Abstract 16243: Beta-Blocker Therapy Reduce Threshold for Exercise Induced Ventricular Arrhythmias in Patients with CPVT
Introduction: Catecolaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac disease which predisposes to exercise-induced life-threatening arrhythmias. The current therapeutic recommendations are beta-blocker therapy and ICD implantation. We aimed to determine the effect of beta-blocker treatment on exercise-induced arrhythmias in CPVT patients.
Methods: A total of 38 CPVT patients were followed for 24 (8–288) months. Of these, 8 were index patients and 30 were mutation positive family members diagnosed by cascade genetic screening. Clinical evaluation including exercise test was performed at inclusion and repeated 3 months after initiation of beta-blocker therapy in maximum tolerable doses. Heart rate and workload at occurrence of ventricular premature beats (VPB), couplets and non-sustained VT (nsVT) were recorded.
Results: Exercise-induced arrhythmias were observed in 28 (79 %) patients before treatment. Resting and maximum heart rate during exercise test were reduced by beta-blocker treatment (p<0.001) (Table). VPBs and most severe arrhythmias on beta-blocker therapy appeared at 14% and 15% lower heart rate, respectively (both p=0.01), but at a similar workload as without beta-blocker therapy (Table). Beta-blocker therapy suppressed nsVT in 4 of 6 mutation carriers (p=0.02). Less serious arrhythmias were not affected.
Conclusion: Exercise-induced arrhythmias in CPVT patients occurred at lower heart rates on beta-blocker treatment. Beta-blocker therapy suppressed nsVT, while less severe arrhythmias were unchanged. Treatment effect of beta-blocker therapy in CPVT should therefore not be evaluated by occurrence of VPBs at exercise test. These findings suggest that the protective effects of beta-blocker therapy in CPVT patients are not only due to negative chronotrophy.
- © 2010 by American Heart Association, Inc.