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

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

P1772 Assesment of total atrial conduction time in patients with atrioventricular nodal reentrant tachycardia with and without drug-induced type 1 Brugada pattern and control subjects

Background

Most forms of atrioventricular nodal reentrant tachycardia (AVNRT) are created by reentry between 2 (or more) atrial connections to the AV node. There is a high prevalence of drug-induced type 1 Brugada ECG pattern (DI-Type1-BrP) among patients with AVNRT. Atrial vulnerability and structural remodeling that leads to reentrant circuits in AVNRT is largely unknown. PA-TDI interval assessed by tissue Doppler imaging is a useful technique to determine total atrial conduction time (TACT) which reflects atrial remodeling and arrhythmic substrate.

Purpose

In this prospective study, we aimed to assess TACT in patients with AVNRT with and without DI-Type1-BrP and control subjects.

Methods

Study population consisted of 62 consecutive patients (age 44 ± 12 years; 74% women) undergoing electrophysiological study and ablation for symptomatic, drug-resistant AVNRT and 42 age and sex matched control subjects. All patients and control subjects underwent ajmaline challenge test and tissue Doppler imaging.

Results

A DI-Type1-BrP was uncovered in 24 of 62 patients with AVNRT (38.7%). PA-TDI interval was longer in patients with AVNRT with or without DI-Type1-BrP compared to control subjects (124 ± 12 ms vs 119 ± 14 ms vs 105 ± 11 ms; P < 0.001, respectively). PA-TDI interval was similar in patients with AVNRT with or without DI-Type1-BrP (124 ± 12 ms vs 119 ± 14 ms; P = NS, respectively). PA-TDI interval was significantly correlated with P-wave duration on the surface ECG (r = 0.23; P = 0.02). Left atrial volume index and left atrial phasic functions were similar in patients with AVNRT with or without DI-Type1-BrP and control subjects.

Conclusion

TACT is prolonged in patients with AVNRT. Further studies are needed to determine the underlying factor(s) such as DI-Type1-BrP that leads to prolonged atrial conduction time.

Characterization of reentrant circuit in macroreentrant right atrial tachycardia after surgical repair of congenital heart disease: isolated channels between scars allow "focal" ablation

BACKGROUND

The purpose of this study was to characterize the circuit of macroreentrant right atrial tachycardia (MacroAT) in patients after surgical repair of congenital heart disease (SR-CHD).

METHODS AND RESULTS

Sixteen patients with atrial tachycardia (AT) after SR-CHD were studied (atrial septal defect in 6, tetralogy of Fallot in 4, and Fontan procedure in 6). Electroanatomic right atrial maps were obtained during 15 MacroATs in 13 patients, focal AT in 1 patient, and atrial pacing in 2 patients without stable AT. A large area of low bipolar voltage (</=0.5 mV) involved most of the free wall in all patients and contained 2 to 7 dense scars or lines of double potentials, forming 29 narrow channels (width </=2.7 cm) between scars in all but 1 patient, who had a single scar and only focal AT. All 15 MacroATs were propagated through narrow channels. Ablation within the channel eliminated all 15 MacroATs with 1 to 3 (median 1) radiofrequency applications. Ablation was performed in 9 other channels identified during MacroAT (5 patients) and in 5 channels identified during atrial pacing (2 patients). Conduction block was obtained across 28 of 29 channels. After ablation, reproducible sustained right AT was not induced in any patient. During follow-up (median 13.5 months), new MacroATs, atrial fibrillation, or palpitations occurred in 3 of 16 patients.

CONCLUSIONS

MacroAT after SR-CHD requires a large area of low voltage containing >/=2 scars forming narrow channels. Ablation within the channels eliminates MacroAT.