Association of Cardiovascular Magnetic Resonance-Derived Papillary Muscle Abnormalities with Non-Sustained...

Background: Risk stratification for ventricular arrhythmias in hypertrophic cardiomyopathy (HCM) remains challenging, particularly in patients who do not fulfill conventional high-risk criteria. This study aimed to investigate the association between cardiovascular magnetic resonance (CMR)-derived phenotypic characteristics and non-sustained ventricular tachycardia (NSVT) in patients with HCM. Methods: A total of 69 consecutive patients with HCM who underwent comprehensive CMR imaging and 24 h Holter monitoring were retrospectively analyzed. CMR assessment included phenotypic characteristics of the left ventricle, mitral valve apparatus, and papillary muscles, as well as late gadolinium enhancement (LGE). Ventricular arrhythmic events were defined as the presence of a premature ventricular complex burden >10%, NSVT, and/or sustained ventricular tachycardia. Univariable logistic regression and multivariable Firth penalized logistic regression analyses were performed to identify variables associated with NSVT. Results: The study population had a mean age of 57.5 years, and 23 patients (33.3%) were female. Ventricular arrhythmic events were detected in 16 patients (23.1%), all of whom had NSVT. Median LGE burden was 4%. LGE was present in 43 patients (62.3%), including papillary muscle (PM)-LGE in 13 patients (19.0%). Anterolateral PM-septum systolic contact was observed in 7 patients (10.0%). In univariable analysis, maximal left ventricular wall thickness (OR 1.29, 95% CI 1.09-1.53; p = 0.004), abnormal chordal attachment (OR 5.56, 95% CI 1.09-28.19; p = 0.039), anterolateral PM mobility (OR 1.45 per 0.1-unit increase, 95% CI 1.10-1.91; p = 0.009), anterolateral PM-septum systolic contact (OR 31.20, 95% CI 3.38-288.0; p = 0.002), and PM-LGE (OR 9.60, 95% CI 2.50-36.84; p < 0.001) were associated with NSVT. In the four-variable Firth penalized logistic regression model, abnormal chordal attachment (OR 9.09, 95% CI 1.18-67.42; p = 0.036), anterolateral PM-septum systolic contact (OR 23.08, 95% CI 2.18-385.17; p = 0.008), and PM-LGE (OR 17.26, 95% CI 2.37-176.64; p = 0.004) remained associated with NSVT. Given the limited number of events, these multivariable findings should be considered exploratory. Conclusions: CMR-derived PM abnormalities were associated with NSVT in patients with HCM. In particular, PM-LGE, abnormal chordal attachment, and anterolateral PM-septum systolic contact emerged as exploratory CMR characteristics that warrant further evaluation in larger prospective studies.