Relation of Ventricular Tachycardia/Fibrillation to Beta-Blocker Dose
Maximization Guided by Pacing Mode Analysis in. Nonpacemaker-Dependent
Patients With Implantable Cardioverter-Defibrillator
We hypothesized that uptitration of beta blockade and adjustment of
pacing parameters to achieve a prevalence of single chamber atrial
inhibited rate-responsive (AAIR) pacing in patients with dual-chamber
implantable cardioverter-defibrillators (ICDs) would result in
maximization of beta-blocker dosage and thus decrease appropriate ICD
therapies. We included patients with ischemic or dilated cardiomyopathy
and implanted ICDs without contraindications to beta blockers and
atrioventricular conduction disturbances. Two 6-month periods were
compared: clinically guided phase (pacing function set at back-up
dual-chamber rate-responsive pacing mode at a lower rate of about 40
beats/min) and pacing-guided phase, during which beta-blocker dosage was
titrated with a target of achieving >90% AAIR pacing (lower rate 60
beats/min). Sixty-one patients (64.2 +/- 8.3 years old) were included.
During the pacing-guided phase the target of >= 90% AAIR pacing was
achieved in 80.3% of patients. Mean metoprolol dose during the
clinically guided phase was 96.7 +/- 29.4 versus 127.0 +/- 39.6 mg/day
in the pacing-guided phase (p <0.001). Appropriate ICD therapies were
recorded in 35 patients (57.4%) during the clinically guided phase
versus 20 (32.8%) during the pacing-guided phase (p <0.001; 1.15 and
0.48 appropriate ICD therapies per patient, respectively, p <0.001). In
multivariate analysis, AAIR pacing and beta-blocker dose were inversely
related to appropriate ICD therapies. In conclusion, a pacing-guided
approach for maximizing beta-blocker doses guided by maximizing AAIR
pacing in patients with ICDs may be beneficial compared to the
conventional strategy. This pacing-guided approach led to higher daily
beta-blocker doses, which were correlated to fewer appropriate ICD
therapies. (C) 2011 Elsevier Inc. All rights reserved. (Am J Cardiol
2011; 107:1812-1817
