• papillary muscles; arrhythmias; CMR; prognosis;

Objectives: we sought to evaluate the prognosis role of papillary muscle abnormalities in patients with ventricular arrhythmias, preserved left ventricular systolic ejection fraction (LVEF) without a definite diagnosis of cardiac disease.
Methods: 391 patients with >500/24h premature ventricular complexes and/or with non-sustained ventricular tachycardia (NSVT), preserved LVEF and no history of cardiac disease, were enrolled. Different features of 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 images. Mitral valve prolapse, mitral annular disjunction (MAD), myocardial LGE were considered.
Results: Dark-Paps was found in 79 (20%) of 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 of LV walls (p=0.005) and to a model including NSVT+LGE (p=0.014). Dark-Paps allowed a significant net reclassification when add 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: Dark-Paps is a novel prognostic marker in patients with ventricular arrhythmias and preserved ejection fraction.