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)