P351Therapeutic inefficacy and pro-arrhythmic nature of metoprolol succinate and carvedilol therapy in patients with idiopathic, frequent, monomorphic premature ventricular contractions

Abstract

Abstract Funding Acknowledgements None Background Anti-arrhythmic drugs remain the first-line therapy for treatment of idiopathic ventricular arrhythmias in clinical practice. Purpose The aim of this study was to assess the therapeutic efficacy of extended-release metoprolol succinate (MetS) and carvedilol for idiopathic, frequent, monomorphic premature ventricular contractions (PVCs). Methods Study population consisted of 115 consecutive patients: 72 received MetS and 43 received carvedilol. All patients underwent 24-hour Holter monitoring at baseline and during drug therapy. PVC burden response to drug therapy was categorized as "Good" (≥80% reduction), "Poor" (either < 80% reduction or ≤ 50% increase) and "Pro-arrhythmic" response (> 50% increase) based on change in PVC burden compared to baseline. Results Presenting symptoms were palpitations in 69 (60%), shortness of breath/chest pain/syncope in 12 (10.5%), and coincidentally discovered in 34 (29.5%) patients. Mean MetS and carvedilol dosages were 65.57 ± 30.67 mg/day and 23.66 ± 4.26 mg/day, respectively. "Good", "Poor" and "Pro-arrhythmic" response was observed in 13.9% and 23.3%, 61.1% and 60.5%, and 25% and 16.2% of patients treated with MetS and carvedilol, respectively. In patients with relatively high (≥16%) PVC burden, "Poor" response was observed in 86.9% and 76% of patients treated with MetS and carvedilol, respectively. Side-effects and/or intolerance were observed in 5.5 % and 13.9 % of patients treated with MetS and carvedilol, respectively. Conclusions MetS and carvedilol for idiopathic, frequent, monomorphic PVCs is frequently inefficient. Therapeutic efficacy decreases further in patients with relatively high (≥16%) PVC burden. "Pro-arrhythmic" response was observed in approximately one quarter of the patients. All patients Metoprolol Succinate (n = 71) Carvedilol (n = 43) p value Good response,n (%) 7 (9.9) 7 (16.3) 0.38 Poor response,n (%) 46 (64.8) 29 (67.4) 0.38 Pro-arrhythmic response,n (%) 18 (25.4) 7 (16.3) 0.38 Patients with PVC burden≥%16 Metoprolol Succinate (n = 22) Carvedilol (n = 25) Good response,n (%) 1 (4.5) 3 (12) 0.56 Poor response,n (%) 20 (91) 20 (80) 0.56 Pro-arrhythmic response,n (%) 1 (4.5) 2 (8) 0.56 Therapeutic response to Metoprolol Succinate and Carvedilol