Mapping and ablation of epicardial idiopathic ventricular arrhythmias from within the coronary venous system
Timir S Baman1, Karl J Ilg, Sanjaya K Gupta
1University of Michigan Health System, Ann Arbor, MI 48109-5853, USA.
Insights
Approximately 15% of idiopathic ventricular arrhythmias originate from the epicardium. Ablation within the coronary venous system (CVS) is effective for these arrhythmias, with successful outcomes in about 70% of cases.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Idiopathic ventricular arrhythmias (IVAs) are common, but the prevalence of those originating from the epicardium and treatable via the coronary venous system (CVS) is unknown.
- Epicardial arrhythmias pose a diagnostic and therapeutic challenge.
Purpose of the Study:
- To determine the prevalence of epicardial IVAs originating from the CVS.
- To evaluate the feasibility and success of ablating these arrhythmias from within the CVS.
Main Methods:
- Activation and pace mapping were used to identify the site of origin (SOO) in 189 patients with IVAs.
- If endocardial mapping failed, mapping and venography of the CVS were performed.
- Ablation was attempted within the CVS for identified epicardial sources.
Main Results:
- The SOO was identified within the CVS in 14% of patients (27/189), primarily in the great cardiac vein.
- Successful ablation within the CVS was achieved in 74% of these patients (20/27).
- Epicardial arrhythmias showed distinct ECG characteristics (broader R wave in V1) compared to endocardial ones.
Conclusions:
- Nearly 15% of IVAs have an epicardial origin, often accessible via the CVS.
- ECG features can help distinguish epicardial from endocardial arrhythmias.
- CVS ablation is a viable option for a majority of epicardial IVAs, though challenges like catheter access and proximity to structures exist.
Background:
The prevalence of epicardial idiopathic ventricular arrhythmias that can be ablated from within the coronary venous system (CVS) has not been described.
Methods And Results:
In a consecutive group of 189 patients with idiopathic ventricular arrhythmias referred for ablation, the site of origin (SOO) of ventricular tachycardia and/or premature ventricular contractions was determined by activation mapping and pace mapping. Mapping was performed within the CVS if endocardial mapping did not reveal an SOO. Venography of the CVS and coronary angiography were performed before ablation in the CVS. In 27 of 189 patients (14%+/-5%; 95% confidence interval), the SOO of the ventricular arrhythmia was identified from within the coronary venous system, either in the great cardiac vein (n=26) or the middle cardiac vein (n=1). The mean activation time at the SOO was -29+/-8 ms. Twenty of 27 patients (74%) underwent successful ablation within the CVS. Epicardial ventricular arrhythmias displayed a broader R wave in V(1) compared with arrhythmias in the control group (85 ms [interquartile range, 40] versus 65 ms [interquartile range, 95]; P<0.01). Two patients had recurrent premature ventricular contractions within 2 weeks after ablation, and no recurrences occurred in the remaining patients during a median follow-up of 13 months (range, 25). In the 7 patients with unsuccessful ablation, failure was because the ablation catheter could not be advanced to the SOO within the great cardiac vein (n=4), inadequate power delivery at the SOO (n=1), proximity to the phrenic nerve (n=1), or proximity of the SOO to a major coronary artery (n=1). Transcutaneous epicardial ablation was effective in 1 of 2 patients in whom it was attempted.
Conclusions:
Almost 15% of idiopathic ventricular arrhythmias have an epicardial origin. ECG characteristics help to differentiate epicardial arrhythmias from endocardial ventricular arrhythmias. The SOO of epicardial arrhythmias can be ablated from within the CVS in approximately 70% of patients.
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