Outflow tract ventricular arrhythmia (OTVA) is the most common type of ventricular arrhythmia, and catheter ablation (CA) is the primary treatment option for patients experiencing symptoms. Accurately identifying the origin site of OTVA is essential for effective catheter ablation, minimizing procedural risks, and enhancing treatment success. However, most studies that developed algorithms or scoring systems for distinguishing OTVA origins excluded participants with structural heart disease and those with paced rhythms from their study groups. A recent prospective evaluation of a hybrid score (HS) that integrates both clinical and ECG data to predict OTVA-SOO, including patients with cardiac implantable electronic devices and those with structural heart disease in our study.

The presented study aimed to assess the effectiveness of the previously described hybrid algorithm in predicting OTVA-SOO in a patient population characterized by a wide basal QRS due to intraventricular conduction defects or paced rhythms.

The Hybrid Score The Hybrid Score (HS), involves a sum of points based on clinical and ECG characteristics. Points are assigned as follows: one point each for being over 50 years old, male, and having arterial hypertension. ECG-based points are allocated according to QRS transition: 3 points for a transition in V1, 2 points for V2, 1 point for V3 if the R-wave in V3 is greater than 1 mV; 1 point is subtracted if V3 has an R-wave less than 1 mV, and further deductions or additions apply for transitions up to V6. A score ≤ 1 suggests an RVOT origin, whereas ≥ 2 suggests an LVOT origin.

ECGs were recorded with a standard configuration at a 25 mm/s sweep speed.

Premature Ventricular Contraction (PVC) Ablation Activation mapping of spontaneous OTVAs was conducted. The procedure aimed to abolish spontaneous OTVAs, with the site of ablation marking the site of origin (SOO).

Collected data

• Patient Information and Consent (procedure must be done within 60 days of consent)
• Demographics (age, gender, etc.)
• Vital signs (length, weight, etc.)
• Medical history, including cardiovascular risk factors, cardiomyopathy and drugs
• ECG data
• Echocardiographic data (left ventricular ejection fraction and left ventricular end-diastolic diameter)
• Procedure data (number of radiofrequency applications, site of effective ablation, total radiofrequency time, total fluoro time, points mapping, procedure time)
• Adverse Events

Inclusion Criteria:

• ventricular arrhythmia with a morphology indicating an outflow tract origin and a wide basal QRS complex
• a QRS width greater than 110 ms was considered wide
• willing and capable of providing written informed consent to the study

Exclusion Criteria:

• catether ablation procedure was unsuccessful
• infrequent arrhythmia requiring ablation guided by pacemapping.

General population undergoing catheter ablation for outflow tract ventricular arrhythmias