Dark papillary muscles sign: a novel prognostic marker for cardiac magnetic resonance

Abstract

Objectives: The prognostic role of left ventricular (LV) papillary muscle abnormalities in patients with preserved LV systolic ejection fraction (LVEF) is unknown. We sought to evaluate the prognosis role of LV papillary muscle abnormalities by CMR in patients with ventricular arrhythmias, preserved LVEF with no cardiac disease.

Methods: A total of 391 patients with > 500/24 h premature ventricular complexes and/or with non-sustained ventricular tachycardia (NSVT), preserved LVEF, and no cardiac disease were enrolled. Different features of LV papillary muscles were considered: supernumerary muscles, papillary thickness, the attachment, late gadolinium enhancement (LGE). Dark-Paps was defined as end-systolic signal hypointensity of both papillary muscles in early post-contrast cine CMR images. Mitral valve prolapse, mitral annular disjunction (MAD), and myocardial LGE were considered.

Results: Dark-Paps was found in 79 (20%) patients and was more frequent in females. It was associated with higher prevalence of mitral valve prolapse and MAD. During a median follow-up of 2534 days, 22 hard cardiac events occurred. At Kaplan-Meier curve analysis, patients with Dark-Paps were at higher risk of events than those without (p < 0.0001). Dark-Paps was significantly associated with hard cardiac events in all the multivariate models. Dark-Paps improved prognostic estimation when added to NSVT (p = 0.0006), to LGE (p = 0.005) and to a model including NSVT+LGE (p = 0.014). Dark-Paps allowed a significant net reclassification when added to NSVT (NRI 0.30, p = 0.03), to LGE (NRI 0.25, p = 0.04), and to NSVT + LGE (NRI 0.32, p = 0.02).

Conclusions: In LV papillary muscles, Dark-Paps is a novel prognostic marker in patients with ventricular arrhythmias and preserved ejection fraction.

Key points: • Papillary muscle abnormalities are seen in patients with ventricular arrhythmias and preserved left ventricular ejection fraction. • Early post-contrast hypointensity of papillary muscles in end-systolic cine images (Dark-Paps) is a novel prognostic marker in patients with ventricular arrhythmias and preserved ejection fraction. • Dark-Paps had an additive prognostic role over late gadolinium enhancement and non-sustained ventricular tachycardia.

Keywords: Cardiac magnetic resonance; Papillary muscles; Prognosis; Sudden cardiac death.

Fig. 1

Post processing analysis of anterolateral (AL) and postero-medial (PM) papillary muscle: In the end-systolic cine short-axis images AL and PM papillary muscle radial angles (a, b) measured as the angle between the anterior right ventricular insertion point and the center of respectively the AL and PM papillary muscle. The end-systolic maximal diameter (c) was measured as the maximal transversal diameter of the muscles. In the same early post-contrast end-systolic frames (d), the signal intensity of papillary muscles and interventricular septum was measured as shown: signal intensity was measured in regions of interest (ROI) traced in papillary muscles avoiding the blood-pool and in the interventricular, then Dark-Paps was defined when the signal intensity of both papillary muscles was lower than the signal of interventricular septum. In panels e and f, two examples of supernumerary papillary muscles. A case with normal mid-ventricular papillary attachment and a case of distal attachment are shown respectively in panels g and h

Fig. 2

Examples of patients with end-systolic hypointensity of papillary muscle (Dark-Paps) in early post-contrast cine-SSFP: In both case a and case b, patients had Dark-Paps and mitral annular disjunction with absence of late gadolinium enhancement (LGE)

Fig. 3

Kaplan-Meier curve analysis for NSVT and LGE

Fig. 4

In the left panels, end-systolic (upper panel) and end-diastolic (lower panel) images of a 21-year-old female with Dark-Paps (end-systolic hypointensity of both papillary muscle in early post-contrast cine SSFP short-axis images). This patient was resuscitated from ventricular fibrillation 3 years after CMR. In the right graph, the Kaplan-Meier curve analysis shows that patients with Dark-Paps had worse survival free from hard cardiac events than those without

Fig. 5

Kaplan-Meier curve analysis for the combination of Dark-Paps with supernumerary papillary muscle (Super) and with mitral annular disjunction (MAD)

Fig. 6

Chi-square improvement and Net Reclassification Improvement analysis