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.