Papillary Muscle Delayed Hyperenhancement: Prevalence and Clinical Implications in a Large Population With Dilated Cardiomyopathy

Background: Papillary muscle–delayed hyperenhancement (papHE) at cardiac magnetic resonance indicates fibrotic or infiltrative processes. Contrary to myocardial HE, the prevalence and prognostic implications of papHE in patients with nonischemic dilated cardiomyopathy are unclear. Objectives: The purpose of this study was to determine the prevalence of papHE and describe its association with adverse clinical outcomes. Methods: This prospective cohort study included 528 patients who underwent late gadolinium enhancement cardiac magnetic resonance. The primary outcomes were all-cause mortality, sudden cardiac death, life-threatening arrhythmia, and hospitalization for heart failure. Patients were allocated into 4 categories: the first without papHE and without myocardial HE, the second with papHE, the third with myocardial HE, and the fourth with papHE and myocardial HE. The hazards of the primary outcomes for each category were compared using multivariable Cox regression. Results: papHE was present in 131 patients (25%). The median follow-up duration was 6.1 years (IQR: 3.7-9.7 years). Isolated papHE and isolated myocardial HE were not significantly associated with any of the prespecified outcomes. Patients who had both myocardial HE and papHE were at an increased risk of all-cause mortality (HR: 2.33, 95% CI: 1.26-4.30), sudden cardiac death (HR: 3.77, 95% CI: 1.59-8.94), life-threatening arrhythmia (HR: 3.94, 95% CI: 1.34-11.58), and hospitalization for heart failure (HR: 2.97, 95% CI: 1.30-6.80). Conclusions: The combined presence of myocardial and papHE was independently associated with adverse outcomes. Future studies should investigate if the incorporation of papHE and myocardial HE may improve clinical decision-making strategies to select dilated cardiomyopathy patients who would benefit the most from ICD implantation.