Effects of Carvedilol on Suppressing the Premature Ventricular Complex/Ventricular Tachycardia From Outflow Tract

Study Overview
=================
Brief Summary
-----------------
Carvedilol is known to be effective in reducing ventricular arrhythmias and mortality in patients with heart failure. It is suggested that one of the mechanisms is its ability to block store overload-induced Calcium release which activates spontaneous calcium release by Ryanodine receptors. Ventricular outflow tract tachyarrhythmia is known to be associated with calcium overload due to activation of Ryanodine receptors. The aim of this study is to evaluate the efficacy of Carvedilol on premature ventricular complex(PVC)/ventricular tachycardia(VT) originating from outflow tract.

Detailed Description
-----------------
Carvedilol is one of the third-generation beta-blockers effective in reducing ventricular arrhythmias and mortality in patients with heart failure. Antioxidative and alpha - blocking effects, along with nonselective beta - blockade, have been described as a mechanism of effect in various diseases. The antiarrhythmic effect of carvedilol inhibiting atrial fibrillation or ventricular arrhythmia has been reported, but its mechanism is not yet clear. Among them, inhibition of store overload-induced Ca2+ release (SOICR) is suggested as an antiarrhythmic mechanism of carvedilol. Stimulation of the beta receptor leads to the entry of calcium into the sarcoplasmic reticulum (SR) by opening the L-type calcium channel. The influx of calcium through the L-type calcium channel also increases the calcium release through the Ryanodine receptor (RyR) in the sarcoplasmic reticulum. This is called Ca-induced Ca release and is known as a normal physiological response. However, when calcium overload in the myofibrillar body occurs, spontaneous calcium release, known as SOICR, can occur through RyR, which can make triggered activity by inducing Na+/Ca2+ exchanger present in myocardium, leading to severe arrhythmia. Among several beta-blockers, only carvedilol has been known as a drug that can directly inhibit SOICR in combination with beta-blockade effect. Ventricular tachyarrhythmia originating from the ventricular outflow tract is an arrhythmia occurring in a patient with normal cardiac function. The mechanism of the arrhythmia is known to be triggered activity which is caused by activation of RyR due to increased cyclic adenosine monophasphate, resulting in calcium overload, eventually causing activation of Na+/Ca2+ exchanger. The aim of this study is to evaluate the efficacy of Carvedilol on PVC/VT originating from outflow tract.

Official Title
-----------------
Effects of Carvedilol on Suppressing the Premature Ventricular Complex/Ventricular Tachycardia From Outflow Tract

Conditions
-----------------
Ventricular Premature Complexes, Outflow Tract, Carvedilol

Intervention / Treatment
-----------------
* Drug: Carvedilol
* Drug: Flecainide


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients with ventricular premature complexes/ventricular tachycardias originating from ventricular outflow tract confirmed on the 12-lead surface ECG Patients with PVC burden of 5% or more in 24-hour Holter monitoring Patients with normal left ventricular function left ventricular ejection fraction ≥50% Patients without structural heart disease Exclusion Criteria: Pregnant, trying to become pregnant or breast feeding History of bronchial asthma History of coronary arterial disease

Ages Eligible for Study
-----------------
Minimum Age: 19 Years
Maximum Age: 80 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Carvedilol group<br>Patients in this group are taking carvedilol to inhibit outflow tract PVC/VT. Dilatrend® sustained release form of Chong Kun Dang Pharmaceutical will be used (initial dose: 8 mg sustained release form). Outpatient follow-up will be performed every 2 weeks and the dose is increased from the initial dose to a maximal tolerable dose, at the discretion of the investigator. | Drug: Carvedilol<br>* Patients in this group are taking carvedilol to inhibit outflow tract PVC/VT.<br>* Other names: Dilatrend;|
| Active Comparator: Flecainide group<br>Patients in this group are taking flecainide to inhibit outflow tract PVC/VT. Tambocor® of JW Pharmaceutical will be used. Outpatient follow-up will be performed every 2 weeks and the dose is increased from the initial dose to a maximal tolerable dose, at the discretion of the investigator. | Drug: Flecainide<br>* Patients in this group are taking flecainide to inhibit outflow tract PVC/VT.<br>* Other names: Tambocor;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PVC burden | Percentage of PVC/VT beat out of 24 hour total heart beat in Holter monitoring | 3 months after reaching the maximum tolerated dose | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Symptom assessment scale | questionnaire for PVC/VT symptoms using symptom assessment scale (Min 0 to Max 100) | 3 months after reaching the maximum tolerated dose | 
| Side effect of drugs | Difference in occurrence of side effects of each drug | 3 months after reaching the maximum tolerated dose | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
carvedilol, SOICR, triggered activity, outflow tract PVC/VT