDE-BB remained as an independent predictor of effective ATP (P < 0.001) and VT-related shock (P = 0.001). Both the mean ATP effectiveness per patient (67 vs. 80 vs. 91%, P = 0.007) and the mean survival time free of VT-related shock (583 vs. 847 vs. 1158 days, P = 0.019, log-rank test) increased linearly with the dose of beta-blockers.


CONCLUSIONS
Beta-blockers increase the effectiveness of ATP through a dose-dependent effect. As a result, they reduce the incidence of shocks due to VT.
Arrhtythmias Unit, Cardiology Department, University Hospital, Paseo de San Vicente, Salamanca, Spain. jimenezcandil@secardiologia.es
Javier
J
Jiménez-Candil
Jesús
J
Hernández
Ana
A
Martín
María
M
Ruiz-Olgado
Jesús
J
Herrero
Claudio
C
Ledesma
José
J
Moríñigo
Cándido
C
Martín-Luengo
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000368:Aged; D002304:Cardiac Pacing, Artificial; D003131:Combined Modality Therapy; D017147:Defibrillators, Implantable; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000517:prevention & control*; D016896:Treatment Outcome
D000319:Adrenergic beta-Antagonists; D008790:Metoprolol