The Dark Papillary Muscle Sign: Prognostic Value in Cardiac MRI of Ventricular Arrhythmias
Overview
This multicenter study evaluated papillary muscle abnormalities, particularly the Dark-Paps sign, in patients with frequent premature ventricular complexes or non-sustained ventricular tachycardia and preserved left ventricular function. The presence of systolic hypointensity in both papillary muscles (Dark-Paps) on early post-contrast cine CMR was identified as a novel prognostic indicator associated with mitral valve abnormalities.
Background
Papillary muscles play a crucial role in left ventricular function by maintaining mitral valve competence during systole. Abnormalities of papillary muscles can be found in various cardiac conditions including congenital heart disease, cardiomyopathies, ischemic heart disease, and mitral valve anomalies such as prolapse and mitral-annular disjunction (MAD). Cardiac magnetic resonance imaging (CMR) is the preferred modality for detailed assessment of papillary muscle morphology, function, and tissue characterization. Recent evidence suggests that MAD is linked to myocardial fibrosis and increased risk of ventricular arrhythmias, highlighting the importance of papillary muscle evaluation in arrhythmic patients.
Data Highlights
Parameter
Measurement Method
Definition
Supernumerary Papillary Muscle
Long- and short-axis CMR views
Accessory muscle ≥50% diameter of main muscles with separate LV wall attachment
Radial Angles
Medio-ventricular short-axis view
Angle between ventricular centroid, RV insertion point, and papillary muscle center
End-Systolic Maximal Diameter
Manual measurement on CMR
Maximal diameter of papillary muscles at end-systole
Signal Intensity (SI)
End-systolic and end-diastolic cine frames
Hypointensity defined when papillary muscle SI < septal SI; Dark-Paps when both muscles hypointense
Key Findings
Dark-Paps sign is characterized by systolic hypointensity of both anterolateral and posteromedial papillary muscles on early post-contrast cine CMR.
Dark-Paps was observed in a small percentage of patients with frequent PVCs or NSVT and preserved LV function.
There is a significant association between Dark-Paps and mitral valve prolapse as well as mitral-annular disjunction.
Supernumerary papillary muscles and altered radial angles were assessed but the Dark-Paps sign emerged as a novel prognostic marker.
CMR provides comprehensive evaluation of papillary muscle morphology, function, and tissue characteristics, aiding risk stratification in ventricular arrhythmia patients.
Clinical Implications
Recognition of the Dark-Paps sign on early post-contrast cine CMR can improve risk stratification in patients presenting with ventricular arrhythmias and preserved LV function. Its association with mitral valve abnormalities suggests that detailed papillary muscle assessment should be integrated into routine CMR protocols for arrhythmic patients. This may guide closer monitoring and tailored management to mitigate arrhythmic risk.
Conclusion
The Dark-Paps sign represents a novel and potentially important prognostic indicator detectable by CMR in patients with ventricular arrhythmias. Its identification alongside mitral valve abnormalities underscores the value of comprehensive papillary muscle evaluation in clinical practice.
References
Various Authors 2006-2015 -- Papillary Muscle Abnormalities and Cardiac MRI Studies
by Giovanni Donato Aquaro, Carmelo De Gori, Giulia Grilli, Roberto Licordari, Andrea Barison, Giancarlo Todiere, Umberto Ianni, Matteo Parollo, Crysanthos Grigoratos, Luca Restivo, Antonio De Luca, Lorenzo Faggioni, Dania Cioni, Gianfranco Sinagra, Gianluca Di Bella, Emanuele Neri
New US cardiovascular statistics document persistent gaps in prevention and treatment across hypertension, diabetes, obesity, and cholesterol management, with marked disparities by age, income, and race.
