Impact of Intramural Scar on Mapping and Ablation of Premature Ventricular Complexes

Catheter Ablation of Parahisian Premature Ventricular Complexes From the Right Sinus of Valsalva

BACKGROUND

Cather ablation of parahisian premature ventricular complexes (PVCs) often requires ablation in multiple cardiac chambers, including the sinuses of Valsalva (SoV). The safety and efficacy of ablation within the right SoV to target parahisian arrhythmias has not been widely reported.

OBJECTIVE

To report on the demographic and procedural characteristics of patients undergoing catheter ablation of PVCs who underwent ablation in the right SoV, and to examine the impact of late-gadolinium enhanced cardiac magnetic resonance (LGE-CMR) on procedural findings.

METHODS

Consecutive patients undergoing ablation of parahisian PVCs and ablation in the right SoV with preprocedural LGE-CMR were included.

RESULTS

Eleven patients were included in the study population (11 males (100%), median age: 68 ± 7 years, median ejection fraction: 53% ± 7%, PVC burden 23% ± 13%). Intramural LGE-CMR scar was present in all patients and involved the basal anteroseptum/outflow tract in nine patients. Ablation within the right SoV eliminated (n = 9) or suppressed (n = 2) PVCs in all patients. The successful SoV site displayed the absolute earliest presystolic activation time or matching pacemaps in only 44% and 55% of patients, respectfully. Transient heart block during right SoV ablation occurred in 1/11(9%) patients. The post procedure PVC burden decreased from 23% ± 13% to 7% ± 6%, procedural success was attained in 10/11(91%) of patients.

CONCLUSIONS

Parahisian PVCs ablated from the right SoV are often intramural, may require ablation in multiple chambers, and colocalize with intramural LGE-CMR scar. Traditional EGM markers of successful ablation sites were less frequently seen at successful site of SoV ablation, long term success was achieved in 91% of patients.

Clinical Impact of High-Intensity Targeted Ablation of Identifiable Critical Zones in Scar-Related Ventricular Tachycardia

BACKGROUND

Ventricular tachycardia (VT) isthmus boundaries correlate with a localized line of conduction block (LOB) identified by substrate mapping during baseline rhythm. In particular, a rotational activation pattern (RAP), which is characterized as a wavefront propagation pivoting around the edge of the fixed LOB accompanied by conduction slowing, may have a high proclivity toward re-entry.

OBJECTIVES

This study aimed to assess outcomes of ablation targeting the RAP around the LOB identifiable during substrate mapping.

METHODS

We studied 81 patients (median age 68 years; 85% male; 25% ischemic cardiomyopathy) who underwent ablation primarily targeting the regions exhibiting a RAP around the LOB associated with clinical VT.

RESULTS

High-resolution substrate mapping identified a RAP in 41 patients (51%). Of these, 30 patients (Group A) underwent ablation of an area with a radius >1 cm, including the targeted RAP regions. In 11 patients (Group B), RAPs were unable to be ablated because of the proximity of the RAP site to the conduction system, coronary arteries, or phrenic nerves, or based on the operator's discretion to avoid hemodynamic decompensation. The remaining 40 patients (Group C) had no identifiable RAP, and none of them had no mid-diastolic activities during VT due to intramural or contra-surface arrhythmogenic substrate. During 1-year follow-up, 83% freedom from VT recurrence was achieved in Group A, compared with 41% and 39% in Groups B and C, respectively (P = 0.003).

CONCLUSIONS

The identification of critical zones of the VT re-entrant circuit, which may be co-localized with regions hosting RAP around the LOB, as well as high-intensity ablation targeting these regions, appear to be important for successful ablation.

Relationship of Structural Abnormalities of Papillary Muscles to the Site of Origin of Ventricular Arrhythmias

BACKGROUND

Arrhythmias originating from papillary muscles (PAPs) can be challenging when targeted with catheter ablation. The prevalence and impact of structural abnormalities on PAPs in patients with focal PAP arrhythmias is unknown.

OBJECTIVES

The purpose of this study was to analyze, in a consecutive patient series with focal PAP arrhythmias, the impact of structural abnormalities detected by multimodality imaging.

METHODS

In a series of 43 consecutive patients with focal PAP arrhythmias referred for ablation, the prevalence and location of structural abnormalities on PAPs were assessed with cardiac magnetic resonance imaging, computed tomographic angiography and intracardiac echocardiography (ICE). Sites of origin of ventricular arrhythmias (VAs) were correlated with structural abnormalities.

RESULTS

On PAPs, late gadolinium enhancement (LGE) was present on cardiac magnetic resonance imaging in 19 of 43 patients, calcifications on computed tomography in 2 of 43 and on ICE in 3 of 43 patients, and increased echogenicity on ICE in 39 of 43 patients. A total of 141 focal PAP arrhythmias were identified, and VA target sites were localized adjacent to areas with increased echogenicity on ICE for 59 of 141 (44%) VAs, adjacent to LGE for 35 of 141 (25%) VAs, and adjacent to calcifications for 14 of 141 (10%) VAs. At least one VA target site was localized to areas of structural abnormalities in 32 of 43 (74%) patients.

CONCLUSIONS

Multimodality imaging identifies arrhythmogenic PAPs preprocedurally and in real time during the ablation procedure in most patients. Increased echogenicity, LGE, and calcifications are often seen on PAPs in patients with focal PAP arrhythmias and can indicate the site of origin.

Ventricular arrhythmias in patients with bicuspid aortic valves

INTRODUCTION

Bicuspid aortic valves (BAV) are the most common congenital heart defects and the extent of ventricular arrhythmias (VA) in patients with BAV is unclear. The objective of this study is to describe VAs and late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR) in patients with BAV.

METHODS

A total of 19 patients with BAV (18 males, age: 58 ± 13 years) were referred for VA ablation procedures. Ten patients had BAVs at the time of ablation, nine patients had prior aortic valve replacement for a BAV. All but one patient had LGE-CMR and all patients underwent programmed ventricular stimulation at the time of the ablation.

RESULTS

Frequent PVCs were the targeted VAs in 17/19 patients and VT in 2/19 patients. Monomorphic ventricular tachycardia (VT) was inducible in 6 patients. A total of 15 VTs were inducible (2.5 ± 1.0 VTs per patient with a mean cycle length of 322 ± 83 msec). LGE was present in 13 patients. Patients with inducible VT had larger borderzone and core scar compared to non-inducible patients (7.8 ± 2.1 cm3 vs. 2.5 ± 3.1 cm3 and 5.1 ± 2.6 cm3 vs. 1.9 ± 3.0 cm3, p-value < .05 for both). PVCs and VTs were mapped to the periaortic valve area in 12 patients and 4 patients, respectively. The PVC burden was reduced from 27 ± 13 to 3 ± 6 (p < .001) and the ejection fraction improved from 49 ± 13% to 55 ± 9% (p = .005).

CONCLUSIONS

VAs in patients with BAV often originate from the perivalvular area and patients often have LGE and inducible VT. LGE may be due to ventricular remodeling secondary to the presence of BAV and harbors the arrhythmogenic substrate for VT.

Ablation of Focal Intramural Outflow Tract Ventricular Arrhythmias

Most idiopathic ventricular arrhythmias (VAs) originate from the outflow tract (OT) region and can be targeted with ablation either from the endocardial aspect of the right and left ventricular outflow tracts or from the aortic sinuses of Valsalva. It is important to exclude scar in patients with OT VAs. In some patients, the site of origin may be intramural. Ablation of intramural OT VAs can be challenging to map and ablate due to deep intramural sites of origin. The coronary venous branches may permit mapping and ablation of intramural OT VAs.